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Description of key information

Short description of key information on bioaccumulation potential result: 2 in vivo rat PK studies using 14C-DBDPEthane, in vitro studies 

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

The potential absorption and elimination of DBDPEthane has been studied in in vivo and in vitro systems. The absorption, distribution, metabolism and elimination of 14C-DBDPEthane were studied in rats following a single oral dose (Sims 2004).  No14C-activity was detectable in the plasma, bile or urine of treated rats at any time point (up to 168 hours post-dosing).  A mass balance could not be determined because the presence of the test article in the feces prevented combustion and subsequent quantitation of 14C-CO2; however, levels of 14C-activity in plasma, bile, urine and cage rinses were below the limit of detection in all samples.  Based on the absence of14C-activity in these samples, the majority of the administered dose was not recovered and indicates that the test article was not orally absorbed and therefore excreted in the feces. DBDPEthanewas very poorly, if at all, absorbed from the gastrointestinal tract, and was subsequently eliminated in the feces. No or negligible absorption is consistent with the poor solubility and high molecular weight of the test article.

A second rat PK study was performed using a single oral dose in bile duct and jugular vein catheterized rats (Black 2012). 14C-DBDPEthane was not absorbed to any appreciable extent from the GI tract after a single oral dose.  The essentially background levels of radioactivity in blood, plasma, bile, urine and tissues indicate negligible absorption. (LOQs were equivalent ~0.01% of the administered dose/tissue.) The majority of the dose was eliminated in feces as the parent molecule within 48 hrs. HPLC-βRAM analysis of feces from treated rats indicated that 14C-DBDPEthane was excreted unchanged in the feces, without prior absorption, following oral administration.  A lack of metabolism was also observed in vitro using rat and other mammalian hepatic microsomal fractions (McKinney et al. 2012).

In another study (Knudsen et al., 2017) female SD rats were administered a single dose of [14C]-DBDPE by oral, topical or IV routes. Another set of rats were administered 10 daily oral doses of [14C]-DBDPE. Male B6C3F1/Tac mic were administered a single oral dose. . DBDPE was poorly absorbed following oral dosing, with 95% of administered [14C]-radioactivity recovered in the feces unchanged, 1% recovered in the urine and less than 3% in the tissues at 72 h. DBDPE excretion was similar in male mice and female rats. Accumulation of [14C]-DBDPE was observed in liver and the adrenal gland after 10 daily oral doses to rats. Rat and human skin were used to assess potential dermal uptake of DBDPE. The dermis was a depot for dermally applied DBDPE; conservative estimates predict 14 ± 8% of DBDPE may

be absorbed into human skin in vivo; 7 ± 4% of the parent chemical is expected to reach systemic circulation following continuous exposure (24 h). . Following intravenous administration, 70% of the dose remained in tissues after 72 h, with the highest concentrations found in lung (1223 ± 723 pmol-eq/g), spleen

(1096 ± 369 pmol-eq/g) and liver (366 ± 98 pmol-eq/g); 5 ± 1% of the dose was recovered in urine and 26 ± 4% in the feces.

In an in vitro system commonly used by the pharmaceutical industry in drug development, DBDPEthane had very poor solubility such that the tests in vitro cell systems could not be performed (Cyprotex 2008). DBDPEthane's poor solubility in organic solvent and the aqueous buffer system used with the cell cultures suggests it will have limited ability to permeate cells. A substance must first be in solution prior to being absorbed or metabolically transformed by intracellular enzymes. DBDPEthane limited solubility will impact its absorption and potential for bioaccumulation and metabolic transformation. Based on these results, the substance does not have bioaccumulation potential.

In a study with domestic house cats DBDPE was found in high concentrations in all dust (median 154 pmol/g) and food samples (median 0.7 pmol/g lw) but was below detection in serum samples, suggesting low or no bioavailability for DBDPE in cats (Engdahl et al., 2017)..