1,2-Benzenedicarboxylic acid, di-C9-11-branched alkyl esters, C10-rich

Bioaccumulation: aquatic / sediment

Description of key information

The key BCF parameter is a calculated value. However, additional measured data from a biomagnification study support the use of the calculated value to characterize the BCF of di-isodecyl phthalate and also suggest that di-isodecyl phthalate (DIDP) has a low  bioaccumulative potential, not expected to accumulate through food chains in the aquatic environment.

Key value for chemical safety assessment

BCF (aquatic species):

3.2

Additional information

DIDP has a low potential to bioaccumulate in the environment based on results from a bioaccumulation food-web field study, a biomagnification dietary lab study with a fish, a calculated bioconcentration factor value, and a measured biota-soil accumulation factor (BSAF) for a soil-dwelling invertebrate.

Biomagnification: High molecular weight phthalate esters (di-C8 PEs to di-C10 PEs) have been shown not to biomagnify through the food web, but rather decrease in tissue concentration with increasing trophic position. The results of a study to assess the bioaccumulation of high molecular weight phthalate diesters in an aquatic food-web that included 18 marine species, showed that DIDP 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 dilution from 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 di-isodecyl phthalate was 0.44.

Biomagnification: The finding above is consistent with a laboratory fish bioaccumulation study in which rainbow trout were fed a DIDP spiked diet for 14 days. The low water solubility and high Kow of DIDP prevent conducting an aqueous exposure BCF (bioconcentration factor) study. At the end of the exposure period, fish were sampled after different depuration times (0, 0.6, 1, 3 days). Results demonstrated limited bioaccumulation with a lipid normalized biomagnification factor (BMF, concentration ratio in tissue to that in diet) of 0.1 and rapid subsequent depuration with a tissue elimination half-life of 1 day. The half-life of 1 day was used to calculate a BCF in fish of 1 L/kg for DIDP.

Bioconcentration: Calculated BCF data for di-isodecyl phthalate (DIDP) suggest that it has a low potential to bioconcentrate in the aquatic environment.

BSAF: Data to assess the potential for terrestrial bioaccumulation of DIDP were reported in a 14-day earthworm (Eisenia fetida) toxicity study. The biota-soil accumulation factor (BSAF) as measured in a natural soil was 0.015 based on a DIDP concentration in the earthworm of 120 mg/kg (wet weight) and in soil of 7829 mg/kg (dry weight). A BSAF value of 1 indicates a lack of bioaccumulation.