Butane-1,3-diol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

22-23 September 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

according to outdated OECD 209 (adopted 1997), max. concentration tested was 100 mg/L

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

adopted 1997

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 1999

GLP compliance:

yes

Analytical monitoring:

not required

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Oakley sewage treatment works
- Laboratory culture: no
- Preparation of inoculum for exposure: homogenisation, filtration through Whatman GFC filter paper; synthetic sewage (50 mL/L) was added and the mixture aerated overnight
- Initial biomass concentration: 4 g suspended solids/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

of dilution water (dechlorinated tap water): 200 - 250 mg/L as CaCO3

Test temperature:

Values (°C) at start (0 h) and end (3 h)
----------------------------------
Controls: 19.7-20.0 / 19.1-19.2
1,3-BG (1, 10, 100 mg/L): 20.0-20.1 / 18.8-19.6
3,5-DCP (3, 10, 32 mg/L): 19.7-19.8 / 18.6-19.4

pH:

Inoculum (activated sludge): pH 7.3
Reference substance (3,5-DCP) stock solution (500 mg/L): pH 7.8
Test substance (1,3-BG) stock solution (500 mg/L): pH 8.2

Values at start (0 h) and end (3 h)
------------------------------
Controls: 7.1-7.4 / 7.8
1,3-BG (1, 10, 100 mg/L): 7.3-7.4 / 7.8-7.9
3,5-DCP (3, 10, 32 mg/L): 7.1-7.3 / 7.8-8.0

Nominal and measured concentrations:

Nominal: 0, 1, 10, 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: test beakers, fill volume: 500 mL
- Aeration: oil-free compressed air via Pasteur pipette
- No. of vessels per concentration (replicates): 1 replicate each for 1 mg/L and 10 mg/L, 3 replicates for 100 mg/L
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): not applicable


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dilution water to prepare synthetic sewage: tap water, softenend and treated by reverse osmosis and purified by UHP (resisitivity: 18 Megohm/cm); synthetic sewage was prepared following the guideline


OTHER TEST CONDITIONS
- Adjustment of pH: no


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : BOD after 3 h of exposure (duration of measurement: 10 min)


TEST CONCENTRATIONS
- Spacing factor for test concentrations: factor 10

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3,5-DCP)

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 3.0, 10.0, 32.0 mg/L
- Other: EC50 = 11.2 mg/L (95% CL: 8.7 - 14.6 mg/L)

Nominal concentration (mg/L)		Respiration rate
		mg O2/g*h	% inhibition
Control 1	0	26.8	-
Butane-1,3-diol	1	27.3	0
	10	26.3	3
	100	26.3	3
	100	28.3	0
	100	27.8	0
3,5-DCP	3	20.3	25
	10	15.9	41
	32	5.4	80
Control 2	0	27.3	-

Validity criteria fulfilled:

yes

Remarks:

- 3-h EC50 for 3,5-DCP (11.2 mg/L) is within the required range (5 -30 mg/L); variation of respiration rates in the control < 15%

Conclusions:

The 3-h EC50 of 1,3-butanediol for respiration inhibition of activated sludge is > 100 mg/L.

Executive summary:

The effects of 1,3 -butanediol on the respiration rate of activated sludge were tested in a 3 -h respiration inhibition test following OECD TG 209. Three test concentrations plus two controls (0 mg/L) were set up: 1, 10, 100 mg/L. The highest concentration was tested in triplicate. 3,5 -DCP was used as reference compound and was tested at 3, 10 and 32 mg/L. With the test substance no adverse effects were measured up to 100 mg/L. Therefore, the 3 -h EC50 is > 100 mg/L. The validity criteria were fulfilled. Disturbances of waste water treatment processes are not to be expected when 1,3 -butanediol is released in appropriate amounts.

Description of key information

3-h EC50 (respiration inhibition of activated sludge) > 100 mg/L (OECD TG 209, Barnes, 1999)

40h-IGC50 (growth inhibiting effect to ciliate Tetrahymena pyriformis) = 18035 mg/L (TETRATOX assay, Schultz, 1997)

Key value for chemical safety assessment

EC50 for microorganisms:

18 035 mg/L

Additional information

Weight of evidence approach for toxicity to microorganisms of butane-1,3 -diol

There were two studies available that tested the toxicitiy of butane-1,3 -diol to microorganisms. In the first study, the effects of 1,3 -butanediol on the respiration rate of activated sludge were tested in a 3 -h respiration inhibition test following OECD TG 209 (RL2). Three test concentrations plus two controls (0 mg/L) were set up: 1, 10, 100 mg/L. The highest concentration was tested in triplicate. The test substance showed no adverse effects up to 100 mg/L. Therefore, the 3 -h EC50 > 100 mg/L. The validity criteria were fulfilled. In the other study, the growth inhibiting effect of 1,3 -butanediol on the ciliate Tetrahymena pyriformis was determined using the TETRATOX assay (RL2). The resulting IGC50 (40 h) of 18035 mg/L indicated no significant toxicity of 1,3 -butanediol to microorganisms (ciliates).