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Description of key information

DIPA was found non-irritating to the rabbit skin after 4 hours of exposure under semiocclusive conditions in a study performed according to OECD guideline 404. Undiluted DIPA applied to the skin of 24 human volunteers, caused dermal irritation in 6 individuals. The available data do not trigger classification.
An eye irritation study in rabbits, performed according to OECD guideline 405, indicated that DIPA is irritating to the eyes.
Inhalation of 500 - 2069 mg/m3 DIPA for 3 hours induced sensory and little pulmonary irritation in mice; not triggering classification.

Key value for chemical safety assessment

Additional information

In an OECD TG 404 test, small white Russian rabbits were exposed to DIPA on the abraded skin for 4 hours under semiocclusive conditions, followed by a 72 hour observation period. The application caused only slight erythema in 4/6 animals, which was fully reversible within 48 hours. Thus, DIPA was judged non-irritating to the skin (1985a, RL1). 

In another study, two Vienna White rabbits were exposed to DIPA under occlusive conditions for up to 20 hours, followed by an 8 -day observation period. No effects were observed after exposure for 1, 5 and 15 minutes. Irritation was observed in animals exposed for 20 hours only (mean erythema scores of 2.5), which was not fully reversible in one animal (1965, RL2). Since an exposure period of 20 hours is substantially longer than suggested in OECD test guideline, and a complete recovery might occur after a full recovery period (14 instead of 8 days, as described by the guideline), this finding cannot be used for drawing a conclusion regarding skin irritation.

In a human study, in which 24 volunteers received undiluted DIPA to the skin, dermal irritation was observed in six individuals (1980, RL4; see IUCLID section 7.10.5).

DIPA was found irritating to the eyes. In rabbits, irreversible effects were observed predominantly expressed by heavy erythema, iritis, opacity, and chemosis. Several animals showed bleeding of the mucous membrane and circum-corneal injections (Huels AG, 1985b). Similar results were obtained in another study (BASF AG, 1965). It was concluded that DIPA is irritating and injurious to the eyes.

There are 3 different in vitro eye irritation studies available. In an Isolated Rabbit Eye (IRE) test the test substance showed an slight irritating potential (Guo, 2010). Also in the Short Time Exposure Test (STE) (Takahashi, 2008; Hayashi, 2013) and in the LabCyte Cornea-Model (Katoh, 2013) DIPA showed an irritating potential.

In a study on respiratory irritation, mice were exposed to aerosol concentrations of 500 to 2069 mg/m3 DIPA (Detwiler-Okabayashi, 1996; see IUCLID section 7.2.2). The 3-hour exposure caused sensory irritation (immediate onset) and little pulmonary irritation (delayed onset). No mortality was observed. Post-exposure recovery of the breathing frequency was poor. The RD50 (concentration capable of evoking a 50% decrease in mean breathing frequency; -/+ 95% CI) was calculated to be 3200 (1940 - 32832) mg/m3.

Justification for classification or non-classification

Based on the available data, DIPA is currently not classified as irritating to the skin according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.

The findings do meet the criteria for classification as eye irritant according to GHS (eye irritation Category 2, assigned H319).