Chronic pesticide poisoning from persistent low-dose exposures in Ecuadorean floriculture workers: toward validating a low-cost test battery.

Chronic pesticide poisoning is difficult to detect. We sought to develop a low-cost test battery for settings such as Ecuador's floriculture industry. First we had to develop a case definition; as with all occupational diseases a case had to have both sufficient effective dose and associated health effects. For the former, using canonical discriminant analysis, we found that adding measures of protection and overall environmental stressors to occupational category and duration of exposure was useful. For the latter, factor analysis suggested three distinct manifestations of pesticide poisoning. We then determined sensitivity and specificity of various combinations of symptoms and simple neurotoxicity tests from the Pentox questionnaire, and found that doing so increased sensitivity and specificity compared to use of acethylcholinesterase alone--the current screening standard. While sensitivity and specificity varied with different case definitions, our results support the development of a low-cost test battery for screening in such settings.

Poverty, production, and health: inhibition of erythrocyte cholinesterase via occupational exposure to organophosphate insecticides in Chiapas, Mexico.

Occupational exposure to organophosphate pesticides and its effects on the concentration of erythrocyte cholinesterase in the rural population of Chiapas, Mexico, are described. The authors surveyed agricultural production and pesticide use was surveyed among 199 campesinos (peasants) in three communities that used various agricultural production systems. The authors measured the concentration of the cholinesterase enzyme in blood samples obtained from 65 campesinos before and after exposure to the insecticide. The authors established a comparison value for the population that was not exposed occupationally. The exposure values of the enzyme concentration were significantly lower than preexposure values (p = .00001) and reference group values (p = .0008). Individuals in the community characterized by subsistence production had significantly lower levels of the enzyme than individuals in the other two communities (p = .01). This result suggested that a greater risk of adverse health effects existed among the poorest communities.

Butyrylcholinesterase variants (BCHE and CHE2 Loci) associated with erythrocyte acetylcholinesterase inhibition in farmers exposed to pesticides.

Farmers exposed to pesticides and classified as mildly poisoned and controls on the basis of erythrocyte acetylcholinesterase (AChE) activity were examined for butyrylcholinesterase (BChE) genetic variability. The mildly poisoned group showed a significantly higher frequency of non-usual phenotypes (13.1%) than the control group (1.7%). These phenotypes showed a relative risk (RR) of 8.8 of erythrocyte AChE inhibition when compared to the usual phenotype. Among the subjects with the usual phenotype, the CHF2 C5- phenotype was more frequent in the mildly poisoned group (94.3%) than in the control group (81.0%), leading to an RR of 3.9 when compared to the CHE2 C5+ phenotype. When the total sample was classified into two groups (usual CHE2 C5+ and other phenotypes), the usual CHE2 C5+ phenotype was found to be responsible for a preventive fraction of about 14% of the cases of mild poisoning. The present data suggest that BChE genetic variability offers differential protection against erythrocyte AChE inhibition.

Cholinesterase activities of workers exposed to organophosphorus insecticides in Pakistan and Haiti and an evaluation of the tintometric method.

Five reference laboratories were established in Pakistan for monitoring cholinesterase (ChE) activities of workers exposed to organophosphorus compounds. ChE activities were determined by the Michel and tintometric method. Observations of ChE activities were made during two malaria seasons. The first season showed that although a significant depression of cholinesterase occurred among some of the workers, the ChE activities of workers were within the normal range during the following season. The reason for the difference is discussed. Similar studies were undertaken in Haiti. Mean and standard deviations (SD) were calculated for comparison of the tintometric versus the Michel method. The data show a correlation between the methods. For further evaluation of the tintometric method, organophosphorus and oxon analog inhibition of cholinesterase were determined in vitro. The tabulated data show that the tintometric method is adequate for determining whether a worker is exposed to dangerous amounts of insecticides.