SPL16 HEALTH EFFECTS OF ORGANOPHOSPHORUS PESTICIDES ON CHILDREN WORKING IN THE AGRICULTURAL INDUSTRY
Authors: Rohlman Diane , Abdel-Rasoul Gaafar , Ismail Ahmed , Hendy Olfat , Olson James , Bonner Matthew 
Published: July 2024

Organophosphorus (OP) insecticides are cholinesterase inhibitors and are commonly applied around the world. Although their use has been phased out, they are still applied in developing countries due to their low cost and effectiveness. Children are exposed to pesticides through their diet, living near fields where pesticides are applied, and through para-occupational exposure. Furthermore, children and adolescents may be engaged in agricultural activities, often working on family farms, performing the same tasks as adults. International labor laws allow children at younger ages to work in agriculture compared to other industries.

Studies examining pesticide exposure in children have focused on prenatal or early life exposures and there are limited studies focused on adolescents who may be working as pesticide applicators or in fields where pesticides are applied. Fewer studies have examined occupational exposure among children, and most have only utilized a single time point and not repeated measures of exposure. Our goal was to determine the impact of repeated exposure to chlorpyrifos, an OP insecticide, on biomarkers of exposure and neurobehavioral performance in adolescents across an application season. Information about the exposure pathways was used to develop an intervention to reduce exposure.

Adolescents in Egypt are exposed to pesticides through both occupational and non-occupational pathways. Male adolescents (applicators and non-applicators) were assessed before, during, and after the pesticide application season. At each session, participants completed a neurobehavioral test battery, symptom questionnaires, and urine was collected for analysis of the chlorpyrifos metabolite 3,5,6-trichloro-2 pyridinol (TCPy). Blood samples were collected at several time points to assess cholinesterase activity.

TCPy metabolite levels increased during the application season and decreased after application ended. Butyrylcholinesterase activity was inhibited during the application season and recovered after application ended. Increased symptoms, neurobehavioral deficits, and reduced lung function were found in applicators compared to non-applicators. Changes in neurobehavioral performance across the application season showed a pattern of impaired performance among the high exposed compared to the low exposed, deficits increased during the application season and remained after application ended. The findings indicate that neurobehavioral deficits increase during the application season, as exposure also increases, and remain after the application ends, even when the biomarkers of exposure are reduced. In addition, a dose-response gradient was found between urinary TCPy levels and attention deficit hyperactivity disorder (ADHD).

Recognizing the need to reduce exposures, an intervention was developed in partnership with the Ministry of Agriculture focused on behaviors during pesticide application and hygiene practices. An educational intervention, incorporating a behavioral change theory, led to an immediate increase in knowledge and awareness of risks associated with pesticides. This increase was sustained over time and led to changes in behavior.

This work was supported by the National Institute of Environmental Health Sciences and the Fogarty Institute through R21 ES017223 and R01 ES022163.