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Description of key information

4-chloro-o-cresol is considered to be highly corrosive. 

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (corrosive)

Eye irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Additional information

The Scantox guideline (1982d) study was taken as the key study as this was considered to be the most reliable, however a number of other studies were reported in the EU Risk Assessment Report from the Rapporteur Member State.

These studies namely Hazleton laboratories (1977a) and a BASF study were cited in the BUA-Stoffbericht 134 report (1994). The reported details are very limited, however the Hazleton study showed necroses after dosing with 500mg PCOC and after 24 hours pronounced erythema with light oedema was observed.

The BASF study concludes that 4 -chloro-o-cresol is highly corrosive as after only one minute of exposure, necrosis was found and persisted such that after day eight the skin was still scarred.

Both these reports support the Scantox study (1982d).

In the case of eye irritation, the same BUA-Stoffbericht 134 report (1994) cited in the EU Risk Assessment report, reports that eye irritation studies were performed on rabbits by BASF AG (1978) and Hazleton labs (1977a).

The BASF study reports 50mg PCOC in 80% aqueous solution as strongly corrosive. The eye turned red and after 1 hour oedema and opacity of the cornea was found. After 8 days the clinical observations were unchanged and a staphyloma was found.

Although some of these studies are quoted from secondary references the results together with the Scantox report conclude that 4 –chloro-o-cresol must be considered as highly corrosive.

Effects on skin irritation/corrosion: highly corrosive

Effects on eye irritation: highly corrosive

Justification for classification or non-classification

Based on the study results above, 4-chloro-o-cresol is classified as R35 highly corrosive under the DSD regulations, based on the fact that full thickness destruction of the skin occurs as a result of up to 3 minutes of exposure. Under GHS regulations, the same criteria result in a classification of skin corrosivity category 1A.

Although results show that the substance is also corrosive to the eye, the R35 and skin corrosivity classifications assigned above are sufficiently severe to supercede any subsequent corrosivity classification.

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