Sulfite liquors and Cooking liquors, green

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.016 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.032 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.002 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

30 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

no data available: testing technically not feasible

Sediment (marine water)

Hazard assessment conclusion:

no data available: testing technically not feasible

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Test results for Green liquor samples (GL1) and (GL2) are available for short-term aquatic acute toxicity (algae, invertebrates and fish) and a long-term (21 d) Daphnia magna reproduction test (GL3).

All the test results are valid and the identity of test material is the same as the registered substance. To avoid unnecessary use of fish, a threshold approach according to OECD guidance document ("The Threshold Approach for Acute Fish Toxicity Testing", December 2009) was applied.

The representative GL1 sample of Green liquor was somewhat more toxic to invertebrates than the GL2 sample but there was no difference in algal toxicity between the samples. The most sensitive of the tested species is Daphnia, and the test results on Daphnia drive the environmental/aquatic classification and PNEC derivation.

 

The results are given on the basis of wet weight (wwt.) of the substance (water included) and on the basis of dry solids content of the test item (dry weight/dw.). The results on dry weight basis are used for classification and PNEC derivation purposes.

Summary of test results (1 = GL1 sample, 2 = GL2 sample):

Algae (Pseudokirchnerella subcapitata):

          

1 EC50 (72h) 1380 mg/l (growth rate) (wwt.) 244 mg/L (dw.)

2 EC50 (72h) 1230 mg/l (growth rate) (wwt.) 230 mg/L (dw.)

Aq. invertebrate (Daphnia magna):

1 EC50 (48h) 9 mg/l (wwt.), 1.6 mg/L (dw)

2 EC50 (48h) 40 mg/l (wwt.), 7.5 mg/L (dw)

1 NOEC (21 d) 2.4 mg/L (dw) (reproduction)

Fish (Danio rerio):

1 LC50 (96h) > 9 mg/l (wwt.), > 1.6 mg/L (dw)

PNEC aquatic

PNEC values are derived for GL based on the test results. There are three valid acute study results (fish, Daphnia, algae) and two valid chronic study results (Daphnia, algae) available. If two long-term results (e.g. EC10 or NOECs) from species representing two trophic levels (fish and/or Daphnia and/or algae) are available this makes it possible to use AF = 50 for fresh surface water PNEC derivation.

The assessment factor of 50 applies to the lowest of two long term results (NOECs) covering two trophic levels when such results have been generated covering that level showing the lowest L(E)C50 in the short-term tests. This should however not apply in cases where the acutely most sensitive species has an L(E)C50 value lower than the lowest long term result NOEC value. In such cases the PNEC might be derived by using an assessment factor of 100 to the lowest L(E)C50 of the short-term tests. This is the case in GL assessment, since L(E)C50 1.6 mg/l for Daphnia is lower than the chronic NOEC 2.4 mg/l for Daphnia.

The lowest effects value is the acute EC50 value 1.6 mg/l for Daphnia magna and it will be used as the reference value in PNEC aquatic generations (for more details of the assessment rules see Table R.10-4 Assessment factors to derive a PNECaquatic in the ECHA publication CSA Guidances, Part R.10 – Dose [concentration]-response regarding environment).

PNEC intermittent

The determination for GL applies short-term L(E)C50 values. The PNECwater, intermittent is normally derived by application of an assessment factor of 100 to the lowest L(E)C50 of at least three short-term tests from three trophic levels. The assessment factor is designed to take account of the uncertainty that exists in extrapolating from the results of short-term laboratory toxicity tests to short-term effects that can be anticipated in the ecosystems. The constituents of GL are known to have relatively high toxicity in aquatic animals and the mode of action is expected to be specific (respiratory inhibition). The tolerance window for acute effects in aquatic invertebrate animal species is narrow (very deep slope in the exposure to effects curve). Therefore it is not seen justified to use lower assessment factor than 50 for intermittent releases.

 

Conclusion on classification

The conclusion on environmental hazard classification is based onthe CLP criteria and the aquatic standard test results for fish, invertebrate and green algae, of which invertebrate (Daphnia) was the most sensitive organism and therefore drives the classification.

The available data fulfills the minimum (Annexes VII-VIII in the REACH regulation) requirements, and has been generated with standard organisms and standardized methods. Therefore the information is relevant for the environmental classification of Green liquor for aquatic effects. All the tests on Green liquor were carried out applying nominal test substance concentrations and classification is based on dry solids content of the substance (water excluded).

 

Conclusions on classification:

Acute: Aquatic Acute 1, if S^{2 -} in green liquor ≥ 6 % wt.

Justifications: The existing dataset of GL consists of three aquatic acute toxicity test results (algae, invertebrate, fish).

All the acute LC/EC50 test result values are just above the trigger value (1 mg/l) and therefore these green liquor samples shall not be given an Aquatic Acute classification. Sulfide (S^2-) is known to be the main factor in promoting acute aquatic toxicity and therefore sulfide based specific concentration limits are given for acute classification.

The sulfide based specific concentration limits were made by extrapolation from existing test results of the green liquor test results. No environmental classification is given for green liquor if the sulfide (S^2-) concentration in dry solids and mixture is < 6% by weight.  

	Sulfide in green liquor
S^2-  wt % in Dry Solids and in water mixture	≥ 6 %
Classification: Environment	Aquatic Acute 1 Warning H400: Very toxic to aquatic life

Chronic: No classification

Justifications: There are no chronic toxicity data available for all three trophic level. The algae 72hr study is already available and the study may be regarded as a chronic study. A valid 72 hr algae study is a multigeneration study and a NOEC value has been derived (NOEC 52.4 mg/l dry wt.). The algae result alone will not trigger the chronic classification. There are no chronic results available for fish (REACH waiving) and therefore CLP Table 4.1.0 b iii must be used. The chronic test results for invertebrates Daphnia magna 21 day reproduction study resulted a NOEC 2.4 mg/l (dry weight).

Degradation is one of the chronic criteria. Rapidly degradable substances must not be classified for chronic categories. (CLP Table 4.1.0 b iii) Note 3: When no useful data on degradability are available, either experimentally determined or estimated data, the substance should be regarded as not rapidly degradable.)

Sulfide (S^{2 -}) is known to be the main factor in promoting acute and also chronic aquatic toxicity of green liquor. Based on environmental transformation studies available, sulfides are oxidized rapidly in aerobic water courses in fresh and marine environment.  The transformation products are oxidized sulphur species (eg. SO^3-, SO4^2-) that are known to be significantly less toxic than sulfides. Therefore Green liquor, as a UVCB mixture, is regarded rapidly degradable in ecotoxicological point of view and need not to be classified for any of the Aquatic Chronic categories. This justification is also supported by the list of harmonised CLP classification (ATP 3-8) where the listed simple sulfides (Na₂S, K₂S, H₂S) have Aquatic Acute 1 classification only (M factor = 1), but not any of the Aquatic Chronic classifications.

As a conclusion, No chronic aquatic classification is given for green liquor.Green liquor is regarded as readily degradable in the environment in ecotogicological point of view (transformation to low toxicity constituents) and consequently

, since sulfides are known to be rapidly oxidised in natural waters in aerobic conditions and other constituents of GL have no or very low toxicity.