Bioaccumulation of Phthalate Esters in Aquatic Food-Webs
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This chapter explores the bioaccumulation behavior of several phthalate esters in aquatic food-webs. It includes: (i) a compilation of bioconcentration data from reported laboratory studies in the literature, (ii) an overview and discussion of the results from a recently completed food-web bioaccumulation field study, and (iii) an analysis of the results of a bioaccumulation modeling study. The study concludes that laboratory and field studies indicate that phthalate esters do not biomagnify in aquatic food-webs. Higher molecular weight phthalate esters (DEHP, DnOP, and DnNP) show evidence of trophic dilution in aquatic food-webs, which is consistent with findings from laboratory and modeling studies which indicate that metabolic transformation is a key mitigating factor. Bioaccumulation patterns of DBP, DiBP, and BBP indicate no significant relationship with trophic position consistent with a lipid-water partitioning model. The lowest molecular weight phthalate esters (DMP and DEP) show bioaccumulation factors in laboratory and field studies that are greater than predicted from a lipid-water partitioning model. The considerable variability in the field-derived bioaccumulation factors (BAFs) for lower molecular weight phthalate esters across aquatic species suggests that species-specific differences in metabolic transformation can have a significant effect on observed bioaccumulation. With some exceptions discussed below, the bioconcentration and bioaccumulation factors of the phthalate esters discussed in this paper are below the UNEP bioaccumulation criterion of 5000. The low bioavailability of the high-molecular weight phthalate esters in natural waters is the main reason why the BAFs of the higher molecular weight phthalate esters are below the UNEP bioaccumulation criterion. Since the intention of the bioaccumulation criteria is to identify substances as being "bioaccumulative", if they (like PCBs) biomagnify in the food-web then current evidence supports the conclusion that phthalate esters do not appear to be "bioaccumulative".
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