Isomers are more likely to cause collapse of Daphnia magna populations than Di-(2-ethylhexyl) phthalate (DEHP)

Abstract

Di-(2-ethylhexyl) phthalate (DEHP) is the most commonly used phthalate and is ubiquitous in surface water. Based on its well-established toxicological profile, many countries and regions have adopted specific environmental quality standard (EQS) for DEHP. In China, the EQS value for DEHP is 8 μg/L. However, information on isomers structurally similar to DEHP is limited. Among the isomers of DEHP, di-isooctyl phthalate (DIOP) and di-n-octyl phthalate (DnOP) have received limited attention. The goal of this paper was to study effects and toxic potencies of DEHP, DIOP, and DnOP to individuals and predict effects on populations of female Daphnia magna (cladoceran crustacea) in media containing environmentally relevant concentrations of single PAEs for three consecutive generations (21 days for every generation). Exposure to all three PAEs resulted in reduced survival and reproduction and cause collapse of populations at the highest concentrations. DnOP was the most potent for causing adverse effects followed by DIOP, while DEHP was the least potent. 8 μg DnOP/L were found to reduce the population size by 37 % in the F2 generation. These findings demonstrate that PAE isomers other than DEHP can cause adverse effects.