Children BEWARE: Lead Glazes and Lead Paints
By Zara Rashid
WHAT IS THE POINT?
LEADED GLAZE
MEXICO CITY LEAD CASES
Lead is one of the earliest metals discovered by human beings. With an
atomic number of 82, lead is soft, malleable, dense, resistant to corrosion,
and toxic. Lead has been used for plumbing, stained glass, statues, and
coffins. Not only was lead used for objects, it was regarded as a great
sweetener for wine; lead acetate can be referred to as sugar lead. Lead was
further used in paints, glazes, gladiator costumes, preservatives, and writing
tools. Some recent uses of lead include semiconductors, car batteries, and
shields for radiation. Although lead is commonly thought of as an element, it
is also greatly responsible for the progress of civilizations and their possible
falls. For example, lead was a great economic source for the Romans, but it is
also hypothesized to have caused the fall of the Roman Empire. Although lead
clearly plays a beneficial role to the progression of humanity, the purpose of
this poster is to illustrate the negative effects of lead on children. Therefore,
the focus will be on the effects of leaded glazes and paints on children. It is
important to recognize the fatality of lead poisoning on children in order to
prevent it in the future. To illustrate this further, studies from the United
States, Mexico, and Australia will be used.
Lead poisoning is a serious disease caused by man-made hazards. Lead
poisoning occurs when too much lead enters the body; it usually builds up
over time. Lead can enter the body in five ways: subcutaneously, gunshot
wound, inhalation, digestive track, and injection. When lead enters the body,
it is carried into the bloodstream and throughout the organs, including the
brain, nervous system, and kidneys. No one is safe from lead poisoning, but
children across the globe are at the greatest risk. Although childhood lead
poisoning has decreased in the United States, it is extensive in
underdeveloped nations due to the lack of capacity to measure blood lead
levels and due to the limited ability to deal with the toxic exposures.
The earliest glazes are traced to the Egyptians. Across the continent, the Chinese invented
sancai (tricolor glaze) by adding metal oxides to the original lead glaze. The Silk Road helped to
further ideas to the Islamic potters in the Middle East who invented a majolica (white high-luster
ceramic) through lead-tin glazing. This then traveled throughout Europe and became specific to
each location. It further traveled to the Americas, where Mexico partook in the majolica creation.
Lead glaze is toxic due to the presence of lead oxide. Unless the leaded glaze is fired at a
temperature above a normal fire (500-600 C), the lead in the glaze will remain unstable. Acidic
substances kept in traditional pottery are more likely to be contaminated because solubility of
lead increases at low pH. The highest lead content observed in pottery is from Guadalajara,
Mexico City, and Oaxaca.
Studies have shown a clear correlation between the use of lead-glazed ceramic ware for
cooking or food preparation and elevated blood lead levels. Lead glazing of ceramics for food
storage and cooking is a focal source for Latin America. In La Victoria, Ecuador, the production of
lead glazing of ceramics is the primary occupation. Furthermore, lead is extracted from
automobile batteries and used for glaze in the production of roof tiles. Children live, play, and eat
near the lead-glazing kilns. Due to their close proximity, when 166 children (4 months to 15 years)
were tested, the mean blood lead level was 40.0 mcg/dL. In Mexico, it is estimated that there are
around 500 lead-glazing kilns. An incident at the U.S. Embassy in Mexico occurred where a child
drank left over fruit punch from a lead-glazed punch bowl. When tested, his blood lead
concentration was 92 mcg/dL.
Experiment: A study was done to discover the amount
of lead from the lead-glazed ceramic that is leached into
food. For the experiment, bowls with lead-glaze were
bought from Boxasni, Mexico. Some ceramic bowls was
filled with 4% acetic acid (vinegar) and allowed to stand
for 24 hours. In another experiment, a large quantity of
red salsa with tomatoes, red chilies, and onions, bought
from Queretaro, Mexico, was put into bowls and mixed
periodically.
At the end of the experiment, it was found that the
mean level of lead in the salsa was 0.93  0.13 ppm,
which was higher than expected. Through the results, it
was concluded that the highly acidic foods (salsa)
extracted considerable amounts of lead, which
supported earlier studies.
In order to find the amount of lead poisoning in children, a study was created to
test private and public schools around Mexico City. The researchers collected
information and performed analysis on samples including colored pencils and
ceramics taken from a Mexican market.
Due to the frequent use of lead chromates, the proportion of lead can reach 50%
for exterior lead-based paint. Because lead is soluble in acidic liquids, it can be
released into the environment through acid rain and drainage water. Lead pigments
were further used in children’s toys and pencils, which children tend to bite and thus,
ingest the chips. Second and third graders, aged seven to nine years, were chosen
from two public schools. The parents filled out questionnaires and the blood lead
levels were tested.
TOXICITY in CHILDREN
Toxicity Levels
Statistics
 More than 3 million children sixyears-old and younger have lead
poisoning
 In 2005, 8123 children were found
to have lead poisoning in Illinois
 1 in 20 preschoolers has high blood
lead levels
 Each year in the United States,
 CDC lowered definition of lead
310,000 one to five-year-olds have
toxicity to 10 mcg/dL from 60 mcg/dL unsafe blood lead levels
in 1960s
 In 3.4% cases of lead poisoning,
 Mean blood lead level in 1975 was children sustain permanent mental
15.5 mcg/dL (2 mcg/dL in 2004)
retardation
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Class I: less than 10 mcg/dL
Class II-A: 10 to 14 mcg/dL
Class II-B: 15 to 19 mcg/dL
Class III: 20 to 44 mcg/dL
Class IV: 45 to 69 mcg/dL
Class V: more than 70 mcg/dL
Symptoms
constipation,
stomachaches,
decreased appetite,
hyperactivity,
sleeping problems,
poor attention span,
Complications
headaches,
weight loss,
vomiting,
anemia,
abdominal pain,
irritability
coma, mental retardation,
death,
speech handicap,
stroke, learning disabilities,
convulsions, behavioral problems,
lowered I.Q., neurological deficits,
kidney disease,
heart disease
Lead is more harmful to children because it greatly affects the child’s
developing nerves and brain. A level of 10 mcg/dL or more is considered
unsafe for a child. The American Academy of Pediatrics recommends that all
kids get tested for lead when they are infants. Lead is tested through a blood
test. If the child has a high blood lead level, chelators are given through
intravenous or intramuscular injections or by mouth; the chelator attaches
itself to the lead and pulls it out into the urine.
Comparison to Adults
Symptoms of adults include pain,
tingling of the extremities, memory loss,
mood disorders, reduced sperm count,
muscular weakness, blurred vision, wrist
drop, Burton’s lines, and hallucinations
may occur.
Since children are affected to a greater
extent, the more lead they have in their
system, the quicker they approach death.
Adults, however, are able to handle
more lead than children and thus, have
different complications including high
blood pressure, digestive problems, nerve
disorders, cataracts, memory and
concentration problems, muscle and joint
pain, and pregnancy complications.
Effects of lead on children and adults
Toxicological Profile for Lead (1989)
LEADED PAINT
In early history, pigments were formed from lead. The white
pigment was lead carbonate (cerruse), black was galena, yellow was
lead-tin chromate, and red was minium. Lead played a great role in
paint because it was stable and easy to manufacture. Spinello
Aretino’s The Madonna and Child Enthroned with Angels has leadtin yellow and red lead on a white lead background; blue comes
from mixing deep blue with white lead.
There were two types of lead-tin yellow pigment. The yellow
occurred when minium was treated with tin. Lead-tin II was
replaced by lead-tin I, which was then replaced by lead antimonate.
Lead chromate was itself nontoxic, but the yellow chrome was used
as an adulterant in food. The yellow coloring was added to sweets
and custard. Red lead was minium and when used in egg tempura, it
was stable. When exposed to air, however, it turned dark. Red lead
paint was used for primers since it was an anti-corrosion inhibitor.
Furthermore, Accum (1820) reports that red lead was used as an
adulterant in cayenne pepper, and Hungarian paprika.
Red Lead Recipe (1751)
Stir lead over heat in an
open vessel until a grey
powder (masticot) is
formed. Heat the powder
to form the minium.
Yellow Lead Recipe in
Bolognese Manuscript
Yellow lead is to be
roasted with minium and
finely ground sand.
The Madonna and Child Enthroned with Angels
by Spinello Aretino
White Lead Recipe from Aristotle
Place lead, the size of a brick, into a
jar over vinegar. In ten days, open
the jar and scrape the mold off of
the lead. Repeat this until all lead is
gone. The part that is scraped off is
then ground in a mortar. White lead
is left at the bottom.
Leaded paint is highly toxic to children since it causes pica, an eating disorder that gives one
cravings for nonfood items; occurs when kids eat paint chips. They are exposed to lead from paint
through either directly eating the paint chips or ingesting lead contaminated house dust because
of hand-to-mouth activity. Lead based paint can contaminate dust when it deteriorates or is
disturbed during maintenance, repainting, demolition, or paint removal. Because of higher
metabolism and greater physical activity, children inhale more lead per unit of body weight. Leadbased paint in old, ill-kept housing is the major source of exposure for children.
A random sample of 831 housing units were evaluated from 1998 to 2000. Sixty-four million
had lead paint in 1990 compared to 38 million in 2000. In 1990, the U.S. Department of Housing
and Urban Development (HUD) showed that lead-based paint was prominent in numerous
dwellings. Results of the sample showed that 25% of the nation’s housing (24 million units) had
significant lead-based paint hazards. They concluded that childhood lead poisoning was caused in
older housing due to the lead-based paint.
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Blood lead level ranged from 5.0 mcg/dL to 40.6 mcg/dL
88.6% of children had level more than 10 mcg/dL
41% of kids bit pencils had level of 21 mcg/dL
Compared to 18 mcg/dL for those who didn’t bite pencils
In another study, the researchers looked into lead-glazed ceramics. The pottery
was hardened at a low temperature allowing the lead to remain in the glaze and later
be released. Children aged seven to nine years from two public schools were tested
to see if whether they ate from lead-glazed ceramics and drank juice kept in leadglazed pottery.
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Blood lead level ranged from 3.0 mcg/dL to 48.0 mcg/dL
23% reported to using ceramics had mean of 18.8 mcg/dL
Compared to 11.8 mcg/dL for those who did not
Mean level of 22.2 mcg/dL for those who drank juice
Compared to 12.4 mcg/dL who did not
Researchers concluded that the major predictors of lead
levels for children were the use of ceramics to prepare foods
and store juice, traffic, and habit of biting colored pencils.
AUSTRALIAN LEAD CASES
In June 1993, the NHMRC revised its level of concern, then set at 25 mcg/dL, to
proclaim a new national blood lead upper goal for all Australians of 10 mcg/dL and
specified that 90% of children aged 1 to 4 years should have blood lead level less than
10 mcg/dL by 1998.
Toddlers are at an increased risk because they engage in greater hand-to-mouth
activity; they absorb more lead than older persons. A study was conducted on children
attending child care centers in the Eastern Sydney Area. There was a questionnaire
distributed to parents asking about age of housing, removal of paint, play surfaces,
hobbies involving lead, frequency of thumb-sucking, and pica.
 13.6% of the study population had lead level equal to or above 10 mcg/dL
 Range in blood lead was 2.8-15.7 mcg/dL
 Girls who were frequent thumb-suckers had mean of 1.8 mcg/dL higher than girls
who were infrequent thumb-suckers
 Thumb-sucking led to greater hand-to-mouth activity and a greater tendency for pica;
greater effect in girls than boys (uncertain why this is the case)
In 1904, an article was published regarding lead poisoning in children in Queensland.
The researcher claimed that painted walls and railings were the source of lead. There
were four children in the study who lived in rooms that had been recently painted.
Furthermore, the freshly painted surfaces and those exposed to sun and air were more
toxic.
The two-year-old child moved on December 14th and became ill with colic and
vomiting. It was found that the house had fresh paint that would contaminate a child’s
hands. Samples were taken from the walls, floor and verandah.
 Walls had 2 mg of lead carbonate
 Floor had 2 mg of lead carbonate
 Verandah had 12 mg of lead carbonate
It was thus concluded that the older children became lead poisoned due to biting
their nails. The younger children became lead poisoned by eating paint chips and
sucking their thumbs.
BATHTUB LEAD
In April 1995, Good Morning America reported the dangers of bathtubs. Bathtubs
can contain up to 88% lead in the glaze. Manufacturers used lead because it was
inexpensive, durable, and could be fired at low temperatures.
Lead-glazed bathtubs are dangerous for children under 7-years-old because the
enamel can crack and allow for the lead to leak into the water during bath time.
The hotter the water is, the more lead is
leached. Young children and infants are more
sensitive since their bodies are still
developing. The lead from the tubs and sinks
rubbed off and ended up on cloths, which
was sometimes ingested by the children.
Vermont Housing found that 75% of tubs
tested in pre-1978 housing were positive for
lead and 40% had a detectable amount.