C H A P T E R 37Herbicides and Fungicides pp 657-680Pawan K. Gupta
INTRODUCTION
Ever since the dawn of civilization, it has been the major task of the human race to engage in a continuous endeavor to improve its living conditions. One of the main tasks in which human beings have been engaged is securing relief from hunger, one of the basic needs. In addition, the control of insects, weeds, fungi, and other pests is of utmost importance to our environment (Gupta, 1984). Thus pesticides occupy a unique position among the synthetic chemicals that humans encounter daily. Among pesticides, herbicides and fungicides have found extensive use in the control of plant diseases and the eradication of unwanted plants (Gupta, 2010a,b, 2014). In fact, these chemicals have significantly reduced the strong competition of weeds with important and essential food crops. Along with the improvement in crop varieties, both herbicides and fungicides have increased crop yields, decreased food costs, and enhanced the appearance of food. Without proper controls, however, the residues of these chemicals that remain on foods can create potential health risks (Gupta, 1985, 1987a). Before 1910, no legislation existed to ensure the safety of food and feed crops that were sprayed and dusted with pesticides. In 1910 the first pesticide legislation was designed to protect consumers from impure or improperly labeled products. During the 1950 and 1960s, pesticide regulation, including herbicides and fungicides, evolved to require maximum allowable residue levels of pesticides on foods and to deny registrations for unsafe or ineffective products (Gupta, 1986). In 1961, severe birth defects in infants following thalidomide ingestion by pregnant mothers had a major impact on the field of developmental toxicity. As a result of the thalidomide catastrophe, regulatory agencies in many countries began developing animal testing requirements for evaluating the effects of drugs on pregnancy outcome separately from chronic toxicity studies. Their biochemical mechanisms are complex and less was known about the use of these synthetic chemicals. Subsequent research revealed that long-term low-dose exposure is linked to ill effects, such as immune suppression, hormone disruption, diminished intelligence, reproductive and developmental abnormalities, decline of bird populations, and even cancer (Vettorazzi, 1985; Gupta, 1993; Descatha et al., 2009). With a few exceptions, most of the newly developed chemicals have a low order of toxicity to mammals (Gupta, 2006b, 2016). Out of these, several have been evaluated for their toxic potential and acceptable daily intake by the WHO/FAO Joint Meeting on Pesticide Residues, and guidelines for pesticide residues have been recommended (Gupta, 2006a). Currently, most of the data available is derived from experiments performed on laboratory species or in vitro models. Great care should be taken when extrapolations to other species or environmental situations are attempted. This chapter describes the reproductive and developmental toxicity of herbicides and fungicides in humans and animals.
Reproductive and Developmental Toxicology
http://dx.doi.org/10.1016/B978-0-12-804239-7.00037-8
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