Introduction Pesticide poisoning is widely accepted as a major public health problem in low- and middle-income countries (LMICs) (Buckley1 et al., 2004; Thundiyil2 et al., 2008; Eddleston,3 2018; Jors4 et al., 2018), yet the true scale of the problem is unknown. In the early 1990s, a World Health Organization (WHO) study conservatively estimated that there could be 25 million cases of occupational pesticide poisoning each year, of which around 3 million were considered ‘acute, severe’. The same paper estimated that pesticide poisoning resulted in around 220 000 deaths annually, the majority being a result of self-poisoning, not accidental poisoning (Jeyaratnam5, 1990). No credible estimates have been published since then despite global pesticide use in agriculture almost doubling since 1990, reaching over 4 million tonnes of active ingredient by 2017 (FAO STAT, 2020). This figure does not include other significant pesticide uses, such as domestic use or spraying for vector control. As concerning as they are, these estimates of acute pesticide poisoning are likely to significantly understate the scale of the problem. Studies have shown that a very high number of unintentional poisonings go unreported or misreported (London and Bailie6, 2001; Murray7 et al., 2002; Laborde8 et al., 2015). High levels of acute pesticide poisoning (APP) also signify a potentially larger problem of chronic pesticide exposure, the health impacts of which are even more difficult to quantify. Epidemiological studies examining occupational pesticide exposure have found associations between pesticide exposure and multiple serious chronic illnesses ranging from cancers, to neurological illnesses such as Parkinson’s disease, to reproductive and developmental disorders (e.g. Ntzani9 et al., 2013; Koutros10 et al., 2016; Gallo11 et al., 2018). Some groups are particularly vulnerable to pesticide poisoning, such as women, particularly expectant and nursing mothers, and children. These groups form a relatively large proportion of agricultural workers. According to FAO, women represent 43 percent of the agricultural labour force worldwide (FAOSTAT, 2020). About 59 percent of all children in hazardous work aged 5–17 work in agriculture (ILO IPEC12, 2010). Even if children are not working on farms, many live on farms where the risk of pesticide exposure is relatively high. In addition to accidental exposures, deliberate self-harm is a very significant problem. One in five global suicides are estimated to be due to intentional self-poisoning with pesticides (WHO13, 2004). Pesticide suicides primarily occur in rural areas of LMIC countries in Africa, Central America, South-East Asia and the Western Pacific. Such incidents can be significantly reduced by removing the most acutely hazardous pesticides from sale. As an example, by removing just seven HHPs from use, Sri Lanka is estimated to have prevented 93,000 deaths from suicide (Manuweera14 et al., 2008) without a negative impact on agricultural productivity (Manuweera15 et al., 2008). The high level of poisoning places a heavy financial burden on LMICs. A study by UNEP estimated that the health costs of pesticide poisoning – defined as lost work days, outpatient medical treatment and inpatient hospitalization – in smallholder farming in 37 sub-Saharan countries amounted to US$4.4 billion in 2005 (UNEP16, 2013). Furthermore, regular episodes of mild- or medium-level health effects place an economic burden on farming households in terms of lost work, treatment and travel costs and possible reductions in productive capacity (Sherwood17 et al., 2005; Williamson18, 2011).
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