Environmental lead in Mexico, 1990-2002.

From the data presented here, it can be concluded that despite some important progress in recent years, in particular, the phaseout of the use of lead in gas, environmental exposure to lead remains a particularly severe problem in Mexico. The lack of recent and adequate information on the presence of lead in air, dust, soil, surface waters, the marine environment, and food is noteworthy. In particular, there are no data on the presence of lead in the environment of industrial cities or in areas where mining and metallurgical activities are predominant, including their nearby environment, such as river sediments or air, and in their inhabitants. As a result, the official conclusion that the major present source of lead for Mexicans is the manufacture and use of lead-glazed ceramics, and the few official actions in this regard lack a solid basis because they rely on data from a few limited studies carried out mainly in Mexico City and its Metropolitan Zone. Although there have been few studies in Mexico on the adverse effects of long-term exposure to lead, the data provided on its presence in human milk, lungs, and bones and the results of the scant studies on its neuropsychological effects on children should be taken into consideration to establish more effective control and protective measures and to support the additional studies required to document the present situation. In particular, more studies should be carried out in lead glazed-ceramic-producing communities and on the hazards of lead to the communities established near industrial areas and along river banks. In future studies, special attention should be paid to establishing a common protocol, with adequate analytical control measures, if possible, with intercalibration of the participating laboratories; this is essential, because at present many of the available data cannot be compared or extrapolated due to their deficiencies in this regard. The situation around the only primary lead smelter in Mexico, Met Mex Peñoles, is a relevant example. Although to date the government and the company have supported the determination of lead in more than 11,000 samples of children's blood, the analyses were carried out in several laboratories, without the minimum requirements to allow them to be valid or compared; thus, the number of children with lead above the different levels recommended by the CDC to establish their risk is not known. In closing, there is still much to be done to document the presence of lead in the environment in Mexico and its adverse effects for health and ecological equilibrium in order to control and reduce its sources; this will require a sustained effort from research institutions and continued support of the authorities, particularly those responsible for health and environment matters. Until these goals are achieved, it will not be possible to state that lead in the Mexican environment is no longer a problem or that it is restricted to particular sources or populations. It is also important to strengthen the legal framework of control to provide adequate enforcement and oversight measures; otherwise, both the existing standards and the new ones will be useless to improve the situation.