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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

The key BCF parameter is a calculated value. However, additional measured data for DIUP and its analogs from biomagnification studies support the use of the calculated value to characterize the BCF of DIUP and suggest that DIUP has a low bioaccumulative potential, and is not expected to accumulate through food chains in the aquatic environment.

Key value for chemical safety assessment

Additional information

The results of a study to assess the bioaccumulative potential of high molecular weight phthalate diesters in an aquatic food-web that included 18 marine species showed that DIDP, an analog of DIUP, did not biomagnify but rather decreased in tissue concentration in organisms of increasing trophic position. Decreasing concentrations also referred to as biodilution, can be quantified by food-web magnification factors (FWMFs). A FWMF that is greater than 1.0 is an indication of chemical biomagnification within a food-web, whereas a value of less than 1.0 indicates biodilution or decreasing concentrationsfrom lower to higher trophic levels. Study results showed that lipid equivalent concentrations of the high molecular weight phthalate diesters significantly declined with increasing trophic level and that the FWMF for DIDP was 0.44 (Mackintosh et al., 2004).

The finding above is consistent with a laboratory fish bioaccumulation study in which rainbow trout were fed a DIUP spiked diet for 9 days (ExxonMobil, 2005). The low water solubility and high Kow of DIUP prevent conducting an aqueous exposure BCF (bioconcentration factor) study. At the end of the exposure period, fish were sampled after different depuration times (1 and 3 days). Results demonstrated a low potential for bioaccumulation with a lipid normalized biomagnification factor (BMF, concentration ratio in tissue to that in diet) of 0.0045 and rapid subsequent depuration with a tissue elimination half-life of less than 1 day. The half-life of less than 1 day was used to calculate a BCF in fish of less than 1 L/kg for DIUP. 

A low bioconcentration factor (BCF) value, 3.2 (log BCF = 0.5), is estimated for DIUP using the U.S. Environmental Protection Agency model, EPI SuiteTM(USEPA, 2000).