PCBs are higher than DDTs in sediment and biota (Varanasi et al. 1989C). A 

 substantial amount of DDT was directly discharged into Southern California 

 waters over several years especially prior to 1972, contributing to the 

 contaminant exposure of marine mammals from that area (O'Shea, et al. 1980). 

 The Gulf coast dolphins in this present study showing high proportions of DDTs 

 may reflect concentrations in the environment where they may have foraged, but 

 little is known about their migratory habits or sources of DDTs in the area. It is 

 obvious therefore that more inforaiation on profiles of PCBs, DDTs and other 

 CH concentrations is needed for the habitat and food organisms of these dolphins 

 as well as for incidentally caught animals to better assess the importance of 

 relative levels and distribution of these compounds found in the stranded animals. 



Detailed evaluation of profiles of CUs revealed another interesting finding 

 showing that three of the dolphins had a higher ratio of p,p'-DDT to one of its 

 breakdown products p,p'-DDE than has previously been found in various species 

 of dolphins from U.S. waters (O'Shea, et al. 1980). In fact, the DDT:DDE ratio 

 of one of these three Gulf Coast bottlenose dolphins (PO 095) better compares 

 with cetaceans from Asia where DDT may still be used (O'Shea, et al. 1980). 

 The higher ratio of DDT:DDE in the bottlenose dolphin could indicate exposure 

 to a relatively recent source of the pesticide. The use of DDT has been highly 

 restricted in the U.S. since 1972. Since DDT breaks down in the environment 

 into several products, including DDE and DDD, the latter are the predominant 

 foims fnnnd now in U.S. coastal waters. Onoe again, stomach content analyses 

 would be helpful to shed light on the relative recent source of contaminants that 

 these animals may have encountered. Both tissue and stomach content 

 contaminant levels could aid in assessing the short and long term effects of toxic 

 levels of pollutants. 



DNA-xenobiotic adducts in Livers 



The initial analyses of the livers for levels of DN A-adducts showed that tissue 

 integrity appeared to be an important factor in the ability to use these biochemical 

 indicators with tissues from stranded dolphins. In light of these findings, a 

 comprehensive study is underway to assess the effect of tissue quality on the use of 

 hepatic DNA-adducts as bioindicators of exposure to contaminants such as aromatic 

 hydrocarbons. 



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