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Diss Factsheets

Administrative data

Description of key information

Green liquor sludge is typically produced as alkaline paste like material. The water content is ca. 40-50%. Based on the test results (the key studies) GLS is classified as hazardous since it is irritating to the skin and corrosive to the eyes. 
Irritation to the respiratory track has not been studied. Dry (aged) GLS may have different properties, since pH will decrease in time by the action and absorption of atmospheric CO2 into the material. Primarily CaCO3 is formed from hydroxides. Dry GLS is capable of forming respirable dusts and potentially cause respiratory 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)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Additional information

Effects on skin irritation/corrosion: irritating

Effects on eye irritation: corrosive

Effects on respiratory irritation: irritating

Justification for classification or non-classification

Classification for Skin irritation:

Irritant Category 2, H315: Causes skin irritation (CLP)

Xi; Irritant, R38: Irritating to skin (DSD)


Justification for classification of Green liquor sludge is based on the study results and classification criteria. On the basis of its pH and alkalinity reserve, GLS does not meet the criteria to be classified for corrosion/irritation as the pH + 1/12 alkaline reserve value for GLS is 12,19 which is below the threshold of 14,5 for corrosion and the pH + 1/6 alkaline reserve value is 12,26 which is below the threshold of 13 for irritation.

The results from the epiderm skin corrosivity test show that GLS is not corrosive to skin. The tissue viability after three minutes exposure to GLS was 96,1 %, which is significantly higher than the 50 % limit for corrosion and the viability after a 3 hour exposure was 15,3 % which was just above the threshold of 15 %. According to the CLP application guidance (section, 'Decision logic for classification of substances' and the REACH testing regulation (EC No 440/2008, B.40 BIS), GLS shall not be classified for skin corrosion.

However, according to test B.46 referred to in the regulation 761/2009/EC (amending the test method regulation 440/2008/EC) the test substance is considered to be irritant to skin in accordance with UN GHS category 2 'if the tissue viability after exposure and post-treatment incubation is less than or equal to 50 %'. The tissue viability for GLS was 8,8 %. Based on the test results the classification Irritant shall be assigned.


Classification for Eye irritation:

Eye Damage 1, H318: Causes serious eye damage (CLP)

Xi; Irritant, R41: Risk of serious damage to eyes (DSD)


Justification for classification of Green liquor sludge is based on the study results and classification criteria. According to the ECHA CLP application guidance (section there are no OECD adopted in vitro/ex vivo tests for serious eye damage/eye irritation at present. However, there is a regulatory acceptance in the EU that a substance can be considered a severe eye irritant (Serious eye damage Category 1) based on positive results in the Bovine Corneal Opacity and Permeability (BCOP) test (OECD Guideline 437).

According to the test a substance that induces an IVIS (In vitro irritancy score) ≥ 55,1 is defined as a corrosive or severe irritant. For GLS this score was 78,6 which for the purpose of classification for eye damage clearly indicates a corrosive/irritating capacity in the substance.

Further, according to the CLP guidance (decision logic chart, section, step 5a) GLS shall be classified as Category 1 for irreversible eye effects on the basis that the test results do not allow for discrimination between the classes Eye Dam.1 and Eye Irrit. 2.

Classification for Respiratory irritation:

The respiratory tract exposure route is not highly relevant for fresh GLS, which is normally a non-volatile wet paste/solid. Exposure through respiratory tract is possible only through dustiness in the handling of dry GLS. In drying the initial high pH of GLS will get slightly lower through absorption of CO2 from the air. It is expected that the material is still relatively alkaline and has potential to cause irritation through the pH effect in the respiratory tract. There is not sufficient information to draw a firm conclusion regarding the classification for respiratory irritation. Taking into account that the substance is already classified irritant to skin and corrosive to eyes, a classification of GLS as a respiratory irritant is not regarded necessary.