Lead exposure in Latin America and the Caribbean. Lead Research Group of the Pan-American Health Organization.

As a result of the rapid industrialization of Latin America and the Caribbean during the second half of this century, exposure to lead has become an increasingly important problem. To obtain an estimate of the magnitude of lead exposure in the region, we carried out a survey and a literature search on potential sources of lead exposure and on blood lead concentrations. Sixteen out of 18 Latin American and 2 out of 10 Caribbean countries responded to the survey. Lead in gasoline remains a major problem, although the lead content has decreased in many countries in the last few years. The impact of leaded fuel is more important in urban settings, given their high vehicular density. Seventy-five percent of the population of the region lives in urban areas, and children younger than 15 years of age, the most susceptible group, comprise 30% of the population. Other sources of lead exposure identified in the region included industrial emissions, battery recycling, paint and varnishes, and contaminated food and water. Lead is recognized as a priority problem by national authorities in 72% of the countries that responded to the survey, and in 50% of the countries some legislation exists to regulate the lead content in certain products. However, compliance is low. There is an urgent need for a broad-based coalition between policy makers, industry, workers, unions, health care providers, and the community to take actions to reduce environmental and occupational lead exposures in all the Latin American and Caribbean countries. ImagesFigure 1.Figure 2.

'batuery reyln,pitsdvrihe,adcnaiae dan e.La srcgie asa priorintyproblem by+ ational ahorti. in 72% of e contries th t r te Suy nd in 50% oftc ies s exists rgla e l-;tea in prd ucts. However mp ice s low. e is an t need for a broad-basdi coalition between policy makers, industry, workrs, un , helth ca iders, and te m ity to take actions to reduce eanronmentl and pationil lead expres in allthe Latimercan and Caribbean cotries Keywo Catin America lead, so o e. Environ HeaLt Pmpft t105: 398-405 (1997) Rapid industrial development in Latin America and the Caribbean (LAC) has caused the bioaccumulation of some potentially toxic substances, including lead. Several studies have shown that increased blood lead levels may cause behavioral problems or a decrease in the intelligence quotient. In adults, lead exposure may produce hypertension, among other health problems (1)(2)(3).
The main producers of lead in the world are, in decreasing order, Australia, the United States, China, Canada, Kazakhstan, Peru, Mexico, Sweden, the Republic of South Africa, North Korea, and Russia (4). LAC, where Peru and Mexico are the biggest producers, contributes 14% of the world's lead (5). Lead, in its different forms and compounds, is used in many industrial activities. Precise estimates of the number and types of uses of lead in LAC are not available. However, lead is widely used in batteries, paint, and varnishes, as an anti-knock compound in gasoline, as a cable and pipe covering, and in welding and printing (5-).

Materials and Methods
To obtain an estimate of the magnitude of lead exposure in LAC, we conducted a survey through the offices of the Pan American Health Organization (PAHO) in each country. Questionnaires were completed by PAHO environmental engineers using available information from governmental and institutional reports. The survey covered the following topics: 1) lead production, export, and import (in tons per year); 2) industrial uses of lead; 3) vehicular and industrial lead emissions into air; 4) other major sources of lead exposure (water, paint, food); 5) studies on lead content in environmental samples; 6) information on results of blood lead concentrations; and 7) data on rules and regulations to control lead pollution. In addition, we reviewed the literature, government reports, and other unpublished documents and collected information from these sources.
The overall response rate to the survey was 64.3%, or 18 of the 28 countries we contacted. However, while Latin American countries had a response rate of 88.8%, the Caribbean countries had a response rate of only 20%. The countries that replied to the survey were Argentina, Belize, Bolivia, countries using the highest proportion of unleaded gasoline (100, 80, and 46%, respectively). The Dominican Republic, Bolivia, Chile, Colombia, and Argentina follow with 29, 25, 13, 10, and 6% use, respectively. In Peru, the use of unleaded gasoline is minimal (0.2%). El Salvador, Costa Rica, and Honduras did not provide information about the amount of unleaded gasoline used by cars. In most of the previously mentioned countries, regulations have been introduced to control airbome lead levels. However, data reported in the survey (Table 3) suggest that lead concentrations in air have not been routinely monitored except in Brazil, Mexico, Peru, and Venezuela.
Although vehicular lead emissions are considered by 78% of the countries to be a potential health risk, other sources of lead exposure beside vehicular emissions must be considered. While 61% of the countries surveyed consider lead emitted into the air by fixed sources such as foundries, petrochemical products, and mines to be an important health hazard, 67% consider lead-based paint to also be a significant source of lead exposure. Battery recycling is also considered a health hazard. For 50% of the countriescountries like Mexico, Peru, Ecuador, and Honduras, where lead-containing varnishes are used as a glaze for ceramics used in food preparation-contamination of food also constitutes a source of exposure. Finally, for 22% of the countries, water pollution may be considered a problem (Fig. 2).
Lead in environmental samples. Data on lead content in environmental samples (Table 4) have been analyzed in the countries Argentina, Bolivia, Brazil, Chile, Colombia, the Dominican Republic, El Salvador, Guatemala, Honduras, Mexico, Peru, Trinidad and Tobago, Uruguay, and Venezuela. Analyses were performed in air, sediment, dust, food (fish, shellfish, and vegetables), and water samples (13)(14)(15)(16)(17)(18)(19)(20)(21). Some samples contained lead levels that exceeded international standards (22)(23)(24)(25)(26). However, the lack of laboratory certification for many of these analyses compromises the validity of the data. Research carried out in Mexico with environmental samples from 200 randomly chosen households in Mexico City revealed that samples that frequently exceeded standards for lead content were leadglazed ceramics, street dust, and, to a lesser extent, paint. The analysis did not show significant lead concentrations in house dust or residential soil samples (16).
Blood lead levels in the generalpopulation and in occupationally eposedpopulatons. Several countries have monitored lead in the general population, both in children and adults (27)(28)(29)(30)(31)(32)(33)(34)(35). Table 5 presents some of the samples studied, sorted by the sub-jects' residence and age. In general, blood lead concentrations are higher for people who live near fixed sources of lead emissions. In children, average blood lead concentrations varied from 11.5 jig/dl [standard deviation (SD) = 3.7] to 39.0 pg/dl (SD = 5.0).
The proportion of children with blood lead concentrations l higher than 10 pig/dl varied from 45  In urban populations, the average blood lead level ranged between 3.4 psg/dl (SD = 1.6) in Trinidad and Tobago and 28.8 pg/dl in Ecuador. The proportion ofchildren with blood lead concentrations above 10 jg/dI varied from 0 to 100%. For adults, concentrations were similar, although generally slightly higher. In Mexico, unleaded gasoline was introduced in 1991, and a significant decrease in blood lead concentrations has been observed in the population of Mexico City. Today, the proporton of children estimated to have blood lead concentrations exceeding 10 pg/dl ranges between 30 and 50% (36). In adults, this proportion is somnewhat higher. The use of lead-glazed ceramics by some groups to cook and store food may partially explain this observation. For people occupationally exposed to lead, blood levels were higher-between 21.4 and 48.8 pg/dl and within a range of  pg/dl (37)(38)(39)(40). However, data are insufficient to determine the magnitude of lead poisoning in this population.
Legislation and control measures. Finally, it is important to determine the government's perspective on the problem of lead exposure and to know if a given country is taking action to prevent or control such exposure. In 72% of the countries that answered the survey, government rep-  resentatives identified lead as a public health problem. In 50%, existing legislation regulates lead contents in various environments, but enforcement of regulation is low, only 28%. In 44% of the countries, legal instruments exist to control lead exposure, and in 50% of the countries, some control measures have been applied.

Discussion
The information in this survey must be interpreted with some caution because of the lack of complete data from many coun-

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HonurasProduction  tries. In addition, there are few laboratories in LAC certified for blood and environmental lead measurements, which limits the evaluation of lead exposure in the region and the assessment of control programs. Nevertheless, the results presented suggest that lead poisoning is a significant problem in this region. Most of the governments are aware of this problem, but actions to confront it are limited. Based on this survey, 13 countries have at least begun to introduce unleaded gasoline; however, the use of unleaded gasoline is still very limited.
Lead poisoning is a preventable disease. During the 1994 Summit of the Presidents of the Americas, it was agreed that lead should be phased out of gasoline as an important step toward the prevention of lead intoxication. The results of this survey and literature search emphasize the need to implement the agreement of the summit in LAC. In most of the countries, some part of the population presents average blood lead concentrations that exceed the 10 ,ug/dl recommended by the Centers for Disease Control and Prevention (2. It is also important to note that toxic effects in children and adults have been observed at even lower concentrations (3). The population in LAC is mainly urban-75% of all people in the e is used but the contents are unknown; NU, not used.  (36,(42)(43)(44). In general, residents in areas of intense vehicular traffic have blood lead levels much higher than populations exposed to less vehicular traffic (45). Continued attention should therefore be given to reducing the lead content of gasoline because this will markedly reduce lead exposure for a significant proportion of the LAC population. In order to evaluate the impact of phasing lead out of gasoline on the blood lead levels in high risk populations (particularly in children and women of reproductive age), it would be useful to develop and implement a standardized surveillance system in different countries. In Mexico, such a system has been established and the decrement of blood lead levels in a randomly selected sentinel population was observed in relation to the decrement in atmospheric lead as low-lead and unleaded gasoline was introduced (36). The phasing out of lead from gasoline has clearly shown a positive benefit with respect to cost (46). A similar evaluation conducted in Mexico has also provided evidence of such economical benefits (43). Although leaded gasoline is a major source of lead exposure in many countries, it is important to remember that there are other important sources of exposure, such as industrial use (including paint, varnishes, and batteries) and contamination of food and water. However, there are few data on the effects of these other uses have on population lead exposure. Broad-based coalitions are needed between policy makers, industry, workers, unions, health care providers, and the community in order to implement actions to reduce environmental and occupational lead exposure and to prevent lead poisoning in all the countries of the Americas (4?).    Environmental Health Perspectives * Volume 105, Number 4, April 1997