Reaction mass of disodium carbonate and disodium sulfate and sodium chloride

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No guideline study without detailed description..

Justification for type of information:

See attached file

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
n.a.

Analytical monitoring:

no

Details on sampling:

n.a.

Vehicle:

no

Test organisms (species):

Nitzschia sp.

Details on test organisms:

Described as Nitschia linearis

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

120 h

Post exposure observation period:

n.a.

Hardness:

100 mg/L as CaCO3

Test temperature:

not specified

pH:

not specified

Dissolved oxygen:

not specified

Salinity:

not specified

Nominal and measured concentrations:

not specified

Details on test conditions:

not specified

Reference substance (positive control):

no

Duration:

120 h

Dose descriptor:

EC50

Effect conc.:

2 430 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Results with reference substance (positive control):

n.a.

Reported statistics and error estimates:

No statistic described, no error estimates provided.

Conclusions:

EC50 (120 hr, Nitzschia linearis, cell counts) = 2430 mg/L

Executive summary:

The study tested EC50 /LC50 for fish (Lepomis macrochirus), snail (Physa heterostropha), and algae (Nitzschia linearis, diatom) to conclude on relative sensitivity. Sodium chloride was tested for fish and algae toxicity only. The 120 hr EC50 with NItzschia linearis based on cell count was determined as 2430 mg/L. Bluegill was less sensitive with 96hr-LC50=12946 mg/L (not summarised in this dataset).

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

other: assessment of publicly available data

Adequacy of study:

weight of evidence

Study period:

2015

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Data relating to the effect of sodium carbonate and sodium bicarbonate on algal growth, which is readily available in the media, has been assessed and evaluated. No actual data values are available for this end point and thus the conclusion is subjective

Qualifier:

no guideline followed

Principles of method if other than guideline:

Assessment of publicly available data

GLP compliance:

no

Test organisms (species):

other: algae, various

Dose descriptor:

NOEC

Effect conc.:

1 - 10 mg/L

Nominal / measured:

estimated

Remarks on result:

other: data is assessment based on pH

Dose descriptor:

EC50

Effect conc.:

10 - 100 mg/L

Nominal / measured:

estimated

Remarks on result:

other: data is assessment based on pH

Conclusions:

Sodium carbonate is a potential growth stimulant, but extreme pH can effect vigour.
Naturally occurring levels of sodium and carbonate in water courses are significant and variable. Additional sodium carbonate discharge is unlikely to contribute significantly to the natural levels already present

Executive summary:

An initial pH higher than 9 will reduce the growth and therefore the theoretically calculated NOEC will probably be 1-10 mg/l. The EC50 will probably be in the range of 10-100 mg/l. However the ecotoxicological assessment should be based on the inherent properties of the substance and not the pH effect. Indeed the pH effect depends on the buffer capacity of the aquatic ecosystem especially for algae. Therefore, this results are not used to assess the acute toxicity towards algae and cyanobacteria of the reaction mass.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study is missing too much information to be able to assign reliability score. However due to the very low toxicity of sodium sulfate in all ecotoxicological endpoints and the comparable reference substance data, data from this study may be used with care. Previous expert opinion has also recognised the limitations of the study but permitted its use see below for iuclid 4 / SIDS rationale. Iuclid 4 Rationale: In this test a different algae species is used than recommended in the OECD-guidelines. When the results of Potassium dichromate (72 h, EbC50) used as a reference substance, are compared with the results given in the EC-directive 92/69/EEC (mean 0.53 mg/l, range 0.20 - 0.75 mg/l) the sensitivity of Nitzschia linearis is not significantly different from that of Selenastrum capricornutum or Scenedesmus subspicatus. It is recognised that the duration of this study was greater than the recommended OECD study time but as the reference result from this study is on the lower boundary of the EC recommendation, the two results are considered comparable. This study would be considered as validity 3 because of the shortcomings. However, based on the other data, Sodium sulfate is a substance of very low toxicity and the results of this study confirm this, therefore this study is evaluated as valid with restrictions (2).

Qualifier:

according to guideline

Principles of method if other than guideline:

Pre-Guideline study was intended to look at variation between different species for common industrial wastes.

GLP compliance:

no

Remarks:

not applicable: pre-GLP

Analytical monitoring:

no

Test organisms (species):

other: Nitzschia linearis

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

120 h

Remarks on exposure duration:

Static

Duration:

120 h

Dose descriptor:

EC50

Effect conc.:

1 900 mg/L

Iuclid 4 Data

- Nominal/measured concentrations: nominal
- Effect data/Element values: growth (cell counts)
- Cell density data: not described
- Growth curves: not described
- Reference substance: Potassium dichromate, TLm = 0.208 mg/l

Validity criteria fulfilled:

no

Conclusions:

This result shows that Sodium sulfate is not a substance of concern for diatoms. The reference test data are comparable to that of data for OECD approved algae species. The response of the tested diatom species is therefore likely to be similar to approved test species. The data may therefore be used with care.

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

See Read across justification attached.
Data on the reaction mass itself are not available. Therefore data on the three components are used. Based on the available studies, the EC50 for the three components are far higher than 100 mg/L. The lowest EC50 is for Sodium Carbonate. Therefore only the EC50 for Sodium Carbonate are reported and retained as a worst case.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

120 h

Dose descriptor:

EC50

Effect conc.:

1 900 mg/L

Conc. based on:

test mat.

Basis for effect:

cell number

Conclusions:

Not classified according to EU GHS Based on the data on the three components.

Description of key information

No experimental data are available that assess the toxicity of the reaction mass of disodium carbonate and disodium sulphate and sodium chloride to algae and cyanobacteria.

Nevertheless, the EC50 of the reaction mass was defined based on a worst case (i.e. the lowest EC50 of the three constituents was selected to reflect the EC50 of the reaction mass). Accordingly, the EC50 for algae and cyanobacteria of the reaction mass of disodium carbonate and disodium sulphate and sodium chloride is 1900 mg/L (based on the EC50 of sodium sulphate as the EC50 of 1 -10 mg/l reported for the sodium carbonate is based on the pH effet and therefore not relevant for a ecotoxicological assessment which should be based on the inherent properties).

Key value for chemical safety assessment

EC50 for freshwater algae:

1 900 mg/L

Additional information

No experimental data are available to assess the toxicity to algae and cyanobacteria of the reaction mass of disodium carbonate and disodium sulphate and sodium chloride. Nevertheless, reliable information is available for the three components sodium chloride, sodium carbonate and sodium sulphate.The acute toxicity towards algae and cyanobacteria of each constituents of the reaction mass (i.e.sodium chloride, sodium carbonate and sodium sulphate) is known and the EC50 of the reaction mass can thus be predicted. To this end, the key study assessing the acute toxicity of each compound identified in the REACH registration dossier and in the OECD SIDS dossiers (available via internet) was selected and used in a weight of evidence approach in order to assess the acute toxicity towards algae and cyanobacteria of the reaction mass.

 

For the sodium carbonate, aquatic toxicity studies with plants and algae have not been found. According to the OECD SIDS the results can be predicted based on the increase of the pH of the test solution. An initial pH higher than 9 will reduce the growth and therefore the theoretically calculated NOEC will probably be 1-10 mg/l. The EC50 will probably be in the range of 10-100 mg/l. However the ecotoxicological assessment should be based on the inherent properties of the substance and not the pH effect. Indeed the pH effect depends on the buffer capacity of the aquatic ecosystem especially for algae. Therefore, this results are not used to assess the acute toxicity towards algae and cyanobacteria of the reaction mass.

Three studies are available from published literature on acute toxicity of sodium chloride to algae and cyanobacteria. The diatom Nitzschia linearis was found to be the most sensitive species with an EC50 (120 h, cell number) of 2430 mg/L (Patrick et al., 1968). Unfortunately, the article does not provide sufficient information to conclude on a No Observed Effect Concentration for Nitzschia linearis. Only this study was reported in this dossier to assess the acute toxicity to the reaction mass.

For the sodium sulphate, the same study (Patrick et al., 1968) was selected as key study (REACH registration dossier and in the OECD SIDS dossier).The diatom Nitzschia linearis was found to be the most sensitive species with an EC50 (120 h, cell number) of 1900 mg/L. In the same way as the souim chloride, unfortunately, the article does not provide sufficient information to conclude on a No Observed Effect Concentration for Nitzschia linearis. Only this study was reported in this dossier to assess the acute toxicity to the reaction mass.

 

As a conclusion, the substance is a solution of inorganic salts in water. The constituents are inorganic substances which are naturally occuring in aquatic ecosystems. The EC50 of the reaction mass was defined based on a worst case (i.e. the lowest EC50 of the two constituents (having a useful EC50) was selected to reflect the EC50 of the reaction mass). Accordingly, the EC50 for algae and cynaobacteria of the reaction mass of disodium carbonate and disodium sulphate and sodium chloride is 1900 mg/L.