Chemical contaminants in foodstuffs, health damaging effects
The number of recorded chemical substances is well above 10 millions, from which 70-80
thousand the number of chemicals that may be in direct contact with humans. Majority of
these substances potentially may occur also in foodstuffs and may adversely influence the
health of consumers. The classification of foodborne health damaging substances and the
induced adverse effects can be seen in teh following Tables.
Table
Chemical compounds in food with public health hazards
Added, residual and environmental materials
Residues and environmental
contaminants
Veterinary drug residues
Pesticide residues
Contaminants of environmental
origin
Contaminants of technological
origin
Contaminants of biological origin
Additives
Preservatives
Technological additives
Taste improving and aromatics
Colouring agents
Harmful compounds of
natural origin
Alkaloids (e.g. solanine,
morphine)
Cyanoglycosides
Methyl-alcohol
Nitrates
Certain nutritives (e.g. lactose,
phenylalanine)
Toxins of plant origin (e.g. toxins
of moulds)
Table
Health damaging effects of chemical compounds occurring in foodstuffs





Clinical toxicosis
Microtoxicosis
Latent toxic effects: mutagen, teratogen, carcinogen effects
Immunosuppressive effect
Allergenic effects



Damaging effect on intestinal flora (dysbacteriosis)
Bacterial resistance potentiating effect
Other, special effects (e.g. aplastic anaemia)
The background of regulations
Considering the high number, widespread use, occurrence and generation of chemical
substances, the complete freedom from chemical contamination of foodstuffs is practically
impossible. In order to protect consumers’ health, the (exposing) quantity of chemicals must
be reduced in a measure that can prevent the development of health damage during their
lifelong intake. This purpose can be achieved by establishing so called limit values based on
data originated from risk analysis and evaluation carried out by international expert
bodies/commitees. This means the obligatory prescription, observation and control of
tolerable upper limit concentrations of residues in foodstuufs which are without public health
hazard.
The principle regulatory prescriptions of chemical contaminants in food can be found in
Regulation 1881/2006/EC. Undiscussed issues, in harmony with this regulation, are
regulated on National level in Decree 17/1999. (VI.16.) Ministry of Health
Separate rules contain the tolerable MRLs (maximum residue limits) of veterinary drugs in
foods of animal origin, the tolerable concentrations of herbicide residues in foods and raw
materials of plant origin, furthermore the tolerable level of radioactive contamination of
foodsatuffs. A separate law describes the rules of monitoring-examination of healthhazardous residues in fooddstuffs of animal origin.
In Hungary, the rules corresponding to food additives, materials used in direct contact with
foodstuffs, furthermore the sampling and analytical test methods of chemical substances are
described in the Hungarian Codex Alimentarius (Next Table).
2
Table
Principle prescriptions and rules regulating the chemical-*toxicological safety of
foodstuffs
Regulation/prescription
Regulation 1881/2006/EC
Decree 17/1999. (VI.16.) Ministry of
Health





Regulation 2377/90/EEC


Regulation 396/2005/EC


Decree 34/2004. (IV.26.) Ministry of
Health
Decree 5/2002. (II.22.) Ministry of
Health – Ministry of Agriculture
Regulation 3954/87 EURATOM
Decree 10/2002. (I.23.) Minisitry of
Agriculture
Prescriptions of the Hungarian Codex
Alimentariusi






Regulated issues
Contaminants of biological origin (mycotoxins)
Contaminants of environmental origin (toxic metals,
dioxins and PCB-s, prohibited pesticides)
Contaminants of technological origin
Pesticide residues in foodstuffs of animal origin
(authorised substances)
Harmful materials of natural origin (pl. solanine, cianhydrogen, methanol, nitrites and nitrates)
Residues of veterinary preparations
Active subsatnces prohibited to use for treatment in
production animals
Herbicide residues in foodstuffs of plant and animal origin
Pesticide residues in foodstuffs of animal origin
Herbicide residues in foodstuffs and raw materials of plant
origin
Radioactive contamination
System of residue monitoring for
- banned/anabolic active substances, and
preparations
- veterinary drug preparations, and
contaminating materials
Food additives
Materials used in direct contact with foodstuffs
Test methods, sampling
Veterinary drug preparations, banned active substances
One of the basic condition of chemical safety of foodstuffs of animal origin is that they must
not contain drug residue(s) in consumers’ health threatening quantities. For this reason, in
treatment of food production animals only those acive substances and vehicles (in form of
products) may be used for the residues of which (following their application) in the edible
tissues of the animals and in products (milk, eggs, honey) official tolerable (from aspects of
public health and sometimes also industrial processing) limit values (Maximum Residue
Limit = MRL) have been established.
In the European Union these limit values are determined by the Committee of Veterinary
Medicinal Products (CVMP) based on the several times modified Regulation 2377/90/ECC
and observing the proposals of The Joint Expert Committee of FAO and WHO (Working
Committee on Veterinary Medicinal Residues In Foodstuffs).
3
The evaluated active substances, groups of active substances are classified into 4 groups
(Annex I-IV). Those substances are belonging to the first group for which final MRLs are
established. In the second group those substance are found for which the elaboration of MRL
is not necessaary. For the members of the third group only provisional MRLs are established
because important data are absent. No MRL available for substances of the fourth group (not
possible to establish ADI/MRL and/or not required/initiated). The members of this latter group
are prohibited to use in production animals (banned substances) for any purpose (medical
treatment, prevention, growth promotion). There are, however, anabolic substances which
may be used for treatment but not for growth promotion (steroid and polipeptide hormons,
furthermore, beta-agonists).
Banned substances
Main groups of the banned substances and anabolic compounds are shown in next Table.
Table
Most important active substances not permitted for treatment of production animals
Active compounds
Remark
Chloramphenicol
Nitrofuranes (e..g. furazolidone)
Nitroimidazole (e.g. dimetridazolel, ronidazole,
metronidazole)
Stilbene and its derivatives
Steroid drugs)
Growth hormon (e.g. BST, PST)
Thyreostatics
Beta-agonists e.g.(clenbuterol, cimaterol)
Antibacterial growth promoters (e.g. avoparcin, zincbacitracin, virginiamcin)
Except for therapeutical and zootechnic
purposes
Except for therapy
Among the banned substances, the intake of chloramphenicol causes ten times increase in
the rate of manifestation of fatal aplastic anaemia (a severe disturbance in haematopoesis) in
sensitive consumers. Seventy per cent of patients suffering in this disturbance will die within
some months (in spite of careful medical care), in survivors the incidence of leucaemia will be
increased. Considering that the effect practically is independent from the dose (not dosedependent), the measure of daily acceptable intake (ADI) by the consumer cannot be
determined, consequently the related MRL cannot be calculated.
4
The residues of the 5-nitrofurane-derivatives and the nitroimidazols may induce tumors in
sensitive consumers. Similarily, the synthetic stibene-derivatives are also carcinogens (e.g.
diethyl-stilbeostrol: DES). In children of women who are consuming DES-containing
foodstuffs, the incidence of mammary carcinoma was significantly increased. Stilbenes are
also belonging to the banned substances.
Compounds used only for therapeutic purposes (hormons, beta-agonists)
The natural steroid hormons (androgens, oestrogens, gestagens) produced in the animal
and human organisms and their synthetic derivatives (e.g. trenbolone, melengestrole)
furthermore the myco-oestrogen zearanol are anabolics but they must not be used as growth
promoters. In spite of the severe legal ban, they may illegally be applied in animal farming of
several countries, e.g. by implanting the active-substance pellet into the connective tissue of
skin behind of ears. Eating foodstuffs containing the residues of anabolic hormones,
oestrogen or androgen efffect can develop (depending on the type of the hormon) in
consumers. The repeated intake of these hormons may result in disturbances in the
development of secondary sexual characteristics, infertility, abortion, teratogenic defects.
In the Member states of the European Union and in Third Countries exporting foodstuffs of
animal origin into the EU, prohibited the use of biotechnologically produced polypeptidehormons (growth hormons, BST, PST) for growth promotion.
The beta-agonists, especially clenbuterol were the most „popular” growth promoters in the
1990s. These compounds, by stimulating the beta-adrenoreceptors (primarily 2),
therapeutically beneficially relax the smooth muscle of the bronchi and the uterus (registered
preparation is available also in Hungary for bronchodilation in respiratory diseases of
horses). Beta agonists mixed in feed and fed continuously can increase the protein synthesis
and the decomposition of lipids, reduce the protein catabolism resulting in higher protein/lipid
ratio in muscle. To achieve the described effects, higher dose than the therapeutic one is
necessary, consequently in the edible tissues (especially in the kidney and liver) the
accumulation of residues occur in quantities representing risk for the consumer’s health. Due
to this mal-practice, in the past 10-12 years in Spain, France and Italy several severe
clinically manifested human disease cases occurred (CNS excitation, tachycardia, general
muscle-pain) mostly following the consumption of calf-liver (less frequently veal). These
toxicoses, outlasting for 1-3 days and mostly requiring hospitalisation, were caused by the
consumption of liver or veal containing 0.2-1 g/g clenbuterol-residue.
5
Antibiotics
The application of those antibiotics as growth promoters that used also in human therapy
(e.g. penicillins, tetracyclines) was banned in most European countries at the begining of the
1970s. Following this, specifically for feeding purpose antibacterial growth promoters were
developed and placed into the market (e.g. avoparcin, zinc-bacitracin, virginiamycin,
flavophospholipol, avilamycin). These antibiotics are not used in human therapy, teherfore for
a long time they were considered that their application is without significant influence on the
antibiotic-sensitivity of human pathogens.
In the past decade, the significant increase of antimicrobial resistance of important human
pathogen bacteria (e.g. Staphylococcus aureus, pneumococci, members of the
Enterobacteriaceae family), furthermore zoonotic agents (e.g. Salmonella spp.,
Campylobacter spp.) called again the attention to the potential risks of use of antibacterial
growth promoters. It was found that Enterococcus strains (Gram-positive intestinal indicator
microorganisms) that can be isolated from the intestinal tract of clinically healthy slaughter
animals (including poultries) are prone to transfer transpozons, plasmids carrying the genetic
codes of resistance-mechanisms. This horisontal transfer is directed to bacteria regardless to
bacterial species living in the surrounding environment. Thereby, the resistance mechanisms
developed in animals’ intestinal bacteria are transferred to bacteria living in the human
intestinal tract. Accordingly, a relationship was established between the widespread use of
the glycopeptide antibiotic avoparcin as gowth promoter and the incidence of occurrence
of the structurally related vankomycin-resistant Enterococcus faecium strains. Bacteria
becoming resistant and contaminating the foodstuff of animal origin can get into the intestinal
tract of human consumers. While multiplicating in the intestines, they may transfer the
resistance to human pathogen strains which represent potential infection source of severe,
hardly treatable diseases.
As a consequece, the application of avoparcin as growth promoter was banned in Denmark
at 1995, next year in Germany and subsequent year in the other countries of the European
Union and Hungary. Later, considering the potential risk of development of cross-resistance
to antibiotics used in human therapy, the application of all antibiotics in growth promotion was
banned in the member states of the European Union including Hungary.
From safety point of view, among the registered veterinary drug preparations used for
prevention or treatment, the antibacterial ones are especially important. The presence of their
residues in the edible tissues and animal products (e.g. milk) may represent potential allergic,
intestinal flora damaging and bacterial resistance inducing effects. A special issue is the
residue contamination at site of injection following the application of long-acting parenteral
injection preparations.
6
Among antibiotics, principally penicillins are the allergens, already 10 UI penicillin-residue is
able to evoke allergic reaction in atopic individuals. In spite of low toxic potential of penicillins,
due to the allergic potential, their MRLs in edible tissues and milk are low (50 and 4 g/kg,
respectively) compared to other active substances.
Thr observation of the withdrawal time for milk is specifically important also in preventing the
inhibitory effect of penicillins in the starter cultures applied in milk-product manufacture (0.01
IU/ml concentration is already inhibitory: 1 IU benzyl-penicillin = 0.6 g).
In order to prevent the intestinal-flora damaging effect, on course of risk analysis (carried
out by the mentioned Joint Expert Committee) while the toxicological characteristics are
evaluated, the potential adverse microbiological consequences are also considered.
Accordingly, beside the calculation of the Acceptable Daily Intake (ADI) for humans based on
the corresponding toxicological results, the microbiological ADI is also calculated. The effects
of antibacterial residues are evaluated on the composition of intestinal flora, metabolic
activity, barrier function in inhibiting colonisation, furthermore the effect on the selection
(pressure) of resistant strains. The highest dose level yet without effect is determined for
each effect (No Observed Effect Level = NOEL) and from these, the microbiological ADI
value is calculated.
At determining the MRLs from the toxicological and microbiological ADIs, the lowest value
(respresentig the highest safety for consumers) is used for further calculations. The less toxic
antibacterial substanaces which have potent effects also against anaerobe bacteria, the
lower value usually belongs to the microbiological ADI. Among the microbiological effects,
the inhibition of colonisation barrier is outstandingly important because it may
promote/facilitate the multiplication of important foodborne zoonotic-pathogens (e.g.
Salmonella- and Campylobacter-strains). The prevention of development of antimicrobial
resistance by sufficiently low intake of antimicrobials is also important.
In preventing the discussed undesirable effects, special attention should be paid to the
application of the so called long-acting products and the to the residues enriched at the site
of injection. At the site of injection, occasionally visually observable oedema and hard
nodules are developping, in which the antibiotics are captured in active form and high
concentration. During meat inspection, these sites must be excised and condem and the
edible tissues must be sampled for laboratory residue determinations. If the sample is
positive for banned substance(es) or the authorised substance is present in concentrations
over the related MRL, the whole carcase is unfit for human consumption and a survaillance
program is initiated at the site of origin. (see also later).
The illegal use of banned substances or neglecting the observation of the coresponding MRL
value of authorised drug preparations or the presence of certain contaminating chemicals in
foodstuffs of animal origin of (e.g. pesticides, other toxic compounds, mycotoxins) are
examined in the framework of nation-wide monitoring program carried aoutby the competent
7
authority and based on random sample selection. Beyond the monitoring activity, the
competent authority is carrying out ad hoc control examinations.
Pesticide residues
Pesticides represent residues of chemical substances applied in plant protection, furthermore
in extermination of rodents and insects and they may be present on the surface or inside of
foodstuffs. The majority of pesticides are the herbicides, the quantity of which has been
significantly reduced in Hungary during the past 10-15 years. The number of varieties of the
active substances is also restricted but the less selective compounds that are toxic also to
the higher organisms including man are still used. Understandable why the observation of the
related withdrawal times, similarily to the veterinary drug preparations, is so important.
Among the high number of pesticide active substances, the chlorinated hydrocarbons and
less importantly the other insecticides are worth to mention because of their potential
presence in foodstuffs of animal origin and and their toxicological profile. The residues of
other herbicides such as weed-killers and fungicides may be important contaminants in
foodstuffs of plant origin but usually cannot be detected in foodstuffs of animal origin.
The chlorinated hydrocarbons are highly lipid soluble, and the mostly are persistant in the
environment and are prone for accummulation in the in living organisms. Certain
representatives of the group (e.g. DDT, the beta-isomer of hexachlor-cyclohexane) are
magnificating (enriched) in the food-chain, reaching espcially high concentrations in the
maternal milk. DDT and the β-HCH can be present in the maternal milk about 30 times
higher concentration than in the cow-milk.
The use of the definitely persistant chlorinated hydrocarbons, such as DDT was already
banned in 1968, but the residues of the substances and their degradation products still can
be detected in the fat-tissues of wild animals. The detectable quantities, however, have
been greatly reduced by the 90s years. The concentrations of total DDT (parent compound
and metabolites) was only between 0.01-0.4 mg/kg, and this is significantly lower than the
tolerable 1 mg/kg threshold value. In case of slaughter animals, the measure of DDT
contamination was <0.1 mg/kg in the 90s years and since then this value, similarily to the
contamination in games, further reduced. There is an interesting relationship between the
time of contamination with DDT and in the ratio of DDT-parent compound and its DDEmetabolite in fat tissues. The DDE/DDT ratio is about one in freshly contaminated samples,
by time it is gradually increasing reaching one magnitude change during 20 years (>10). This
way, based on the DDE/DDT ratio, the time of the contamination can be determined.
Among the less persistant chlorinated hydrocarbons, the gamma isomer of the hexachlorcyclohexane (Lindan) and especially the endosulphane compound are more toxic to warmblooded animals than DDT but neither are prone for accumulation or biomagnification. Their
detectable quantities in slaughter animals in Hungary is <0.01 mg/kg for years and this is
8
less by at least one magnitude than the related tolerable threshold value (Lindan: 1 mg/kg,
endosulphane 0.1 mg/kg). In animals living in the wild, the measure of contamination is also
well below the tolerable value.
The organophosphates and the insecticid carbamates are less persistant in the
environment than the chlorinated hydrocarbons and they mostly decompose fast in the
environment and in the animal organisms. They are, however, usually are more toxic for
warm-blooded animals and man (they may cause acute toxicosis). The organophosphates
and the insecticid carbamates are cholinesterase-inhibitory compounds, and the inhibition
can be developed following repeated intake (biological accumulation). Their tolerable
threshold values for foodstuffs of animal origin are ranging between 0.01-0.05 mg/kg, the
analytically detectable (LOD) quantities (if detectable anyway) are lower by one magnitude.
In contrast, in foodstuffs of plant origin (mostly in early products), they can be detected more
frequently above the tolerable value.
The pyrethrines and their synthetic derivatives, the pyrethroids are potent insecticides. They
are less toxic for mammals and birds (fish are very sensitive) and regularly are fastly
decomposed in the environment and in animal organisms. Owing to their definite insecticide
property and low toxicity, they are frequently used also in veterinary practice. In foodstuffs of
animal origin, pyrethrines or pyrethroids have not been detected over the detectable level
(0.01 mg/kg) following plant-protection or veterinary applications.
Up to now in Hungary, residues of other herbicides (weed killers, fungicides), or insecticides
and rodenticides have not been detected in foodstuffs of animal origin.
In contrast to the zero detectable pesticide contamination in foodstuffs of animal origin, in 1-2
percent of the marketed products of plant origin, residues of mainly fungicides being over
the tolerable limit were found during the recent years in Hungary. In import foodstuffs of plant
origin, (mostly in seasons) however, several times the residues of already banned (but in
certain tropic developing countries still used) herbicides have been detected (e.g. DDT,
aldrin, dieldrin, HCB).
Contaminants of environmental orgin
From the great number of potential environmental contaminants, the most important food
related ones are the toxic heavy metals and the metalloids such as cadmium, lead, mercury
and arsenic, furthermore the polychlorinated compounds (derivatives). This latter group
involves the dibenzo-dioxins and -furans, the polychlorinated biphenyls and certain banned
persistant chlorinated hydrocarbons (discussed earlier). A part of these compounds (e.g.
heavy metals) are also natural components of the environment, but the consumer primarily
uptake them as food contaminants generated by human activities (industrial, agricultural and
domestic ones, transportation and waste combustion).
9
In order to protect consumers’ health, the acceptable/tolerable maximum daily, weekly, and
monthly (this latter in case of cummulative-type substances) intake (TDI/TWI/TMI) for the
principal contaminants are determined, respectively. These quantities are without healthdamaging effect even if continuously taken for life. The international organisation responsible
for the determination of the tolerable intake quantities based on risk analyses (Joint Expert
Committee of FAO/WHO, JECFA) often is able to erect only provisional values (PTDI/PTWI,
PTMI) because of imperfect set of data. The Committee periodically re-evaluate/revise these
provisional values in the mirror of new toxicological and epidemiological data and if
necessary change them.
Taking into consideration of the tolerable intake values determined by the JECFA, countries
or group of countries (e.g. the European Union) are determining threshold values in
foodstuffs which are the basis of official control. It should be kept in mind that in case of
contaminants of environmental origin (considering their unordered formation and
uncontrollable application), the risk probability factor is higher than in case of offically well
controlled preparations discussed earlier. This is specifically true for the miscellenous
polychlorinated contaminants.
Many of the environmental contaminants are very persistant, they are decomposing only very
slowly, through several decades. These are termed also as POP-substances (persistent
organic pollutants, POP). The group includes the already discussed pesticides of persistent
chlorinated hydrocarbons (e.g. DDT, aldrin, dieldrin), furthermore several polychlorinated
industrial ingredients (e.g. polychlorinated biphenyls, hexachlor-benzol), and organic
contaminants (e.g. polychlorinated dibenzo-dioxins and -furanes). The polyaromatic
hydrocarbons (PAHs) are also can be classified into the group of POP and we are going to
discuss these contaminants as of technological origin.
Toxic heavy metals, metalloids
Cadmium, lead
Cadmium is the most dangerous heavy metal. It damages the function of several organs and
organ systems including the testicles, the liver, and the metabolism of the skin and bone but
the nephrotoxic effect is the most important component. A part of the toxic effects can be
attributed to its zinc antagonistic effect. Cadmium is taken up by humans via the food or less
importantly by inhalation at smoking. It is a natural component of the environment but it can
be enriched as a result of human activity, in phosphate- fertilizers contaminated by the metal,
in the smoke and the effluent of metal-processing plants, and released during the combustion
of fossil fuels.
The dissolution of cadmium into the soil and into the sediment of natural waters is facilitated
by the drop of pH (acidification). The relased cadmium is taken up through their roots by
plants and are stored in plant tissues. In contrast to lead, the cadmium primarily can be found
10
in the plant tissues, therefore, the contamination cannot be diminished by even careful
washing. In water biotops (e.g. in sea) following the pH-dependent dissolution of cadmium
from the mud and it is also present as floating suspended particles, cadmium is taken up
mainly by shells and crabs.
In food production animals (mammals, birds), the majority of cadmium is in the kidneys and
liver. The main sources of human uptake are the kidney and liver of slaughter animals, the
shells and crabs, furthermore, the oily seeds and vegetables. The average concentrations in
kidneys are 100-1000 g/kg, in liver 10-100 g/kg, in meat and fruits <10g/kg, in fish 20
g/kg, in shells 200-1000 g/kg. The daily average cadmium uptke by non-smoking
individuals is 10-35 g. Smoking is increasing the daily uptake by (daily 20 cigarets) 2-4 g.
Cadmium taken up by drinking water is usually <2 g.
After taken up into the intestinal tract, about five percent (3-7%) of cadmium is absorbed but
in iron-defficient individuals, the absorption rate may reach the 15-20%. The absorbed
cadmium is bound to metallothionein in the liver, and it is gradually released into the blood
and is filtrated in the kidneys and is reabsorbed in the proximal tubules. In the tubular cells,
the toxic Cd2+ is released from the protein binding and by gradual accumulation it causes
irreversible nephropathy. The critical cadmium level in the cortex of kidneys that induces
tubular dysfunction in 10% of persons is estimated to be 200 mg/kg. This quantity can be
taken up by ingestion of daily 175 g cadmium through 50 years. The uptake of daily 100 g
cadmium could result in a critical overload in 2% of a regular population.
In order not to overcome the 50 mg/kg renal cadmium concentration and taking into account
the average 5% absorption of the metal, and the very slow excretion rate and its cummulative
character, its PTWI value was defined as 7 g/kg by The Joint Expert Committee of
WHO/FAO. In the Member States of the European Union, the average measure of the
weekly cadmium uptake ranges between 2.8-4.2 g/kg, and this is 40-60% of the PTWI
value. The tolerable maximum cadmium and other heavy-metal content of foodstuffs of
animal origin in Hungary is described in thze following Table.
Table
Maximum tolerable concentrations of heavy metals in food of animal origin
Food/product
Maximum concentration (mg/kg)
Cd
Pb
Hg
As
0.05
0.1
N.a.a
N.a.
0.5-1.0
0.5
N.a.
N.a.
0.05-0.1
0.3
0.5-1.0
N.a.
0.5-1.0
0.5-1.5
0.5
N.a.
0.1
0.5
0.5
1.0
0.1
0.15
0.03
0.2
N.a.
0.02
N.a.
N.a.
0.02
0.02
0.02
0.1
0,05
0.1
0.02
0.3
Fresh meat (cattle, sheep, swine, poultry)
Edible offals (catle, sheep, swine, poultry)
Fish meat
Crabs, shells
Fresh game meat and products
Meat products
Cow milk
Butter
Cheese
a not available
11
In foodstuffs of animal origin, the number of official measures due to heavy metal
threshold/tolearble level violations are greatly reduced in the past 10 years in Hungary (it is
already only <0.2%). Earlier, the over-the-tolerance-levels were detected in the kidneys of
pigs and cattle, but by the reduction of age of slaughter animals, the number of objections
was also reduced from the second part of the 1990s. Several times were detected intolerable
levels, however, in foodstuffs of plant origin (n oily seeds, oil, season paprika, and sometimes
in vegetables).
Lead is the oldest known environmental contaminant heavy metal. Its toxic effect, similarily to
cadmium, is very complex, the most important in humans are the haem-synthesis
inhibitory and the central nervous system (CNS) damaging effects and kids are most
sensitive than adults. In children already as low as <10 g/100 ml lead concentration inhibits
the activity of delta-aminolevulinacid-dehydratase that is important in the haem-synthesis.
Anaemia, manifesting also in CNS clinical signs appears only at >40 g/100 ml blood
concentrations. In children, the most important CNS symptom is the reduction of the mental
power. Results of high number of studies show that the increase of blood lead concentration
from 5 g/100 ml value to 20 g/100 ml level is accompanied by about a 5 point IQ reduction.
Another CNS finding is the occasionally developing polyneuritis.
Lead can get into the human organism by contaminated food, water and air. The ordinary
level of lead in soil is 5-100 mg/kg, but in heavily contaminated soil it may surpass even the
10.000 mg/kg-concentration. The most important sources of environmental lead
contaminations are the transportation and industrial activity. In the past 10-15 years, by
reducing, later terminating of using added lead in fuels and the regulated reduction of
industrial emmission, the measure of lead contamination and the corresponding lead
concentrations in human blood significantly dropped in developed countries. According to a
survey, in the USA, the average blood-lead concentration of the population was 12.5 g/100
ml at the end of 70s and this diminished to 2.8 g/100 ml by the begining of 90s. A similar but
a lower rate of decline was observed also in the European countries. The lead much less
intensively dissolved from the soil than the cadmium, therefore it is not deposited in the
tissues of plants but appear as plant surface contamination. In the animals, it initially
accumulating in tissues having good blood supply (liver, kidneys), followed by accumulation
in bones from which as a result of calcium metabolism it continuously can be released into
the blood.
In human adults the absorption of lead from the gastrointestinal tract is only 10%, but in
children, it may be up to 50%. Following absorption, it initially is deposited in the red blood
cells, liver, kidneys, finally it is accumulating in the bones. Its half-life in soft tissues is 1-2
months, in bones it is 5-30 years. Its toxic effects are well known and the neurotoxic effects
12
are the most crucial and important also in determining the measure of the tolerable weekly
uptake. JECFA determined the PTWI value of lead originating from any possible sources as
25 g/kg. An European common consumer may ingest about 20 g/kg by foodstuffs. In
Hungary, the estimated weekly lead-intake is 13.1 g/kg, this is about the half of the PTWI
value.
The lead content of the Hungarian foodstuffs has been gradually reduced in the past 10
years. This drop is due to, beside the moderate control of potential general industrial and
environmental contaminations, modernisations in the food-industry, the gradual replacing of
soldered to welded cans, the diminsihed use of machinary, equipment and packaging
materials coated with lead-releasing tin. The lead contamination in foodstuffs of animal origin,
in accordance with the general tendency, is also significantly reduced. The 5-6% positivity at
the begining of the 1990 years in muscle and liver samples of pig and cattle has practically
beeen reduced to zero during 10-15 years.
Mercury, arsenic
Mercury in its elementary form, and in forms of inorganic and organic compounds is widely
present in the environment. It generally can be detected in the air (in a usual concentration of
<10 ng/m3) and in the natural waters at 10-50 ng/l concentrations. The mercury content of
foodstuffs is mostly low (<0.01 g/g) and this low concentration is in elementary form or in
inorganic compounds. Fish and shells are special because in these species the
concentration of mercury might be much higher and most cases (>90%) is present in form of
methyl-mercury. The mostly industrial origin inorganic mercury compounds released into the
surface fresh waters and seas are bio-methylated through microbial activity and this methylmercury is accumulated in low-ranked water living creatures and later ingested by shells and
fish.
Due to the described magnification in the nutrition chain, the methyl-mercury is enriched in
the organisms and it can reach specifically high concentrations in predatory fish such as in
shark, sword-fish, catfish and hake/pike. The usual concentration of methyl-mercury in fish is
<0.4 mg/kg, but in predatory-fish it may be several times higher. The majority of people
consume a daily maximum of 20-30 g, but at certain regions the measure of fish consumption
may be as high as daily 400-500 g. Accordingly, the methyl-mercury intake of food origin can
be ranged between 0.2 and 3-4 g/kg.
The lipid-soluble methyl-mercury is fastly and almost fully absorbed from the consumers’
alimentary tract, easily penetrates the blood-brain barrier and is accumulating in the CNS. It
is neurotoxic and specifically damages the cerebellar granular cells, furthermore the
auditory and visual cortices. It easily can penetrate also the placenta and causes severe fetal
developmental disturbances. In a sea-side settlement of Japan, the consumption of heavily
contaminated fish with methyl-mercury caused a mass-toxicosis resulting in 46 deaths at the
13
1950s (Minamata-disease). In foetuses of mothers with less severe symptoms, grave
developmental abnormalities were detected indicating the high fetal sensitivity to the
neurotoxic effect of methyl-mercury. In order to protect the developping foetuses, the earlier
tolerable weekly intake of 3.3 g/kg methyl-mercury was reduced to 1.6 g/kg in 2003.
In Hungary the detected mercury content of foodstuffs is very low. Evidently, the highest
concentrations can be found in fish but mercury contamination over the tolerable level (0.5-1
mg/kg) has never been detected in domestic or import fish and fish-products during the past
years. In contrast, several foreign publications reported over the tolerable intake level of
mercury contamination in benetic fish at the nearby seas (e.g. Adriatic sea), indicating the
importance of the official control of import fish.
Arsenic almost anywhere can be found in the nature in low quantities. Its elementary form
practically is not toxic, but its organic and inorganic compounds of 3-and 5 valents are toxic.
The inorganic substances (e.g. arsenic-trioxide) are potent poisons, the organic derivatives
(e.g. arsenic-acid) are less toxic. It occurs in form of arsenate in the soil and surface waters.
The arsenic content of the natural waters usually is 1-2 g/l, but in certain regions (mainly
due to earlier vulcanic activity) the arsenic concentration of the drinking water can be higher
even by thousand times. At certain parts of Hungary (e.g. Békés-County), the natural arsenic
content of spring-water is rather high, more than 100 g/l (the new threshold value is 10 g/l),
for this reason there the arsenic is removed.
The concentraton of arsenic in foodstuffs regularly is low, <0.25 g/g. Certain marine fish
and shells are exempt, these organisms are building the arsenic into organic molecules, e.g.
into arseno-betain, arseno-choline, arsenic sugar-derivaties and their arsenic content may
become higher. These organic arsenic compounds, however, are less toxic and are quickly
excreted from the human organsims. According to measurements, the ratio of organic
derivatives usually is 95 % and 2-5% is the ratio of toxic inorganic arsenic compounds in the
often high total arsenic content of fish and shells. The weeky tolerable intake of inorganic
arsenics is 15 g/kg (WHO). There is no PTWI-value for the organic derivaties from which
fish consuming individuals weekly may ingest more than 300-350 g but direct health
damaging effect has not been recorded.
In Hungary no tolerable intake level is prescribed for arsenic (neither organic nor inorganic
compounds) in fish, fish-products. Before the implementation of the new regulation, between
2000-2002, in 11 % of import fish and crabs (within: 32% of predatory fish) the total arsenic
content was over the formerly prescribed threshold value (determined by the Laboratory of
the Food and Feed Safety Directorate of the Hungarian Central Agricultural Office).
Polychlorinated organic contaminants
Among the several, different organic contaminats that are potentially present in foodstuffs,
from part of the health/safety of the consumer, the most important are the polychlorinated
14
diaromatic carbohydrates. In the practice, simply these altogether are termed as dioxins.
More precisely, three distinct family of compounds are included, namely the polychlorinated
dibenzo-p-dioxines (PCDD), the polychlorinated dibenzo-furans (PCDF) and certain
polychlorinated biphenyls (PCB). More than 400 compounds are belonging to the three
groups that may be different concerning their physico-chemical properties and especially
their biological effects.
Dioxins
The group of the most important „dioxins”, from point of view of food-toxicology, includes 29
compounds (7 dibenzo-dioxins, 10 dibenzo-furans and 12 bifenyls). Their toxicological
properties and biochemical mechanism of action are similar to the most toxic basic-molecule
of 2,3,7,8-tetrachlor-dibenzo-p-dioxins (TCDD). Their biological-toxicological potencies,
however, are different. To facilitate their comparability in toxicity and consequent influence on
consumers’ health and calculatability of tolerable intake levels for consumers, the use of
toxicity equivalency factors have been introduced (TEF). The toxic potency of 2,3,7,8-TCDD
is considered to be 1, and the potential toxic potency of other compounds are related to this
one. The toxicity equivalency of some characteristic dioxin-like compounds determined by
The Joint Committee of WHO are shown in the next Table.
15
Table
Toxicity equivalency factors of some dioxins, dibenzofuranes and PCBs with dioxinlike effect
(WHO TEF 2005)
Congeneer
Toxicity equivalency factor
Dibenzo-p-dioxins
2,3,7,8-TCDD
1,2,3,7,8-PentaCDD
1,2,3,4,7,8-HexaCDD
1
1
0.1
1,2,3,4,6,7,8-HeptaCDD
OCDD (okta-)
0.1
0.0003
Dibenzo-furans
2,3,7,8-TCDF
2,3,4,7,8-PentaCDF
1,2,3,7,8-PentaCDF
1,2,3,4,7,8-HexaCDD
OCDF
0.1
0.3
0.05
0.1
0.0003
Polychlorinated biphenyls
3,3’,4,4’,5-PentaCB (PCB 126)
0.1
3,3’,4,4’,5,5’-HexaCB (PCB 169)
3,3’,4,4’-TetraCB (PCB 77)
2,3,3’,4,4’,5,5’-HeptaCB (PCB 189)
0.03
0.0001
0.0003
The demonstrated data indicate that the toxic potencies of the different compounds are lower
than that of TCDD. By applying the equivalency factors, the measured quantities of the given
compounds in the environment or in foodstuffs can be converted into "TCDD-equivalency"
(TEQ), and this is the basis of risk-assessments and derived tolerable value determinations.
Dioxins are typical contaminants formed during the (imperfect) combustion of organic
materials (e.g. waste-incineration, forest fires) or during the production of certain
polychlorinated aromatic compounds (e.g. pentachlor-phenol used for wood-preservation or
chlorinated phenoxy-aceticacid herbicides). These are almost insoluble in water, extremely
persistant in the environment and are ready for accumulation in the animal and human
organisms and for biomagnification in the food-chain.
The consumer can uptake these compounds first of all by ingesting contaminated plants
(vegetables, fruits), or by consuming meat, offals, milk, eggs of animals fed by contaminated
feed, furthermore by fish meat and fishery products. Nighty percent of the uptake of dioxinlike compounds is performed with contaminated foodstuffs and 80 percent within this is with
16
foodstuffs of animal origin. As environmental contaminants, they may contaminate the most
different kind of natural materials (e.g. additives used in food industry), representing another
type of risk to the consumer. They are readily absorbed from the alimentary tract and are
accumulating in the fat tissues. Dioxins are able to disturb of several biochemical
mechanisms, they are immunotoxic, teratogens and carcinogens. The carcinogen effect
is manifested mainly in the liver.
The tolerable weekly intake level (TWI) of dioxins and PCBs with dioxin-like effect is 14 pg
TEQ/kg.
The European Committee accepted a strategy plan in 2001 for the reduction of dioxin-like
materials in the environment, feed and in foodstuffs. As a part of the plan, tolerance threshold
values were prescribed for fresh meat and meat products (ruminants, pigs, poultry), for liver,
fish-meat és fishery products, for milk and milk-products, for eggs, egg-products furthermore
for fats of animal origin, plant oils and fish oils intended for human consumption. These
values were valid only for dioxins and not for dioxin-like PBCs. Since then, sufficient number
of data accumulated also for dioxin-like PCBs opening the possibility for establishing a
common tolerable value for both.
The tolerable maximun levels (in fat) of dioxins in foodstuffs of animal origin usually is 1-3
pg TEQ/g, in fishmeat (in the wet mass), and in liver, liver products the tolerable maximum
level is 4-6 pg TEQ/g. The sum of the tolerable values for dioxins and dioxin-like PCBs are
usually 1.5-2 times of the tolerable value of dioxin itself.
The dioxin contamination of different kind of foodstuffs gradually declined in the 1990s years.
According to West-European data, the regular dioxin content of meat and milk-products was
<0.1 pg/g, eggs contained <0.2 pg/g, while in fishmeat it was <0.5 pg/g. At special areas,
however, e.g. in certain fish species at the Baltic sea (hering, salmon) the contamination of
environmental origin is much higher and the resulted dioxin levels may exceed the tolerable
value.
According to the data of the European Committee, the present dioxin contamination of
foodstuffs in the Member States is resulting in a daily average uptake of 30-100 pg/day. An
additional daily uptake is the estimated 60-110 pg quantity of the dioxin-like PCBs. These
data reflect the average, the effective uptakeby by certain members of the population may be
2.5-times higher. Beyond the tolerable threshold values, the European Committee
determined those concentrations („intervention levels”) above which the existence of an
actual contamination source should be suspected. The identification and elimination of these
sources is the basis of further potential reduction of the dioxin-exposition.
17
Polychlorinated biphenyls
The group of the polychlorinated biphenyls (PCBs), beyond 12 dioxin-like PCBs that
possess dioxin-like effect, includes high number of further less toxic compounds
without dioxin-like toxicity. Earlier, the PCBs were widely used in different industrial
processes (in heat-transfering and hydraulic systems, transformators and
condensators, etc.), but their application was banned in developed countries in the
1980s because of the potential of high environmental contamination.
Contaminants of technological origin
Chemical compounds potentially damaging the consumers’ health and applied in foodindustrial technologies or formed in the foodstuffs during the technological processes are
belonging into this group including contaminants getting into the foodstuffs during ordinary
contact from production and technical objects, packaging materials. Considering that the use
of these materials is strictly regulated and the conditions of their formation are well-known,
their health damaging potential is essentially lower than that of the formerly discussed
contaminants of environmental origin.
On course of technological processess, however, potentially carcinogen compounds are also
formed which may play a role in the pathogenesis of human tumour development. These
substances are for example, the polycyclic aromatic hydrocarbons (PAHs), the
heterocyclic amines (HCA-k) and the nitrosamines. According to certain opinions, about
one third of malignant tumorous diseases may be linked somehow to foodstuffs, or
malnutrition. The detectable quantities of genotoxic compounds in foodstuffs regulary are
very low per component, but their simultaneous presence and activity in concenrt may
promote the development of tumours in humans.
Polycyclic aromatic hydrocarbone, heterocyclic amines
The PAH substances are generated during the imperfect combustion of organic materials
(e.g. wood, oil, coal/carbon). Todays, approximately 100 such compounds are known and
one quarter of these are proved carcinogens including the widely known 1,2-benzpyrane.
The main mediators of human PAH exposition are the air, foodstuffs, drinking water and
tobbaco smoke. Foodstuffs are contaminated by smoke-gases present in the air and for
example by (preservative)smoking, heat treatment, drying procedures during which
foodstuffs are direct contact with combustion products. The PAH-contamination is exceeding
the 10 g in foodstuffs of plant origin, especially in vegetables possessing large leaves,
consequently grand surfaces (e.g. lettice). In plant oils the PAH-concentration may reach
even the 10-20 g/kg value. The PAH-contamination of foodstuffs of animal origin generally
is very low (<1 g/kg). Due to (preservative)smoking, the concentration of PAH in meat and
18
specifically in fish may reach the 50-100 g/kg level. Similarily high PAH concentration may
be developed at charcoal grilling of meat (>100 g/kg) if the meat is in direct contact with
flame or if the melting fat is contacting glowing wood.
The measure of daily PAH intake with foodstuffs is estimated to be about 3 g/nap (0.06
g/kg). The majority of this quantity is taken up by contaminated foodstuffs of plant origin and
only a minor portion by foodstuffs of animal origin. This quantity usually is smaller than the
quantity taken up by tobacco smoke (1 box/day cigarette results in 2-5 g). The health
damaging potential of food-mediated PAH is subject of debate.
The measurement of benzpyrane concentration serves as marker for the carcinogen PAH
contamination of foodsuffs in the European Union. According to the related regulations in
force, the benzpyrane content of fats, oils and fishmeat must not exceed the threshold value
of 2 g/kg-ot, while in smoked meat and meat products and fish the threshold value of 5
g/kg. The threshold quantity in nutrients and baby foods is 1 g/kg.
During roasting of meat and fish, specifically if they are roasted abruptly at high temperature
(>200oC) and for a longer time, genotoxic heterocyclic amines may also be formed. Their
concentration is usually highest in grilled meat. Their estimated daily intake is mostly <0.1 g,
which in itself probably is without health risk but may increase the health risk of other
genotoxic materials of nutritional origin.
Nitrosamines
The third big group of carcinogen compounds of technological origin potetially present in
foodstuffs are the nitrosamines (in general the N-nitrose substances). These are originating
from the reaction of secondary amines containing =N-NO-group and of nitrites (specifically
nitric acid). Approximately 80 seems to be carcinogen from the about 100 known
nitrosamines from which the dimethyl-nitrosamine is the most widespread and most toxic.
They can be present in the human organism from two sources: taken up exogenously with
foodstuffs and/or by forming endogenously in the alimentary tract. This latter may be realised
by the reaction of secondary or tertiary amines and nitrites in the stomach (pH 1-3).
The most important exogenous nitrosamine sources are the cured and roasted meats, fish
(especially the grilled on charcoal ones), smoked meat products, fish and cheeese, certain
beers and cereal alcohols (e.g. whisky). In the recent two decades, the nitrosamine content
of pickled meat and fish has been reduced due to the diminished authorised quantity of nitrite
usable for curing. The nitrosamine concentration of cured products mostly is <10 g/kg,
which, taking daily 100 g consumption. means daily <1 g intake. Much more nitrosamine
can be drinken by beers, the consumption of 1 litre may result in up to 5 g nitrosamine
intake. Considering our present consumption pattern, Hungarian consumers ingest an
average of <1g nitrosamine. This quantity probably is without direct health-damaging
19
potential but regarding the possible interactiion with other genotoxic materials present in the
organisms, we should endevour for the further reduction of their intake.
Contaminants of biological origin
Among chemicals present in foodstuffs with potential public health hazard, we have
discussed the food-toxicological importance of veterinary drug and pesticide residues and
contaminants of environmental and technological origin.
The main characteristics of substances belonging to the former group is that they are present
in tissues of animals and plants (serving as potential foodfoodstuffs or raw materials)
following a targeted and authorized application. In other words, their application is regulated
and their residuological innocuity is garanteed by observing the determined and prescribed
withdrawal time.
In contrast, the contaminants of environmental origin (e.g. toxic heavy metals and
miscellenous polychlorinated organic substances) may be the natural components of the
environment or can be accumulated there under less controlled conditions. Consequently,
the risk of contamination of food is essentially higher than that of the officially controlled
veterinary drug and pesticide preparations or even of potentially harmful materials formed
during the technological processes or during the preparation of food.
In the followings, we are going to discuss the food-toxicological importance of contaminants
of biological origin. This group involves all health damaging chemical compounds which are
formed by the activity of microorganisms in foodstuffs or in their raw material of animal or
plant tissue origin or by eaten by animals.
The contaminants of biological origin in foodstuffs can be sorted into four main groups:
 Mycotoxins produced by moulds,
 Marine and fresh water biotoxins produced by microscopic algae,
 Histamine and other biogen amines formed by microbial decarboxylation,
 Bacterial toxins.
In spite of that bacterial toxins as chemical compounds are belonging to the chemical
contaminants of biological origin, on traditional reason, we are discussing them with the
microbial contaminants. Therefore, in the followings, we are going to evaluate the foodtoxicological importance of mycotoxins, marine and fresh-water biotoxins, histamine and
other biogen amines and neglect bacterial toxins.
20
Mycotoxins
Mycotoxins are the secondary metabolic products of moulds. The toxin producing moulds
are widely distributed in the nature and they can be detected in the soil, in different plants
and agricultural products. To multiplicate, they need oxygen, appropriate temperature and
humidity. About two hundres species out of the several thousand moulds are considered of
being important toxin producers. The characteristics of approximately 20 toxins or groups of
toxins are known in detail from which the members of four groups exhibit/show public health
importance such as the aflatoxins, ochratoxins, patulin and fusariotoxins.
Table
Main characteristics of mycotoxins of public health importance
Group
Aflatoxins
Compounds
B1, B2, G1, G2,
M1, M2
Toxin producing moulds
Aspergillus flavus, A.
parasiticus, A. nomius,
hydroxylated metabolites
Penicillium verrucosum
Aspergillus species
Occurrance
Oily seeds, corn,
cereals, soya, spices,
milk, milk products
Cereals, coffe-, cacaoand soya been,
grapes, wine
Ochratoxins
Ochratoxin A
Aspergillus and
Penicillium species
Apple, other fruits,
vegetables, apple
juice
Fusarium species
Zearalenon
T-2 and HT-2
toxin, DON,
DAS
F-2 toxin
Cereals (wheat,
barley, ryes, oats,
rice), cereal products
Cereals (corn, wheat,
barley, rice)
Fumonizines
B1, B2, B3
Fusarium moniliforme,
other Fusarium species
Patulin
Fuzariotoxins
trichotecens
Fusarium species
Corn and corn-based
foodstuffs
Toxic effects
carcinogen, hepatotoxic,
immunosupressive
carcinogen, teratogen,
nephrotoxic,
immunosupressive,
neurotoxic
Enzyme inhibition,
genotoxic, oedema
inducing
Protein synthesis
inhibition, hemato- and
immunotoxic necrotic
Oestrogenic effect,
fertility disturbances,
infertility, damaging of
spermatogenesis
Nephro- and hepatotoxic,
pulmonary oedema,
encephalomalacy,
oesophagus and liver
carcinoma (?)
Moulds may cause spoilage, nutritional devaluation of foodstuffs and their toxins are able to
induce several kind of health damaging effects. The most important are the carcinogen,
teratogen, immunosuppressive and neurotoxic effects.
Mycotoxins are getting into the consumers’ organism by contaminated foodstuffs of plant
origin and by foodstuffs of animal origin deriving from animals fed with feed contaminated
with the toxin (primarily with milk, eggs and offals). The principal source of mycotoxin
contaminations are the foodstuffs of plant origin; the appearance and concentrations of
mycotoxins in foodstuffs of animal origin is depending on the absorption, distribution,
biotransformation and excretion of toxins in the animal organisms, specifically in the edible
tissues and milk, eggs. Bibliographic data show that aflatoxins, ochratoxin A and
21
deoxynivalenol are readily absorbed from the digestive tract while the absorption of
fumonizin B1 is poor.
Among the well absorbing toxins, the aflatoxins are rapidly metabolised in the liver (they are
covalently bound to the macromolecules and they severily damage them); among
metabolites, the hydroxylated derivatives partially are excreted also by the milk (the letters of
M1 and M2 are indicating milk) and they are representing food-safety risk. The half-life of
ochratoxin A is much longer, therefore in internal organs of animals consuming feed
contaminated by the toxin, mainly in kidneys and (in descending concentrations) in muscle,
liver and fat residue accumulation can be developed. Deoxynivalenol (and probably
diacetoxyscirpenol and T-toxin also trichotecenes) are fastly metabolized and exctreted in
short time from the organism, thereby in practice they are without residue concern.
Among food of animal origin with food safety importance, the potentially mycotoxincontaminated milk is especially important. Aflatoxin B1, ochratoxin A and possibly zearalenon
may represent safety risk because they may appear in the milk in unchanced form or as
active metabolites (aflatoxin M1,  zearalenol).
The inactivation of mycotoxins in food by ordinary heat-treatment procedures is extremely
difficult because these usually are heat-stable compounds. The principal method of
protection is therefore, the prevention of contamination of foodstuffs and raw materials.
Aflatoxins
Aflatoxins are mycotoxins produced mainly by the Aspergillus flavus and Aspergillus
parasiticus species. The four most important toxins are sorted into B and G groups (blue and
green) based on their fluorescency under UV-light. From the A, B1, B2, G1 and G2 metabolites
the B1 and G1 toxins are the prelevant in grains. The 4-hydroxy-metabolites, biotransformed
from B1 and B2 toxins in the organism of cow that consumed feed contaminated by the toxins,
are termed also as milk toxins of M1 and M2. Usually 1-3 % of the toxin present in the feed is
secreted in the milk but this ratio may individually be different as well as can be changed in
the same individual periodically.
Aflatoxins are potent toxins. They are genotoxic carcinogens, and the B1 toxin is the most
potent. Comparing to B1 toxin, the carcinogen potential of M1 is lower by approximately one
magnitude. Their main target is the liver but on sustained exposure, they are
immunsuppressive already at lower doses.
Aflatoxin producing mould species my occur also in Hungarian grains and most of them have
toxin producing potential. Fortunately, our climate is not favoring to the toxin production (it
requires long-lasting temperature of >30oC and >80-85% humidity), therefore Hungarian food
of plant origin are practically free of aflatoxin. In contrast, the continous control of import
foodstuffs, especially of the oily seeds is very important (peanut, pistacia, nuts). Most
frequently the peanut and pistacia consignments are contaminated. The import of this latter
22
was transiently prohibited into the European Union from Iran in the mid 1990 because of the
high contamination over the tolerable level.
Considering the food of animal origin, the potential aflatoxin (M 1) contamination of milk and
milk products is significant. A linear interrelationship was detected between the B 1
contamination of feedstuffs and M1 content of milk.
To prevent to surpass of the tolerable level (0.05 g/kg) of aflatoxin M1 contamination in
milk, the daily B1 uptake by milking cow should not be more than 40 g/nap. Supposing a
daily 12 kg/cow concentrate consumption, this means a maximum aflatoxin feed
contamination of 3.4 g/feed kg.
In respect of aflatoxin B1 contamination of cow-feed and consequent M1 contamination of
milk, the highest risk is the use for feeding of press-cake (a by-product oil manufacture from
oily seeds) containing about 85% of total aflatoxin. Since in Hungary the use of peanut for
feeding of animals is prohibited, the probability of aflatoxin M1 contamination of milk is low.
Aflatoxin M1 in fresh milk and in milk poducts is relatively stabile, it cannot be inactivated by
pasteurasation. It is not soluble in milk-fat, therefore at manufacture of milk products,
especially of skimmed milk, it is accumulated in the way, etc.
On course of butter making, about 10% of M1 appear in the cream and only 10% in the butter,
the majority of toxin is concentrated in the buttermilk. It is relatively stabile also in acidic milk
products, and is concentrated in milk powder.
Concerning food of animal origin, tolerable aflatoxin (M1) maximum level is existing only for
milk and milk products (0.05 g/kg). Foodstuffs of plant origin for direct human consumption
have a more strict tolerable level (4 g/kg of total aflatoxin, and 2 g/kg B1) versus products
that will be selected and cleaned before use (10 or 15 g/kg total aflatoxin, and 5 or 10 g/kg
B1).
In Hungary, almost 4-7 thousand food samples of plant origin are examined yearly for
mycotoxin including aflatoxins, ochratoxin, fuzariotoxins and patulin. In the recent years, over
the tolerable levels of aflatoxin primarily was found in samples of, peanut, import ground
paprika and rice. Mycotoxin contamination has not been detected in the majority of food of
animal origin.
Ochratoxins
Ochratoxins are biologically very active mycotoxins primarily produced by Aspergillus and
Penicillium strains. Under continental climate the toxin production of Penicillum verrucosum
strains is important. They are multiplicating only at 30C temperature and 0.80 water
activity and are the main source of ochratoxin-contamination of cereals in Mid and North
Europe. Since at these territories, the grain is widely used also as animal feed, the toxins of
P. verrucosum may appear in certain animal tissues, especially in pig kidney and liver. Under
23
subtropic and tropic climates, miscellenous Aspergillus strains are responsible for the toxin
production (A. ochraceus, A. alutaceus, A.carbonarius).
Concerning biological activity and toxicity, the most important ochratoxins are the chlorine
atom containing ochratoxin A, which most frequently and in the highest quantity occurs in
cereals, beens (coffee-, cacao- and soya been) furthermore in grapes and in wines. The
toxin may be formed also under the Hungarian climatic conditions and it occasionally may
reach sigificant levels in feedstuffs. Certain ochratoxin-producing strains are able to
synthetise also other mycotoxins (e.g. citrinin, penicillin-acid), the presence of which may
influence the toxicity.
Ochratoxin A is slowly but relatively well absorbed from the gastrointestinal tract and it is
accumulating in the highest concentration in the kidneys, in less quantity in the liver, muscle
and fat of animal and human organisms. It appears also in the milk in form of ochratoxin  (a
metabolite formed in the rumen of ruminants) and it is less toxic than the parent compound.
Ochratoxin A is definitely nephrotoxic in mammals, causing tubulo-nephrosis and kidney
fibriosis. The proximal tubule is the primary site of its cytotoxic and carcinogen effect. Most
sensitiuve species is the pig and in less measure the laboratory rodents. In rodens the
carcinogen effect requires higher dose than the nephrotoxic one. The toxin can penetrate the
placenta and it is embryotoxic and teratogen and is immunosuppressive and neurotoxic at
higher doses in animal experiments.
It is nephrotoxic also in humans and earlier it was the supposed causative of the so called
balcanic endemic nephropathy (a tumorous urinary disease) manifested mainly in the
countryside population in Romania and former Yugoslavia. Recent epidemilological and
clinical data have not been supported this assumption, therefore other nephrotoxic agents
may also be involved in the pathogenesis.
The established value of tolerable weekly intake of ochratoxin A is (PTWI) 100 ng/bw kg.
According to collected data, the average weekly ochratoxin intake in Europe is 45 ng/bwkg,
this is less than the half of the tolerable dose. This total value is distributed in cereals and
wines (approximately 25, and 10 ng/bwkg, respectively) in grape juice and coffee (each 2-3
ng/bwkg), in pigmeat and offals (1.5 ng/bwkg) and in the other potential sources such as
dried fruits, cacao, tea, milk, etc. (1 ng/ttkg).
In the European Union the tolerable ochratoxin A level in cereals, in products of cereal origin,
raisin, rosted coffee, wines and grapes is in the range of 2-10 g/kg. There is no prescribed
value for fooodstuffs of animal origin.
In Hungary, during the recent years ochratoxin in over the tolerable level has been found only
in coffee samples. The half of the examined foodstuffs of plant origin, however, contained
ochratoxin in below the tolerable level (usually 1-4g/kg), indicating a regular potential
dietary exposition also in Hungary.
24
Patulin
Patulin is produced by several Aspergillus and Penicillium moulds, and they most often
induce the spoilage of apples. They may occur also in other fruits, vegetables, cereals, and
occasionally on the surface of meat products kept in frigo. Practical importance, however,
only have the contamination of apple and apple juice.
Following its discovery, patulin was intended to be applied as an antibiotic, but its toxicity
also for higher organisms was realised soon. According to animal experiments, patulin
increases the permeability of vascular capillaries and may induce oedema. It exhibits high
affinity to sulphhydryl groups, thereby inhibiting the function of several enzymes. The
genotoxic effect may be addressed to this property (it inhibits the DNA synthesis). Patulin
does not accumulate in the organism, therefore its established tolerable intake level is daily
0.4 g/bwkg.
In the European Union tolerable threshold value is existing only for fruit juices, alcohols, solid
apple products (25-50 g/kg). In Hungary, during the recent years relatively few samples
were examined for patulin but the number of contaminated samples fallen over the 25 g/kg
value was high. This finding indicates that on course of apple processing, the so called
brown-spoilage fruits should be removed because this abnormality is caused by the patulinproducing P. expansum.
Fusariotoxins
Aflatoxins, ochratoxins and patulin are belonging to the storage-moulds, the fusariotoxin
producing Fusarium moulds are belonging to the so called fieldland-moulds, i.e. their
optimum multiplication conditions primarily are found on the tillage (plough-land). Fusarium
moulds are widely distributed in all over the world and most of them are toxin producer. They
are able to synthetise several kind of toxins under a relatively wide range of temperature,
including the Hungarian climate conditions. The members of three groups are important such
as trichotecens, zearalenon and fumonizines.
The group of trichotecen-skeletal toxins include more than 50 chemical varieties with
complex chemical structures. Their most important representatives are the T-2 toxin, the HT2 toxin, deoxynivalenol (DON), nivalenol, the diacetoxyscirpenol (DAS) and the fusarenon-x.
The T-2, the HT-2 toxins and DON are the most significant food-contaminants. They are
frequently occurring on cereals (wheat, corn, barley, rye, oat, rice). The DON in itself or
altogether with other trichotecens, or with zearalenon can be detected in almost any grainproducts.
They are protein synthesis inhibitory, haemato and immuno toxic compounds which
may contribute to the higher incidence of infective diseases. Ingesting in higher quantity, they
25
are able to induce vomiting, diarrhoea, necrosis in the mouth and oesophagus, contactinflammation of the skin, furthermore the drop in leucocyte count.
Fusariotoxins are heat-resistant. During the milling process, however, their quantity is greatly
reduced due to the removal of the surface contamination on course of hulling before milling.
They are not present in food of animal origin in significant quantities because animals
refuse to consume feed significantly contaminated with trichotecens and the ingested toxin
avidly metabolised in and fastly excreted from the animals’ organism.
The provisory maximum tolerable daily intake level of DON is 1g/bwkg, while of T-2 and HT2 toxins (individually and altogether) it is 6 g/bwkg.
According to the related regulation of the European Union, bread, paste and grains-intendeddirectly-for-human-consumption may contain maximum 500-750 g/kg DON, while flour and
milling products may contain 300 g/kg T-2 and HT-2 toxins. In the Hungarian grain products
the T-2 and HT-2 toxins only sporadically are present but the DON-contamination
occasionally is significant.
Zearalenon (F-2 toxin) is different from the trichotecens in chemical composition and
biological effects. It is a characteristically oestrogenic mycotoxin. The effect is specifically
manifested in sows exhibiting oedematous endometrium accompanied with intensive cellproliferation. Functional asynchrony is appearing in the function of the uterus and ovaries, the
inplantation of ovum is inhibited, by preventing pregnancy, infertility and in chronic cases,
multiplex ovarial cysts may be developed. The spermiogenesis is also damaged by the F-2
toxin.
Humans are probably also sensitive to the effects of zearalenon, however, the toxin-related
clinical manifestations have never been identified. Hungarian scientific results inndicate that
zearalenon is specifically bound to human receptors and the mycotoxin could be detected in
children showing early pubertic phenomenons.
The tolerable intake level of zearalenon is 0.5 g/bwkg.
Zearalenon is present in cereals as surface contamination and it is accumulating in the bran
during the milling process.
Tolerable threshold levels are existing in the European Union for flour, bran, bread, pate and
biscuit (50-75 g/kg). According to the results of Hungarian examinations, F-2 toxin is rarely
occurring in domestic cereal products.
Fumonizins are the members of a relatively new group of mycotoxins, and based on their
biological effects, they are considered as „aflatoxins of the 90s years”. They primarily are
produced by the Fusarium moniliforme, but other Fusarium species are also able to
synthetise the toxin. The mould can multiplicate under conditions present both on the
fieldlands and storage-sites and they produce toxin during humid conditions following hot and
dry periods. The toxin-generating moulds are distributed all over the world, first of all on
maize. The contamination of damaged corn of maize can be specifically intensive.
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Out of the existing more than ten types, three (B1, B2, B3) occur most frequently and the B1 is
the most important one.
Fumonizins
may
cause
miscellenous
diseases
in
animals
resulting
in
leukoencephalomalacia in horses (ELEM, equine leukoencephalomalacia), pulmonary
oedema and emphysema in pigs (the so called fattening pulmonary oedema, PPE, porcine
pulmonary oedema), liver and renal damage in rats. They may play a role in the
pathogenesis of oesophageal and liver carcinoma.
Fumonizins are concentrated in the embryo and seed-coat of plants. The treatment of
surface of seed, boiling in alkaline, washing and chilling are suitable methods for reducing
the toxin concentration.
The tolerable daily intake level of fumonizin B1, B2 and B3 toxins individually and altogether is
2 g/bwkg. The estimated dietary daily intake of European consumers is about 0.1 g/kg.
Consumers who are regularly eating maize-based products, this value is about 1.0 g/kg. In
the European Union, the tolerable threshold value for maize-based products, fluor, groats, oil
is 400-1000 g/kg.
Marine and fresh-water biotoxins
Those are about 40 out of the several thousands microscopic marine algae species which
are producing miscellenous biotoxins. The toxin containing algae are primarily taken up by
bivalve molluscs, occasionally by fish, thereby the toxin may become a part of the human
food chain generatig potential hazard for the human consumer. Algae in fresh water also may
produce toxin but their public health importance is essentially lower. Toxins produced by
microalgae, are termed also as phycotoxins.
Marine biotoxins
Toxin producing algae are world-wide distributed both at continental and warm climate areas
but a given species and its actual high multiplication altogether with the enriched presence of
its toxin is characteristic for a given area. Public heath hazard due to the consumption of
marine molluscs and fish contaminated by the toxin was restricted to costal areas close to
the territories of the algae, todays, however it has become imternational.
Among the marine phycotoxins, practically the different shell-toxins and the ciguatera toxin
accumulated in fish are important. The most important toxins belonging to the former group
are the paralytic shell poison (PSP), the diarrhoic shell poison (DSP), the amnesic shell
poison (ASP) and the neurotoxic shell poison (NSP). The group of ciguatoxins includes at
least 20 compounds with polyether structure produced by bentic and epiphyte dinoflagellae.
The most important properties of the major toxins are shown in the next Table.
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Table
Major marine biotoxins
Name
Paralytic shellfish poison=
PSP, principal component:
saxitoxin)
Diarrheic shellfish poison=
DSP, complex toxin-group;
okadaic-acid, dinofisistoxins,
yessotoxins, etc.)
Amnesic shellfish
poison=ASP; domoic-acid
Source of human
disease
Marine molluscs
(mainly bivalve
molluscs)
Molluscs
(mainly bivalve
molluscs)
Marine molluscs
Toxic effects
Maximum level*
(related to molluscs
or fishmeat kg)
800 g/kg
inhibition of membrane
conductivity, respiratory
paralysis
(human lethal dose: 20-80
g/bw saxitoxinequivalent)
vomiting, diarrhoea,
Okadaic-acid, dinofisis
abdominal pain and
toxins 150 g/kg
usually recovery in 3 days
yessotoxins: 1 mg/kg
(certain components are
carcinogens?)
vomiting, diarrhoea,
20 mg domoic-acid/kg
disturbances in orientation,
amnesia
vomiting, diarrhoea,
800 g/kg**
paraesthesia, motor
(brevetoxin-equivalent)
incoordination, asthma-like
symptoms
Ciguatera toxins (ciguatoxin, Tropic and subtropic vomiting, diarrhoea,
maitotoxin)
fish
muscle pain, paraesthesia,
circulatory disturbances
Neurotoxic shellfish
poison=NSP; brevetoxin)
* Regulation 853/2004/EC
** FDA recommendation
Marine molluscs
Occurrance
World-wide, continental
and tropic areas
Canada, SouthAmerika, Japan, WestEurope, Skandinavia
Mainly the West-costal
parts of USA, Canada,
Japan, North-Westcostal part of Europe
Floride, New-Zeeland
Floride, Bahamas,
Caribbean-sea, East
costal part of Africa,
Asia
Some natural marine biotoxins are very potent poisons (e.g. already 1-4 mg PSP
can be lethal); but their presence in marine molluscs or fish is without any
organoleptic abormality. They cannot reliably be inactivated by heat-treatment.
Therefore, the basis of protection is the prevention, first of all the regulation of
farming and harvesting of bivalve molluscs. The corresponding prescriptions are
described in the EU Regulation of 853/2004/EU. This Regulation includes the puiblic
health requirements along with the threshold values of toxins for marine molluscs.
They are examined by biological (mouse) and instrumnetal analytical means (LCMS/MS).
Fresh-water biotoxins
Occasionally, the eutrophycation based high degree alga multiplication may cause
public health problem. The causatives are the potentially toxin-producing bluealgae that often termed as cyanobacteria. These toxins, in contrast to the above
discussed marine biotoxins, are not accumulated in vectors but they are acting by
direct contact with the human organism, e.g during swimming (contacting with the
skin) or by the drinking water.
The toxins of the blue algae have different biological activities (e.g. hepato- and
neurotoxins, lipopolysacharides) and the most important is the liver damaging
biotoxin produced by the Microcystis aeruginosa. The direct contact with blue-algae
may evoke allergic dermatitis, occasionally more severe hypersensitivity
reactions/symptoms. There are no reliable data on the possible symptoms following
oral ingestion/intake of the toxins.
Histamine (scombrotoxin)
The biogen amine histamine present in animal tissues has potent biological actions
and normally is synthetised from histidine by the histidine-decarboxylase enzyme.
The enzyme is produced also by certain bacteria while multiplicating. The enzyme
interacting with free histidine found in tissues with high protein content and certain
foodstuffs, produces histamine (microbial decarboxylation). The meat of certain fish
species (especially macrelas, sardinia and tunafish) contains significant quantity of
free histidine, from which big amount of histamine can be formed by histidinedecarboxylase of bacterial origin.
Since bacterial multiplication primarily is temperature dependent, the basic method of
prevention of histamine production is the chilling of fish within 6-9 hours after
catching and its storage at <4oC temperature or freezing up to time of consumption.
The activity of histidine-decarboxylase is preserved even after the death of bacteria
and also under chill condition or it is reactivated fast following freezing and defrosting.
This is the reason why the inhibition of growth of the enzyme producing bacteria is so
important.
Beside, histamine, in rotting fishmeat other polyamines (e.g. putrescine, cadaverine)
can be formed and may adversly affect the health of consumers.
Histamine and also tyramine (potentially is equally harmful for human health) may be
formed from tyrosin by microbial decarboxylation during ageing of certain cheeses
or in wine.
The maximum tolerable concentrations of histamine is regulated altogether with the
microbiological criteria in foodstuffs in Regulation of 2073/2005/EC. Accordingly,
fishery products, made from fish species containing high amount of histidine
(especially macrela, hering, sardella), may not contain histamine over 100 mg/kg
during their shelf-life, and the histamine concentration in 2 out of 9 examined sample
may be fallen between 100 és 200 mg/kg. Fishery products manufactured by
enzymatic ageing in salt solution, the maximum tolerable value may the double of the
previously described ones..
In Hungary the histamine content of the examined fish and cheese samples is
ususally appropriate, pickled fish-cans, however, occasionally may contain over-the
threshold-concentrations of histamine.
Toxic materials of natural origin
Those natural components of foodstuffs are belonging here which in original
quantities or after enrichment may be hazardous for public health. Basically, they can
be sorted into two groups. One group of compounds are nutritives (also) with harmful
effect, the members of the other group are harmful compounds without nutritive
property.
Nutritive materials
Nutritive compounds may cause health damage mostly in the presence of inherited or
acquired enzymopathia (partial or full lack of a metabolic enzyme), consequently the
nutritive compound cannot participate in the metabolism. Characteristic examples are
the lactose intolerance, galactosaemia, phenylketonuria or coeliacia (glutensensitive-enteropathia). In these conditions, the life-long diet of patients must include
lactose, phenylalanin or -gliadin -free foodstuffs. In contrast to the previous
compounds, the eruka-acid and trans-fatty acids are hazardous to any consumers.
Eruka acid may occur in rape-oils at higher quantity. Trans-fatty acids are formed
during processing of oil (hardening and hydrogenisation in manufacturing of
margarin) and similarily to the saturated fatty acids, they have cholesterin level
increasing effect.
30
Toxic natural ingredients without nutritive property
The non-nutritive toxic compounds(ingredients) are natural poisonous components of
certain raw materials. High number of compounds with different biological activities
are belonging here. From part of food safety, the solanin, cyanohydrogen, methyl
alcohol, morphin and its derivatives, furthermore nitrates and nitrites are the most
important components.
Solanine. Chemically, it is a glycoalkaloid which can be hydrolysed to sugar
(solanose) and an alkaloid of solanidine. Solanidine is the toxic component with a
saponine like effect. Locally it is tissue irritant, following absorption it causes
haemolysis and atropin-like neuronal symptoms. Solanine can be found mainly in
potatoes (primarily in the green, germ-like tubers), but it is formed also below the skin
of apple, turkey egg and tomato. Maximum tolerable value is for potato: 180 mg/kg.
Cyanhydrogen (hidrogen-cyanide). It is present in certain plants in glycoside
bound as cyanoglycoside. Cyanoglycosides practically are not poisonous but
enzymatically cyanhydrogen can be released from cyanoglycosides which is strongly
toxic. The compound is bound to tissue oxydative enzymes containing tri-valent iron,
thereby it is going to bind to cytochrome-oxydase and inhibits the tissue oxydative
processes resulting in cytotoxic anoxia.
From food safety point of view, the seed cyanoglycoside content of stone-fruits
(almonds, apricots, cherries, plums) is important. These seeds contain the prunazin
or amigdalin cyanoglycosides, from which at injury of the seed the released emulzin
enzyme is splitting the cyanhydrogen. The consumption of ten pieces of raw, bitter
almond may be lethal for children and the consumption of 15-20 seeds may induce
severe poisoning in adults. On course of industrial processing, the cyanoglycosides
can be decomposed by appropriate treatment. There are maximum tolerable values
for sweet industrial products containing stone-fruits (e.g. marcipan), for fruit compots,
wines, and alcohol (pálinka) preparations: 10 mg/kg, 1 mg/l, and 20-40 mg/l.
Methyl-alcohol (methanol). It is present in alcoholic drinks in low quantity.
Organoleptically (smell, taste), it cannot be distinguished from ethanol. For this
reason it is used for adulteration of alcoholic drinks, sometimes resulting in mass
toxicosis. Methanol is metabilised in the human organism partially similarly to
ethanol:
alcohol-dehydrogenase
Methanol
Formaldehyde
slow
aldehyde-dehydrogenase
folate dependent
Formic ac id
CO2+H2O
fast
very slow
In man, both alcohols are oxydated by alcohol-dehydrogenase into the appropriate
aldehyde (ethanol → acetaldehyde, methanol → formaldehyde), the oxydation of
methanol, however, is much more slower. Aldehydes, formed in the first oxydation,
31
are oxydated further again by a common enzyme, the aldehyde dehydrogenase, into
the appropriate acid (acetaldehyde → acetic acid, formaldehyde → formic acid),
fastly in both cases. Acetic acid is without toxicological significance because in form
of acetyl-CoA it enters the citrate cycle and is transformed into CO2, and water. The
folate-dependent oxydation of formic acid, however, is very slow.
The narcotic alcohol itself and the acidosis furthermore, the retinal damage inducing
formic acid are the reponsible for the toxic effect of methanol. In man, the lethal dose
of methanol is 30-100 ml, but already 8-10 ml may cause severe toxicosis. The
methanol content must be maximum 0.2% of the ethanol content in commercial
palinka, brandy (cognac), and liquor.
Morphin and derivatives. Morphin and related alkaloids, such as codein, tebain,
narcotin, narcein and papaverine are biologically very active compounds and widely
used in medical treatment. They are the main components of opium obtained from
the dried milk of green poppy capsule. The morphin, codein and tebain (fenantrenederivatives) are inhibitors of the central nervous system (CNS), the narcotin, narcein
and papaverine (isochinoline derivatives) are smooth muscle relaxants. The scalding
water of poppy capsules contain about 2-4 mg morfphin. Its lethal dose in adults is
200-400 mg. Tolerable threshold values are established for poppy seed, it is 30
mg/kg for morphin, and 20 mg/kg for the other alkaloids.
Nitrates. Nitrates are the common constituents of the soil, surface fresh-and marine
waters, plants and animal tissues. They are easily converted into nitrites through
microbial activities. Nitrites are vasodilator and methaemoglobin forming compounds.
Reacting with secondary and tertiary amines, they may converted into nitrosamines.
Methaemoglobin may be formed physiologically in small quantities (<10%). In
contrast, if 20% of haemoglobin is converted into methaemoglobin, hypoxaemic
symptoms are appearing, at 60-80% conversion lethal hypoxia is developing.
Nitrosamines may be formed in the stomach of human organisms (pH 1-3), the
process need preformed nitrites to be present. Nitrites are synthetised from nitrates in
the intestines as a result of baterial activities. Nitrates are occurring in green plants,
certain species are intensively accumulate nitrates and several factors may increase
the nitrate content of plants (intensive N-artificial fertilizing, the lack of certain trace
elements, long-lasting drought, etc.).
From part of consumers’ health, the nitrite/nitrate content of drinking water is also
important. In drinking water mainly nitrites are present but, specifically in dug wells, a
major part of nitrates microbically is converted into nitrites. Tolerable threshold value
of nitrates in foodtsuffs is existing for spinach and common lettuce (200 mg/kg), while
in case of nitrites the existing threshold value is 10 mg/kg for baby foods only.
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The control of chemical contamination of foodstuffs
The site of the potentially consumer-health damaging chemical contamination of
foodstuffs basically is the primary production, the farm (residues, contaminants of
environmental origin, majority of contaminants of biological origin, toxic components
of natural origin). Accordingly, in preventing and control of chemical contamination,
the primary production has outstanding importance, such as the animal farming and
plant cultivation, or the food production animal and products of animal origin (fresh
milk, eggs, honey, live bivalve molluscs, snail, fishery products), furthermore the plant
products (cereals, fruits, vegetables, season-plants, etc.).
Basic principles
The chemical-toxicological safety of foodstuffs (as part of the overall food saftey)
primarily is the reponsibility of the food industrial undertaker (producer,
manufacturer, management). The producer may market live animal, products of
animal or plant origin which have not been treated with banned drug/chemical and
the corresponding withdrawal time was observed. The responsibles of the food
processing establishments must do their best in order to receive/accept animals or
products (as raw material) for which the producer in the previous step of the food
chain took the responsibility that those were not treated with banned substance and
the withdrawal times were observed and satisfied their duty on recordings and
information supply.
The state (goverment) contributes to the guarrantee of safety by elaborating and
implementing the related legal framework and controlling the adherence to those
rules. In Hungary the elaboration of the corresponding regulation primarily is the
function of the Ministry of Public Health while the control is the duty of the Ministry of
Agriculture and Country Development.
Basically, two systems of control are operating, the national residue monitoring
program, and the random official control. In Hungary, the Ministry of Agriculture and
Country Development is responsible for the former and the terriorial food control
authorities are responsible for the latter activity.
Monitoring systems
The basic component of the control is the National monitoring system based on
random sampling of foodstuffs of both animal and plant origin. In Hungary, the
operation of the system is the function of the Food and Feed Safety Directorate of
Central Agricultural Office (foodstuffs of animal origin) and the Plant, Soil and AgroEnvironmental Protection Directorate of Central Agricultural Office (foodstuffs of plant
origin).
33
The examinations are carried out following the corresponding yearly study plan that
is elaborated in the previous year and approved by the EU. The study plan includes
the list of chemicals to be determined, the name of study samples, the frequency of
sampling, the list of analytical laboratories involved, the tolerable concentrations
prescribed in the corresponding regulations, and the official measures in case of
positives when banned substance or higher than the tolerable concentration is
detected in foodstuffs of animal or plant origin.
Foodstuffs of animal origin
On course of monitoring of foodstuffs of animal origin, the samples are taken from
live animal, feedstuffs, drinking water, body fluids, excreta, animal tissues and
products of animal origin. The subject of monitoring are cattle, pig, sheep, goat,
solipeds, poultry, farmed water animals, eggs, honey, furthermore, snail, rabbit,
gamemeat and farmed game.
The study items (compounds) are belonging to two groups. In group „A” are the
anabolics and the compounds banned for using in food production animals. In group
„B” are the veterinary drug preparations (products) and miscellenous contaminant
compounds. Concerning group „A” compounds, the purpose of official inspection is to
discover of banned application while in case of group „B” compounds the aim is to
detect potential poor professional use or abuse and check if the withdrawal time was
observed or not. Higher portion of samples must be examined for compounds of
group „A”.
The number of examined samples in the actual year is determined taking into
consideration respectively the number of animals slaughtered in the previous year
and production rate. The minimum animal number is 0.4% of the slaughtered cattle,
0.05% of slaughtered pigs, and after each 200 tonnes in a year, 1 broiler chick or 1
turkey sample but minimum 200 samples per year.
A portion of samples are taken at the farm (group „A”), the other portion of samples
are taken at the slaughterhouse (groups „A” and „B”). Sampling is the duty of the
official vet. Samples must be transported frozen and urgently into the laboratory.
The laboratory examination is going on two levels: screening and confirmative. In
case of group A-compounds always, in case of group B-compounds only when
detected positivity at screening occur, confirmatory examination must be done.
If it is confirmed that banned substance was used, based on decision of the
authentic authority, the animals will be killed without compensation and the flock/herd
will be under veterinary control and a further official sampling program is initiated.
If over the maximum residue level (MRL) was detected, marketing restriction is
ordered for the farm and more severe examination is carried out. In case of repeated
34
occurrence, the live animals and products originating from this same farm must be
inspected more intensively for 6 months (survaillance programme)..
At the slaughterhouse, when suspected that the withdrawal time was not observed
for the animal intended for slaughter, the slaughter must be postponed until receiving
the negative result of the laboratory examination. In case of positive result, however,
the animal is unfit for human consumption. The meat, offals and wastes of animals
that were treated with banned substances, must be destroyed as high risk material.
Processed and unprocessed products and foodstuffs of plant origin
Considering the chemical contamination of agricultrural products and foodstuffs of
plant origin, the pesticide residues are the most important contaminants. Accordingly,
in this product group, the National monitoring program is primarily directed to the
detection of possible pesticide residues and a minor part of the program intends to
examine the heavy metal, nitrate, nitrite content of unprocessed agricultural products
of plant origin. In Hungary, the planning and execution of monitoring examinations
are the function of the Plant, Soil and Agro-Environmental Protection Directorate of
Central Agricultural Office and of the County Plant- and Soil Protection Directorates.
In Hungary, the number of authorised active substances is about 270, and in the
framework of monitoring examinations about 200-220 compounds can be checked.
This is a good ratio also in international practice/comparison.
The examinations include the domestic and import products and plant based
processed foodstuffs (baby foods and drinks, flours, muesli, and fruit drinks). In
case of domestic products, the inspection of the prescribed ordinary use of pesticides
and the sampling are carried out at site of cultivation and in framework of inspections
at the market sites. The examination of import products includes foodstuffs
originating primarily from third countries and done at the borders furthermore in
framework of import market inspections at wholesalers and at the big market-chains.
Reasonably, the sampling of domestic products is carried out during harvesting at
site of cultivation and at the market sites while in case of import products it is done at
the borders and at the big wholesale market chains.
In Hungary, in the framework of the monitoring system about 3600-3700 samples are
examined yearly, and approximately 50% of these samples are domestic fresh
vegetables and fruits (a minor portion also cereals), 40% are unprocessed import
products and the remainder about 10% is plant based processed foodstuffs. In year
of 2006, 1.6 percent of the examined domestic unprocessed products contained
residues above the tolerable threshold level. The quantity of objectionable samples of
import products (presence of residue in higher concentration than the tolerable value
or the detection of pesticide not authorised in Hungary) was 3.4%. Higher than the
35
usual objection/rejection ratio occurred in case of tropical fruits, fine (dessert) grapes,
tomato and paprika.
The monitoring system is supplemented with random, targeted examinations,
usually in framework of more intensive official inspections (e.g. seasonal ones at
summertime or Christmas time) and on suspect.
36