2,2-bis(hydroxymethyl)propionic acid

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:

1999-08-13

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

Exposure time was reduced from 3 hours to 30 minutes.

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of the test material used in the study report: Dimethylolpropionsäure, 2,2-Bis(hydroxymethyl)propionsäure
- Batch no.: SE 8069
- Purity: 99.4%

Analytical monitoring:

no

Details on sampling:

Not applicable

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

Activated sludge was taken from laboratory wastewater plants treating municipal sewage.

The inoculum was washed, brought to a concentration of 5 g/I dry substance and aerated for about 24 hours. 50 ml were added to a total volume of 250 ml to obtain a concentration of 1 g/I dry substance in the test.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

30 min

Post exposure observation period:

Not applicable

Hardness:

Not applicable

Test temperature:

20 ± 2 °C

pH:

See results tables

Dissolved oxygen:

See results tables

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentration of dimethylolpropionsaure used: 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

other: EC20

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

Not applicable

Results with reference substance (positive control):

Reference substance after 30 min incubation time:
 
EC20(mg/L) - 1.5
EC50(mg/L) - 5.5
EC80(mg/L) - 45

 
 

Reported statistics and error estimates:

Not applicable

pH values during the study

Vessel number	BC1	BC2	BC3	TS1
pH value before adding the inoculum: before correction: after correction:	6.7 7.2	6.7 7.2	6.7 7.4	6.8 7.2
pH value after 30 minute incubation	-	-	-	7.5

 

 

Results of the definitive test after 30 min incubation period with 1000 mg/L dimethylolpropionsaure

Vessel no.	mv BC	TS1	RS1	RS2	RS3
Oxygen concentration start (mg O2/L)	-	7.8	7.4	8.2	8.7
Oxygen concentration after 6 min (mg O2/L)	-	5.8	5.7	7.5	8.5
Oxygen consumption rate (mg O2/L x 6 min)	1.9	2.0	1.7	0.7	0.2
Oxygen consumption rate (mg O2/L x h)	19	20	17	7	2
Specific oxygen consumption rate (mg O2/g x h)	19	20	17	7	2
Change in oxygen consumption rate compared with the blank control (%)	-	-5	11	63	89

mv BC = mean value of blank control

TS = test substance

RS = reference number

 

 

Reference substance after 30 min incubation time

	EC20(mg/L)	EC50(mg/L)	EC80(mg/L)	Highest concentration tested (mg/L)
Reference substance	ca. 1.5	ca. 5.5	ca. 45	100

 

Validity criteria fulfilled:

yes

Remarks:

The EC50 for the reference inhibitor, 3,5-dichlorophenol was in the range of 5 - 30 mg/L.

Conclusions:

The 30-minute EC50 based on respiration inhibition was >1000 mg/L (the highest nominal exposure concentration tested).

Executive summary:

In a 30-minute toxicity study, inoculum (taken from municipal waster water treatment plant activated sludge) was exposed to Bis-MPA at the nominal concentration of 1000 mg/L in accordance with the OECD 209 guideline. The EC₂₀, EC₅₀, EC₈₀ values for respiration inhibition were >1000 mg/L.

This study is classified as acceptable and satisfies the guideline requirements for an activated sludge respiration inhibition test.

Description of key information

A short-term toxicity test with activated sludge inoculum resulted in an EC20/EC50 for respiration inhibition of >1000 mg/L.

Additional information

In an activated sludge respiration inhibition according to OECD test guideline 209 Bis-MPA did not impair the respiration rate of the test inoculum at a concentrations of 1000 mg/L. Therefore, no hazard to microorganisms associated with Bis-MPA has been identified.