Hydrocarbons, C10-C13, n-alkanes

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP guideline study: The results in this study were consistent with the validity criteria with one exception. The mean oxygen uptake in the blank controls was lower than 20 mg/g*h (17 mg/g*h). The reference substance shows an EC50 in the specified range (usual range of EC50 of the last 20 values in the laboratory was 6.0 - 14.1 mg/L). The used activated sludge which was collected from the same waste water treatment plant showed a maximum oxygen consumption of 36.8 mg/g*h and minimum oxygen consumption of 14.5 mg/g*h of the last 20 measurements. For this the study is classified as valid.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Direct addition by initial weight into the test flasks. The test substance was weighed in the required amounts for the test concentrations directly to the test vessels.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Laboratory culture: yes, Municipal activated sludge taken from a laboratory wastewater treatment plant (Mannheim, Germany) fed with municipal sewage.
- Preparation of inoculum for exposure: After arrival of the activated sludge suspension in the test facility the suspension was sieved with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over night at room temperature. At the next day the sludge suspension was washed once with drinking water and the suspension was adjusted to 3 g/L Dw.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

21.5 - 22 °C

pH:

7.5 - 7.6

Dissolved oxygen:

Oxygen concentration during aeration: > 2 mg/L
Oxygen concentration immediately before measurement: > 7 mg/L

Nominal and measured concentrations:

Nominal: 62.5, 125, 250, 500 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 L glass beakers with 500 mL test solution
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to OECD guideline
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Adjustment of pH: no

EFFECT PARAMETERS MEASURED: After the 3h incubation time the oxygen uptake was measured for a period of about 8 to 10 minutes or until the oxygen concentration fell below 2 mg/L.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC10

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):

According to the test guideline OECD 209 the EC50 values of the reference substance 3,5-dichlorophenol should be in the range of 2-25 mg/L after 3 hours of incubation. The EC50 of the reference substance 3,5-dichlorophenol was in the range of 2-25 mg/L in 3 hours. These results indicate that the microorganisms are responding normally to toxicant stress.

Validity criteria fulfilled:

yes

Remarks:

The results in this study were consistent with the validity criteria with one exception: oxygen uptake in the blank controls < 20 mg/g*h (=17 mg/g*h). However, the study is classifed as valid (see rational of reliability).

Conclusions:

No toxicity of the test substance to activated sludge up to a nominal test concentration of 1000 mg/L was observed. Thus, the EC10 (3h) is determined to be > 1000 mg/L.

Executive summary:

The study was performed according to OECD guideline 209 under GLP conditions. Nominal test substance concentrations between 62.5 and 1000 mg/L were tested by direct adding the substance to the test vessels. No respiration inhibition was observed in any treatment compared to the control. Thus, the 3h-EC10 value is determined to be > 1000 mg/L based on the nominal concentration.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

May 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This robust summary has a reliability rating of 1 because the study followed a standard guideline, followed GLP guidelines, and was conducted without deviations that would invalidate the study.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

other: Developed by Huls AG (Dr. Schoberl)

Deviations:

not specified

Principles of method if other than guideline:

Effects were measured by comparing oxygen consumption by the bacterium, Pseudomonas putida, over 5 hours incubation in test systems that contained varying amounts of test substance in comparison to test systems that contained no test substance (control).

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Test systems were 100 ml bottles containing medium. All test systems were stirred through the exposure period. Four innoculated bottles were established per test substance concentration. Two of these bottles at each concentration also contained HgCl2 and acted as autooxidation controls. Four innoculated bottles without test substance and with HgCl2 also acted as controls. Five innoculated bottles without test substance and HgCl2 also acted as controls. All test systems were stirred during the test.

Test organisms (species):

Pseudomonas putida

Details on inoculum:

The original culture was obtained from the Institut fur Wasser-, Boden- und lufthygiene des BGA (Berlin, Germany).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

5 h

Post exposure observation period:

None

Test temperature:

25.3

Nominal and measured concentrations:

Nominal loading levels were 100, 500, 1000, and 2000 ul/L.

Duration:

5 h

Dose descriptor:

other: EL0

Effect conc.:

2 other: ml/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

5 h

Dose descriptor:

other: EL10

Effect conc.:

> 2 other: ml/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

5 h

Dose descriptor:

other: EL50

Effect conc.:

> 2 other: ml/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

5 h

Dose descriptor:

other: EL100

Effect conc.:

> 2 other: ml/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Reported statistics and error estimates:

None were needed as no effect was measured.

Validity criteria fulfilled:

yes

Conclusions:

The test substance at the highest loading rate, 2 ml/L, did not inhibit the respiration rate of Pseudomonas putida over an exposure period of 5 hours.

Executive summary:

The test substance at the highest loading rate, 2 ml/L, did not inhibit the respiration rate of Pseudomonas putida over an exposure period of 5 hours.

Description of key information

There is no data available for this substance. However, key data is available for a structural analogues Hydrocarbons, C11-C13 (odd numbered), n-alkanes, <2% aromatics and Isododecane. The data is read across to this substance based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13. Key information is summarised below:

Hydrocarbons, C11-C13 (odd number), n-alkanes, <2% aromatics presented a 3-h EC10 (respiration inhibition) for activated sludge of >1,000 mg/L.

 

Isododecane presented a 5-h EC50 (respiration rate inhibition) for Pseudomonas putida of >2 mL/L.

Additional information

Two key studies are available for toxicity to aquatic microorganisms.

The study investigating the toxicity of Hydrocarbons, C11-C13 (odd numbered), n-alkanes, <2% aromatics was performed according to OECD guideline 209 under GLP conditions (BASF, 2014). Nominal test substance concentrations between 62.5 and 1000 mg/L were tested by direct adding the substance to the test vessels. No respiration inhibition was observed in any treatment compared to the control. Thus, the 3h-EC10 value is determined to be > 1000 mg/L based on the nominal concentration.

The study for isododecane measured the effects on microorganisms by comparing oxygen consumption by the bacterium, Pseudomonas putida, over 5 hours incubation in test systems that contained varying amounts of test substance in comparison to test systems that contained no test substance (control). At the highest loading rate, 2 mL/L, this substance did not inhibit the respiration rate of Pseudomonas putida over an exposure period of 5 hours (Sasol, 1994).