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Description of key information

The dermal absorption is considered to be 100%. 

Key value for chemical safety assessment

Absorption rate - dermal (%):

Additional information

No valid dermal absorption study using isononanol is known to exist. A default dermal absorption rate of 100% is assumed, taking a molecular weight of 144.25 and a log Pow of <3 into consideration, based on the provisions of the “Guidance on information requirements and chemical safety assessment. Chapter R.7c: Endpoint specific guidance.


Experimental data indicate that the dermal flux of a structurally related substance, 1-nonanol, in human skin (epidermis) in vitro is 0.003 mg/cm2/h (Schueplein, 1971). The same should apply to the isomeric 3, 5, 5,-trimethylhexan-1-ol, as the physico-chemical properties are comparable.


The lack of overt dermal toxicity of n-nonanol in a dermal repeated dose study (contact of 5 mL (1.6 to 2.0 g/kg) of nonyl alcohol for 1 h/day with the skin of rabbits on each of 50 days over a period of 75 days resulted in retarded growth and erythema but no mortality; Fassett, 1963; RL4) is plausible, because a low absorption rate is unlikely to cause rapid systemic availability and peak concentrations.


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