Sources of Pesticide Residues in Food: Toxicity, Exposure, and Risk Associated with Use at the Farm Level

On a global scale, the history of pesticide use in agriculture tells a narrative of beneficial improvements to the standards of living for the overwhelming majority of people. Positive generalizations apart, pesticides have also been responsible for some shocking instances of environmental damage and human harm. The potential for harm is, of course, unsurprising given that pesticides are poisons with definable toxicities to humans, animals and plants. Given also the potentialities of pesticides to cause unintended damage, as constituent members of the food production industry, it behoves us to take measures to minimise the risks associated with their deployment. Although the last 100 years have witnessed an explosion in the scale of pesticide use, it also true to say that the global trend is undeniably towards the use of pesticide active ingredients with reduced environmental and human toxicities. This chapter therefore begins with a brief look at the history of pesticide use from a toxicological standpoint; charting the rise and subsequent decline and fall of pesticide active ingredients whose use is now no longer be considered acceptable. It looks at the methods used to categories active ingredients according to their toxicities and the increasing involvement of international organizations in the regulation of the greatest concerned pesticides. Using these measures, a decline, over time, in the overall toxicity levels of the of pesticide active ingredients available to farmers becomes discernible. This chapter seeks to distinguish between toxicity, exposure and risk; it defines risk as a function of toxicity and exposure where exposure is the actual environmental or dietary concentration of a pesticide. It looks at the means of exposures, including the quality of the decision-making processes at the farm level. Finally, the issue of risk is addressed with emphasis on dietary exposure to pesticides with given toxicities. In this regards, an examination is made by quantifying risk based on the actual exposure levels generated through the consumption of food and beverage commodities.