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Lead in Mexican CraftworksLiliana CastilloDecember 11, 2008

Introduction

Lead in Ceramics/Pottery

Children Exposed to Lead

Studies

Conclusion and Future Directions

References

OPTIONALLOGO HERE

Why the opposition to ban lead?

Blood Lead Concentrations in Ceramic Folk Art Workers

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Health Issues

Policies and Regulations

Figure 1. http://www.flickr.com/photos/citlali/398157371/

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.

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

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.

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/DocServer/usaid_leadfree_frontline.pdf?docID=822

Lead-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 4

http://www.aidtoartisans.org/site/DocServer/usaid_leadfree_frontline.pdf?docID=822

The artisans creating Mexico’s 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 potter’s 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.

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.

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).

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.

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 children’s bodies. Children can also be affected through their mother’s blood lead content while still in the womb. Several birth defects have been correlated with a high blood lead level.

Mexico’s 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).

Figure 3: World Health Organization