TABLE 7.6 Neurobehavioral Effects Without Past History of OP Poisoning


Population: Exposed

Population: Control

Health Outcomes or Test Type

OP Insecticide Exposure




Ames et al., 1995

45 male pesticide applicators involved in California cholinesterase-monitoring program found to have 70% decrease in red-cell AChE or 60% decrease in serum AChE from baseline in records from 1985, 1988, 1989, but with no evidence of frank poisoning

90 male friends who had no history of past pesticide poisoning, past cholinesterase inhibition, or current pesticide exposure; no information on other past OP exposure, but 19% in agriculture

Eight computerized NB tests from NES: mood scales, finger tapping, sustained attention, hand-eye coordination, simple-reaction time, digit-symbol, pattern memory, serial-digit learning; noncomputerized Santa Ana dexterity test, pursuit aiming; regression coefficients to compare controls, exposed provided from regression models

History of use of OP insecticidnes; no information on specifics, but significant enough to lower AChE enough to cause removal from work

Used multiple linear-regression models to adjust for age, grade level, language of test (Spanish or English) for NB testing

For motor coordination tests, models involving ethnicity, age, grade level, height, weight used; no difference in alcoholic drinks, cups of coffee, hours of sleep before testing

No significant differences between referents and exposed on NB tests (except serial-digit performance, in which exposed performed better than referents)

Authors state that workers expected not to have current exposure, but basis for expectation not clear; possible misclassification error because referent group may have had significant OP exposure

Stephens et al., 1995

146 sheep farmers exposed to OP in course of sheep dipping; no dipping; in prior 2 months; contact by random-number selection; 69% response rate

143 nonexposed rural quarry workers from same area, response rate 35%

Eight computer-administered NB tests, General Health Questionnaire, Subjective Memory Questionnaire

Retrospective exposure questionnaire; dose index (average number sheep× number dips/year× number of years using OP insecticides); urine sample for dialkylphosphates to confirm lack of exposure during previuos 48 hours

Age, lifetime alcohol, smoking, computer familiarity, educational level, time of day of testing, first language; key ones included as covariates in multivariate analysis

Farmers significantly worse in tests of motor, visuomotor skills, cognition (simple-reaction time, digit-symbol, syntactic reasoning); dose-effect relationship for syntactic reasoning; farmers more symptomatic on General Health

Specific symptoms not reported; number of years of chronic exposure not reported

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