Reaction product aqueous Phosphoric Acid, 2-Butoxyethanol and 4,4'-Isopropylidenediphenol-Epichlorohydrin

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

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 (Carbon and Ammonium Oxidation))

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

Not a requirement of the test.

Vehicle:

no

Details on test solutions:

In the test flasks, the respective amount of a stock solution of the test item (prepared in ethanol) was given in the glass flasks. After complete evaporation of the solvent (ethanol), the volume was made up to 250 mL with natural water.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The activated sludge was not directly used after sampling from the treatment plant. To keep the viability of the sludge, 80 mL of the synthetic sewage feed were added per litre of activated sludge (the volume taken into account is the volume of settled suspension) and the sludge was aerated overnight. Prior to the tests, the sludge was washed with natural water, and finally suspended in natural water at a concentration twice (target: 3 g/L dry matter in the final mixture) of the final concentration.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Hardness:

26.8 °f H

Test temperature:

20 +/- 2°C

pH:

pH 7 to 8

Dissolved oxygen:

Not relevant for media (used a a measurement for respiration inhibition)

Salinity:

Not specified

Conductivity:

565 μS/cm

Nominal and measured concentrations:

Nominal loading rate 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 1000 mL glass flasks
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 1000 mL containing a total test suspension of 516 mL (300 mL flat bottomed BOD flasks used for measurements)
- Aeration: Yes (by shaking at 150 rpm)
- No. of vessels per concentration (replicates): Six replicate samples
- No. of vessels per control (replicates): Six replicate samples
- No. of vessels per vehicle control (replicates): NA
- No. of vessels per abiotic control (replicates): NA
- Sludge concentration (weight of dry solids per volume): 1.5 g/L dry matter
- Nutrients provided for bacteria: Yes (OECD synthetic sewage)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Natural water periodically assessed for contaminants

OTHER TEST CONDITIONS
- Adjustment of pH: Media adjusted to pH 6 to 7 where required
- Photoperiod: Continuous
- Light intensity: Not specified
- Details on termination of incubation: Measurement phase in BOD bottle

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Respiration inhibition at 3 hours (O2 consumption rates)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Limit test
- Justification for using fewer concentrations than requested by guideline: Limit test
- Range finding study: Yes
- Test concentrations: 10, 316 and 1000 mg/L
- Results used to determine the conditions for the definitive study: Yes (minimal inhibition observed)

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth inhibition

Details on results:

After 3 hours of exposure, no significant inhibition of the activated sludge respiration was observed at the nominal concentration of 100 mg/L as compared to the blank control.

Results with reference substance (positive control):

The EC50 value of the reference item 3,5-dichlorophenol was estimated to be 5.2 mg/L (required 2–25 mg/L).

Reported statistics and error estimates:

Not conducted

Activated sludge respiration inhibition rates after 3 hours of exposure:

Loading rate (mg/L)	Code	O2 consumption (mg O2/L/H	Respiration inhibition (%)	Respiration inhibition (%) mean value
0	B1	34.1	-7.9	0
	B2	32.4	-2.7
	B3	32.2	-2.2
	B4	29.5	6.6
	B5	31.5	0.2
	B6	29.7	5.9
Reference, 3	R1	21.3	32.5	32.5
Reference, 10	R2	7.9	74.9	74.9
Reference, 30	R3	4.4	86.1	86.1
100	T1-A	29.7	5.9	1.6
	T1-B	31.7	-0.4
	T1-C	30.3	4.1
	T1-D	29.9	5.1
	T1-E	32.4	-2.7
	T1-F	32.4	-2.7

Validity criteria fulfilled:

yes

Conclusions:

The 3 hour EC50 (based on a loading rate) was detailed to be greater than the highest test concentration (100 mg/L). The NOEC was set as 100 mg/L.

Description of key information

The 3 hour EC50 (based on a loading rate) was detailed to be greater than the highest test concentration (100 mg/L). The NOEC was set as 100 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

EC10 or NOEC for microorganisms:

100 mg/L