Health and Environmental Effects of Pesticides

Persistent toxic substances (PTS) are pesticides, some industrial chemicals, and some unwanted by-products of industrial processes or combustion. Examples are: DDT, its metabolites & relatives; lindane (γ-BHC), HCH, chlordane, heptachlor, aldrin and its epoxide dieldrin, endrin and its epoxide isodrin, mirex, kepone, toxaphene, endosulfan, pentachlorophenol (PCP, insecticide, fungicide and herbicide), organic mercury and organic tin fungicides, in addition to the herbicides atrazine [1-3]. Other chemicals are: polychlorinated biphenyls (PCBs), which are used in the transformers and capacitors as hydraulic, and heat-exchange fluids, octylphenols, nonylphenols, phthalates, dioxins (PCDDs) and furans (PCDFs) (unintended by-products), PAHs (polyaromatic hydrocarbons), PBDE, chlorinated paraffins, HCB, and chlorodecene [4]. The problems of these chemicals include their persistence in the environment (soil, water, sediments, plants, and animals), bioaccumulate, and establish themselves as part of the food-web (chain) and contaminate all trophic levels. As a result, they were accused of causing endocrine disruption, suppression of immune system functions, and inducement of reproductive and developmental effects. Moreover, the evidence of detrimental effects on living organisms, at the population level, demonstrates that the PTS are a threat to biodiversity, and even have potential for disruption at the ecosystem level [5]. Since the 1960's, the concerns of scientists about this problem have been communicated to governments and the general public with the support of environmental and public interest groups. Many of these substances began to be banned, or their use restricted, particularly in the developed world. Yet, in spite of such action, there is evidence of the continued presence of these chemicals at levels of concern, even in parts of the world where they have never been used, reflecting both their persistence and long-range transport. The Global concern was documented in Rio (Earth Summit, 1992), followed by Basel convention, Rotterdam Convention and Stockholm Convention. The latter convention was established specifically for the Global monitoring of Persistent Organic Pollutants (POPs) and Persistent Toxic Substances (PTS). The main objectives of this convention are substituting these chemicals with alternatives that are environmentally acceptable, banning the use of POPs and PTS or restricting their use, finding a proper technique for eliminating the sources or reducing them, especially the obsolete stocks. In this series, examples of these chemicals, their effects on health and environment will be discussed. In the next series the cutaneous manifestations of some toxicants will be dealt with. Sud J Dermatol Vol.2(2) 2004: 40-4