Solubility and toxicity of eight phthalate esters to four aquatic organisms

Abstract

AbstractSolubility values for eight phthalate esters investigated ranged from 0.020 to 121 mg/L. Acute toxicity tests were conducted with fathead minnows (Pimephales promelas) and all eight phthalate esters. Acute and chronic tests were conducted with rainbow trout (Oncorhynchus mykiss) and Japanese medaka (Oryzias latipes) using di‐2‐ethylhexylphthalate. In addition, the chronic toxicity of the three di‐n‐butylphthalates and a mixture of these three phthalates was examined using daphnids (Daphnia magna). Fathead minnow 96‐h LC50 values for di‐n‐butyl‐ortho‐phthalate, di‐n‐butyl‐tere‐phthalate, di‐n‐butyl‐iso‐phthalate and α, w‐butylene di[o‐(4‐hydroxybutoxycarbonyl)‐benzoate] were 1.1, 0.61, 0.90 and 121 mg/L, respectively. Di‐n‐octyl‐ortho‐phthalate, di‐n‐octyl‐iso‐phthalate and di‐n‐octyl‐tere‐phthalate were not acutely toxic to fathead minnows at concentrations that exceeded the water solubility estimates for each phthalate. Di‐2‐ethylhexyl‐phthalate was not acutely toxic to any tested species at the highest tested concentrations. No significant adverse effects were observed on hatchability, survival or growth of rainbow trout exposed to a mean di‐2‐ethylhexylphthalate concentration of 0.502 mg/L (the highest concentration tested) in a 90‐d embryo‐larval test. However, exposure to a mean di‐2‐ethylhexylphthalate concentration of 0.554 mg/L significantly reduced the growth of Japanese medaka during a 168‐d larval test. Significant adverse effects on reproduction occurred in 21‐d chronic tests with D. magna at concentrations of 1.91, 0.20 and 0.64 mg/L for di‐n‐butyl‐ortho‐phthalate, di‐n‐butyl‐iso‐phthalate and di‐n‐butyl‐tere‐phthalate, respectively. A daphnid mixture test with these three phthalates showed complete additivity, which suggests a similar mode of toxic action.