so small that no effect of salinity on Aroclor 1254 toxicity was ap- 

 parent. 



Development of P. pugio to postlarvae occurred at exposure concen- 

 trations below 15.6 ug/liter (Table 12). At 15.6 ug/liter, 75% of the 

 larvae died on the fifth and sixth days of exposure and all died within 

 11 days. At concentrations of 3.2 and <0.1 ug/liter, percent survival 

 to the postlarval stage did not differ from that of controls. However, 

 the duration of development to postlarvae increased as the concentra- 

 tion increased from to 3.2 ug/liter. Controls averaged 22.7 days to 

 postlarvae. Mean larval duration for groups exposed to 0.1 ug/liter 

 was 24.0 days, and those exposed to 3.2 ug/liter was 26.4 days. Dif- 

 ferences among means were statistically significant at p 0.10. 



Phthalate Esters 



Since DEHP is the most prevalent of the phthalate esters, initial 

 96h LCoo determinations were performed with it. In assays performed 

 with the grass shrimp, Paleomonetes pugio, and with 3 species of fish, 

 Cyprinodon variegatus, Menidia beryllina and Fundulus similis. no 

 toxicities were observed up to the highest level tested normally. Tox- 

 icity studies with two lower molecular weight phthalates, dimethyl 

 (DMP) and dibutyl (DBF) phthalates, have also been performed 

 with the grass shrimp. The 96h LC50S determined for those compounds 

 were 7 ppm for DMP and 6 ppm for DBP. 



Table 12 



Toxicity of Aroclor 1254 to Larval Palaemonetes pugio: Survival and Duration of 



Larval Development. 



Aroclor 1254 concentration 

 (ug/liter) 



(acetone control) 

 <0.1 

 3.2 

 15.6 



-a. 75% died on the 5th and 6th days of exposure at 15.6 ug/liter. No larvae sur- 

 vived longer than day 11. 



39 



