Persistent Organic Pollutants in Soil and Water and their Impact on Human Health

摘要

The large scale production of synthetic organic chemicals commenced in the middle of the nineteenth century. They are very persistent because microorganisms and other agents that normally bring about the biodegradation of natural materials are eitherunable to break down these stable molecules or can do so only extremely slowly. It is now realized that this stability which made them so suitable for their intended use for agriculture and industrial sectors, is causing problems when they are released into the environment. These group of long persistent organic molecules are known as persistent organic pollutants (POPs) after the Stockholm Convention, Sweden, 2001. The POPs are classified (Fig. 1) as (A) poly-nuclear aromatic hydrocarbons (PAHs): benzoa-pyrene, chrysene, naphthalene etc. and (B) haloge-nated hydrocarbons. The halogenated hydrocarbons are classified as (i) organo chlorinated pesticides (OCPs): aldrin, dieldrin, endrin, chlordane, DDT, hep-tachlor, hexchloro cyclohexane, mirex, toxaphane hexachlorobenzene etc. (ii) industrial chemicals: (a) poly-chlorinated biphenyls (PCBs) - a family of 209 individual compounds used as industrial chemicals and (b) industrial by-products polychlorinated diox-ins and furans - a family of 75 compounds as byproducts of industrial processes. The residues of POPs were noticed mostly in all the sphere of earth and in all the environmental components, i.e. soil, ground water, river water, ocean and even high altitude Himalayas. Owing to their lipohilic andhydrophobic nature, POPs are readily concerned in biota and can undergo biomagnifications up the food chain. Animals and humans may suffer adverse affects, such as carcinogenic and mutagenic effects from POPs if thesechemicals are consumed in high quantities through dietary sources.