Insect repellents as an environmental chemical toxicant to human health

Insect repellents are used from the traditional times. The most conventionally used IRs were the naturally derived components that have proved to have insect-repellent activity. With the advancements in the scientific field and research, many synthetically derived insecticides were introduced into the market, like DEET, IR3535, diethylphenyl acetaminde permethrin, and picaridin, which showed good activity of insect repellents but, on the contrary, displayed the toxic effects on the human health too. Thus, this chapter discusses several types of IRs, both naturally and synthetically generated, that are now on the market, as well as their hazardous effects on people, as illustrated by case studies. This chapter also covers several approaches for assessing the toxicity and safety of IRs that are intended for human use.