Effect of phthalates on development, reproduction, fat metabolism and lifespan in Daphnia magna

Abstract

Phthalates are used as plasticizers to increase durability, resistivity and flexibility of plastic materials. The commonly used phthalate, diethylhexyl phthalate (DEHP) is used in different plastic materials like food packaging, toys and medical devices. DEHP has been linked to different toxicities in humans as well as in animals, and as a consequence other phthalates, including dibutyl phthalate (DBP) and diethyl phthalate (DEP) are being introduced. The increased use of phthalates has resulted in contamination of aquatic ecosystem and it directly threatens the aquatic life. In this study, we analyzed the effects of three phthalates DEHP, DEP and DBP using freshwater organism Daphnia magna. Although, exposure of the three phthalates at 1 and 10 μM did not result any lethality and hatching delay, the chronic exposure for 14 days resulted in reduction of body length. There was enhanced fat accumulation on exposure to all the phthalates, as indicated by oil red O staining. qRT-PCR analysis of genes involved in fat metabolism suggests that the increase in fat content could be due to inhibition of absorption and catabolism of fatty acids. Reproduction analysis showed that DBP and DEP did not alter fecundity but surprisingly, DEHP at 1 μM increased reproduction by 1.5 fold compared to control group. Phthalates also showed negative effect on lifespan as DEP at 10 μM and DBP at both 1 and 10 μM significantly reduced the lifespan. Our data indicates that along with the banned phthalate DEHP, the other substitute phthalates DEP and DBP could also have detrimental effect on aquatic organisms.