Organo-chlorine pesticides, toxicity

Generally, not much work was available in the published literature on the levels of persistent toxic substances in the waters along the coastal areas of India. Most of the data available are on the two classic organo-chlorine pesticides, DDT and HCH and some sporadic reports on PCBs, BTs, cyclodines and some other organophosphorus pesticides in the coastal environmental samples. Neverthless, some recent works showed... 

Researchers were also able to establish the link between declines of other predatory species such as the European sparrowhawk and the use of organo-chlorine pesticides other than DDT. For instance, the cyclodiene insecticides aldrin, dieldrin, and he-ptachlor used as seed treatments caused massive mortality of both seed-eating species and their predators. All of the insecticides had the following points in common they were highly soluble in fats and refractory to metabolism. The impacts on the predatory species typically take place in periods of food stress when fat soluble residues are released from fat stores and returned into general circulation. In a food-stressed individual, the brain remains as the most lipid rich tissue and this is where contaminants move to. Toxicity results when threshold values in brain tissue are exceeded. At sublethal levels, documented effects of cyclodiene insecticides in birds have included changes in their reproductive, social, and avoidance behaviors. 

The chemical structures of some organo-chlorine pesticides and their toxicity data as... 

The consistent lack of genotoxicity of organo-chlorine pesticides in liver derived tests strongly supports the negative data obtained in other tests. Thus, it appears that these chemicals are not geno-toxic carcinogens. 

The chemicals that are toxic to all three systems include organophosphate, organo-chlorine, and carbamate pesticides, other persistent organic products, heavy metals, solvents, plasticizers, industrial chemicals, and chemicals used in consumer products. 

There is a vast range of aqueous organic pollutants with a wide toxicity profile. Some, e.g. polychlorinated biphenyls, certain herbicides, fungicides and pesticides, and organo-mercury compounds, are persistent and may bioaccumulate in the food chain. Trace contaminants such as sodium chloride, iron and phenols (especially if chlorinated) may also impart a taste to water. Typical consent levels for industrial discharges are provided in Table 13.10. 

In the past three decades, a dramatic increase in awareness of the effect of various toxic substances on animal life, in particular on aquatic species, has been seen. Among the identified culprits, the chlorinated hydrocarbons used in pesticides, the polychlorinated biphenyls (PCBs), and various organo-metallic compounds stand out. 

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