Monitoring pesticide use and associated health hazards in Central America.

We established methods for monitoring pesticide use and associated health hazards in Central America. With import data from Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama for 2000-2004, we constructed quantitative indicators (kg active ingredient) for general pesticide use, associated health hazards, and compliance with international regulations. Central America imported 33 million kg active ingredient per year. Imports increased 33% during 2000-2004. Of 403 pesticides, 13 comprised 77% of the total pesticides imported. High volumes of hazardous pesticides are used; 22% highly/extremely acutely toxic, 33% moderately/severely irritant or sensitizing, and 30% had multiple chronic toxicities. Of the 41 pesticides included in the Stockholm Convention on Persistent Organic Pollutants (POPs), the Rotterdam Convention on Prior Informed Consent (PIC), the Montreal Protocol on Substances that Deplete the Ozone Layer, the Pesticide Action Network (PAN) Dirty Dozen, and the Central American Dirty Dozen, 16 (17% total volume) were imported, four being among the 13 most imported pesticides. Costa Rica is by far the biggest consumer. Pesticide import data are good indicators of use trends and an informative source to monitor hazards and, potentially, the effectiveness of interventions.

Acute pesticide poisoning and pesticide registration in Central America.

The International Code of Conduct on the Distribution and Use of Pesticides of the Food and Agriculture Organization (FAO) of the United Nations has been for 20 years the most acknowledged international initiative for reducing negative impact from pesticide use in developing countries. We analyzed pesticide use and poisoning in Central America, particularly in Costa Rica and Nicaragua, and evaluated whether registration decisions are based on such data, in accordance with the FAO Code. Extensive use of very hazardous pesticides continues in Central America and so do poisonings with organophosphates, carbamates, endosulfan and paraquat as the main causative agents. Central American governments do not carry out or commission scientific risk assessments. Instead, guidelines from international agencies are followed for risk management through the registration process. Documentation of pesticide poisonings during several decades never induced any decision to ban or restrict a pesticide. However, based on the official surveillance systems, in 2000, the ministers of health of the seven Central American countries agreed to ban or restrict twelve of these pesticides. Now, almost 4 years later, restrictions have been implemented in El Salvador and in Nicaragua public debate is ongoing. Chemical and agricultural industries do not withdraw problematic pesticides voluntarily. In conclusion, the registration processes in Central America do not comply satisfactorily with the FAO Code. However, international regulatory guidelines are important in developing countries, and international agencies should strongly extend its scope and influence, limiting industry involvement. Profound changes in international and national agricultural policies, steering towards sustainable agriculture based on non-chemical pest management, are the only way to reduce poisonings.

Assessment of pesticide exposure in the agricultural population of Costa Rica.

We describe a model for the retrospective assessment of parental exposure to 26 pesticides, selected by toxicity-based prioritization, in a population-based case-control study of childhood leukaemia in Costa Rica (301 cases, 582 controls). The model was applied to a subset of 227 parents who had been employed or self-employed in agriculture or livestock breeding. It combines external data on pesticide use for 14 crops, 21 calendar years and 14 regions, and individual interview data on determinants (task and technology, personal protective equipment, field reentry, storing of pesticides, personal hygiene) of exposure. Recall was enhanced by use of checklists of pesticides in the interview. An external database provided information on the application rate (proxy for intensity of potential exposure) for each pesticide. The calendar time was individually converted to five time windows (year before conception, first, second and third trimester, and first year of the child). Time-windowed individual data on determinants of exposure and their expert-based general weights and their category-specific hazard values jointly provided an individual determinant score. This score was multiplied by the application rate to obtain an individual index of exposure intensity during application. Finally, average exposure intensity during entire time windows was estimated by incorporating in the model the individual time fraction of exposure during application. Estimates of exposure intensities were proxies assumed to be proportional to dermal exposure intensity, which represents the major pathway of occupational exposure to pesticides. A simulated sensitivity analysis resulted in a correlation coefficient of 0.91 between two sets of 10 000 values of individual exposure indices, based on two different but realistic sets expert-assigned weights. Lack of measurement data on concurrent exposures in comparable circumstances precluded direct validation of the model.

Pesticide prioritization for a case-control study on childhood leukemia in Costa Rica: a simple stepwise approach.

Multiple exposures and rapidly changing use patterns are obstacles for adequate recall of pesticide exposures in epidemiologic studies. We present a simple stepwise approach for prioritization of pesticides as part of the exposure assessment strategy in an ongoing case-control study on pesticides and childhood leukemia in Costa Rica. Pesticide imports between 1977 and 2000, approximately the pertinent exposure period, were surrogates for use data. In the first phase, 323 active ingredients were identified, of which 219 were eliminated based on low usage and absence or negative results in a preliminary search in three major toxicity databases. In the second phase, the remaining 104 pesticides underwent scoring for their toxicodynamic potential (TDP) with regard to carcinogenicity, mutagenicity, and teratogenicity, weighted in this order. Bioavailability was assessed when TDP was multiplied by a weight for persistence and bioaccumulation, producing the intrinsic toxic potential (ITP). ITP was multiplied by an index of quantity (QI) of pesticide used in the exposure period, resulting in a weighted toxic potential (WTP). The top 25 positions in each of the four rankings (TDP, ITP, QI, and WTP) yielded together 64 highest-priority pesticides. This prioritization process has to be complemented with a further breakdown into crop-, time-, and biocide-specific shortlists to achieve a recall tool suitable for developing countries. Different parameters for prioritization assure inclusion of all relevant pesticides with regard to toxicity and bioavailability. The method contributes to cancer epidemiology in developing countries with access to basic use data and the Internet. The method is adaptable to other health outcomes.