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Diss Factsheets

Administrative data

Description of key information

The irritation and corrosivity potential of OPA has been examined for both skin and eye irritation by in vivo studies in rabbits.
For skin irritation, the Key and supporting studies are Reliability 1 studies by Allen (1997) and Hofmann (1988).
For eye irritation, only a summary of a screening study (Reliability 4) is available (Hoechst, 1979)
There are no data on irritation to the respiratory system.

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)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Skin irritation/corrosion:

Two GLP-compliant studies are available which followed the OECD guideline 404 (Rel 1) using semi-occlusive applications of OPA to the skin of rabbits. In the study of Allen (Key study, 1997), exposure of one rabbit for 1 or 2 hours produced severe erythema (grade 4) and oedema (grade 3) at 24 hours. Effects indicating dermal corrosion prevented evaluation of erythema or oedema at 48 and 72 hours. Effects persisted to termination of the study at 12 days. In the study of Hofmann (1988), significant erythema was reported in only one out of three rabbits following a 4-hour exposure (individual mean score for 24/48/72 hours: 2.67). Corrosive effects were reported which had not fully resolved in this animal at 21 days after application. 3-minute exposures in each of these studies did not report any signs of irritation. On the basis of the results of these studies it is concluded that OPA is corrosive to the skin for exposures of 1 or 4 hours.

Eye irritation:

In a screening study in two rabbits (Hoechst, 1979) (Reliability 4), exposure to the undiluted substance resulted in complete turbidity of the cornea with iris not visible, no reaction of the iris to light, swelling and reddening of the mucous membranes so that eyelids were completely closed and swelling extended over half the head, with strong discharge. Similar, though less severe symptoms were observed with 10% and 1% solutions. It was concluded that OPA is corrosive to the eye. On the basis of this study and the results of the skin irritation studies, no full OECD 405 study is required, a waiving was proposed.

Respiratory irritation:

No data available

Justification for selection of skin irritation / corrosion endpoint:
The reliability of the study in K1, in accordance with GLP and guideline. This study allowed to classify OPA as corrosive into category 1B, H314 unlike the Hofmann study (K1, 1988) the classification proposed is corrosive into category 1C.

Justification for selection of eye irritation endpoint:
On the basis of this study and the results of the skin irritation studies, a waiving was proposed.

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Justification for classification or non-classification


Corrosive effects from 1, 2 or 4 hour exposures were not fully resolved by end of the 12 or 21 day observation period. No corrosive effects were reported for a 3-minute exposure. Based on these results, OPA is classified as Corrosive, Category 1B (H314: causes severe skin burns and eye damage) according to the criteria of the Regulation (EC) 1272/2008 and as skin corrosive (C-R34) according to the criteria of the Annex VI of the Directive 67/548/EEC.


Based on skin corrosion and the results of a screening study on eye irritation, According to the criteria of the Regulation (EC) 1272/2008, OPA is classified as causing serious eye damage, Category 1 (implicit in skin corrosion classification).

Respiratory System:

No classification is possible due to lack of data.