A number of pesticides are used in India and demand for them is on increase. It is estimated that there is a 15% increase in the consumption of pesticides every year throughout the world. During the last ten years, the use of DDT alone in India has increased nearly four folds. It is

estimated that DDT and BHe requirements during 1985-86 would be about twenty thousand tonnes and ten thousand tonnes respectively, twice the present requirement

Nammalwar, P

CMFRI Digital Repository

ENVIRONMENT Pesticides pollution in marine environment I N recent years, the use of pesti-cides has increased by many folds in many parts of the world. The major cause of pesticidal hazard is faulty application and negligence on the part of the applicator in adopting certain simple precautionary measures. Added to this is the lack of knowledge about proper dosage. Pesticides are economic poisons employed to regulate the impact of various animals and plants upon our life and economy. The effect of vast majority are relatively non-selective and their usage therefore may result in undesirable, even unanticipated, side effects. The use of pesticides has undoubtedly contributed to increased crop yield and to human health, but has also produced a number of adverse effects, including widespread pollution of the natural environment accompanied by damage to marine and inland fisheries, beneficial insects and occasional overt poison-ing of humans. The production of pesticides in India for agricultural development during 1976-80 was about 250,000 tones. It can be assumed that 2§% of pesticides will fmally reach the sea. Such enormous quantities, when added to the seas around India, will undoubtedly have some elTect on water quality of marine environment. There are two main groups of synthe-tic pesticides: (i) organochlorine pesticides and (ii) organophosphate pesticides. Organochlorine com-pounds such as DDT and BHe are most toxic to fishes. Many of these chemicals are stable and are not metabolized nor excreted to any appreciable degree; they remain stored in tissues. Organophosphorus compounds, the commonest of which are malathion and parathion, are generally less toxic to fishes. They are relatively unstable and rarely stored to any extent within animals, but are highly toxic to fish food organisms. A number of pesticides are used in India and demand for them is on increase. It is estimated that there is a 15% increase in the consumption of pesticides every year throughout the world . During the last ten years, the use of DDT alone in India has increased nearly four folds. It is estimated that DDT and BHe requirements during 1985-86 would be about twenty thousand tonnes and ten thousand tonnes respectively, twice the present requirement. Pesticides may enter aquatic eco-system indirectly by drift by spraying on agricultural land from fallout from air-dust particle accumulations in the atmosphere . in run off from agricul-tural lands by direct application to aquatic environment to eradicate mosquitoes, etc., by discharge of industrial waste emanating from a pesticide factory or improper dis-charge of excess pesticides and containers. Aquatic plants and animals can accumulate certain pesticides in many tissues in greater concentrations than can water. This indicates the biological magnification of these chemicals. Such a biological magnification of pesticides may result in high pesticide concentrations in fishes and birds. Organochlorine insecticides have the greatest magni-fication because they are persistent and have a high affmity for lipids. The degree of magnification of insecticides is usually proportional to their persistence and inversely related to their suitability in water. In aquoeus system, pesticides encounter volatili-zation, decomposition by ultraviolet light irradiation, microbial degra-dation, biological magnification and absorption and desorption from suspended matter. All these pheno-mena are not sufficient to result in self-purification of water and so addi-tional treatment and disposal methods are required to eradicate pesticides from aquatic environment. DDT, BHe, chlordane, heptachlor, toxaphene, aldrin, dieldrin and endrin are some of the chemicals most toxic to fishes and other bio-logical communities. About 77,420 tonnes of pesticides and insecticides are used in agricultural development purposes in India every year. In view of the imperative need to increase food production, pesticides appli-cation within the country will further increase. Field research on the nature and extent of pesticide pollu-tion in marine environment is pro-gressing slowly. Recent studies have proved that even very low concentrations of pesticides which enter the environ-ment can alTect productivity of these waters, kill eggs and larvae of clams and oysters; influence thc behaviour of fishes such as schooling and feeding; induce changes in the blood chemistry and enzymatic functions of these organisms; reduce backbonic collagen contents and indirectly interfere with food chains. These pesticides are accumulated more in plants and fatty tissues of fishes . Animals which have become weak and moribund as a result of exposure to pesticides may easily be destroyed by predators . Since very low concen-trations of organochlorine pesticides affect reproduction in fishes. there is every possibility that these pollutants may adversely alTect the local fishery. Pesticide-induced mortality pat-terns of marine molluscs. crusta-ceans and teleosts are also measur-ably related to various physio-chemi-cal environmental parameters. They __________________ ~-----------------------------------ENVIRONMENT include temperature, salinity pH ~ indire,et--.ltarm can result in higher unable to move away from pollution. the medium, type and ' concentration ~sby<:Oncentrationofche.micals The oyster might be particularly of chemical and duration of exposure. Some of the organophosphorus pesti-cides for example are most toxic under conditions of comparatively ~. _ higher temperature, saJinjty and low pH. On the other hand, some organo-chlorine pesticides are most toxic at intermediate temperatures when pH is more than 9 or less than 7 over a wide range of salinities. Inter and Intra-species variations in suscepti-bility to different pesticides are considerable. Age, size, sex, general condition and especially chemical makeup are important in predicting degree of resistance of a species to a specific biocide. There has been an accumulation of vast amount of data on pesticides but we are still unable to define the problem fully or evaluate '>.. the permanent effect of these chemi-cals on aquatic animals and their environment. . Although, direct poisoning is the most obvious influence of pesticides, in their passage through food chains susceptible because of its tendency to or by reduction in numbers ofimpor- concentrate and store trace chemi-tant food organisms. It is reported cals from the surrounding environ-that marine invertebrates can take up ment. pesticides from medi um by concen-tration factors of70,OOO and greater. The importance of pesticide pollu-tion from the human health point of view is being investigated. Today, there is an urgent need of data on the specific areas of pesticides pollution in seas and estuaries, whether the environmental burden is decreasing or increasing and what the sources of contantination are. The establishment of a continuing monitor sytem is necessary despite technical difficul-ties; bioassay of animals offers a reasonable approach to this problem. Various kinds of crustacea that make up the most valuable marine harvests are of course representa~ves of some groups of animals that pesticides are designed to kill. Particular concern is felt for sedentary animals that are Coastal zone receives a vast number of adventitious chemicals including insecticides , herbicides to control marsh plants, synthetic, detergents, factory and domestic wastes and radioactive materials. It is possible, even probable, that some of these chemicals display synergism or antagonism. Therefore, early remedial solution in terms of effective and integrated ecologic,," manage-ment of the coastal and estuarine ecosystem is necessary to restore normal conditions. P. NAMMALWAR Scientist Environmental Sciences Unit Zoology Department Madras Un iversity Madras - 600 005 FOR HER (Continuedjrom page 493) fish oils are likely to be particularly useful. Fish is also a fairly good source of calcium and phosphorus, particularly small fish which are eaten .with bones. It is also a source of iron and of trace elements like copper, iodine, arsenic, etc. Fish has also a fair proportion of B-vitamins apart from being a rich source of vitamins A, D and E. Oil-containing fishes, for example, cod, contain considerable quantities of A, D and E in their liver. Some of the visceral organs contain larger quantities of certain B-vita-mins than does the flesh. Fish can also be preserved for a long time for subsequent consump-tion. Nutritive value of such pro-cessed fish and fish products has been reported to be high. Canning and freezing do not appreciably affect protein value . Salted and sun-dried fish have also a high bio-logical value . Smoking or dehydra-SEPTEMBER 1984 tion at a temperature not higher than 110°F or treatment with cathode rays for sterilization does not signi-ficantly affect amino acid compo-sition of fish protein. The calcium content of canned fish is about 200 mg% which reflects its l)igh nutri-tive value. M. MUMTAZ UDDIN Agriculture Experiment Station Mymen Singh (Bangia Desh) V.K. RAlBANSI Limnology and Fisheries Deplt. M.L. Sukhadia University Udaipur-3J3oo1 Answers to Science Quiz I. Astragal us 14. Nepenthes 2. Botany Bay 15. Oosphere 3. Christmas disease 16. Pink disease 4. Digitalis 17. Quadrats 5. Endeavour 18. Raffiesia 6. Fabricius 19. Salvadora 7. Ginkgo 20. Tamarix 8. Hevea brasiliensis 21. Uracil 9. Interferon 22. Vampire bats 10. Jejunum 23. Wolffia 11. Klinerelter's syndrome 24. Xenophanes 12. Lotus 25 . Yellow fever 13. Metacarpals 26. Zoonomia 497 SCIENCE REPORTER 

Pesticides pollution in marine environment

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Pesticides pollution in marine environment

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