30 SHELLFISH CONTAMINATION FROM SEWAGE-POLLUTED WATERS. 



from the localities where the green oysters had grown. It was 

 demonstrated that the copper contamination undoubtedly came 

 from smelter factories loca'ted on the water front, from which the 

 wastes and effluent drained into the harbor bathing the oyster grounds. 

 The oysters showing the highest amount of copper were collected 

 nearest the factories, and they possessed a distinctly metallic taste. 

 This subject is receiving further study in the Bureau of Chemistry. 

 It is said that certain European varieties of green oysters are 

 cultivated as a luxury and sold at a premium because of their color. 

 Oysters may die from sewage wastes in badly contaminated waters. 

 In one locality it has been estimated that four out of five oysters on 

 certain beds were destroyed from this condition of affairs during 

 one season. 



HANDLING OF SHUCKED OYSTERS.. 



The initial pollution of shucked oysters may be due to the shell 

 stock being taken from sewage-polluted grounds, but in the liquor 

 surrounding the meat and in the intestinal contents of all shellfish 

 there are some bacteria. When the kind of bacteria are such as nor- 

 mally occur in unpolluted sea water, and are present in small numbers, 

 they are considered harmless and their presence is disregarded. On 

 the other hand, when B. coli and similar forms of germ life represent- 

 ing the presence of sewage matter are found the bacteriologist is forced 

 to take a different view of the matter. The B. coli group of organisms 

 may be present in numbers not sufficient to condemn the oysters when 

 fresh, yet when shucked and allowed to stand improperly iced under 

 bad sanitary conditions these few organisms may multiply and pro- 

 duce millions before the oysters are consumed. While it is essential 

 that oyster beds should be free from pollution in order to be assured 

 that the shucked stock has not been contaminated from this source, 

 dirty methods of shucking alone may account for contamination. 

 Oysters grown on soft muddy bottoms are generally covered with a 

 coating of mud, and unless this is removed from the shell before shuck- 

 ing some of the mud is likely to get into the opened stock. The oys- 

 termen claim that this is one of the reasons for floating oysters. If it 

 were done for this purpose alone, in pure water of the proper salt 

 content, there would be no objection to the process; in fact it would 

 be beneficial, in that it would allow the oyster to free itself of the sand 

 and grit contained within the gills and at the same time cleanse the 

 outside of the shell. 



The following results illustrate the relative bacterial content of 

 shell and market-shucked oysters: 



