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Description of key information

The low log Pow (<-1) value and the high water solubility (>10000 mg/L) suggest that the substance may be too hydrophilic to cross the lipid rich environment of the stratum corneum. Dermal uptake for these substances will be low. On the assumption that the physicochemical properties of the test substance reduces the absorption of the test substance, a factor of 10 is introduced when performing dermal to inhalation and dermal to oral extrapolation.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
100
Absorption rate - dermal (%):
10
Absorption rate - inhalation (%):
100

Additional information

Since no toxicokinetic studies are available for the test substance the following assessment is based on the available physicochemical properties and results from other toxicological studies.

The test substance is an dark blue powder with a molecular weight of 938.8 g/mol. The calculated log Pow value is ca.-13 and the solubility in water is 246 g/L.

 

Gastrointestinal absorption: Water-soluble substances may readily dissolve into the gastrointestinal fluids. However, absorption of very hydrophilic substances by passive diffusion may be limited by the rate at which the substance partitions out of the gastrointestinal fluid. The high molecular weight of the test substance does also not favor absorption. Although no oral repeated dose toxicity study is available, in the acute oral toxicity study a LD50 greater than 5000 mg/kg bw was determined and only minor toxic responses were observed and these effects were reversible within 2 days. In conclusion, the test substance may not be readily absorbed by the gastrointestinal tract.

Dermal absorption: The high water solubility (>10000 mg/L) and the log Pow lower than -1 suggests that the substance may be too hydrophilic to cross the lipid rich environment of the stratum corneum. Therefore, dermal uptake will be very unlikely. Furthermore, in the 28 days dermal repeated dose toxicity study, only effects were observed at the treated skin, indicating that absorption of the test substance by the dermal route is limited.

Respiratory absorption: No experimental data is available concerning the respiratory hazard of the test substance. Water soluble dust would readily diffuse/dissolve into the mucus lining of the respiratory tract. However, very hydrophilic substances can be transported out of the respiratory tract, when molecular weights are larger than 200. Furthermore, the low log Pow does not favor absorption. Therefore, the test substance may not be readily absorbed by the respiratory tract.

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