Sulfite liquors and Cooking liquors, green

Endpoint summary

Description of key information

Green liquor is a highly alkaline (pH > 10) aqueous liquid and the identified subclasses of the constituents have known potential to cause skin, eye and respiratory track irritation (1. Hydroxides, 2. Sulfides, 3. Oxidised sulfur constituents (sulfates, thiosulfates, sulfites) and 4. Carbonates). In vitro tests have shown that GL is corrosive to the skin and therefore may also cause severe damage to the eyes. Green liquor may be corrosive also to the respiratory track if vapours/mist is inhaled. Green liquor liberates toxic H2S gas in contact with acids (already in neutral or acidic solutions). Exposure to H2S may also damage the olfactory epithelium (Brenneman 2000 and 2002).

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

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Effects on respiratory irritation: irritating

Justification for classification or non-classification

Conclusion on classification on irritation/corrosion is based on test results on Green liquor (the Key studies on Green liquor) and on the maximum expected concentrations of the identified corrosive constituents.

Positive in vitro results do not generally require further testing and can be used for classification. The human skin model (HSM) tests (TM B.40 bis; OECD TG 431) only allows a classification into Skin Corrosion Category 1. The maximum expected concentration of corrosive constituents confirm the classification to 1A. Therefore it can be concluded that Green Liquor (sulfite process) meets the criteria to be classified for the class:

Skin Corrosion Category 1A, with a hazard statement H314: Causes severe skin burns and eye damage.

Additional labeling provisions may be applied if the substance is classified as Corrosive. Corrosive substances (and mixtures) may be acutely toxic after inhalation to a varying degree, which is only occasionally proved by testing. In case no acute inhalation study is available for a corrosive substance (or mixture) and such substance (or mixture) may be inhaled, a hazard of respiratory tract corrosion may exist. These conditions apply to GL.

The conclusion for classification is based on the pH of GL, the literature search and testing according to OECD guidelines. GL will be classified as corrosive. Discrimination between skin corrosive subcategories 1A/1B/1C is not possible due to lack of animal testing data or suitable in-vitro data.

It is stated in the Annex I of the CLP regulation (section 3.3.3.3.4.2) that regarding mixtures containing strong acids or bases the pH value of the mixture shall be used as the classification criteria rather than the given generic concentration limits as pH is a better indicator of the risk of serious eye damage.

Since the measured pH of GL is 11.5 and the substance is classified as corrosive to skin, it could be concluded that GL should be classified to

Eye Damage 1 -class, with the hazard statement H318: Causes serious eye damage.

However, since GL is classified as Category: Corrosive (see 5.5 Corrosivity), serious damage to eyes is implicit, and there is no need to proceed with classification for eye effects.