Sulphophthalic acid derivatives reaction products of fatty alcohol C12-C14 and sodium hydroxide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June from 01 to 05, 1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

GLP compliance:

not specified

Analytical monitoring:

no

Details on test solutions:

Test item was directly dispersed in water.

Test organisms (species):

activated sludge

Details on inoculum:

- Source: the aeration stage of Severn Trent Water PLC Sewage Treatment Plant, Belper, Derbyshire.
- Preparation of inoculum for exposure: the sample was maintained at 21 °C with continuous aeration and used on the day of collection.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Nominal and measured concentrations:

Nominal 1000 mg/l

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration: 3 replicates.
- No. of vessels per control: 2 replicates.
- Suspended solids: 4.0 g/l, prior to use.

TEST MEDIUM / WATER PARAMETERS
- pH: the pH was 6.8

EFFECT PARAMETERS MEASURED
O2 consumption rates.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 1.0, 10, 100 and 1000 mg/l.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The variation in the percentage inhibition values observed after 3 hours contact time were considered to be due to variations in the respiration rate of the activated sewage sludge micro-organisms when exposed to the test material . The effect was not considered to affect the integrity of the study given that the difference between the control respiration rates was within the range specified in the OECD Guidelines (± 15 %) and the EC50 value for the reference material, 3,5-dichlorophenol, were within the range specified in the OECD Guidelines (5-30 mg/l).

Results with reference substance (positive control):

Reference Material EC50 (3h): 13 mg/l

MAIN TEST

Concentration (mg/l)	O2 consumption rates mg O2/l/min	% inhibition
Control	0.47	-
Control	0.44	-
Test item 1000	0.58	<27>
Test item 1000	0.54	<19>
Test item 1000	0.4	12
Reference substance 3.2	0.4	12
Reference substance 32	0.11	76

<increase>

Variation between controls: ± 3 %

DOSE RANGE FINDING

Concentration (mg/l)	O2 consumption rates mg O2/l/min	% inhibition
Control	0.36	-
Control	0.35	-
Test item 1	0.32	10
Test item 10	0.35	1
Test item 100	0.38	<7>
Test item 1000	0.34	4
Reference substance 3.2	0.32	10
Reference substance 32	0.08	77

<increase>

Variation between controls: ± 1 %

Conclusions:

IC50 (3h) > 1000 mg/l (nominal)

Executive summary:

The inhibitory effect of test item on the oxygen consumption of activated sludge microorganisms was investigated according to the OECD guideline 209. The exposure time of the test substance on the activated sludge was 3 hours. The dose-range finding test was conducted at the concentrations of 1, 10, 100 and 1000 mg/l; because no rignificant inhibition was recorded up to the highest dose, the main test was conducted at the limit concentration of 1000 mg/l.

Two out of three replicates showed an increased oxygen consumption, while the third showed an inhibition of 12 %.

The variation in the percentage inhibition values observed after 3 hours contact time were considered to be due to variations in the respiration rate of the activated sewage sludge micro-organisms when exposed to the test material . The effect was not considered to affect the integrity of the study given that the difference between the control respiration rates was within the range specified in the OECD Guidelines (± 15 %) and the EC50 value for the reference material, 3,5-dichlorophenol, were within the range specified in the OECD Guidelines (5-30 mg/l).

Conclusion

IC50 (3h) > 1000 mg/l (nominal)

Description of key information

IC50 (3h) > 1000 mg/l (nominal)

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The inhibitory effect of test item on the oxygen consumption of activated sludge microorganisms was investigated according to the OECD guideline 209. Two out of three replicates showed an increased oxygen consumption, while the third showed an inhibition of 12 %. The variation in the percentage inhibition values observed after 3 hours contact time were considered to be due to variations in the respiration rate of the activated sewage sludge micro-organisms when exposed to the test material. The effect was not considered to affect the integrity of the study given that the difference between the control respiration rates was within the range specified in the OECD Guidelines (± 15 %).