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Description of key information

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

The test substance is a solid that is characterized by a water solubility of 34.7 mg/l, an octanol-water partition coefficient (log Pow) of 2.6 and a molecular weight of 460.53 g/mol. These data suggest an ability of the substance to pass membranes and therefore, gastro-intestinal absorption might be possible. A further prove was evidence of systemic toxicity at repeated oral doses of 150 and 750 mg/kg bw/day in a 28-day oral toxicity study and at doses of 50 and 150 mg/kg bw/day in a 90-day oral toxicity study.

With regard to dermal absorption, small molecules which are both lipid- and water-soluble (log Pow between -1 to 3.5) are generally expected to be absorbed via the skin. Since the test substance is a solid, only minimal dermal absorption is expected unless the substance will be dissolved on the skin surface by sweat or resident oils. After dissolution dermal absorption could be expected due to the log Kow of 2.6. However, in an acute dermal toxicity study in rats, no systemic or local signs of toxicity were observed after application of 2000 mg/kg bw substance (suspended in polyethylene glycol to improve skin contact) during exposure (24 h) and recovery period, suggesting only limited bioavailability of the test substance after dermal exposure. This suggestion of low dermal absorption is supported by a skin penetration test where max. 1.33% of the applied dose penetrated through human skin.

The particle size distribution of the test substance indicates a low exposure via inhalation. Since only few particles were of a size less than 10.2 µm an accurate assessment of the mass median aerodynamic diameter (MMAD) was not possible and therefore, no MMAD is available. However, 13.5 % of particles had an inhalable size below 100 µm, 11.4 % below 10 µm (e.g. thoracic fraction) and only 2.1% of particles showed a respirable size below 5.4 µm. For the test substance entrained in the nasopharyngeal or tracheo-bronchiolar regions (e.g. thoracic fraction), absorption across the epithelium may occur but is expected to be low.

Thus, absorption of the substance is expected after oral exposure, while absorption via the skin and after inhalation seems to be negligible. The log Pow of 2.6 and an BCF <8 in C. carpio (Gakushuin, 2000) do not indicate a bioaccumulation of the substance .