In the nineteenth century, when pesticides were first used on a large scale in Europe and the USA, compounds of high mammalian toxicity containing for example cyanide and arsenic were widely employed. The use of such materials and organic compounds of high toxicity such as dinitroorthocresol (DNOC) continued well into the twentieth century. Diagrams and photographs from that era show little use of protective clothing or care in handling and storage of pesticides (Figure 7.1), and risks of exposure were undoubtedly very high. It is then not surprising that ill health and fatalities occurred among those involved with the manufacture and application of pesticides. Indeed, deaths of spray operators were linked to the use of compounds such as DNOC as late as the 1950s in the UK, and into the 1970s in some other parts of Europe.
In occupational use, pesticides present a much higher degree of risk to workers and others in developing, often poorer, countries than in developed, wealthier countries and some of the reasons for this are summarised in Table 7.1. Additional risks are posed by the much greater use of insecticides including organophosphates, carbamates (Thompson and Richardson, 2004) and some organochlorines such as endosulfan in warmer climates.
Risks to health from pesticide concentrates
The most pronounced adverse acute effects to human health from pesticides come from exposure to manufactured products since these normally contain high concentrations of the active ingredient.