4,4'-[(isopropylidene)bis(p-phenyleneoxy)]diphthalic dianhydride

Endpoint summary

Description of key information

No toxicokinetic studies are available that directly address absorption, distribution, metabolism, or excretion of the test material following oral administration; however information is available from existing toxicology studies and the physical chemical properties to infer potential toxicokinetic properties.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

10

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

100

Additional information

Absorption

The main physical chemical properties that influence absorption are molecular weight, the physical state and particle size, and water and lipid solubility. The test material is a solid, with 89 % of the particles determined to be > 150 µm and no particles < 38 µm. It has a molecular weight of approx. 520 g/mole and Log Pow of -2.22; water solubility cannot be determined because the substance is hydrolytically unstable with half-life of less than 12 hours. These properties suggest the test material would minimally absorbed by the gastro-intestinal tract following oral exposure. The acute oral toxicity study showed low toxicity, and repeated oral toxicity studies revealed only non-specific systemic toxicity manifested as effects on body weight/body weight gain at the limit dose of 1000 mg/kg bw/day or above. In the absence of quantitative data, oral absorption of the test material is considered minimal (10 %) and equivalent to dermal absorption for risk assessment purposes.

The test material is too large to have the potential to be inhaled, and the particle size (i.e. no particles < 38 µm) could also be too large for being uptaken by macrophages. As a worst-case assumption however, in the absence of quantitative data, inhalation absorption of the test material will be considered complete (100 %) for risk assessment purposes.

Dermal absorption will be limited, because the test material is a solid, and will have to dissolve into the surface moisture of the skin before uptake can begin. In addition, molecular weight is high, molecule is large, and the lipophilicity is not appropriate for allowing the substance to cross the stratum corneum of the skin. Based on the molecular weight > 500 and Log Pow of -2.22, the default dermal absorption value of 10 % is considered appropriate for risk assessment purposes of the test material.

Distribution

Limited distribution can be expected for the test material based on its molecular weight and size.

Metabolism and excretion

No specific target organ of toxicity has been identified in the repeated oral toxicity study. Given its instability to hydrolysis, it is likely that the test material will degrade to BPA-TA (the tetra-acid derivative), which is more polar and consequently will be possibly slightly more widely distributed. The unchanged test material will be excreted mainly via the bile, whereas excretion via the urine appears the main route for the tetra-acid derivative. Overall, potential for bioaccumulation is considered low.