1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. residues

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1999

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. residues

EC Number:

271-832-1

EC Name:

1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. residues

Cas Number:

68609-68-7

Molecular formula:

UVCB, not applicable, see section 1.2 for information on constituents

IUPAC Name:

2,4-diethyl-3-propylpentane-1,5-diol; 2,4-diethyloctan-1-ol; 2-ethylhexan-1-ol; 2-ethylhexane-1,3-diol

Sampling and analysis

Analytical monitoring:

not required

Test solutions

Vehicle:

no

Details on test solutions:

The test substance was weighted directly to the activated sludge at concentrations of 100, 320, 1000, 3200 and 10 000 mg/L.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source: Sewage treatment plant which receives predominantly domestic sewage.
-Origin: Municipal sewage treatment plant of 31137 Hildesheim, Germany
-Laboratory culture: No

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Post exposure observation period:

not applicable

Test conditions

Hardness:

Not indicated

Test temperature:

20.9°C

pH:

7.22

Dissolved oxygen:

not indicated

Salinity:

not indicated

Nominal and measured concentrations:

A non-GLP rang-finding test was conducted before at nominal concentrations of 10, 100 and 1000 mg/L
Nominal: 100, 320, 1000, 3200 and 10 000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 ml Erlenmayer flasks
- No. of vessels per concentration (replicates): 1
- No. of Controls: 2
-Aeration: Continuous aeration for 3 hours
- Suspended solids concentration: Nominal concentration in the inoculum solution 2.8 g/L


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Continuous measurement of oxygen content in the samples, the oxygen measurement was terminated after a 3-minute period.
Test parameter: Respiration rate (Oxygen consumption)

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate

Results and discussion

Effect concentrations

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

1 655 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 1380 - 1985

Details on results:

3h- EC20: 546 mg/L
3h-EC50: 1655 mg/L
3h-EC80: 4991 mg/L

Results with reference substance (positive control):

- Concentrations: 58, 100, 180 mg/L
- Results: EC50 = 101 mg/L

Reported statistics and error estimates:

Not indicated

Any other information on results incl. tables

Preliminary test (rang-finding): Performed

Concentration: 58, 100 and 1000 mg 1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. Residues/L

Main test:

Effect data: A respiration inhibition of 6, 11, 30, 76 and 90% was observed at the concentrations tested. The EC50 value was calculated to be 1655 mg 1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. Residues/L . All validity criteria are fullfilled.

	Concentration [mg/L]	Respiration rate [mgO2/Lh]	Inhibition [%]
Test substance	10 000	4.0	90
	3200	9.6	76
	1000	27.6	30
	320	35.4	11
	100	37.2	6
Control 1	-	38.8	-
Control 2	-	40.4	-
Reference substance	180	10.8	73
	100	15.6	61
	58	32.0	19

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

The difference of the two controls with respect to the respiration rates is below 15%. The RC50 of the reference substance is within the acceptable range of 56 - 146 mg/L.

Conclusions:

The validity criteria required by the OECD Guideline No. 209 can be considered as fulfilled.
- The respiration rates of the two controls were found to be 38.8 and 40.4 mg O2/L/h, respectively. The difference between the two values (4.0 %) complies with the validity criteria of the test (respiration rates must be within 15 % of each other).
- The EC50 of the reference substance was determined to be 101 mg/L; this is in the accepted range of 56 to 146 mg/L for Copper (II) sulphate pentahydrate.

Executive summary:

The 3 hours respiration inhibition test with activated sludge to the test substance 1-Hexanol, 2-ethyl-, manuf. of, by-products from, distn. Residues was performed. The respiration rates of the controls, reference and test substance were measured after a contact time of 3 hours, and the inhibition effect of the test and reference substance were determined by comparison with the control respiration rates. The nominal test concentrations of 100, 320, 1000, 3200 and 10 000 mg/L were used. The EC50 of the test substance was determined to be 1655 mg/L.

The validity criteria required by the OECD Guideline No. 209 can be considered as fulfilled.