Heavy metals: 

 elements to watch 



Pollution means problems for the seafood indus- 

 try. Already almost a fifth of the state's shellfish- 

 ing waters are closed due to pollution. And atten- 

 tion is turning to possible new pollutants — like 

 heavy metals — which may cause trouble in the 

 future. 



North Carolina's waters are in no danger from 

 metal pollution now, according to Ford A. Cross, of 

 the National Marine Fisheries Service (NMFS) in 

 Beaufort. But a combination of factors compels 

 scientists to keep an eye on the elements. 



First, heavy metals can be harmful to man and 

 marine life. Second, it appears that estuaries con- 

 centrate metals. It also seems that the metals are 

 more toxic to young forms of marine life, making 

 the estuarine "nursery" particularly vulnerable to 

 increased metal levels. Metals occur naturally in 

 the estuaries and are added through pollution. 

 With developers and power plant builders — a 

 source of many metal contaminants — eyeing the 

 estuarine shores, many suspect pollution will in- 

 crease. 



Complicated 



Heavy metals are also incredibly complex. Some 

 lose their toxicity as the water gets dirtier, some — 

 like cadmium — gain toxicity as salinity increases. 

 Arsenic is less dangerous when it's "methylated" 

 but mercury is more harmful in the methyl form. 

 And copper, while as necessary to shellfish as iron 

 is to man, can be lethal to larval forms. 



To complicate things even more, different species 

 of fish react differently to metals. Menhaden, for 

 example, can tolerate much more copper than spot 

 can. 



And there are disagreements among scientists 

 about whether heavy metals are even a pollutant. 



"While we don't have a problem now, it's possible 

 if precautions aren't taken and we don't stay on 

 top of things, we could get into a mess," comments 

 Bruce Fowler of the National Institute of Environ- 

 mental Health Sciences. 



Under Study 



Cross and the NMFS are keeping track of how 

 metals get into the estuaries and marine life and 

 figuring out how the metals react and under what 

 conditions they become toxic. 



"Basically what we're trying to do is learn about 

 metals so rational decisions can be made about 

 them based on data," Cross says. 



Over at NCSU, George Giddings is also staying 

 on top of the heavy metals. Giddings, a seafood 

 scientist with a bit of Boston in his speech, is using 

 Sea Grant funds to find out how and why pro- 

 cessing affects potentially harmful heavy metals 

 and healthful trace elements in seafood. 



Giddings is concentrating on shellfish since they 

 get the most processing in North Carolina and are 



George Giddings 



an important part of the state's industry. Shellfish 

 are also most prone to the effects of pollution since 

 they are relatively stationary and live in the areas 

 close to shore which are most easily affected by 

 man. 



Giddings has looked most closely at the calico 

 scallop and found that, indeed, processing can 

 affect the amount of metal in the food. 



When the scallops Giddings studied entered a 

 processing plant they contained essential trace 

 elements manganese and zinc — which are impor- 

 tant for human health. The scallops also contained 

 cadmium — a heavy metal that can cause kidney 

 damage in test animals and may be a carcinogen. 



But when the scallops left the plant they were 

 lower in both cadmium and the trace elements. 

 Giddings traced the losses to the fluming method 

 of transportation. And he says that with this infor- 

 mation — and results from future tests — processors 

 can change their methods to improve the nutri- 

 tional value of their products and decrease the risk 

 of heavy metal contamination. 



The University of North Carolina Sea Grant 

 College Newsletter is published monthly by the 

 University of North Carolina Sea Grant College 

 Program, 1235 Burlington Laboratories, Yar- 

 borough Drive, North Carolina State University, 

 Raleigh, N.C. 27607. Vol. 4, No. 1, January, 1977. 

 B. J. Copeland, director. Written and edited by 

 Karen Jui'gensen and Johanna Seltz. Second-class 

 postage paid at Raleigh, N.C. 27611. 



