Occupational Exposure to Pesticides Applied Among Rice Growers in Malaysia

Abstract

Occupational exposure of rice growers to pesticides can be assessed cost-effectively using mathematical exposure models. This study investigates rice growers’ exposure to pesticides due to the use of knapsack/backpack sprayers, a practice which is widespread in developing countries including Malaysia. Pesticide application information was collected from 23 rice growers during November 2020 – March 2021 using personal interviews and questionnaires. The information was used to predict total daily exposure to individual active substances via dermal and inhalation routes during mixing/loading and application activities using selected exposure models. The estimated exposures were assessed against the agricultural operator exposure levels (AOELs) for single active substances, where any exceedance indicates a potential risk to health. Across the rice growing season, the 23 rice growers had different application practices including total number of active substances applied on single spray days (1–8 compounds), total rice cultivation areas (0.6–3.8 ha), and total number of spraying days (3–13 days). Individuals had estimated average daily exposures to single active substances of 7.7x10− 2 – 1.2 mg kg-bw− 1 day− 1 (7.5x10− 2 – 1.1 and 1.7x10− 3 – 2.2x10− 1 mg kg-bw− 1 day− 1 during application and mixing/loading activities, respectively), where dermal exposure constituted 99.6–99.98% of the total exposure. Overall, 56% of all the applications reported by the 23 growers had exposure estimates that exceeded the AOEL, mainly due to the use of relatively toxic pesticides, products formulated as wettable powders, and growers neglecting to wear gloves whilst handling pesticides. All of these factors can be influenced by provision of training and information on selection of pesticide products and application practices. Study findings can be used to target efforts to minimise pesticide risks to health in developing countries.