The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated 1‐decanol [
112‐30‐1
] to derive a maximum concentration at the workplace (MAK value), considering all toxicity endpoints. Critical effects are irritation and the tumour‐promoting potential on the skin. Neither appropriate data in humans nor inhalation or oral studies of 1‐decanol with animals are available for derivation of a MAK value. An 8‐week feeding study in Wistar rats with the structurally related 1‐dodecanol resulted in a NOAEL of 100 mg/kg body weight and day. The same NOAEL is assumed for 1‐decanol. From this NOAEL, the concentration in workplace air was calculated according to the Commission's procedure to be 245 mg 1‐decanol/m
3
. However, as 1‐decanol is irritating and there are no studies of effects in the respiratory tract, a comparison with structurally‐related substances is indicated as well. The RD
50
values of 45 ml/m
3
and 50 ml/m
3
for 2‐ethylhexanol and 1‐octanol, respectively, are rather similar, which can also be assumed for 1‐decanol. Because of its similar irritating potency, the MAK value for 1‐decanol has been established at 10 ml/m
3
in analogy to 2‐ethylhexanol. As local effects are critical, the substance is assigned to Peak Limitation Category I. The excursion factor of 2 is set in analogy to 2‐ethylhexanol. From a synopsis of all data, 1‐decanol is classified in Pregnancy Risk Group C, despite the small difference between MAK value and NOAEC of 15 ml/m
3
for developmental toxicity. 1‐Decanol is not mutagenic in bacteria. There are no long‐term studies with 1‐decanol. Papillomas, squamous cell carcinomas and severe skin irritation occurred after 60‐week application to the skin of the mouse following initiation with 7,12‐dimethylbenz[a]anthracene. The maximum skin absorption of 10 mg is less than 25% of the systemically tolerable amount of 660 mg which is taken up by inhalation at the MAK value. There are no positive clinical findings of contact sensitization from 1‐decanol, nor are such effects expected from the structure and the comparison with homologous alcohols. Data for sensitization of the airways are not available.