CHRONIC TOXICITY OF 14 PHTHALATE-ESTERS TO DAPHNIA-MAGNA AND RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

Chronic toxicity studies were performed with commercial phthalate esters and Daphnia magna (14 phthalates) and rainbow trout (Oncorhynchus mykiss) (six phthalates). For the lower-molecular-weight phthalate esters - dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and butylbenzyl phthalate (BBP)-the results of the studies indicated a general trend in which toxicity for both species increased as water solubility decreased. The geometric mean maximum acceptable toxicant concentration (GM-MATC) for D. magna ranged from 0.63 to 34.8 mg/L. For the higher-molecular-weight phthalate esters-dihexyl phthalate (DHP), butyl 2-ethylhexyl phthalate (BOP), di-(n-hexyl, n-octyl, n-decyl) phthalate (610P), di-(2-ethylhexyl) phthalate (DEHP), diisooctyl phthalate (DIOP), diisononyl phthalate (DINP), di-(heptyl, nonyl, undecyl) phthalate (711P), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), and ditridecyl phthalate (DTDP)-the GM-MATC values ranged from 0.042 to 0.15 mg/L. Survival was equally sensitive and sometimes more sensitive than reproduction. The observed toxicity to daphnids with most of the higher-molecular-weight phthalate esters appeared to be due to surface entrapment or a mode of toxicity that is not due to exposure to dissolved aqueous-phase chemical. Early life-stage toxicity studies with rainbow trout indicated that survival (DMP) and growth (DBP) were affected at 24 and 0.19 mg/L, respectively. This pattern of observed toxicity with the lower-molecular-weight phthalate esters and not the higher-molecular-weight phthalate esters is consistent with previously reported acute toxicity studies for several aquatic species.