Pesticides are the gathering of synthetics or substance plans utilized in horticulture for shielding yields or crop items from the danger of nuisances, creepy crawlies, spices, weeds and organism etc. A significant number of these agrochemicals are accounted for to be cancer-causing in lab creatures. Epidemiological confirmations of cancer-causing impacts of a portion of the pesticides in creatures are additionally known. The pesticides are ordered into four gatherings viz., organochlorines, organophosphates, carbamates and various sort.
About forty five organochlorine, eight organophosphorus and similar number of cabamate pesticides have been reported to be carcinogenic experimental animals. The important organochlorines with sufficient or limited evidence for carcinogenicity to experimental animal as per the Intentional Agency for Research on Cancer (IARC) evaluations are captan, carbon tetrachloride, chlorobenzilate, chlardane, chlordecone (kepone), chloroform, chlorothalonil, diallate (Avadox), 1,2-dibromo-3-chloro-propane, 1,2-dichloroethane, (edicofol), heptachlor and heptachlor epoxide, hexachlorobenzene, hexachlorobutadine, hexachloro cyclohexane, hexachloroethane, mirex, 1,2,2-tetrachloroethane, tetrachlorvinphos and toxaphene.
The non-judicious use of pesticides (improper selection, repeated application, substandard product, excessive dosage etc.) has been responsible for various ills. Most of these problems can be overcome through a proper pesticide selection. application, post-application care and monitoring to identify undesirable effects, corrective measures to overcome the defects, etc., the aspects which constitute the term pesticide management. During the Year 1994-1995, the global pesticide.
market stood at 27.8 million U.S. Dollars. It showed an increase of 10.1 per cent over the previous years. Pesticide sales across Western Europe revealed a rise of 12 per cent being the largest in France, Italy, Germany, and UK. The ever increasing use of different types of pesticides the world over has been associated with serious environmental problems. Still the fact remains that pesticides are basically poisonous it is also to be acknowledged that the global poverty and illiteracy levels are not likey to improve in the near future, thus ruling out the possibility of a judicious pesticide usage in the forseable future. The harmful effects of pesticides may thus be investable.
Harmful effects of pesticides: The salient harmful effects of pesticides include the contamination of the environment and food, feed and fibre, disruption of non-target organisms, pest resistance, pest resurgence, and so on. These defects have to be overcome while planning pesticide management strategies. Insecticide resistance occurs as a result of inappropriate and large scale use of pesticides particularly at sub-lethal doses, repeated application of the same pesticide or similar group of pesticides over a period of time as well as under dosing due to substandard pesticidal formulations. The situations, besides bringing drastic changes in the pest complex and crop environment, has culminated in outbreaks of several secondary pests. Even some minor ones have assumed the status of major pests.
A statistically significant increase in the pest population as a consequence of pesticide use, in spite of a good initial kill at the time of treatment, was called as “resurgence” or flare back. Evidences were also forthcoming that insecticide residues in host plants and insecticides applied at sub lethal doses simulated the reproduction and survival of phytophagous insects and mites, leading to pest resurgence.
In Asia the resurgence of brown plant hopper following insecticide application was reported in rice. In cotton, the use of synthetic pyrethroides to control boll worm enhanced the population of white fly, Bemisia tabaci. The key examples of pest resurgence in India are listed in Table 1. When insecticides or other pesticides are employed, the poison not only destroys the pest, but also has a serious impact on its natural enemies. In some cases, the destroyed natural enemies are important in controlling certain other pests also. When these natural enemies are eliminated; it may result in outbreak of pests that were previously not a problem in the target crop.