Spent liquor from alkaline pulping and bleaching containing spent inorganic process chemicals and dissolved organic substances originating from the cellulosic raw material.

Endpoint summary

Description of key information

- Black liquor is considered to be non-corrosive but irritant to skin according to the test results. The applied methods were EU Method B.40, OECD 431, DRAFT OECD Guideline “In vitro Skin irritation: Reconstructed Human Epidermis (RhE) Test Method” and EU Method B.46. 
Black liquor is regarded as an ocular corrosive or severe irritant substance according to the method OECD 437 (the BCOP test). 
- The test results and the main identified ingredients of Black liquor indicate need for classification for corrosivity.

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:

adverse effect observed (irritating)

Additional information

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

Skin irritation/corrosion

Based on the test results on corrosivity Black liquor is irritant but non-corrosive. The mean percentage viability of the treated skin discs after 3 minutes of exposure was 92.6 - 94.5 % which is above the threshold of 50 % for classification, and after 1 hour of exposure the viability was 30.7 - 40.6 % which is above the threshold of 15 % for classification.

On the other hand, based on the evaluation of the maximum expected concentrations of the main ingredients Black liquor is considered corrosive according to both the CLP and DSD rules.

Additionally corrosive substances should be considered corrosive to the respiratory tract as well, if no acute inhalation study is available and the substance may be inhaled, according to the CLP guidance.

Eye irritation/corrosion

Black liquor is regarded as an ocular corrosive or severe irritant substance according to the method OECD 437 (the BCOP test). The IVIS (In Vitro Irritancy Score) of Black liquor was 268.2 (which is ≥ 55.1).

 

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Effects on respiratory irritation: irritating

Justification for classification or non-classification

Black liquor is the spent cooking liquor from alkaline pulping and bleaching process.The source materials for Black liquor are softwood, hardwood, agricultural fibres and White liquor. Dry substance content of Black liquor varies from 3 to 80% consisting of ca.30 -77% of inorganics and 23-70% organics.

Black liquor is a UVCB substance with a fluctuating composition.Therefore the irritation/corrosion properties may be somewhat variable.

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

No additional data was found for irritation/corrosion through extensive literature searches. A case study of three occupational accidents resulting in skin and eye hazards is reported for Black liquor in 7.12.

 

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

- Non-corrosive (skin),

- Irritant (skin),

- Ocular corrosive or severe irritant (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 Black liquor typical composition (1.2), which hold a harmonized classification for corrosive properties (sodium hydroxide, EC 215-185-5; sodium sulfide, EC 215-211-5; sodium carbonate, EC 207-838-8; formic acid, EC 200-579-1 and acetic acid, EC 200-580-7.

 

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

- Corrosive (skin and eye).

 

The proposed classification derived from the experimental results and the properties of the main ingredients of Black liquor is:

 

CLP:             Corrosive, Category 1B (Causes severe skin burns and eye damage)

DSD/DPD:     C: Corrosive (Causes burns)

 

Supplemental hazard information:

For the labeling of Black liquor, the supplementary hazard statement EUH071 (Corrosive to the respiratory tract) shall be applied. It is stated in the CLP guidance (section 3.2.4.2) that in case no acute inhalation study is available for a corrosive substance and such substance may be inhaled, a hazard of respiratory tract corrosion may exist.