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Lead in Mexican Craftworks Liliana
Castillo December 11, 2008
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Introduction
Children Exposed to Lead
Health Issues
The adverse effects of lead in the human system
have been documented for centuries. They include
mild symptoms of nausea, abdominal pain,
excessive lethargy or hyperactivity, and chest
pains. More extreme long-term symptoms include
seizures, comas, and death.
Young children in Mexico are especially
at risk of lead poisoning for various reasons.
They are first of all, highly exposed to it
simply by living in a ceramics producing town.
Lead-glazed pots fired in simple kilns release
lead into the atmosphere. Also, the children
might play in contaminated soil or be directly
exposed, through their families, to the ovens and
the greta. It is of great concern to watch high
lead blood levels in children because it affects
them differently than it does to adults. The
potential for adverse effects is heightened in
children because the intake of lead per unit of
body weight is higher and their bodies are still
rapidly developing. Lead is also very chemically
similar to calcium and is rapidly absorbed by
young childrens bodies. Children can also be
affected through their mothers blood lead
content while still in the womb. Several birth
defects have been correlated with a high blood
lead level.
For more than five centuries, the
lead glaze technology brought to the Americas by
the Spanish has been essential to the creation of
a unique Mexican craftworks tradition. Today,
lead glazed pottery is one of the greatest
sources of lead exposure for Mexicans, especially
children. Although the leaching of lead from
certain glazes has been acknowledged for
centuries, it is not until recent decades that
the public has seen attempts to regulate or solve
the problem. Occasional exposure to lead has been
documented among a number of different
occupations but the level of poisoning discovered
in those in the ceramics and pottery industry of
Mexico has been, proved through various studies,
high enough to produce detrimental health effects
and raise environmental concerns. This often
means little though, to nearly 500,000 Mexican
potters and their families whose subsistence
depends on making these traditional leaded glaze
ceramics and who do not see the hazards of lead
right away. It is thus a continuing struggle for
the Mexican government to rid craftworks of lead.
Studies
The World Health Organization indicates that the
pre-industrial or natural blood lead level in
humans is estimated to have been about 0.016
mg/dl. A concentration of over 15 µg/dL is
considered a high blood level. Oaxaca, Mexico
(Rural area) Sample of 553 men and women over
the age of 15 years data was collected for 413
subjects. The mean blood lead concentration of
the entire study group was 43.8 mg/dl, the median
at 43.2 mg/dl, with concentrations ranging from
8.4 to 99.6 mg/dl. Men tended to have higher
concentrations than women. Among nonpotters,
people using lead-glazed cooking utensils tended
to have higher concentrations of lead in their
blood. Around 30 of the Mexican urban population
uses these utensils. Mexico City, Mexico
(Urban area) Sample of 527 women residing in
Tlalpan, the southern district of Mexico City
among them, 107 women provided blood samples.
Blood lead levels ranged from 1 to 52 µg/dL, with
a mean of 10.6 µg/dL. Five percent of the women
had a blood lead level over 25 µg/dL and 22
over 15 µg/dL. Concluded that the risk of high
blood lead content attributable to use of lead
glazed ceramics was 58. This emphasizes the
public health importance of investigating lead
glazed pottery in Mexico City and highlights the
benefit expected by the regulation of the lead
content in pottery production (Environmental
Health Perspectives, 1991, p119).
Lead in Ceramics/Pottery
Figure 4 http//www.aidtoartisans.org/site/DocServ
er/usaid_leadfree_frontline.pdf?docID822
Figure 3 World Health Organization
The artisans creating Mexicos
traditional ceramic craftworks are usually
habitants of a small pueblo or settlement with
less than 2,500 people. They support their
families mainly by the making and selling of
traditional clay crafts and dishes that are
decorated with a leaded glaze. Pottery is first
painted, then finished and glazed with lead
oxides such as greta, a mixture of approximately
80 lead oxide and 20 water, to produce the
desired glazed result. To give the greta better
adherence, the fired pots are cleaned by rubbing
away the ash marks and surface irregularities
with a fabric. This process is usually done by
the potters assistant which might include
children. Before the second firing of
the pots, the glaze is quickly applied by bathing
the whole or part of the pot in a tin containing
the mixture of lead monoxide and water. It is
then set to dry. Sometimes, to get a black glaze,
a potter might mix a black powder with the lead
monoxide and water and it is then applied with a
brush. The leaded glaze, besides serving
aesthetic purposes, is used to help prevent the
food from sticking to the inside of cooking
utensils. Then the glaze is also applied to the
outside so that the pot yields better resistance
in the fire for cooking. When in contact with
acidic foods however, such as tomatoes and chili,
both a staple of any Mexican diet, the lead in
the glaze is leached onto the foods and therefore
enters the blood through the digestive system.
Exposure to lead is also obtained
through the respiratory system. During the firing
process of lead-glazed ceramics, significant
amounts of lead are released into the air.
Several results of various studies have shown
that lead absorption may be increased in children
who live in communities where kilns, such as the
one picture below, release lead into the air. Air
may be the most significant source of lead for
them.
Policies and Regulations
Mexicos position as a major lead producing
country has brought about strong measures to
minimize potential sources of lead exposure.
Since 1991, the implementation of surveillance
systems has reduced air lead concentrations. More
recently, the establishment of regulations
through the Health Industry on numerous products
including lead-glazed ceramics. A lot of these
measures include public education on the
issues An important element of these programs
is an informed population. Parents who know the
potential sources of lead exposure can and likely
will act to decrease exposure by regularly
washing younger children's hands, teaching older
children to wash their hands often, and avoiding
the use of lead-glazed ceramic ware to prepare or
store food (Environmental Health Perspectives,
1995).
Blood Lead Concentrations in Ceramic Folk Art
Workers
Conclusion and Future Directions
The folk art of Mexican pottery and
ceramics making has deep traditional roots that
slows any change in the production of it. The
growing concern for lead poisoning from
lead-based glazes has caused the Mexican
government to look for solutions. Working with
international agencies such as UNESCO, the
Lead-Free Pottery Alliance, USAID, Aid to
Artisans, and the Mexican Foundation for the
Development of Folk Art, Mexican chemists have
now created lead-free glazes that work as well as
the traditional lead-based formulas. This advance
will not only improve the health of the local
population but it will open an international
market of the products of these artisans,
previously unable to meet export market standards
of lead-free pottery. This will then provide an
economic incentive for artisans to make the
switch to lead-free glazes. USAID mission
director Edward Kadunk Jr. explains, We think
that Aid to Artisans will create better economic
opportunities for Mexican potters by opening
markets and developing products that can compete
in global markets. It is certainly a progressive
step to better the lives of many people.
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References
Ceramic Production in San Marcos Acteopan,
Puebla, Mexico. Druc, Isabelle C. Ancient
Mesoamerica, 2000, Vol. 11, p77-89 Environmental
Lead Exposure a Public Health Problem of Global
Dimensions.Tong, Shilu von Schirnding, Yasmin
E. Prapamontol, Tippawan. Bulletin of the World
Health Organization, 2000, Vol. 78 Issue 9,
p1068-1077 Environmental Urban Lead Exposure and
Blood Lead Levels in Children of Mexico City.
Romieu, Isabelle Carreon, Tania Lopez, Lizbeth
Palazuelos, Eduardo Rios, Camilo Manuel, Yves
Hernandez-Avila, Mauricio. Environmental Health
Perspectives, 1995, Vol. 103 Issue 11 Factors
Associated with Lead Exposure in Oaxaca, Mexico.
Hernandez-Serrato, Isidra Mendoza-Alvarado,
Laura Rojas-Martinez, Rosalba


Gonzalez-Garza, Carlos Hulme, Jennifer
Megan Olaiz-Fernandez Gustavo. Journal of
Exopsure Analysis and Environmental Epidemiology,
Sep2003, Vol. 13 Issue 5, p341-347 Getting the
Lead Out in Mexico. Mindling, Eric. Ceramics
Monthly, Mar2002, Vol. 50 Issue 3, p16 High
blood lead levels in ceramic folk art workers in
Michoacan, Mexico. Fernandez, Gustavio Olaiz
Martinez, Rosalba Rojas. Archives of
Environmental Health,
Jan/Feb97, Vol. 52 Issue 1, p51-55 Lead
Elimination by Traditional Acidic Curing.
Torres-Sanchez, Luisa Lopez-Carrillo, Lizbeth
Rios, Camilo. Salud Pública de México, 1999, Vol.
41 Issue 2, pS105-S108 Lead-Free Mexican Pottery
Sells Better (2003, October). Retrieved December
7, 2008, from http//www.aidtoartisans.org/site/Do
cServer/usaid_leadfree_frontline.pdf?docID822 Le
ad-Glazed Ceramics as Major Determinants of Blood
Lead Levels in Mexican Women. Hernandez Avila,
Mauricio Romieu, Isabelle Rios, Camilo Rivero,
Aracely Palazuelos, Eduardo. Environmental
Health Perspectives, 1991, Vol. 24 p117-120 Lead
in Mexican Children. Weinhold, Bob. Environmental
Health Perspectives, Jul2004, Vol. 112 Issue 10,
pA569-A569
Figure 2. High blood lead levels in ceramic folk
art workers in Michoacan, Mexico. Fernandez,
Gustavio Olaiz Martinez, Rosalba Rojas. Archives
of Environmental Health, Jan/Feb97, Vol. 52 Issue
1, p54
Why the opposition to ban lead?
If lead has been known to be toxic for
so many years, why has the government and the
people been so hesitant to ban it? There are
several answers. First of all, the livelihoods of
about 1.5 million families depends on the
production of leaded glazes. The production of
their craftworks is largely possible due to the
inexpensive component of lead, to take this away
is to deprive these families of a means of making
pottery economically. Secondly, substitutions for
lead are being experimented with but none of the
new glazes produces the same shine or tone as the
leaded glaze. This is what produces traditional
colors and in a culturally rich country like
Mexico, tradition is strong. Lastly, both potters
and consumers do not see a cause and effect
relationship in terms of lead poisoning since it
happens so slowly and gradually often producing
many symptoms that could have been caused by a
variety of other things.
Figure 1. http//www.flickr.com/photos/citlali/3
98157371/