2-amino-2-methylpropanol

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:

Not applicable

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline 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 aerobic
conditions 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 System
The 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 Apparatus
Control, 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

Key result

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

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: 30% increased respiration at this concentration

Key result

Duration:

3 h

Dose descriptor:

LOEC

Effect conc.:

300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 100 - < 300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

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 Hazard
Evaluations. 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%.

 

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

Validity criteria fulfilled:

yes

Conclusions:

In activated sludge, 3h values (as mg active substance/L) for inhibition of respiration by activated sludge were:
- EC50: 342.9 mg/L;
- EC10: between 100 and 300 mg/L;
- NOEC: 100 mg/L (with 30% increased respiration).

Description of key information

All available studies evidence negligible acute toxicity to activated sludge:

• NOEC, EC10 and EC50 values of 100, between 100 and 300, and 342.9 mg/L resp. over 3h (at 100 mg/L there was actually 30% increased respiration);


• LOEC and EC50 values of 68 and 119 mg/L over 120h (NOEC/EC10 could not be determined).

In addition, no significant toxicity was observed in toxicity controls in biodegradation assays.

All values are nominal (no analytical follow-up) and expressed as mg active substance/L. Reported nominal NOEC/LOEC/EC10/EC50 values were converted into active substance equivalents taking into account the water content of the test items. Measured concentrations in two 2014 algae studies demonstrated the stability in both fresh- and saltwater media over 96h.

Key value for chemical safety assessment

EC50 for microorganisms:

342.9 mg/L

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

Up to 100 mg/L, there is actually an increase in activated sludge respiration.