Spent liquor from semi-chemical pulping containing spent inorganic process chemicals and dissolved organic substances originating from the wood raw material

Endpoint summary

Description of key information

- SCP liquor was considered to be non-corrosive and non-irritant to skin according to the test results (EC 440/2008 B.40 and B.46, OECD 431, Draft OECD Guideline "In vitro Skin irritation: Reconstructed Human Epidermis ").
- SCP liquor was not regarded to be an ocular corrosive or severe irritant (OECD 437, BCOP test).
- The test results of of SCP liquor indicate no need for classification for irritation or corrosivity. However, the identified main ingredients suggest a need for a precautionary classification for skin irritation.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

There were two experimental in vitro studies available concerning skin irritation/corrosion and one in vitro study concerning eye irritation (the Key studies). Other studies could not be found in the literature search.

Epiderm skin corrosivity test with SCP liquor

Based on the test results on skin corrosivity SCP liquor is not corrosive. The mean percentage viabilities of the treated skin discs after 3 minutes of exposure were 99.8% and 98.7%, and after 1 hour of exposure the viability was 101.4% and 102.7%, which are above the threshold of 15 % for classification.

Epiderm skin irritation test with SCP liquor

Based on the test results on skin irritation SCP liquor was not irritant. The mean percentage viabilities of the treated skin discs were 94.7 % and 104.5%, which are above the threshold of 50 % for classification.

Eye irritation test with SCP liquor

Based on the test results on eye irritation SCP liquor was not ocular corrosive or severe irritant. The IVIS (In Vitro Irritancy Score) for SCP liquor was 1.1, and no increase in opacity or permeability was observed.

Effects on skin irritation/corrosion: irritating

Effects on eye irritation: irritating

Effect level: empty Endpoint conclusion: Adverse effect observed

Justification for classification or non-classification

Spent liquor from semi-chemical pulping (SCP liquor) is a process liquor from CTMP and NSSC pulping obtained after treatment of wood raw material with process chemicals. The source materials are softwood, hardwood and process chemicals. Dry substance content of SCP liquor varies from 5 to 77% depending on the degree of evaporation. SCP liquor is a UVCB substance with a fluctuating composition. Therefore the toxicological properties are somewhat variable as well.

The irritation/corrosion properties (Annex VII, REACH regulation) of two representative SCP liquor samples were tested by the Seibersdorf Labor GLP laboratory during 2009 -2010 (the Key studies).

No data was found for irritation/corrosion endpoints other than those tested in the key studies, through extensive literature searches. SCP liquor is registered as a transported isolated intermediate and no testing data outside Annex VII in the REACH regulation is required.

According to the experimental results the corrosive properties of SCP liquor were:

- Non-corrosive (skin)

- Non-irritant (skin)

- No ocular corrosion or severe irritation (eye)

Additionally, the need for classification according to the CLP and DSD/DPD rules was evaluated based on the expected maximum concentrations of those identified main ingredients reported in the SCP liquor typical composition (1.2), which hold a harmonized classification for corrosive properties. Formic acid (EC 200-579-1) and acetic acid (EC 200-580-7) hold Skin.Corr. 1A / C; R35 classification, but the sodium salts of these substances are not classified. Sodium carbonate (EC 207-838-8) has a harmonized classification Eye Irrit.2 / Xi; R36.

The maximum concentration of volatile carboxylic acids (mainly as sodium salts of formic and acetic acids) is estimated to be 25% w/w). The suggested precautionary classification for skin irritation is given according to the limit values in harmonized CLP classification, and is based on the assumption that maximum formic acid concentration would be 2%<C<10% and/or maximum acetic acid concentration would be 10%<C<25% in SCP liquor. However, it should be kept in mind that in neutral pH the substances are mainly as their sodium salts. The estimated maximum concentration of sodium carbonate does not suggest a need for classification.

A substance classified for Skin Irritation, Cat.2 is considered to hold also class Eye irrit. 2 (CLP Annex I, 3.3.2.3), and no additional classification for eye irritation is needed.

According to the main ingredients the corrosive properties of SCP liquor were:

- Irritant (skin and eye)

The proposed classification for irritation/corrosion, derived from the experimental results and the properties of the main ingredients of SCP liquor is:

CLP:             Skin Irritation Cat.2

DSD/DPD:     Xi; R38