Variability and predictors of weekly pesticide exposure in applicators on organic, sustainable, and conventional smallholder farms in Costa Rica

Description

Background
Estimates of pesticide exposure within agricultural settings in low- and middle-income countries are scarce and hardly any exposure assessment method is readily available.
Aim
We examined the variability in weeklong pesticide exposure among applicators in Costa Rica and identified its predictors.
Methods
We conducted a cross-sectional survey among 221 pesticide applicators from organic, sustainable, and conventional smallholder horticulture farms in 2016. We administered structured questionnaires to assess pesticide application practices at two time points during the application season (4-6 weeks apart). We adapted an existing algorithm to derive weekly pesticide exposure scores and used linear mixed-effect models to examine within- and between-worker score variability. We then identified socio-demographic and occupational predictors of weekly pesticide exposure scores.
Results
We observed large within- (180-fold) and between-worker (70-fold) variability in weekly pesticide exposures (ICC = 0.40). Training on pesticide use appeared to reduce weekly pesticide exposure scores by a third (ß 0.66, 95% CI 0.98-1.01). Increasing work experience with pesticides also resulted in lower exposure scores e.g., an increase of 10 years resulted in a 10% decrease in exposure (ß 0.99, 95% CI 0.45-0.98). Pesticide applicators working on conventional and sustainable farms had exposures two-fold (ß 2.15, 95% CI 1.09-4.23) and 1.5-fold higher (ß 1.63, 95% CI 0.79-3.39) than those working in organic farms, respectively.
Conclusions
We found that weekly pesticide exposure was highly variable within- and between-workers over a relatively short time window during the main pesticide spraying season in smallholder farms in Costa Rica. Younger less experienced pesticide applicators working on conventional farms and who did not receive training on pesticide use appeared to have the highest pesticide exposure.

Period	26 Sept 2019
Event title	31st annual conference of the International Society for Environmental Epidemiology (ISEE 2019)
Event type	Conference
Degree of Recognition	International