Octane-1-thiol

Endpoint summary

Description of key information

Based on assessment of the available data, octane-1-thiol should be considered slightly irritating to skin and eyes. No upper respiratory tract irritation was observed in mice exposed to 196 ppm (1.51 mg/L or 1510 mg/m3) for one minute, followed by 10 minutes in room air, followed by another one minute exposure.  In the acute inhalation study by Hardy and Jackson (1987), it was reported that there was a slow, shallow respiratory pattern in rats exposed to 0.24 mg/L octane-1-thiol, which was attributed to the irritant nature of the vapour.  However, no overt signs of respiratory tract irritation were reported.  Furthermore, inhalation studies on the structurally-related compound dodecane-1-thiol showed no evidence of respiratory irritation in rats, mice or dogs.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Skin Irritation

One key study in rabbits was identified to evaluate the primary skin irritation potential of octane-1-thiol.

In a key primary dermal irritation study (Moon, 1981c; Klimisch score = 2), 6 young adult albino rabbits were dermally exposed to 0.5 mL of octance-1-thiol under occlusive wrap for a period of 24 hours. The test material was applied to one square inch of abraded skin and the animals were subsequently observed for 7 days. Irritation was scored by the method of Draize. The test material elicited very slight erythema on both abraded and unabraded sites in 2 animals at 25 hours post dosing. One animal had slight erythema on the abraded site only while the remaining three animals appeared normal. At 72 hours post dosing, two animals exhibited slight erythema at the abraded and unabraded sites. All other animals had either returned to normal or remained normal. On day 7 post-exposure, erythema and/or edema were not observed in any animal. All animals, except one (#612) which exhibited a very slight induration, appeared to be normal.

Eye Irritation

One study in rabbits was identified to evaluate the eye irritation potential of octane-1-thiol.

In a key primary eye irritation study (Moon, 1981d; Klimisch score = 2), 0.1 mL of octane-1 -thiol was instilled into the conjunctival sac of the right eye of 6 young adultwhite rabbits for 4 seconds while the untreated left eye served as control. Animals were subsequently observed for 7 days. Irritation was scored by the method of the Draize. Octane-1-thiol demonstrated irritation in 4 out of 6 rabbits, with a mean Draize score of 0.4.  Most of the effects observed were reversible in the first 24 hours post exposure, and all were reversible 7 days after exposure. In this study, octane-1-thiol was considered to be slightly irritating to the eye by the study authors. However, octane-1-thiol is not considered to be an ocular irritant under the current EU regulations. 

Respiratory Irritation

In a respiratory irritation tract study (Pence, 1983b; Klimisch score = 2), 4 male outbred SPF mice were exposed via head only inhalation to 1.51 milligram per liter (196 ppm) of octane-1-thiol for two periods of one minute exposures separated by a ten minute exposure to room air. Animals were then observed for five minutes or until the respiratory rate returned to pre-exposure rates. The test material was applied as a vapor in a head only exposure chamber attached to a plethysmograph. None of the four mice demonstrated changes in respiratory rates during either one minute exposures to 1.51 mg/L octane-1-thiol. Based on the results the authors concluded that the test material is not an irritant when 1.51 mg/L (196 ppm or 1510 mg/m³) is inhaled by mice. Compound-induced corrosion was not reported. 

Additionally, in the acute inhalation study by Hardy and Jackson (1987) that there was a slow, shallow respiratory pattern observed in rats exposed to 0.24 mg/L, which was attributed to the irritant nature of the vapor. However, in the 4-week inhalation studies on dodecane-1-thiol (close structural analog), there was no indication of respiratory tract irritation in rats, mice or dogs. Based on the weight of evidence available, octane-1-thiol is not considered to be a respiratory irritant.

Effects on skin irritation/corrosion: slightly irritating

Effects on eye irritation: slightly irritating

Justification for classification or non-classification

Octane-1-thiol does not meet the criteria for classification and labelling as a skin irritant under EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008.

Octane-1-thiol does not meet the criteria for classification and labelling as an eye irritant as defined by EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008.

Octane-1-thiol does not meet the criteria for classification and labelling as a respiratory irritant as defined by EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008.