Dodecylbenzenesulphonic acid, compound with 2-amino-2-methylpropan-1-ol (1:1)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Remarks:

the tested substance is AMP one of the components of the compound

Adequacy of study:

key study

Study period:

Not applicable

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted under GLPs

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):Not applicable

Analytical monitoring:

no

Details on sampling:

The contents of the first control vessel were transferred to a BOD bottle and dissolved oxygen concentrations were measured every 10 seconds over a 10 minute period, or until the DO measurement dropped below 1.0 mg O2/L using a YSI Model 50B-115 Dissolved Oxygen Meter. The respiration rate in subsequent vessels was determined in an identical manner at 15 minute intervals. The contact time for each concentration of reference or test substance with the activated sludge was three hours.

Vehicle:

yes

Details on test solutions:

The test substance was dosed by volumetric addition using a stock solution of the test substance prepared in NANOpure® water at a nominal concentration of 2000 mg/L. This method was deemed appropriate based on the solubility of the test substance in water.Test mixtures were prepared at 15 minute intervals starting with the first control. The control contained 16.0 mL of synthetic sewage, 200 mL of inoculum, and enough municipal water to bring the total volume up to 500 mL. The mixture was promptly aerated at a rate sufficient to provide aerobicconditions and keep the solids in suspension. Subsequent mixtures contained 16.0 mL of synthetic sewage, 200 mL of inoculum, the appropriate amount of test substance stock or reference substance stock solution, and enough municipal water to bring the total volume up to 500 mL. Finally, a second control was prepared. All mixtures were aerated for three hours.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge collected from the Denton Wastewater Treatment Facility, Denton, Maryland USA on 15 February 2010 was utilized as the inoculum for the test. The Denton facility receives wastes from predominately domestic sources. The sludge was sieved using a 2 mm screen and allowed to settle for approximately 30 minutes. The supernatant above the settled solids was removed and the total suspended solids (TSS) concentration of the settled sludge was determined. Total suspended solids in the settled sludge were adjusted to a nominal concentration of approximately 4000 mg/L by dilution with municipal water. 50 mL of synthetic sewage was added to each liter of adjusted sludge. The sludge was maintained at a temperature ranging from 21.5 to 22.3 °C and continuously aerated overnight. The pH and total suspended solids concentration of the activated sludge were determined on the day of use in the study.

Test type:

static

Water media type:

freshwater

Total exposure duration:

3 h

Post exposure observation period:

Not applicable

Test temperature:

21.5 to 22.3 °C

pH:

7.8

Nominal and measured concentrations:

10, 30, 100, 300 and 1000 mg/L.

Details on test conditions:

Test SystemThe biological test system was a consortium of microorganisms common to the activated sludge treatment process. The organisms responsible for the decomposition of organic materials are principally aerobic and facultative aerobic bacteria. The test system was chosen because it is representative of a treatment process that may receive the test substance.Test Conditions and ApparatusControl, reference, and treatment test mixtures were incubated at temperatures ranging from 21.6 to 22.2 °C and aerated for three hours at a rate sufficient to provide aerobic conditions and maintain solids in suspension. The mixtures were prepared and aerated in 1000 mL Erlenmeyer flasks and then transferred to fill 300 mL biochemical oxygen demand (BOD) bottles to conduct dissolved oxygen (DO) measurements. Test mixtures were identified by project number, test substance identification, test concentration, and bottle number.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol; Lot Number: 15809KI; Physical Description: Solid; Purity (%): 97; Storage Conditions: Ambient

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

342.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL

Details on results:

The EC50 value for AMP (2-Amino-1-Methylpropanol) was determined to be 342.9 mg/L. No inhibition was observed at a test concentration of 100 mg/L. Thus, the no observed effect level was ≥ 100 mg/L.

Results with reference substance (positive control):

The EC50 value for the reference substance (3,5-dichlorophenol) was 11.8 mg/L and was within the 5 to 30 mg/L range considered acceptable for the test.

Reported statistics and error estimates:

When the dose response pattern (percent inhibition versus test substance concentration) allowed for the calculation of an EC50 value, the data were analyzed using the computer program of C.E. Stephan (Stephan, C.E. 1978. U.S. EPA, Environmental Research Laboratory, Duluth, Minnesota. Personal Communication.). The program was designed to calculate the EC50 value and the 95% confidence interval by probit analysis, the moving average, or binomial probability with nonlinear interpolation (Finney, D.J. 1971. Statistical Methods in Biological Assay. Second edition. Griffin Press, London; Thompson, W.R. 1947. Biological Reviews. Vol. II, No. 2. Pp. 115-145; Stephan, C.E. 1977. “Methods for Calculating an LC50,” Aquatic Toxicology and HazardEvaluations. American Society for Testing and Materials. Publication Number STP 634, pp 65-84.). Confidence limits (95%) for the EC50 and the EC50 value itself (when applicable) were determined using binomial probability with nonlinear interpolation only.

Temperatures measured throughout the period of sludge maintenance and during the test ranged from 21.5 – 22.3°C. The initial total suspended solids (TSS) concentration of the activated sludge after removal of the supernatant layer measured 13,780 mg/L. The measured TSS concentration of the sludge on the day of testing was 3813 mg/L. The measured pH of the sludge on the day of testing was 7.8.

The respiration rates observed in the two controls were 86.4 and 86.4 mg O2/L/hr, or a difference of 0.0%. The EC50 value for the reference substance was 11.8 mg/L and was within the 5 to 30 mg/L range considered acceptable for the test. Confidence limits (95%) for the EC50 and the EC50 value itself, were calculated using binomial probability with nonlinear interpolation. The observed percent inhibitions for AMP (Amino Methyl Propanol) ranged from –29.6 to 85.9%

Validity criteria fulfilled:

yes

Conclusions:

Inhibitory effects upon respiration by the test substance at the concentrations evaluated in this study were observed, and exhibited a concentration dependent dose response pattern. The EC50 value for AMP (Amino Methyl Propanol) was determined to be 342.9 mg/L, with 95 percent confidence limits of 100 mg/L and 1000 mg/L. No inhibition was observed at a test concentration of 100 mg/L. Thus, the no observed effect level was ≥100 mg/L.

Executive summary:

The effect of AMP (Amino Methyl Propanol) on activated sludge microorganisms maintained in an

aerobic environment was assessed by the Activated Sludge Respiration Inhibition Test Method (OECD

Guideline 209). The test contained control, reference and treatment groups. The control replicates were

used to determine the background respiration rate of the sludge and were not dosed with the test or

reference substance. The reference group was dosed with 3,5-dichlorophenol, a known inhibitor of

respiration, at concentrations of 3, 15 and 50 mg/L. The treatment group was dosed with AMP (Amino

Methyl Propanol) at concentrations of 10, 30, 100, 300 and 1000 mg/L. After an exposure period of three

hours, the respiration rates of the test solutions were measured using a YSI Model 50B-115 Dissolved

Oxygen Meter. The respiration rates in the two controls were 86.4 and 86.4 mg O2/L/hr. The difference

between the two control respiration rates was 0.0 %, and was within the 15% difference limit established

for the test. The validity of the test was further supported by the results from the 3,5-dichlorophenol

reference group, which resulted in an EC50 value of 11.8 mg/L, with 95 percent confidence limits of

3 mg/L and 15 mg/L. The EC50 for the reference substance was within the 5 to 30 mg/L range considered

acceptable for the test. An inhibitory dose response effect was observed for the treatment group. The

EC50 value for AMP (Amino Methyl Propanol) was determined to be 342.9 mg/L. The following is a

summary of the results:

Test Substance	Nominal Concentrations mg/L	Respiration Rate mg O2/L/hr^1	Percent Respiration Inhibition^1
Control 1	0	86.4	NA
Control 2	0	86.4	NA
3,5-dichlorophenol	3	180.0	-108.3%
3,5-dichlorophenol	15	32.0	63.0%
3,5-dichlorophenol	50	14.0	83.8%
AMP (Amino Methyl Propanol)	10	94.2	-9.0%
AMP (Amino Methyl Propanol)	30	112.0	-29.6%
AMP (Amino Methyl Propanol)	100	112.0	-29.6%
AMP (Amino Methyl Propanol)	300	47.2	45.4%
AMP (Amino Methyl Propanol)	1000	12.2	85.9%
1Calculations performed using MS Excel 2000 in full precision mode. Manual calculations may differ slightly. NA - Not Applicable

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Remarks:

the tested substance is the sodium salt of DDBSA one of the components of the compound

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Principles of method if other than guideline:

The purpose of the study was to determine the toxicity of five purehomologues of LAS to the activated sludge of a treatment plant basically operating on domestic sewage. A contact time of 3 hours instead of 15 minutes was chosen to better simulate the real residence time used in wastewater treatment plants (4-6 hours).

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

activated sludge

Test type:

other: aquatic

Limit test:

no

Total exposure duration:

3 h

Details on test conditions:

Activated sludges:The activated sludge from the aeration pond of the sewage treatment plant of Estepona. This sludge has a carbon content of 40% and moisture level of 82%.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

500 - 723 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

Acute toxicity to Microorganism (activated sludge): 3hr-EC50 is 500-723 mg/L (nominal).

Results with reference substance (positive control):

The 3-hour EC50 range for the reference substance (3,5-dichlorophenol) ranged from 20- 30 mg/L, within the valid range of 5-30 mg/L

Validity criteria fulfilled:

yes

Conclusions:

Acute toxicity to Microorganism (activated sludge): 3hr-EC50 is 500-723 mg/L (nominal).

Description of key information

For DDBSA the 3hr-EC50 is 500-723 mg/L (nominal).

Inhibitory effects upon respiration by AMP at the concentrations evaluated in this study were observed, and exhibited a concentration dependent dose response pattern. The EC50 value was determined to be 342.9 mg/L, with 95 percent confidence limits of 100 mg/L and 1000 mg/L.  No inhibition was observed at a test concentration of 100 mg/L. Thus, the no observed effect level was ≥100 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

342.9 mg/L

Additional information

In a worst case approach the 342.9 mg/L EC50 will be used as starting point for risk assessment.