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Description of key information

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

A study on the absorption, distribution and excretion in rats of a close structural analogue (CAS 16090 -02 -1) is available.

Following an oral dose of 14C-labeled of CAS 16090 -02 -1 in water at 5.9 mg/kg bw to rats of both sexes, rapid and complete excretion of radioactive material was observed, with an excretion half life ranging from 7-13 hours. Feces were practically the only route of excretion (more than 95% of the administered radioactive material was excreted within 48 hours), indicating, in combination with the short half life times, that no significant amounts were absorbed from the gastro-intestinal tract. No radioactivity was found in blood, liver kidney, brain, muscle, or fat 96 hours after dosing (limit of quantification 0.005 - 0.01 ppm equivalents). The total recovery of radioactivity was 97.5% and 95.2% of the orally applied dose for males and females, respectively.

A further study done with another close structural analogue (CAS 13863 -31 -5) (CIBA-GEIGY Limited, Basel, Switzerland 1975a) which examines the skin absorption is available. 14C-labeled test substance was topically applied to the depilated back of male rabbits at a dose of 20 μg/cm². Within three days approximately 2% of the applied radioactivity was excreted with urine and faeces; by far the major portion was still on the skin. The subcutaneous tissue underneath the application area contained 0.2% and the total skeletal muscle certainly less than 1% of the applied radioactivity assuming the radioactivity found in muscle underneath the subcutaneous tissue of the application area to be representative for the total muscle radioactivity. The radioactivity in the blood, monitored during 72 hours, contained only minute amounts of radioactivity. Even at the peak, reached within two hours, the amount present in the total blood was still below 0.1%. After six hours the blood radioactivity was below the limit of quantitation or even below the limit of detection being 0.016% and 0.006% or 2.7 ppb and 0.9 ppb, respectively. From these data it is assumed, that the test substance is not absorbed by rabbits after topical application. The small amount of radioactivity excreted with urine and faeces is probably due to impurities present in the14C-labeled test substance used in this study and to degradation products which may be formed in trace amounts on the skin during prolonged contact with the compound.

Conclusion: reading across, these studies demostrate that the substance CAS 133 -66 -4 is almost completely excreted after oral exposure and that a dermal absorption is poor.