SECTION 5 
PHTHALATE ESTERS AND RELATED CHEMICALS IN THE CHESTER RIVER 
INTRODUCTION 
The immediate purpose of this work is to assess the potential 
for bioaccumulation of alkyl phthalates as a way to explain the 
recent past mortality of oysters in the Chester River. Our 
starting approach involved dual plans to use both gas and liquid 
chromatography. Careful technique is needed to avoid contamina¬ 
tion by the ubiquitous presence of the phthalate esters in the 
environment, including their reported presence in the chemical 
laboratory. Our own facilities proved to be no exception. 
Two main problems needed to be solved: positive errors due 
to contamination during the measurement process, and negative 
errors due to incomplete extraction. Hopefully, both problems 
have been solved. Several models were considered for influx of 
alkyl phthalate waste from the Tenneco plant. These considera¬ 
tions were used to guide the sample selection and interpretation 
process. In brief, our overall approach emphasized measurement 
reliability, it narrowed the number of samples for analysis, and 
it gave a conceptual base to guide future work. Alkyl phthalate 
contamination in the Chester River clearly includes di(2- 
ethylhexyl)phthalate (DEHP). Our finding of massive contamina¬ 
tion in Tenneco Pond is consistent with the pollution conse¬ 
quences that are consistent with the existing discharge permit 
which has been approved by the State of Maryland. 
Geographic and Background History 
The Tenneco factory is sited on a tributary of Morgan Creek 
approximately 7 miles (10.6 km) upstream from where the creek 
empties into the Chester River. The location is shown in Figure 
5. The oyster mortality starts 12 miles (19.2 km) downstream 
from Morgan Creek toward the mouth of the Chester River. The 
mortality involved a downstream progression. Tne progressive 
movement is evident in Figure 6, which shows the status of 
mortalitities in oyster beds monitored in 1970-1975 (see 
Appendix A). The progression of the total mortality zone (0 
percent live oysters) is seen by comparing the 1973 and 1975 
results where the mortality front is seen to advance 5.2 km in 
the downstream direction. 
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