Many countries in the Asia and the pacific regions are primarily agriculture dependent. Agriculture also is heavily dependent on chemical fertilizers and indiscriminate use of pesticides. Pesticides are used against pests which causes a loss in agricultural production as well as for controlling insect borne diseases. Indiscriminate use of pestcides cause pollution, endanger public as well as wildlife health, resurgence of new pests and destruction of non-target organisms. POPs (Persistent Organic Pollutants) are highly toxic chemicals. They persist in the environment for a long time, and accumulate in living animals mainly in fatty tissue. Their concentration increases through food chain. The highest concentration is found in top predator like human. Many POPs are endocrine disruptors, some are carcinogenic and others are mutagenic or teratogenic.
Carson in her book Silent Spring
focused on the harmful effects of chlorinated hydrocarbon insecticides, especially DDT on organisms and ecosystems. The global chemical industry has increased about 9 folds since the Stockholm Conference, 2004 which sets out control measures for 12 chemicals, the so called “dirty dozen”. POPS are pesticides or some industrial wastes. Of many POPs, 12 including 8 organochlorine pesticides viz. DDT, aldrin, dieldrin, endrin, chlordane, heptachlor, mirex, and toxaphene, 2 industrial chemicals viz PCB and HCB, along with 2 industrial waste products viz.dioxins and furans, are most dangerous to wild life, human health, and environment. POPs are semi volatile substances, resistant to degradation and transport through air, water, and migratory species. They are known as “poisons without passports”.
The POPs effects on eagles, cormorants,and trout are eggshell thinning, metabolic changes, birth defects, and cancers. The Arctic and sub-Arctic regions is becoming a sink for persistent contaminants including pesticide POPs. Aldrin/ dieldrin persist in soil with a half life of 5 years, and causes convulsion, hypersensitivity, and neuronal degradation in wildlife. They enter human body through food or through dermal contact or direct inhalation. Human exposure through fish, poultry, and beef is recorded. In humans, they damage liver, cause headache, nosea, loss of appetite, convulsions, and are suspected to be the probable human carcinogens. Dieldrin is suspected to be associated with Parkinson’s disease. Endrin is extremely persistent. Exposure to endrin results in enlarged kidneys in dogs. Occupational exposure in human causes mental diffusion, and improper bone formation. Chlordane exists in soil for more than 73 years. Human exposure occurs through diet. Occupational exposure increases the risk of cardiovascular disease. This is also suspected to be carcinogen.DDT decreases fertility in male, remain stored at the highest concentration in breast milk, and placenta and result in developmentally vulnerable offspring. Human exposure to heptachlor occurs mainly through ingestion of food and inhalation. Liver enlargement in rats, kidney lesions and gill damage in fish are known effects of mirex. Toxaphene, with a half life of up to 12 years in the soil, enters human body primarily through fish consumption. It alters enzyme activities in liver and affects kidney, and thyroid.
The Stockholm Convention which came into force on 2004 aims to eliminate 12 significant POPs and addresses the routes through which hazardous POPs might enter the environment, contaminate food chains, and can threaten human health. Prevention of POP use can be achieved by banning their production .There are many different ways of treating POPs in existing waste. Several technologies have promised effective destruction of POPs waste. Use of biopesticides, which are effective, safe and eco-friendly, could possibly provide a viable option. Neem is reported and tested as an alternative effective, biodegradable pesticide. Other biopesticide such as abamectin and emmamectin have been recognized as broad spectrum pesticides. Promotion of biopesticides would ensure sustainable agriculture for the small and marginal farmers, and can provide an alternative to POP pesticides.
Our knowledge about serious effects of pesticide POPs need immediate translation into actions. Sharing knowledge among people throughout the globe would have significance in this context. Problems related to pesticide issue should no longer in the private domain of the scientific community, rather the gains from the research work should be shared with the concerned people to promote the concept of sustainable development. The present communication is based on a review work published in the Journal of Environment and Sociobiology. The review was done by the present author along with two other scientists.