Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 268-615-9 | CAS number: 68131-33-9 The solution formed by reacting the sodium salts of green liquor with calcium hydroxide.
Ecotoxicological Summary
Administrative data
Hazard for aquatic organisms
Hazard for air
Hazard for terrestrial organisms
Hazard for predators
Additional information
White liquor is registered as a transported isolated intermediate and is manufactured and consumed under strictly controlled conditions during its whole life cycle. The derivation of PNECs is required for the chemical safety assessment (CSA) of substances manufactured/imported/used in quantities from 10 t/y onwards. CSA does not need to be performed for transported isolated intermediates.
The conclusion on classification is based on aquatic acute toxicity data according to Annex VII in the REACH regulation, applied for transported isolated intermediates, where no terrestrial or long-term aquatic toxicity information is required.
No data on sediment or terrestrial toxicity of White liquor was available based on an extensive literature search. White liquor recycles in the pulping process and no spillages occur in normal process conditions. Hence little ecotoxicological studies have been conducted on White liquor. The dry solids/water ratio of the tested sample was 17/83 % by weight.
White liquor was the most toxic to Daphnias (EC50 4.4 mg/l (dwt.) (26 mg/l (substance wet weight)), which drives the classification.
The EC50 value is higher than the limit value for the acute classification Aq. Acute Cat.1 (< 1 mg/l).
The criteria for Chronic Cat. hazard classification requires additional information of (bio)degradability and/or bioaccumulation and/or chronic toxicity. Based on scientific literature information, sulfide (S2-) which is known to be the most toxic constituent of White liquor, is readily oxidised in aquatic environment in abiotic and microbial processes.
Conclusion on classification
White liquor is an aqueous alkaline solution of inorganic cooking chemicals in kraft or soda pulping process. The source materials for White liquor are sodium salts of green liquor and calcium oxide. White liquor is a UVCB substance with variable composition. Therefore the exotoxicological properties are also somewhat variable and dependent on the sulfide content of the mixture.
The aquatic toxicity of a representative White liquor sample were tested in a GLP laboratory during 2009-2010 (the Key studies). No additional data on ecotoxicological endpoints was found through extensive literature searches.
According to the experimental results the ecotoxicological properties of White liquor were:
- Hazardous to the acuatic environment (Acute toxicity to Daphnia magna, EC50 <10 mg/l (dry weight of the substance)
- Not toxic to aquatic algae within the classification limits (Toxicity to Pseudokirchneriella subcapitata, 100 > EC50 > 10 mg/l (dwt)
Additionally, the need for classification according to the CLP rules was evaluated based on the expected maximum concentration of the only identified main ingredient reported in the White liquor typical composition (1.2), which holds a harmonized classification for aquatic hazard (sodium sulfide, EC 215-211-5).
The overall toxicity of White liquor is expected to be decreased relatively rapidly in the aquatic environment in the presence of oxygen (degradation rate of sulfides is comparable to readily biodegradable organic substances). Rapid oxidation of sulfides is predominantly an abiotic process, even if microbes are also capable of effectively oxidizing sulfides to elemental sulphur, sulfites and sulfates. As a conclusion White liquor (as a registered UVCB substance) can be regarded here as a readily (bio)degradable substance in ecotoxicological point of view. Regarding the Aquatic toxicity of white liquor, sulfides are known to be the main driver in promoting aquatic toxicity observed for White liquor. The tested sample contained 10 % sulfides equal to 24.4 % Na2S in dry solids.
Overall conclusion on environmental classification of White Liquor
Sulfide based specific concentration limits have been derived for environmental Classification of White liquor dry solids. The limits have been set on the basis of combination of test results for white liquor, bridging principles applying test result data for Green liquor and applying summation rules of the CLP regulation.
White liquor dry solids is classified to Aquatic Acute 1 category. Classification applies to those substances that contain > 10 % sulfides (S2-) in dry solids.
White liquor does not meet the criteria for classification for any of the Aquatic Chronic categories.
White liquor does not meet the criteria for classification for other hazard classes i.e. hazard to the ozone layer.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
