Alkanes, C7-8

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

12 December 1996 - 25 November 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions.

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 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): aliquot of fresh activated sludge from a domestic wastewater treatment plant in New Jersey, USA

- other: 10^6 CFU/mL

- sludge was obtained on day 1 of test
- total suspended solids of the sludge was determined to be 3.02 g/L.
- sludge was homogenized, the homogenated sample was allowed to settle for 30 min, and the supernatant was decanted and used for final preparation. The supernantant was added at a 1% loading volume of sludge to test medium.

Duration of test (contact time):

70 d

Initial conc.:

49 - 57 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS

- Test temperature: 22 ± 1°C
- Composition of medium: Activated sludge and test medium were combined prior to test material addition. Test medium consited of glass distilled water and mineral salts (Phosphate buffer, Ferric chloride, Magnesium sulfate, Calcium chloride)

TEST SYSTEM
- Culturing apparatus: test vessels were 1L glass flasks placed in a waterbath and electronically monitored for oxygen consumption
- Other: Triplicate test system for test material. Duplicate test system for positive control at approx. concentrations of 51 mg/L through day 28

SAMPLING
- Sampling frequency: continuously monitored by an automated respirometer during a 70 day testing period

Reference substance:

benzoic acid, sodium salt

Test performance:

Sodium benzoate achieved 80.31% biodegradation with a standard deviation of 0.95% by day 14. Therefore the test is considered valid.

Key result

Parameter:

% degradation (O2 consumption)

Value:

10.5

St. dev.:

1.66

Sampling time:

15 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Key result

Parameter:

% degradation (O2 consumption)

Value:

49

St. dev.:

1.81

Sampling time:

43 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Key result

Parameter:

% degradation (O2 consumption)

Value:

60.2

St. dev.:

0.82

Sampling time:

60 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Key result

Parameter:

% degradation (O2 consumption)

Value:

61.81

St. dev.:

1.34

Sampling time:

70 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Details on results:

The biodegradation half-life was < 7 weeks. 10% biodegradation of the test material was achieved on approx. day 15, 50% on approx. day 46.
Test material biodegradability mean at day 28 was 22.4% (21.8, 23,5, 21.8 %).
Test material biodegradability mean at day 70 was 61.81% (60.4, 63.0, 62.1 %).

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Executive summary:

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

20 February 1997 - 25 November 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions.

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:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Principles of method if other than guideline:

Based on OECD guideline 301F the test phase was prolonged for inherent testing.

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): aliquot of fresh activated sludge from a domestic wastewater treatment plant in New Jersey, USA

-other: microbial activity of of inoculum: 10^5 CFU/mL

- Inoculum preparation for Inherent biodegradability testing: On day 70 of the ready biodegradability test, all systems were disassembled. The contents of MRD-96-587 test systems were centrifuged at 10,000 rpm for 20 min. The supernatant was poured off and filtered through a Whatman #4 filter. The solids were combined and then resuspended with a minimal volume of filtered supernatant.The final volume was ~ 150mL. The remaining supernatant was then filtered through 0.45 µm microfiber filters. The biomass solids remaining on the filter were gently scraped into the previous collected biomass. The harvested biomass was blended for approx. 2 min. Exactly 100 mL of the harvested biomass was added to 10mL of test medium. Each new blank, sodium benzoate and MRD-96-587 test system contained one liter of the inoculated test medium. The microbial activity of the inoculum was determined to be 100000 CFU/mL. The phase 2 inherent biodegradability test was the conducted for 75 days.

Duration of test (contact time):

75 d

Initial conc.:

49 - 57 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS

- Test temperature: 22 ± 1°C
- Composition of medium: Activated sludge and test medium were combined prior to test material addition. Test medium consited of glass distilled water and mineral salts (Phosphate buffer, Ferric chloride, Magnesium sulfate, Calcium chloride)

TEST SYSTEM
- Culturing apparatus: test vessels were 1L glass flasks placed in a waterbath and electronically monitored for oxygen consumption
- Other: Triplicate test system for test material. Duplicate test system for positive control at approx. concentrations of 51 mg/L through day 28

SAMPLING
- Sampling frequency: continuously monitored by an automated respirometer during a 70 day testing period

Reference substance:

benzoic acid, sodium salt

Test performance:

In the inherent test sodium benzoate achieved 97.76% with a SD of 1.13% by day 14. Therefore the test is considered valid.

Key result

Parameter:

% degradation (O2 consumption)

Value:

64.06

St. dev.:

10.53

Sampling time:

75 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Key result

Parameter:

% degradation (O2 consumption)

Value:

60.3

St. dev.:

9.59

Sampling time:

42 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Key result

Parameter:

% degradation (O2 consumption)

Value:

51.3

St. dev.:

11.91

Sampling time:

28 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Key result

Parameter:

% degradation (O2 consumption)

Value:

26.83

St. dev.:

8.59

Sampling time:

11 d

Remarks on result:

other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.

Results with reference substance:

>60% biodegradation by day 14

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Executive summary:

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

9 January - 1 July 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline 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:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Chester Sewage Works, Welsh Water
- Preparation of inoculum for exposure: Inoculum was collected the day before the test. It was homogenized for two minutes, then allowed to settle. The supernatent was filtered through medical gauze.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: OECD mineral salts medium
- Test temperature: 21.4-21.7 degree C
- Aeration of dilution water: aerated with moist air for 22 h


TEST SYSTEM
- Culturing apparatus: respirometer flask
- Number of culture flasks/concentration: 3 test substance only, 2 test substance and sodium benzoate (inhibition controls)
- Measuring equipment: Co-ordinated Environmental Servies Ltd. Aerobic Respirometer
- Test performed in closed vessels due to significant volatility of test substance: yes, closed with CO2 trap

SAMPLING
- Sampling frequency: hourly
- Sampling method: respirometer


CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Other: 2 controls using sodium benzoate


STATISTICAL METHODS: C.E.S. CESAN Data Analysis Program v1.1

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

83

St. dev.:

16

Sampling time:

16 d

Remarks on result:

other: stated in study: end of 10 day window; reading from graph indicates day 16

Key result

Parameter:

% degradation (O2 consumption)

Value:

98

St. dev.:

12

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

81

Sampling time:

28 d

Remarks on result:

other: inhibition control

Details on results:

% degradation of test samples at end of 10 day window: 87, 96, 65
% degradation of test samples on day 28: 104, 104, 84
% degradation of inhibition controls: 81, 82 - test substance does not inhibit degradation.

Results with reference substance:

The reference substance was 95% degraded by day 14, and degraded 104% (mean) by day 28.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

This study examined the ready biodegradability of hydrocarbons, C6-C7, n-alkanes, isoalkanes, cyclics, < 5% hexane. Activated sludge was exposed to a concentration of 100 mg/l of test substance. The O2 consumption was then monitored for the next 28 days. Sodium benzoate was used as the reference substance. The test substance was 98% degraded at the end of 28 days, and 83% degraded at the end of the 10-day window. The reference substance was 104% degraded, therefore the test is valid. The test substance is readily biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Executive summary:

This study examined the ready biodegradability of hydrocarbons, C6-C7, n-alkanes, isoalkanes, cyclics, < 5% hexane. Activated sludge was exposed to a concentration of 100 mg/l of test substance. The O2 consumption was then monitored for the next 28 days. Sodium benzoate was used as the reference substance. The test substance was 98% degraded at the end of 28 days, and 83% degraded at the end of the 10-day window. The reference substance was 104% degraded, therefore the test is valid. The test substance is readily biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Description of key information

There is no data available for this substance. However, key data is available for structural analogues, Hydrocarbons, C7 -C9, isoalkanes, Hydrocarbons, C6 -C7, n-alkanes, isoalkanes, cyclics, < 5% hexane, and presented in the dossier. 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.

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

This study examined the ready biodegradability of hydrocarbons, C6-C7, n-alkanes, isoalkanes, cyclics, < 5% hexane. The test substance was 98% degraded at the end of 28 days, and 83% degraded at the end of the 10-day window. The reference substance was 104% degraded, therefore the test is valid. The test substance is readily biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable