Sodium (xylenes and 4-ethylbenzene)sulfonates

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

other: Read across from another member of the category

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

use of copper(II)sulphate pentahydrate as reference item instead of 3,5-dichlorophenol

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test substance was directly weighed into the test vessel
- Controls: 2 control samples without test item were included, one at the beginnning and one at the end of the test
- Evidence of undissolved material (e.g. precipitate, surface film, etc): not applicable

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Non adapted activated sludge from the sewage plant at Sarsted is well suited as it receives predominantly municipal sewage and hardly industrial chemical waste.
The sludge was washed twice with autoclaved tap water and adjusted corresponding to a dry weight of 4.0 g/L +/- 10
%- Initial biomass concentration: 4.14 g/L dry sludge concentration

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

18-22°C

pH:

6.68

Nominal and measured concentrations:

1000 mg a.i./L (nominal), corresponding to 3355.7 mg test item/L

Details on test conditions:

TEST SYSTEM
- Test vessel
- Material, size, headspace, fill volume: 500 mL Erlenmeyer flasks, DIN 12380
- Aeration: permanent
- No. of vessels per concentration (replicates): one
- No. of vessels per control (replicates): two
- Composition of test medium: 200 mL inoculum, 16 mL synthetic waste water, 284 mL autoclaved tap water and test item concentration (directly weighing of 1677.9 mg test item)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): oxygen depletion by means of an oximeter

TEST CONCENTRATIONS
Limite test based on Dose Range finding study
Test concentrations DRF: 2.98, 29.8, 298 and 1000 mg a.i./L
Results used to determine the conditions for the definitive study: no inhibition at any of the concentrations tested

Reference substance (positive control):

yes

Remarks:

copper (II) sulphate pentahydrate p.a.

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

corresponding to 3355.7 mg test item/L

Basis for effect:

growth inhibition

Results with reference substance (positive control):

- Results with reference substance valid? Yes
Relevant effect levels: EC50 = 117 mg/L

Table 1: respiration rates and Inhibition of Respiration of Test and Reference Item Concentrations
	concentration [mg a.i./L]	Respiration rate [mg O2/L*h]	Inhibition [%]
Test item	1000	22.4	2
Control 1	-	23.6	-
Control 2	-	22.0	-
reference item	180	6.0	74
	100	14.0	39
	58	19.2	16

Validity criteria fulfilled:

yes

Conclusions:

EC10 <= 3355.7 mg/l corresponding to 1000 mg/l active ingredeint

Executive summary:

A respiration inhibition test with activated sludge according to official Guideline OECD 209 was carried out on Sodium toluene 4-sulphonate. The test was carried out under static conditions with the limit concentration 1000 mg a.i./L, corresponding to 3355.7 mg test item/L on activated sludge of the municipal treatment plant of Sarstedt, Germany. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. No inhibition was observed for the test item. In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC50-value for the reference item was 117 mg/L. Validity criteria of the test guideline were fulfilled. The test item Sodium toluene 4-sulphonate is not toxic at concentrations <= 1000 mg/l based on active substance (3355.7 mg test item/L) to activated sludge of a municipal sewage treatment plant.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

other: Read across from another member of the category

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

use of copper(II)sulphate pentahydrate as reference item instead of 3,5-dichlorophenol

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test substance was directly weighed into the test vessel
- Controls: 2 control samples without test item were included, one at the beginnning and one at the end of the test
- Evidence of undissolved material (e.g. precipitate, surface film, etc): not applicable

Test organisms (species):

activated sludge of a predominantly domestic sewage

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

18-22°C

pH:

6.68

Nominal and measured concentrations:

1000 mg a.i./L (nominal), corresponding to 2500 mg test item/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 500 mL Erlenmeyer flasks, DIN 12380
- Aeration: permanent
- No. of vessels per concentration (replicates): one
- No. of vessels per control (replicates): two
- Composition of test medium:
200 mL inoculum
16 mL synthetic waste water
284 mL autoclaved tap water and test item concentration (directly weighing of 1250 mg test item)

EFFECT PARAMETERS MEASURED: oxygen depletion by means of an oximeter
TEST CONCENTRATIONS
Limit test based on Dose Range finding study
Test concentrations DRF: 4, 40, 400 and 1000 mg a.i./L
Results used to determine the conditions for the definitive study: no inhibition at any of the concentrations tested

Reference substance (positive control):

yes

Remarks:

copper (II) sulphate pentahydrate p.a.

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

corresponding to 2500 mg test item/L

Basis for effect:

growth inhibition

Results with reference substance (positive control):

Results with reference substance valid?
Yes, Relevant effect levels: EC50 = 117 mg/L

Table 1: respiration rates and Inhibition of Respiration of Test and Reference Item Concentrations
	concentration [mg a.i./L]	Respiration rate [mg O2/L*h]	Inhibition [%]
Test item	1000	23.2	-2
Control 1	-	23.6	-
Control 2	-	22.0	-
reference item	180	6.0	74
	100	14.0	39
	58	19.2	16

Validity criteria fulfilled:

yes

Conclusions:

EC10 <= 2500 mg/l corresponding to 1000 mg/l active substance

Executive summary:

A respiration inhibition test with activated sludge according to official guideline OECD 209 was carried out on Sodium p-cumenesulphonate. The test was carried out under static conditions with the limit concentration 1000 mg a.i./L, corresponding to 2500 mg test item/L on activated sludge of the municipal treatment plant of Sarstedt, Germany. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. No inhibition was observed for the test item. In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxiciy was determined. The EC50-value for the reference item was 117 mg/L. Validity criteria of the test guideline were fulfilled. The test item Sodium p-cumenesulphonate is not toxic at concentrations <= 1000 mg/l based on active substance (2500 mg test item/L) to activated sludge of a municipal sewage treatment plant.

Description of key information

The HYDROTOPES Category comprises the following 6 substances:
STS - Sodium toluene 4-sulphonate (CAS 657-84-1, EC 211-522-5)
SXS - Sodium (xylenes and 4-ethylbenzene) sulphonate (EC 701-037-1)
NH4XS - Ammonium (xylenes and 4-ethylbenzene) sulphonate (EC 943-024-5)
SCS - Sodium p-cumenesulphonate (CAS 15763-76-5, EC 239-854-6)
KCS - Potassium p-cumenesulphonate (CAS 164524-02-1, EC 629-764-9)
NH4CS - Ammonium p-cumenesulphonate (CAS 680972-33-2, EC 811-484-5) 
In addition CaXS (Calcium Xylenesulphonate, CAS 28088-63-3, EC 248-829-9) was evaluated for complete the assessment despite it is not registered under REACH.

There are available studies about toxicity on micro-organism perfomed on two subgroups (toluene and cumene).
The results of the available studies are:
STS (2009, GLP): EC10 3 h > 1000 mg/l (a.i.)
SCS (2009, GLP): EC10 3 h > 1000 mg/l (a.i.)

The two studies showed the same results and the EC10 value used for the assessment is > 1000 mg/L.
The key study is a respiration inhibition test carried out using activated sludge and the test substance sodium p-cumenesulphonate in accordance with OECD Guideline No. 209. The test was performed under static conditions with the limit concentration 1000 mg a.i./L, corresponding to 2500 mg test item/L. The respiration rates of the control, reference and test substance replicates were measured after a contact time of three hours and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. No inhibition was observed for the test substance corresponding to an EC10 of >= 1000 mg a.i./L. The supporting study (Fiebig, 2009) was undertaken at the same time by the same laboratory using the same protocol, but using the test substance sodium toluene 4-sulphonate. The 3-hour EC10 (and NOEC) was >=1000 mg/L active substance (nominal); the only concentration tested. These studies indicate that of the Hydrotropes substances are comparable in term of effects on microorganisms and show low toxicity to the microorganisms involved in sewage treatment processes. These studies indicate that the Hydrotropes substances are comparable in term of effects on aquatic invertebrates and show low toxicity.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L