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Description of key information

Skin irritation / corrosion
Urea phosphate did show corrosivity in an in vitro skin corrosion test.
0.5 mL of a 80% phosphoric acid solution was observed to be corrosive to rabbit skin after 24 hours of exposure.
Eye irritation:
No reliable data are available for the eye irritation endpoint. Nevertheless as the substance is skin corrosive and classified accordingly, the substance is as well considered as eye corrosive. This is as well in accordance with the results of the unreliable studies.

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

Urea phosphate will be dissociated into urea and phosphoric acid in aqueous environment.

Skin irritation / corrosion:

An in vitro skin corrosion test with urea phosphate itself (comparable to OECD 435 guideline and validated according to ECVAM), did show that this substance passess a chemical barrier in approx. 17 minutes, which shows it is a corrosive substance.

BASF (1980) studied the skin irritant/corrosive properties of phosphoric acid on Vienna White rabbit skin (6 male rabbits tested according to guideline 1500.41 in the Federal Register Vol. 38, No. 187, S. 26019 from 1973 -09 -27). 0.5 mL of an 80% solution was applied to the shaved test sites (half of the test sites were abraded). After 24 hours of exposure, observations were done at 24 and 72 hours and at 8 days post dosing. The substance was observed to be corrosive to rabbit skin.

No evidence of skin irritation was seen in a modern guideline study with urea.

Eye irritation:

Phosphoric acid is classified as a skin corrosive substance category 1B (concentration > or = 25%) and an eye irritant (10% < or = concentration < 25%) according to the CLP Regulation Annex VI, table 3.1 (EC Regulation 1272/2008 on classification, labelling and packaging of substances and mixtures). This data supports the in vitro skin corrosivity as tested for urea phosphate and supports the urea phosphate classification as corrosive. Therefore, according to the REACH Regulation, in vitro testing for eye irritation with this substance does not need to be conducted (column 2 adaptation, Annex VII, section 8.2). In vivo testing can be waived according to the REACH Regulation as phosphoric acid is classified as corrosive to the skin and as an eye irritant (column 2 adaptation, Annex VIII, section 8.2.1).

Urea was found to be a mild eye irritant in a guideline-compliant study, but is not classified as such.

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Justification for classification or non-classification

Based on the available data urea phosphate is classified according to Directive 67/548/EC as C 'Corrosive', R34 'Causes burns' and based on phosphoric acid with specific concentration limits (<10% = no classification and ≥10%≤C<25% = R36/38).

In addition, the harmonized classification (Annex VI, Table 3.1) of the CLP Regulation (EC) No 1272/2008 reports that phosphoric acid is a skin irritant substance category 1B, H314 'Causes severe skin burns and eye damage' at following concentration limits: (<10% = no classification and ≥10%≤C<25% = SKin cat. 2 H315).

According to the CLP Regulation (EC) 1272/2008 (Annex VI, Table 3.1), phosphoric acid is considered as an eye irritant substance category 2, H319 'Causes serious eye irritation' with a concentration limit of ≥10%≤C<25%.

These concentration limits are also taken over by urea phosphate based on the corrosivity as shown fort he substance itself in an in vitro test.

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