Occupational risks and health effects of pesticides in three commercial farming systems in Ethiopia

Abstract

Occupational pesticide exposure is one of the most important occupational risks among farmers and farm workers in Africa. In Ethiopia agriculture contributes 47% of the total Gross domestic product (GDP) and employs 80% of the work force. The main objective of this study was to assess pesticide related knowledge, occupational pesticide exposure and adverse health effects due to pesticide exposure in different commercial farming systems including newly developing farming systems in Ethiopia. The study was conducted in the Central Eastern part of Ethiopia by including occupationally exposed farmers and farm workers selected from large-scale greenhouses (LSGH), large-scale open farms (LSOF) and small-scale irrigated farms (SSIF). Also occupationally unexposed study subjects were selected from small scale subsistence farm areas and office farm workers. The study consisted of two cross-sectional surveys in 2012 and 2014 which were conducted sequentially in the same study area and farming systems. Pesticide related knowledge, attitude, practices (KAP) study indicated an increase (6-13 fold) in pesticide use intensity from previous estimates, use of DDT on food crops, poor attainment of pesticide related trainings, limited use of personal protective equipment (PPE) and hazardous empty pesticide container management. To assess the exposure of individuals participating in the two surveys we developed semi-quantitative occupational pesticide assessment algorithms (i.e. one for applicators and another for re-entry workers). The algorithms were used in our studies on acute as well as chronic health effects of pesticides. A survey on neurobehavioral symptoms and acute pesticide poisoning (APP) in pesticide applicators indicated a16.0% prevalence of APP. This study also indicated a decrease of APP risk with years of employment and an association of both cumulative pesticide exposure and past APP with neurobehavioral symptoms. Two consecutive cross-sectional surveys performed on respiratory health indicated exposure-response associations of chronic cough and shortness of breath with estimated pesticide exposures. The lung function measurements of the second survey indicated a reduction in FEF 25-75 %, FEV1 and risk of FEV1/FVC ratio< 0.8 with increasing pesticide exposure. The observed effects of exposure to pesticides on respiratory function of Ethiopian farmers and farm workers are clinically significant with a predicted decrease of 41.1 ml and 127.6 ml/s in FEV1 and FEF 25-75 % per year of exposure to pesticides, respectively. Results from the secondary sex ratio (SSR) study indicated diversions from Ethiopian expected values in opposite direction for paternal (applicators) exposure to pesticides (relatively more boys) compared to maternal (re-entry work) exposure to pesticides (relatively more girls). After controlling for potential confounders being an applicator showed a border line significant increase of SSR (+0.113 SE 0.067). Interestingly, life style factors as alcohol and Khat consumption showed significant but opposite associations with SSR in male applicators. This study is the most comprehensive epidemiological study to date that was carried out on occupational pesticide risks and health effects among Ethiopian farmers and farm workers. The study showed a stark increase in pesticide use, poor pesticide related knowledge and increased respiratory, neurological and reproductive health effects among exposed farmers and farmworkers. Farmers’ and farm workers’ occupational health and safety must be guaranteed and should not be compromised at any cost in Ethiopian agriculture.