Measuring pesticide ecological and health risks in West African agriculture to establish an enabling environment for sustainable intensification

Abstract

We outline an approach to pesticide risk assessment that is based upon surveys of pesticide use throughout West Africa. We have developed and used new risk assessment models to provide, to our knowledge, the first detailed, geographically extensive, scientifically based analysis of pesticide risks for this region. Human health risks from dermal exposure to adults and children are severe enough in many crops to require long periods of up to three weeks when entry to fields should be restricted. This is impractical in terms of crop management, and regulatory action is needed to remove these pesticides from the marketplace. We also found widespread risks to terrestrial and aquatic wildlife throughout the region, and if these results were extrapolated to all similar irrigated perimeters in the Senegal and Niger River Basins, they suggest that pesticides could pose a significant threat to regional biodiversity. Our analyses are presented at the regional, national and village levels to promote regulatory advances but also local risk communication and management. Without progress in pesticide risk management, supported by participatory farmer education, West African agriculture provides a weak context for the sustainable intensification of agricultural production or for the adoption of new crop technologies.

Keywords: food security; pesticide regulation; risk assessment; sub-Saharan Africa; sustainable intensification.

Figure 1.

Diagrammatic portrayal of the roles that education and existing agricultural knowledge (A.K.), and pesticide regulation and its enforcement play in pest management decision-making by farmers. Decisions are affected by many other factors, summarized as drivers and eco-regional context in the figure. Farmers monitor attributes of the system (outputs), as should regulatory authorities, and ideally feedback from the status and trends in outputs will enable adaptive responses by farmers and also the capacity of regulations to limit adverse effects of pesticide use. The diagram illustrates the connection between these feedback processes and the outcomes that underlie sustainable production, and ultimately food security. ‘FAB’ represents functional agricultural biodiversity. (Online version in colour.)

Figure 2.

Pesticide risk impact areas (hectare) expressed as the product of risk index values from ipmPRiME and the area over which a given chemical was applied throughout West Africa in the surveyed villages in 2007 and 2010. Vertical axis gives the mean ipmPRiME risk score derived for each pesticide. The horizontal axis serves to spread out the impact area bubbles, to enable individual pesticides to be identified (numbers above each bubble indicate the individual compounds, listed in table 5). Only pesticides that exhibited a cumulative risk score of more than 0.1 are shown in the figure, to focus on chemical uses that led to intermediate or high risks in a given index. (Online version in colour.)