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Administrative data

Link to relevant study record(s)

Description of key information

Short description of key information on bioaccumulation potential result: 
An assessment of the toxicological behaviour of the substance has been conducted to the extent that can be derived from relevant available information.

Key value for chemical safety assessment

Bioaccumulation potential:
low bioaccumulation potential

Additional information

TEST MATERIAL

The test substance comprises a purple flaky solid but is made commercially available in liquid form with a refined mineral oil. Therefore the substance was administered as a solution in the available in vivo studies.

The low vapour pressure value of the neat substance shows that it is not volatile and therefore inhalation is not a significant route of exposure. The neat substance is also not expected to undergo hydrolysis under physiological conditions. As a result, exposure to hydrolysis products, following oral ingestion, is not expected.

The test substance has a relatively high molecular weight (765 g/mol), which suggests absorption across biological membranes is unlikely to be significant. However, based on a moderately high octanol/water partition coefficient (5.32 ± 0.31 at 40 degrees Centigrade), the substance may have the potential to cross biological membranes. The available physico-chemical data on the neat substance and toxicological data on the preparation of neat substance and carrier oil were reviewed and, although the presence of carrier oil in the studies was taken into account, the assessment of toxicokinetic behaviour was based on the neat substance.

ABSORPTION

The repeat-dose oral toxicity study in rats showed that the substance is absorbed via the gastro-intestinal tract. The moderately high log octanol/water partition coefficient will also favour absorption of the substance from the gut. Publically available absorption, distribution, metabolism and excretion (ADME) data for the carrier oil shows very poor permeability across the membrane. However, signs of absorption for the test material are seen in the skin sensitisation test in guinea pigs. This may have been enhanced by the skin irritation produced by the substance since damage to the skin surface may increase penetration of the substance through the skin to some extent. Low volatility of the substance suggests that the test material would not be available for inhalation.

DISTRIBUTION

There is some evidence to suggest that the substance is distributed systemically in oral studies. The positive response in a skin sensitisation study in the guinea pig suggests that the test material gets to and binds to carrier proteins in the circulatory system. The relatively high log octanol/water partition coefficient suggests that the substance may distribute into the adipose tissue, although no evidence of accumulation in body fat is available and bioaccumulation potential is unlikely to be significant.

METABOLISM

The substance is hydrolytically stable under physiological conditions and is likely to undergo further metabolism prior to excretion. The results of the long-term oral toxicity studies show evidence of an adaptive response in the livers of rats, which is normally associated with enhanced metabolism. The results of the in vitro genotoxicity assays do not show any evidence that addition of the S9 metabolising system and hence further metabolism either enhances or diminishes the activity of the substance.

EXCRETION

There is no evidence to indicate the main route of excretion but poorly water soluble products with high molecular weight are unlikely to be excreted in the urine and biliary excretion may well be a significant route for this material. Any test material that is not absorbed will be excreted in the faeces.