Pesticide exposure and adverse health effects in Malaysian farmers

Introduction: Agriculture remains an important sector in the Malaysian economy and pesticides are widely used in this sector. The use of pesticides poses a serious health threat to the population especially occupationally exposed populations. However, there is limited information on pesticide exposure and their health effects among farmers in Malaysia. Hence, the aims of this study were to assess pesticide exposure and investigate the health impact of pesticide use. Methods: A cohort study was conducted in Bachok and Kota Bharu districts, Kelantan state, east coast of Malaysia between September 2018 and February 2019. Information on demographics, general health, working practices and pesticide exposure was collected. A symptom diary was used to collect data on self-reported ill-health symptoms for seven days. The symptoms were categorised into pyrexial and respiratory factors based on previous published literature. Pesticide spraying was observed in order to complete the Dermal Exposure Assessment Method (DREAM) and pesticide exposure algorithms used to estimate exposure intensity scores based on Agricultural Health Study (AHS) and Ethiopian Farmer Study (EFS). Urine samples were collected in pre- and post-spraying and were analysed by using liquid chromatography-mass spectrometry. Associations between pesticide exposure and self-reported ill-health were examined. Results: 150 farmers growing either rice (n=83) or vegetables/fruits (n=67) participated. For farmers who reported using a specific pesticide, urine levels of the pesticide metabolite postspraying were higher than pre-spraying levels for chlorpyrifos (p < 0.01), pyrethroids (p < 0.01) and cypermethrin (p < 0.01). All of the farmers who had minimal/low level of urinary metabolites used backpacker sprayers. Farmers who had high/very high level of urinary metabolites were exposed more on their head or face (p=0.03). The median EFS pesticide exposure intensity was higher for rice farmers compared to vegetable/fruit farmers (p < 0.01). 32.7% of farmers reported on at least one occasion a health symptom occurring within 48hours after spraying in the spraying week. Symptoms were more common among the rice farmers (p=0.04) and the most common symptoms were feeling unusually tired which was reported by 16% of farmers, followed by feeling sweaty, shivery and feverish (13.3%) and having a headache (13%). 18.7% of the farmers were identified as having either a pyrexial factor occurring within 48 hours of spraying. The farmers who wore face shields had an increased risk of having the pyrexial factor (OR 2.9; 95% CI: 1.01, 8.71) and the farmers who wore chemically resistant boots had a reduced risk of having the pyrexial factor (OR 0.23; 95%CI: 0.08, 0.70). The farmers who sprayed less than 1 day per week had 5-fold increased risk (OR=5.22; 95%CI: 1.69, 17.22) of having average/poor health and the farmers who had an incident while using pesticides had increased risk of having high blood pressure (OR=4.06;95%CI:1.21,11.66) and Parkinsonism/neurology symptoms (OR=4.48; 95%CI: 1.46, 10.94), respectively. Conclusions: Farmers were exposed to pesticides in the spraying session based on assessment of urine metabolites, pesticide exposure intensity score and DREAM score parameters. Acute health symptoms were observed among the farmers following pesticide exposure. However, the symptoms were not specific to pesticide and might be due to other causes. The results collected in his study will provide baseline data on pesticide exposure and health effects in Malaysia.