IMPACT OF TOXIC ORGANICS ON THE 

 COASTAL ENVIRONMENT 



Dr. John D. Costlow 



Director, Duke University Marine Laboratory 

 Beaufort, North Carolina 28516 



The variety of toxic organic compounds being introduced into estuarine and 

 coastal waters of the United States and the extent to which they may affect the envi- 

 ronment present awesome considerations for the eighties. Most of the compounds 

 described as toxic to estuarine organisms fall within five general categories: herbi- 

 cides, fungicides, pesticides, petrochemicals, and industrial compounds or their by- 

 products. Although some of the effects of both herbicides and fungicides on marine 

 organisms have been investigated, there is little indication to date that these com- 

 pounds represent a serious threat to the estuarine environment. Many toxic organic 

 compounds are associated with petroleum and its refined products, but, as with the 

 industrial compounds, these organics do not constitute a continuous and long-term 

 threat because they are not routinely used in the coastal environment. Many toxic or- 

 ganic compounds are also associated with industrial processes and. in some cases, 

 the polychlorinated biphenyls(PCBs), for example, are introduced into the estuarine 

 environment through carelessness or by accident rather than through routine use in 

 areas adjacent to tidal waters, as with pesticides. 



This review will focus largely on the impact of pesticides and on certain industrial 

 products. It will consider the extent to which some of these compounds have a 

 deleterious effect on estuarine and marine organisms. It will also identify those 

 aspects of the basic problem of impact that have not been adequately addressed in 

 light of the emerging problems, those associated with further development and 

 future use of increasingly sophisticated compounds. 



At the beginning of the seventies, individual scientists as well as state and federal 

 agencies began to be concerned with how the continuous addition of pesticides to 

 estuarine and marine ecosystems might affect individual species, the marine eco- 

 system as a whole, and humankind as well. The banning of the use of DDT in the 

 United States in 1972 led to the development and use of many new compounds. Pri- 

 marily, these were more specific in their action and thought to be less persistent in 

 either the marine environment or in biological systems. The majority of these com- 

 pounds were organochlorine or organophosphate compounds. Publications through- 

 out the decade have reported the effects on marine organisms of several of the 

 organochlorine compounds including aldrin, dieldrin, mirex, methoxychlor, and 

 Kepone. Virtually all of the organochlorine insecticides act on the nervous system. 

 Less scientific interest has been demonstrated in the effects of the organophosphates, 

 compounds that apparently inhibit the action of enzymes. This group includes 

 parathion, malathion, and diazinon. The effectiveness of several of the newer 

 organophosphate pesticides stimulated the development of still other compounds 

 designed to inhibit enzyme activity, including the carbamates and such compounds 

 as diflubenzuron (Dimilin®), which inhibits the normal secretion of cuticle in 

 arthropods. Concurrently, a group of insecticides identified as third generation 

 pesticides were developed by the chemical industry. These either are insect hormones 



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