the Tenneco, Inc. plant and the Chestertown sewage treatment 
plant. No significant oyster mortality was observed. 
It appears that a comparison of our measurements with the 
known toxic effects of phthalate esters on oysters and other 
aquatic organisms is unable to explain the Chester River oyster 
mortality during 1973-1975. However, there is enough evidence 
to cause concern over long-term effects on aquatic organisms 
especially with expected future increases production of alkyl 
phthalates. 
83 
