الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
The accumulation of three chlorinated hydrocarbon insecticides DDT, dieldrin and lindane (¥ BHC) by two different bacteria (Brevibacterium flavum and Caulobacter fusiformis), three fungi (Aphanomyces euteiches, Saprolegnia ferax and Achlya racemosa), two green algae (Chlorella fusca and Scenedesmus acuminatus) and one diatom (~haeodactylum tricornutum) was studied. The microorganisms were exposed to 0.1 ppm (0.,1 ug/ml) 140 DDT, 140 dieldrin or 140 1(BHC for a period of four hours at controlled temperature. After this exposure tine, the microorganisms were separated by centrifugation and the radioactivity in the supernatant as well as in cells was deter . mine d . .. To evaluate the effect of. bioconcentration on the transfer and accumulation of insecticides in higher animals, mice were fed on ~.flavum exposed to DDT or dieldrin and the concentration of these insecticides in various tissues of mice was deter mine d . . Results obtained in this invest1gation indicate that: 1. DDT, dieldrin and )(BHC were uptaken by all or ganisms studied. 2. The concentration of DDT and dieldrin accumulated by bacteria, fungi, green algae or diatom wee much higher than that in the surrounding medium which indicates that these organisms can sorb and concentrate DDT and dieldrin. . 3. In contrary to DDT and dieldrin which were highly concentrated by all organisms studied, lindane (~BHC) was apparently concentrated only by ~.flavum and the fungus !.euteiches. 4. Autoclave killed bacteria and fungi sorb as much or more insecticide as the viable ones which in dicates that the accumulation of insecticides by microorganisms does not involve any metabolic process. \ 5. In all organisms studied, the highest accumula tion of insecticide (expressed in ng/mg dry weight) was observed in case of DDT and the lowest in case of ’(BHC. 6. There was also a clear difference between the ~ different types of organisms in ..their upt ake of DDT, die Idrin or ”(’BHC. T he accumulation of Dill, dieldrin or ¥BHC was highest in li.flavum and lowest in the green algae S.acuminatus end c. fus ca. The accumulation of insecticides by :fungi was intermediate. 7. Distribution ratios B/A (ng insecticide/mg dry weight organism over ng insecticide/ul super natant) and CiA (ng insecticide per cells contained in 1.0 ul exposure medium over ng insectic:.ide/ul supernatant) in cases of organisms exposed to DDT or dieldrin were above 1.0. These results indicate that DDr and dieldrin are bioconcentrated by all microorganisms studied. 8. B/A ratios for dieldrin and DDT ranged from 1463 to 100478 Which indicate that microorganisms con centrate these insecticides thousands of times above ambient levels. , . 9. In case of ¥BHC the calculated El A end Cl A ratios were much lower than t he corresponding values for DDT and dieldrin. 10. There is a definite relationship between the uptake of DDT, dieldrin and ~BHC by the various microorganisms and the hexene/water partition .’ .. coefficient of these insecticides. r 11. The process of sorption and concentration of . chlorinated insecticides by various bacteria, fungi, green algae and diatom Which has been clearly demonstrated in this ~tudy may play an important role in the fate of these pesticides in the environment. The biomagnification of insecticides by microorganisms could be an important avenue for massive movement of these pOllutants from one trophic level to another and thus represents a serious public health hazard. 12. DDT and dieldrin accumulate in the tissues of mice fed on ~.flavum exposed to these insecti cides. T he accumulated DDT end die ldrin remain in mouse tissues for a considerable length of time . These results indicate that insectidies could be transferred to higher aqimals after feeding on lower organisms Which bioconcentrate these insecticides. 13. Mouse adipose tissue was the tissue which showed the highest degree of ,accumulation of either DDT or die ldrin. The liver, kidneys and brain showed ~lso high degree of accumulation of these insecti cides. *11 \ 14. There was a higher accumulation o~ dieldrin in adipose tissue, brain and liver o~ mice’ as compared to DDT. 15. Dieldrin persisted in many mouse tissues ~or a longer period of time as compared to DDT.