Impact of regional bans of highly hazardous pesticides on agricultural yields: the case of Kerala

Abstract

Abstract Background Removing highly hazardous pesticides from agricultural practice in low- and middle-income countries is crucial to ensuring community and environmental health and occupational safety of farmers. However, the approach has been challenged as threatening food production, despite evidence from Asian countries that curbing agricultural use of highly hazardous pesticides does not affect crop yields. In 2011, the state of Kerala, India, banned 14 highly hazardous pesticides resulting in a marked reduction in deaths from pesticide poisoning. Objective We aimed to determine whether the Kerala pesticide bans impacted agricultural yields. Methods We collected data on agricultural production, area under cultivation, and rainfall, published by the Kerala state agricultural department from 2004 to 2018 for eight key crops that had been treated with the banned pesticides. Trends in crop yields (total production/area under cultivation) and rainfall across 14 districts in Kerala were aggregated and analysed using joinpoint regression. These trends were evaluated to ascertain possible associations with the pesticide bans. Results The joinpoint regression analyses showed no evidence for any change in yield trends for any of the eight crops in the year of the pesticide bans (2011), or the subsequent year (2012), suggesting a negligible impact of the bans on crop yields. Steady trends of predominately reductions in overall rainfall, without any change around the time of the pesticide bans, was observed in Kerala throughout the period. No evidence of district-level changes in rainfall that might have offset any potential adverse impacts of the pesticide bans on crop yields was noted. Fluctuations in yield until 2018 could be explained by variation in rainfall, changes in land use, and agricultural policies. Conclusion We found no evidence of an adverse effect on agricultural yields in Kerala that could be attributed to bans of highly hazardous pesticides. This work provides further evidence that such pesticides can be withdrawn from agricultural use without affecting yields. Further studies are required for the whole of India after the national bans of 12 pesticides in 2018 to identify state-level effects of the bans.

Keywords

• Pesticide regulation
• Pesticide ban
• Agricultural output
• Food production
• Pesticide poisoning
• Kerala