Reaction mass of 1,3-dioxane-5,5-dimethanol and 1,3-Propanediol, 2-(hydroxymethyl)-2-[(methoxymethoxy)methyl]-

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:

From 08 JAN 2010 to 09 FEB 2010

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

Not applicable

Vehicle:

no

Details on test solutions:

A 5 g Polyol PX/L stock solution was prepared by adding Polyol PX (4.99986 g) to a 1000 mL volumetric flask and bringing to volume with deionised water. The solution was ultrasonicated for ca 5 min to aid dissolution.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

A sample of activated sewage sludge was obtained from Haddington Municipal Sewage Works (a local sewage processing plant, which handles predominantly domestic sewage) on 06 April 2010. On arrival at the laboratory, the sludge was aerated. The solid content of the sludge was determined by shaking the bottle of sludge by hand to homogenise thoroughly. Duplicate sub-samples (5mL) of the homogenised sludge were dried in an oven at
approximately 105°C and the suspended solids content determined as 3.1 g/L. Synthetic sewage feed was then added at a rate of 50 mL/L sludge and the sludge left aerating overnight. To concentrate the solid sewage flocculent to the required level, the sludge was allowed to settle before 2 L of the overlying supernant was siphoned off. The solid content of the sludge was then re-determined and found to be 4.2 g/L, which was acceptable for use.
The pH of the sludge was measured as 7.84 upon receipt.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Not applicable

Hardness:

Not applicable

Test temperature:

18.9 to 19.5°C

pH:

The pH of the sludge was measured as 7.84 upon receipt.

Dissolved oxygen:

Measured during the study.

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal exposure concentrations were 10, 31.6, 100, 316 and 1000 mg/L.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

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:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

The 3 h EC50 for 3,5-dichlorophenol to activated sludge was estimated to be 12.14 mg/L with 95 % confidence limits of 10.54 and 13.98 mg/L, under the conditions of this test.

Reported statistics and error estimates:

The respiration rate for each vessel was calculated from the recorded oxygen concentrations and expressed as mg O2/L/h for the period between approximately 6.5 and 2.5 mg O2/L. Where respiration was low the calculation was conducted over the full linear range.

The EC50 and associated 95% confidence interval was estimated using the non-parametric Trimmed Spearman-Karber Method (Hamilton et al, 1977), where appropriate.

Respiration rates and percentage inhibition

Treatment	Nominal concentration (mg/L)	Respiration rate (mg O2/L/h)	% inhibition
Control 1	0	77.4	-
Control 2	0	68.80	-
Mean of controls	-	73.10	-
% difference in controls	-	11.1	-
3,5,-DCP	5	69.60	4.79
	15	26.02	64.40
	30	12.76	82.54
Polyol PX	10	81.00	0
	31.6	78.90	0
	100	80.00	0
	316	80.40	0
	1000	82.20	0

 

Validity criteria fulfilled:

yes

Conclusions:

As there was no inhibition of respiration at any Polyol PX concentration, the 3 h EC50 for Polyol PX to activated sludge was estimated as >1000 mg/L, under the conditions of this test.

Executive summary:

The toxicity of Polyol PX to activated sewage sludge was investigated in a respiration inhibition test according to OECD test guideline 209. Following three hours exposure to Polyol PX the EC50 was observed to be > 1000 mg/L (based on nominal exposure concentrations), the corresponding NOEC was observed to 1000 mg/L.

Description of key information

A reliable study (Klimisch 1) is available. The toxicity of Polyol PX to activated sewage sludge was investigated in a respiration inhibition test according to OECD test guideline 209. Following three hours exposure to Polyol PX the EC50 was observed to be > 1000 mg/L (based on nominal exposure concentrations), the corresponding NOEC was observed to 1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L