2,2,6,6-tetramethylpiperidinooxy

Endpoint summary

Description of key information

According to REACH Regulation (EC) No. 1907/2006, the test substance 2,2,6,6-tetramethylpiperidinooxy (TEMPO) does not need to be tested for acute toxicity as the substance is classified as corrosive to the skin. Therefore, an acute oral toxicity study is not available, however, in order to fulfill TSCA 8e requirements the substance was tested earlier for acute dermal and inhalation toxicity.

The acute inhalation toxicity study was considered to be invalid and was disregarded for classification due to major methodological deficiencies. The study was set up as limit study, but the results revealed an LC100 below the test concentration (nominal test concentration of 4.5 mg/L), and no further doses were tested in order to characterize the toxic concentration range. Moreover, the test material condensed on the surfaces of the delivery apparatus and inhalation chamber during delivery, so that the actual test concentration is unknown. It was estimated that the rats were exposed to vapor concentrations at least 10-fold less than the nominal concentration. Since the test item is corrosive to the skin, corrosion to the respiratory tract might have contributed to the lethal effect and hampered the investigation of inhalation toxicity. Due to the corrosive nature of the test substance, risk management measures to avoid inhalation exposure (technical measures and use of personal protective equipment) are in place.

The mean acute dermal lethal dose (LD50) of 2,2,6,6-tetramethylpiperidinooxy was found to be lower than 2000 mg/kg bw in male and female rabbits in a limit test. A full test was not performed. Since the test item was shown to be corrosive to the skin and the estimated cause for mortality in this study were severe corrosive effects, the study is considered to be invalid for the estimation of dermal toxicity.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Data waiving:

other justification

Justification for data waiving:

the study does not need to be conducted because the substance is classified as corrosive to the skin

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is classified as corrosive to the skin

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is classified as corrosive to the skin

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

According to REACH Regulation (EC) No. 1907/2006, the test substance 2,2,6,6-tetramethylpiperidinooxy (TEMPO) does not need to be tested for acute toxicity, as the substance is classified as corrosive to the skin. Therefore, an oral acute toxicity study is not available and an acute inhahalation and an acute dermal toxicity study were disregarded due to major methodological deficiencies and cannot be used for classification. As a conclusion, the test substance cannot be classified for acute toxicity in accordance to the CLP Regulation (EC) No 1272/2008.