BTEX Fact Sheets
Benzene
GUIDELINE
Based on health considerations the concentration of benzene in drinking water should not exceed
0.001 mg/L.
GENERAL DESCRIPTION
Benzene is a clear, colourless-to-yellow liquid and highly flammable aromatic hydrocarbon. It is
present in petroleum products such as motor fuels and solvents, and motor vehicle emissions
constitute the main source of benzene in the environment. Benzene occurs naturally in crude oil and
is an additive and a by-product of oil-refining processes. It constitutes approximately 1-2% of
unleaded gasoline by volume (US DHHS, 2011). Tobacco smoke is another significant source of
exposure (WHO, 2010).
Human exposure to benzene occurs primarily through inhalation (WHO, 2010). When released to
surface waters, benzene rapidly volatilises to the air (WHO, 2010). Benzene is not persistent in
surface water or soil and either volatilises to air or is degraded by bacteria under aerobic conditions
(WHO, 2010). For water contamination, benzene is therefore of most concern in groundwater.
Benzene is also used widely as an industrial solvent by the chemical and pharmaceutical industries in
the production of styrene/ethylbenzene, cumene/phenol and cyclohexane. The use of Benzene as a
solvent has been greatly reduced in recent years.
Unlike other petroleum hydrocarbons such as ethylbenzene, toluene and xylene the odour threshold
for benzene is relatively high at 10mg/L (WHO, 2003).
TYPICAL VALUES IN AUSTRALIAN DRINKING WATER
Benzene has only rarely been identified in Australian drinking waters. Natural concentrations in most
water sources are usually very low. However, contamination can occur, usually via exposure to
petrochemicals in surface waters or groundwaters. Known sources of groundwater contamination
include leakage from sub-surface fuel storage tanks (do Rego & Netto, 2007). Emissions of fuel
components from boating use is a known source of contamination of multiple-use lakes and
reservoirs (Schmidt et al., 2004). Benzene was reported in 9% of samples from an extensive
groundwater survey undertaken in Denmark with the highest concentration being 34 ug/L (Juhler &
Draft for public consultation – November 2012
Felding, 2003). Benzene has been reported at up to 4 ug/L in municipal drinking water in Taiwan
(Kuo et al., 1997) and is occasionally detected in drinking waters in the USA (Williams et al., 2004).
TREATMENT OF DRINKING WATER
Volatile organic chemicals such as benzene are most commonly treated in drinking water by aeration
stripping and/or adsorption to granular activated carbon (GAC). A conventional biologically active
sand filter has been shown to be highly effective for the removal of benzene from contaminated
water, under suitable conditions (Arvin et al., 2004). Effective bioremediation of highly
contaminated groundwaters has also been demonstrated (Sedran et al., 2004; Zein et al., 2006).
MEASUREMENT
A purge and trap gas chromatographic procedure can be used for the analysis of benzene (APHA,
AWWA & WEF, 2012). An inert gas is bubbled through the sample and benzene is trapped on an
adsorbent. The adsorbent is then heated and benzene analysed using gas chromatography with
mass spectrometric (GC-MS) detection (Method 6200 B) or photoionisation (PI) detection (Method
6200 C) (APHA, AWWA & WEF, 2012). The method detection limit is 36 ng/L for GC-MS and 17 ng/L
for GC-PI (APHA, AWWA & WEF, 2012).
HEALTH CONSIDERATIONS
Benzene is rapidly and efficiently absorbed (30-50%) following inhalation. Following ingestion,
animal data indicate that nearly all is absorbed from the gastrointestinal tract. Less than 1% is
absorbed through the skin. Following absorption it is widely distributed throughout the body. It is
metabolised predominantly into phenol by the liver, and also by bone marrow (WHO 2003).
Human health data are mainly from studies where benzene had been inhaled. Acute exposure to
high concentrations affects the central nervous system causing dizziness, nausea, vomiting,
headache and drowsiness. Inhalation of very high concentrations can cause death. Chronic and
subchronic exposure to lower concentrations leads to a range of adverse effects on the blood
system including pancytopenia, aplastic anaemia, thrombocytopenia, granulocytopenia and
lymphocytopenia with white blood cells being the most sensitive (WHO 2003; Health Canada, 2009).
There is considerable evidence that occupational exposure to low benzene concentrations for
periods as short as 1-5 years may result in leukaemia (ATSDR 2007).
In animal studies, benzene caused leukaemia and other cancers when administered orally and by
inhalation to rats and mice. It can also induce chromosome damage and gene mutation in
mammalian cells. It was not found to be mutagenic in tests with bacteria.
The International Agency for Research on Cancer has concluded that benzene is carcinogenic to
humans (Group 1, sufficient evidence of carcinogenicity in humans) (IARC 1987).
DERIVATION OF GUIDELINE
The European Union (1998), WHO (2011), Health Canada (2006), USEPA (2008) and New Zealand
(MoH NZ 2008) have set drinking water guidelines for benzene of 0.001-0.01 mg/L based on
carcinogenic potential of benzene in humans from inhalation exposures and/or a 2 year oral study in
rats and mice (NTP 1986).
WHO (2003) determined that concentrations of 0.01 mg/L or 0.001 mg/L in drinking water would
entail a maximum lifetime risk of one extra case of cancer per 100,000 people or 1 million people
respectively . This was based on data on leukaemia from human epidemiological studies involving
inhalation exposure (WHO 1993) and analysis of data from a 2 year gavage study in rats and mice
(NTP 1986) using the robust linear extrapolation model.
Draft for public consultation – November 2012
The approach described by WHO (2003) has been adopted in setting a drinking water guideline of
0.001 mg/L based on an estimated additional lifetime risk of one fatal cancer per 1 million people.
WHO (2011) adopted a guideline value of 0.01 mg/L based on an estimated additional lifetime risk of
one fatal cancer per 100,000 people.
REFERENCES
Agency for Toxic Substances and Disease Registry (ATSDR) (2007) Toxicological profile for Benzene.
Public Health Service, US, Department of Health and Human Services, Atlanta, Georgia.
American Public Health Association (APHA), American Water Works Association (AWWA) and Water
Environment Federation (WEF) (2012). Standard Methods for the Examination of Water and
Wastewater, 22nd Edition. Eds. Rice EW, Baird RB, Eaton AD and Clesceri LS.
Arvin, E., Engelsen, P. and Sebber, U. (2004) Biodegradation of gasoline compounds (BTEX) in a water
works sand filter. Water Science & Technology: Water Supply, 4(5-6), 29-33.
do Rego, E. C. P. and Netto, A. D. P. (2007) PAHs and BTEX in groundwater of gasoline stations from
Rio de Janeiro City, Brazil. Bull. Environ. Contam. Tox., 79(6), 660-664.
European Union (1998) Council Directive 98/83/EC on the quality of water intended for human
consumption. Official Journal of the European Communities. L330.
Health Canada (2006) Guidelines for Canadian Drinking Water Quality. Ottawa, Ontario.
Health Canada (2009) Guidelines for Canadian Drinking Water Quality. Guideline Technical
Document Benzene, Ottawa, Ontario.
IARC (International Agency for Research on Cancer) (1987) IARC Monographs on the Evaluation of
Carcinogenic Risks to Humans: Overall Evaluations of Carcinogenicity. An updating of IARC
monographs volumes 1 to 42. Supplement 7., Lyon.
Juhler, R. K. and Felding, G. (2003) Monitoring methyl tertiary butyl ether (MTBE) and other organic
micropollutants in groundwater: Results from the Danish National Monitoring Program. Water Air
Soil Poll., 149(1-4), 145-161.
Kuo, H. W., Chiang, T. F., Lo, L. I., Lai, J. S., Chan, C. C. and Wang, J. D. (1997) VOC concentration in
Taiwan's household drinking water. Sci. Total Environ., 208(1-2), 41-47.
MoH NZ (2008) New Zealand Ministry of Health, Drinking-water standards for New Zealand 2005
(Revised 2008), p 9. Ministry of Health, Wellington.
National Toxicology Program (1986) Toxicology and carcinogenesis studies of benzene in F344/N rats
and B6C3F1 mice (gavage studies). Research Triangle Park, NC, US Department of Health and Human
Services (Technical Reports Series No. 289).
Schmidt, T. C., Haderlein, S. B., Pfister, R. and Forster, R. (2004) Occurrence and fate modeling of
MTBE and BTEX compounds in a Swiss Lake used as drinking water supply. Water Res., 38(6), 15201529.
Sedran, M. A., Pruden, A., Wilson, G. J., Suidan, M. T. and Venosa, A. D. (2004) Biodegradation of
methyl tert-butyl ether and BTEX at varying hydraulic retention times. Water Environ. Res., 76(1), 4755.
US Department of Health and Human Services (US DHHS) (2011) Report on Carcinogens. 12th ed.,
pp. 60.
US Environmental Protection Agency (2008) National Primary Drinking Water Standards.
Williams, P. R. D., Benton, L. and Sheehan, P. J. (2004) The risk of MTBE relative to other VOCs in
public drinking water in California. Risk Anal., 24(3), 621-634.
Draft for public consultation – November 2012
World Health Organization (1993) Benzene. Environmental Health Criteria No.150.
World Health Organization (2003) Background document for development of WHO Guidelines for
Drinking-water Quality. WHO/SDE/WSH/03.04/24.
World Health Organization (2010) Exposure to Benzene: A Major Public Health Concern.
World Health Organization (2011) Guidelines for drinking-water quality, fourth edition.
Zein, M. M., Suidan, M. T. and Venosa, A. D. (2006) Bioremediation of groundwater contaminated
with gasoline hydrocarbons and oxygenates using a membrane-based reactor. Environ. Sci. Technol.,
40(6), 1997-2003.
Draft for public consultation – November 2012
Toluene
GUIDELINE
Based on aesthetic considerations (taste and odour), the concentration of toluene in drinking water
should not exceed 0.025 mg/L.
Based on health considerations the concentration of toluene should not exceed 0.8 mg/L.
GENERAL DESCRIPTION
Toluene is a colourless liquid, which occurs naturally as a component of crude oil and is present in
petrol. It can enter water sources through atmospheric deposition, by leaching from synthetic
coatings used to protect storage tanks, and by point-source pollution.
Toluene, also known as methylbenzene is produced in large quantities during petroleum refining and
is a byproduct in the manufacture of styrene and coke-oven preparations. It also occurs in natural
gas and emissions from volcanoes, forest fires, and cigarettes.
Toluene has a taste and odour threshold at 0.025mg/L.
TYPICAL VALUES IN AUSTRALIAN DRINKING WATER
Toluene has only rarely been identified in Australian drinking waters. Natural concentrations in most
water sources are usually very low. However, contamination can occur, usually via exposure to
petrochemicals in surface waters or groundwaters. Known sources of groundwater contamination
include leakage from sub-surface fuel storage tanks (do Rego & Netto, 2007). Emissions of fuel
components from boating use is a known source of contamination of multiple-use lakes and
reservoirs (Schmidt et al., 2004). Toluene was reported in 19% of samples from an extensive
groundwater survey undertaken in Denmark with the highest concentration being 2.4 ug/L (Juhler &
Felding, 2003). Toluene has been reported at up to 1 ug/L in municipal drinking water in Croatia
(Karaconji et al., 2006), up to 63 ug/L in municipal drinking water in Taiwan (Kuo et al., 1997) and is
occasionally detected in drinking waters in the USA (Williams et al., 2004).
TREATMENT OF DRINKING WATER
Volatile organic chemicals such as toluene are most commonly treated in drinking water by aeration
stripping and/or adsorption to granular activated carbon (GAC). A conventional biologically active
sand filter has been shown to be highly effective for the removal of toluene from contaminated
water, under suitable conditions (Arvin et al., 2004). Effective bioremediation of highly
contaminated groundwaters has also been demonstrated (Sedran et al., 2004; Zein et al., 2006).
MEASUREMENT
A purge and trap gas chromatographic procedure can be used for the analysis of toluene (APHA,
AWWA & WEF, 2012). An inert gas is bubbled through the sample and toluene is trapped on an
adsorbent. The adsorbent is then heated and toluene analysed using gas chromatography with mass
spectrometric (GC-MS) detection (Method 6200 B) or photoionisation (PI) detection (Method 6200
C) (APHA, AWWA & WEF, 2012). The method detection limit is 47 ng/L for GC-MS and 23 ng/L for
GC-PI (APHA, AWWA & WEF, 2012).
Draft for public consultation – November 2012
HEALTH CONSIDERATIONS
In humans, toluene is readily absorbed from the gastrointestinal tract after ingestion, and is
distributed preferentially in adipose tissue, then the kidneys, liver and brain. It is rapidly metabolised
by the liver to benzyl alcohol, benzoic acid, and to a lesser extent, phenols.
Data on human health effects come mainly from inhalation studies. The predominant effects of
acute exposure were impairment of the central nervous system and irritation of the mucous
membranes, with fatigue and drowsiness being the most obvious symptoms.
Rats exposed to toluene vapour for 2 years exhibited decreased blood haematocrit values at high
toluene concentrations (380 ppm in air). No data are available on long term oral toxicity; however, a
13 week gavage study using rats and mice reported increased liver weights at doses from 625 mg/kg
body weight per day (NTP 1990).
Toluene generally did not exhibit genotoxic activity in tests on bacteria, yeast cells, and mammalian
cells in vitro.
The International Agency for Research on Cancer has concluded that toluene is not classifiable as to
its carcinogenicity in humans (Group 3, inadequate evidence in humans and in animals) (IARC 1989).
DERIVATION OF GUIDELINE
The health-based guideline value of 0.8 mg/L for toluene in drinking water was determined as
follows:
0.8 mg/L = 312 mg/kg bodyweight/day x 70 kg x 0.1 x 5/7
2 L/day x 1000
where:

312 mg/kg body weight per day is the no effect level based on a 13-week oral study using
rats (NTP 1990)

70 kg is the average weight of an adult

0.1 is the proportion of total daily intake attributable to the consumption of water

2 L/day is the average amount of water consumed by an adult

1000 is the safety factor in using the results of an animal study as a basis for human
exposure (10 for interspecies variations, 10 for intraspecies variations and 10 because a less
than lifetime study was used)

5/7 is used to convert data based on a 5 day per week gavage study to a 7-day week
equivalent.
This health-based guideline value exceeds the taste threshold of toluene in water of 0.02 mg/L.
The WHO guideline value of 0.7 mg/L is based on an adult body weight of 60 kg. The difference in
guideline values is not significant.
REFERENCES
American Public Health Association (APHA), American Water Works Association (AWWA) and Water
Environment Federation (WEF) (2012). Standard Methods for the Examination of Water and
Wastewater, 22nd Edition. Eds. Rice EW, Baird RB, Eaton AD and Clesceri LS.
Arvin, E., Engelsen, P. and Sebber, U. (2004) Biodegradation of gasoline compounds (BTEX) in a water
works sand filter. Water Science & Technology: Water Supply, 4(5-6), 29-33.
Draft for public consultation – November 2012
do Rego, E. C. P. and Netto, A. D. P. (2007) PAHs and BTEX in groundwater of gasoline stations from
Rio de Janeiro City, Brazil. B. Environ. Contam. Tox., 79(6), 660-664.
IARC (International Agency for Research on Cancer) (1989) IARC Monographs on the Evaluation of
Carcinogenic Risks to Humans: some organic solvents, resin monomers and related compounds,
pigments and occupational exposures in paint manufacture and painting., Lyon.
Juhler, R. K. and Felding, G. (2003) Monitoring methyl tertiary butyl ether (MTBE) and other organic
micropollutants in groundwater: Results from the Danish National Monitoring Program. Water Air
Soil Poll., 149(1-4), 145-161.
Karaconji, B., Skender, L. and Karacic, V. (2006) Benzene, toluene, ethylbenzene, and isomeric
xylenes in various water samples in Croatia. B. Environ. Contam. Tox., 76(3), 458-462.
Kuo, H. W., Chiang, T. F., Lo, L. I., Lai, J. S., Chan, C. C. and Wang, J. D. (1997) VOC concentration in
Taiwan's household drinking water. Sci. Total Environ., 208(1-2), 41-47.
NTP (National Toxicology Program) United States Department of Health and Human Services (1990)
Toxicology and carcinogenesis studies of toluene in F344/N rats and B6C3F1 mice. NTP Report No
371. NIH Publication No. 90 2826.
Schmidt, T. C., Haderlein, S. B., Pfister, R. and Forster, R. (2004) Occurrence and fate modeling of
MTBE and BTEX compounds in a Swiss Lake used as drinking water supply. Water Res., 38(6), 15201529.
Sedran, M. A., Pruden, A., Wilson, G. J., Suidan, M. T. and Venosa, A. D. (2004) Biodegradation of
methyl tert-butyl ether and BTEX at varying hydraulic retention times. Water Environ. Res., 76(1), 4755.
Williams, P. R. D., Benton, L. and Sheehan, P. J. (2004) The risk of MTBE relative to other VOCs in
public drinking water in California. Risk Anal., 24(3), 621-634.
Zein, M. M., Suidan, M. T. and Venosa, A. D. (2006) Bioremediation of groundwater contaminated
with gasoline hydrocarbons and oxygenates using a membrane-based reactor. Environ. Sci. Technol.,
40(6), 1997-2003.
Draft for public consultation – November 2012
Ethylbenzene
GUIDELINE
Based on aesthetic considerations (taste and odour), the concentration of ethylbenzene in drinking
water should not exceed 0.003 mg/L.
Based on health considerations the concentration of ethylbenzene in drinking water should not
exceed 0.3 mg/L.
GENERAL DESCRIPTION
Ethylbenzene is a clear colourless liquid, which occurs naturally as a component of crude oil and is
present in petrol, but in small quantities.
Ethylbenzene is produced commercially by the alkylation of benzene with ethylene, and by
fractionation of petroleum. It is a major component of commercial xylene and is used commercially
in paints, insecticides, blends of petrol, and in the production of styrene. It can also be found as a
constituent of asphalt and naphtha.
Ethylbenzene has a taste and odour threshold of 0.003mg/L.
TYPICAL VALUES IN AUSTRALIAN DRINKING WATER
Ethylbenzene has only rarely been identified in Australian drinking waters. Natural concentrations in
most water sources are usually very low. However, contamination can occur, usually via exposure to
petrochemicals in surface waters or groundwaters. Known sources of groundwater contamination
include leakage from sub-surface fuel storage tanks (do Rego & Netto, 2007). Emissions of fuel
components from boating use is a known source of contamination of multiple-use lakes and
reservoirs (Schmidt et al., 2004). Ethylbenzene has been reported at up to 0.2 ug/L in municipal
drinking water in Croatia (Karaconji et al., 2006), up to 11 ug/L in municipal drinking water in Taiwan
(Kuo et al., 1997) and is occasionally detected in drinking waters in the USA (Williams et al., 2004).
TREATMENT OF DRINKING WATER
Volatile organic chemicals such as ethylbenzene are most commonly treated in drinking water by
aeration stripping and/or adsorption to granular activated carbon (GAC). A conventional biologically
active sand filter has been shown to be highly effective for the removal of ethylbenzene from
contaminated water, under suitable conditions (Arvin et al., 2004). Effective bioremediation of
highly contaminated groundwaters has also been demonstrated (Sedran et al., 2004; Zein et al.,
2006).
MEASUREMENT
A purge and trap gas chromatographic procedure can be used for the analysis of ethylbenzene
(APHA, AWWA & WEF, 2012). An inert gas is bubbled through the sample and ethylbenzene is
trapped on an adsorbent. The adsorbent is then heated and ethylbenzene analysed using gas
chromatography with mass spectrometric (GC-MS) detection (Method 6200 B) or photoionisation
(PI) detection (Method 6200 C) (APHA, AWWA & WEF, 2012). The method detection limit is 32 ng/L
for GC-MS and 28 ng/L for GC-PI (APHA, AWWA & WEF, 2012).
Draft for public consultation – November 2012
HEALTH CONSIDERATIONS
Ethylbenzene is readily absorbed from the human gastrointestinal tract. It can be stored in fat and is
metabolised to mandelic and phenylglyoxalic acids and excreted in the urine. It can cross the
placenta.
No data are available on the health effects in humans after oral exposure, and inhalation data are
limited to short term studies.
A 6 month gavage study using rats reported enlargement of the liver and kidney at high doses (400
mg/kg body weight per day) (Wolf et al., 1956). Mellert et al (2007) also reported liver and kidney
related impacts in addition to hepatocyte hypertrophy from 4 and 13 week gavage studies using rats
at doses above 75 mg/kg bw/day. No longer-term studies are available.
Studies on the mutagenic activity of ethylbenzene to bacteria, insects and mammalian cells have
reported negative results.
DERIVATION OF GUIDELINE
The health-based guideline value for ethylbenzene in drinking water was determined as follows:
0.3 mg/L = 75 mg/kg bodyweight/day x 70 kg x 0.1
2 L/day x 1000
Where:
•
75 mg/kg body weight per day is the no effect level based on a 4 and 13 week gavage
study using rats (Mellert et al 2007).
•
70 kg is the average weight of an adult
•
0.1 is the proportion of total daily intake attributable to the consumption of water
•
2 L/day is the average amount of water consumed by an adult
•
1000 is the safety factor in using the results of an animal study as a basis for human
exposure (10 for interspecies variations, 10 for intraspecies variations and 10 for the
limited data and short duration of the study)
This health-based value exceeds the taste and odour threshold of 0.003 mg/L for ethylbenzene in
water.
REFERENCES
American Public Health Association (APHA), American Water Works Association (AWWA) and Water
Environment Federation (WEF) (2012). Standard Methods for the Examination of Water and
Wastewater, 22nd Edition. Eds. Rice EW, Baird RB, Eaton AD and Clesceri LS.
Arvin, E., Engelsen, P. and Sebber, U. (2004) Biodegradation of gasoline compounds (BTEX) in a water
works sand filter. Water Science & Technology: Water Supply, 4(5-6), 29-33.
do Rego, E. C. P. and Netto, A. D. P. (2007) PAHs and BTEX in groundwater of gasoline stations from
Rio de Janeiro City, Brazil. B. Environ. Contam. Tox., 79(6), 660-664.
Karaconji, B., Skender, L. and Karacic, V. (2006) Benzene, toluene, ethylbenzene, and isomeric
xylenes in various water samples in Croatia. B. Environ. Contam. Tox., 76(3), 458-462.
Kuo, H. W., Chiang, T. F., Lo, L. I., Lai, J. S., Chan, C. C. and Wang, J. D. (1997) VOC concentration in
Taiwan's household drinking water. Sci. Total Environ., 208(1-2), 41-47.
Mellert W., Deckhardt K., Kaufmann W and van Ranvenzwaay B. (2007) Ethylbenzene: 4- and 13week rat oral toxicity. Arch Toxicology 81: 361-370
Draft for public consultation – November 2012
Schmidt, T. C., Haderlein, S. B., Pfister, R. and Forster, R. (2004) Occurrence and fate modeling of
MTBE and BTEX compounds in a Swiss Lake used as drinking water supply. Water Res., 38(6), 15201529.
Sedran, M. A., Pruden, A., Wilson, G. J., Suidan, M. T. and Venosa, A. D. (2004) Biodegradation of
methyl tert-butyl ether and BTEX at varying hydraulic retention times. Water Environ. Res., 76(1), 4755.
Williams, P. R. D., Benton, L. and Sheehan, P. J. (2004) The risk of MTBE relative to other VOCs in
public drinking water in California. Risk Anal., 24(3), 621-634.
Wolf, M. A., Rowe, V. K., McCollister, D. D., Hollingsworth, R. L. and Oyen, F. (1956) Toxicology
studies of certain alkylated benzenes and benzene: experiments on laboratory animals. AMA
Archives of Industrial Health, 14, 387–398.
Zein, M. M., Suidan, M. T. and Venosa, A. D. (2006) Bioremediation of groundwater contaminated
with gasoline hydrocarbons and oxygenates using a membrane-based reactor. Environ. Sci. Technol.,
40(6), 1997-2003.
Draft for public consultation – November 2012
Xylenes
GUIDELINE
Based on aesthetic considerations (taste and odour), the concentration of xylenes in drinking water
should not exceed 0.02 mg/L.
Based on health considerations the concentration of xylenes should not exceed 0.6 mg/L.
GENERAL DESCRIPTION
The term ‘xylenes’ encompasses three isomers of dimethylbenzene. The isomers are distinguished
by the designations ortho- (o-), meta- (m-), and para- (p-), which specify to which carbon atoms (of
the benzene ring) the two methyl groups are attached. o-xylene is also known as 1,2dimethylbenzene, m-xylene is also known as 1,3-dimethylbenzene, and p-xylene is also known as
1,4-dimethylbenzene. The mixture is a slightly greasy, colourless liquid commonly encountered as a
solvent.
Xylenes represent about 0.5–1% of crude oil, depending on the source (hence xylenes are found in
small amounts in petrol and aviation fuels). It is mainly produced from reformate, but is also
obtained from coal carbonisation derived from coke ovens.
Xylenes have a taste and odour threshold of 0.02 mg/L.
TYPICAL VALUES IN AUSTRALIAN DRINKING WATER
Xylenes have only rarely been identified in Australian drinking waters. Natural concentrations in
most water sources are usually very low. However, contamination can occur, usually via exposure to
petrochemicals in surface waters or groundwaters. Known sources of groundwater contamination
include leakage from sub-surface fuel storage tanks (do Rego & Netto, 2007). Emissions of fuel
components from boating use is a known source of contamination of multiple-use lakes and
reservoirs (Schmidt et al., 2004). Xylenes were reported in 3% of samples from an extensive
groundwater survey undertaken in Denmark with the highest concentration being 0.03 ug/L (Juhler
& Felding, 2003). Xylenes have been reported at up to 0.5 ug/L in municipal drinking water in Croatia
(Karaconji et al., 2006), and are occasionally detected in drinking waters in the USA (Williams et al.,
2004).
TREATMENT OF DRINKING WATER
Volatile organic chemicals such as xylenes are most commonly treated in drinking water by aeration
stripping and/or adsorption to granular activated carbon (GAC). A conventional biologically active
sand filter has been shown to be highly effective for the removal of xylenes from contaminated
water, under suitable conditions (Arvin et al., 2004). Effective bioremediation of highly
contaminated groundwaters has also been demonstrated (Sedran et al., 2004; Zein et al., 2006).
MEASUREMENT
A purge and trap gas chromatographic procedure can be used for the analysis of xylenes (APHA,
AWWA & WEF, 2012). An inert gas is bubbled through the sample and xylenes are trapped on an
adsorbent. The adsorbent is then heated and xylenes analysed using gas chromatography with mass
spectrometric (GC-MS) detection (Method 6200 B) or photoionisation (PI) detection (Method 6200
C) (APHA, AWWA & WEF, 2012). The method detection limit is 38 ng/L for GC-MS and 24 ng/L for
GC-PI (APHA, AWWA & WEF, 2012).
Draft for public consultation – November 2012
HEALTH CONSIDERATIONS
Xylenes are readily absorbed after inhalation and metabolised almost completely to methyl benzoic
acid. They can cross the placenta. No data are available on human absorption after ingestion, or on
health effects of oral exposure in humans.
A 2-year gavage study using rats and mice reported decreased growth at high doses (500 mg/kg
body weight per day) but no xylene-related lesions (NTP 1986). There was no evidence of
carcinogenicity in oral and skin administration studies using rats and mice, and xylenes were not
mutagenic in tests using bacteria and mammalian cells.
The International Agency for Research on Cancer has concluded that xylenes are not classifiable as
to their carcinogenicity in humans (Group 3, inadequate evidence in humans and in animals) (IARC
1989).
DERIVATION OF GUIDELINE
The health-based guideline value for xylenes in drinking water was determined as follows:
0.6 mg/L = 250 mg/kg bodyweight/day x 70 kg x 0.1 x 5/7
2 L/day x 1000
where:

250 mg/kg body weight per day is the no effect level based on a 2-year gavage study using
rats (NTP 1986).

70 kg is the average weight of an adult

0.1 is the proportion of total daily intake attributable to the consumption of water

2 L/day is the average amount of water consumed by an adult

1000 is the safety factor in using the results of an animal study as a basis for human
exposure (10 for interspecies variations, 10 for intraspecies variations and 10 for the limited
toxicological end point)

5/7 is used to convert data based on a 5 day per week feeding study to a 7-day week
equivalent.
The WHO guideline value of 0.5 mg/L is based on an adult body weight of 60 kg. The difference in
guideline values is not significant.
The health-based guideline value exceeds the taste and odour threshold of xylenes in water of 0.02
mg/L.
REFERENCES
American Public Health Association (APHA), American Water Works Association (AWWA) and Water
Environment Federation (WEF) (2012). Standard Methods for the Examination of Water and
Wastewater, 22nd Edition. Eds. Rice EW, Baird RB, Eaton AD and Clesceri LS.
Arvin, E., Engelsen, P. and Sebber, U. (2004) Biodegradation of gasoline compounds (BTEX) in a water
works sand filter. Water Science & Technology: Water Supply, 4(5-6), 29-33.
do Rego, E. C. P. and Netto, A. D. P. (2007) PAHs and BTEX in groundwater of gasoline stations from
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