Persistent pesticides in Mexico.

As part of the recent increase in the international interest in persistent organic pollutants and their environmental and health hazards, it was found that although most of them have been severely controlled in developed countries, in most developing countries--including Mexico--their import, use, and in some cases production have continued up to the present without sufficient or adequate controls. Despite the large and continuing use of persistent organic chemicals in Mexico in agriculture, public health, and industry, data on their import, production, use, disposal, and the presence of their residues in the environment, food, and human tissues are extremely scarce and widely dispersed. This review is devoted only to the use of persistent pesticides in Mexico; it is the first effort to locate, gather, and analyze this information and to summarize and discuss the past and current situation of the control of these chemicals in Mexico. This review discusses the general background for the use of these pesticides in the country, including historical development, the reasons for substitution by less persistent products in crops intended for export, and the undesirable effect of this substitution on the health of migratory agricultural workers. The current status of the legal framework for the control of pesticides in Mexico is presented with emphasis on its slow and haphazard development; the legal, technical, and administrative reasons for the insufficient enforcement and oversight of the existing regulations and standards are highlighted. The low priority of this research area for the Mexican science and technology authorities and the negative consequences of this low priority on the existence of sufficient reliable data on pesticide residues in the environment and humans in Mexico are also discussed. The available data on production and uses of persistent pesticides in Mexico are presented, and the existing information on their residues in the environment, biota, food, and human tissues in the country is summarized; maps with the location of the main studies are included to stress the lack of information for most of the country, especially for remote areas and regions of agriculture devoted to crops for local, domestic, or self-consumption. The major characteristics of these studies are discussed in specific sections and, on this basis, a general comment on the current situation and forecast for the near future is made. The conclusions summarize the information presented, with particular emphasis on the need to improve and update the legal framework and strengthen the technical and administrative infrastructure essential for the oversight and control of the regulations. The urgency of carrying out new studies, in particular interdisciplinary studies, to establish the current pattern for pollution by these chemicals in Mexico is stressed.

Environmental lead in Mexico.

From the data presented here, it can be concluded that environmental exposure to lead is a particularly severe problem in Mexico. As has been shown, there are very important sources of exposure to this metal: (a) for rural populations who manufacture and/or utilize lead-glazed pottery, (b) for urban populations who are exposed to high air lead concentrations due to the continued use of lead fuel additives, (c) for workers of several industries, mainly those of batteries and pigments, (d) for consumers who routinely eat canned foods such as hot peppers and fruit products, and (e) for the general population living in the vicinity of smelters, refineries and other industries that emit lead. Therefore, in Mexico only those native populations living in very primitive communities, far away from all civilized life, could be expected to be free from this exposure. At the same time, and despite the relatively few data available, it can be stated that the exposure to lead of populations in Mexico could be approaching levels that might be highly hazardous, in particular for the neuropsychological health of children. Regarding the presence of lead in the environment, despite the fact that the available studies are not enough, it is evident that pollution by this metal is widespread and that there is a serious lack of studies for most regions of the country, including several that might be expected to be highly polluted. At the same time, it is evident that the official attention paid to the problem, either in regulations, support of further studies, or implementation of effective control measures has been far from the level needed according to the available data. Lead in gasoline is still used at very high concentrations in all the country, with the exception of Mexico City and its surrounding area, while no studies have been carried out to determine the potential health and environmental impact of this practice in regions outside Mexico City. Despite the fact that the Torreón smelter is one of the largest in Latin America, and although it is located less than two km from downtown Torreón, with the predominant winds blowing in the direction from the smelter towards the residential and central areas of the city, no large scale study has been carried out on the impact of this source on the health of its residents.(ABSTRACT TRUNCATED AT 400 WORDS)

A survey of organochlorine pesticide residues in cheese samples from three Mexican regions.

Organochlorine pesticide residues were determined in cheese samples from three Mexican regions. All samples were found to be contaminated by these residues: p,p'-DDE was present in 100% of the samples. Other pesticides found with high frequencies were HCB, three of the BHC isomers, as well as heptachlor and its epoxide. Also found, although less frequently, were residues of p,p'-DDD, p,p'-DDT, aldrin, dieldrin and endrin. Samples from the region known as Comarca Lagunera had the highest number of pesticides per sample. The highest concentrations of residues were found in cheese samples from the Soconusco and the Comarca Lagunera regions.