Hydrocarbons, C12-C18, isoalkanes, cyclics, 2-30% aromatics

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

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:

22-Aug-1994 to 23-Sep-1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study was given a reliability of 1, because it followed an OECD standard guideline, which describes a procedure specifically designed to evaluate this endpoint, and the results were reviewed for reliability and assessed as valid.

Justification for type of information:

The justification for read across is provided as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

15.4

Sampling time:

4 d

Parameter:

% degradation (O2 consumption)

Value:

50.4

Sampling time:

11 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

60.7

St. dev.:

2.77

Sampling time:

28 d

Details on results:

Test material was readily biodegradable, but failed the 10-day window. The biodegradation half-life was <2 weeks. On day 28, 60.7% degradation of the test substance was observed. 10% biodegradation was achieved on approximately day 4, 50% on approximately day 11, and 60% on day 27. By day 3, >60% biodegradation of the positive control was observed. No excursions from the protocol were noted.

The study was extended to Day 31, where the test substance achieved a mean percent biodegradation of 61.5%.

Results with reference substance:

Sodium benzoate, the positive control, achieved 99.0% degradation after 14 days, and therefore this test may be considered valid. On Day 28 of the study, the mean percent degradation of the positive control was 88.7%.

Biodegradation was based on oxygen consumption and the theoretical oxygen demand of the test material as calculated using results of an elemental analysis of the test material.

 

	% Degradation*	Mean % Degradation
Sample	(day 28)	(day 28)
Test Material	66.8, 56.2, 59.1	60.7
Na Benzoate	89.9, 87.5	88.7

 

* replicate data

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

Hydrocarbons, C14 -C18, n-alkanes, isoalkanes, cyclics, aromatics (2 -30%), a multi-component substance, biodegraded to an extent of 61% after 28 days. The data support characterizing the test substance as rapidly biodegradable, readily biodegradable, not expected to persist in the environment under aerobic conditions. Although it did not meet the 10 -day window requirement, it is characterized as readily biodegradable because the criteria is not applied to multi-component substances when assessing their ready biodegradability.

Executive summary:

This data is being read across from the source study that tested Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, aromatics (2-30%) based on analogue read across.

Hydrocarbons, C14 -C18, n-alkanes, isoalkanes, cyclics, aromatics (2 -30%), a multi-component substance, biodegraded to an extent of 61% after 28 days. The data support characterizing the test substance as rapidly biodegradable, readily biodegradable, not expected to persist in the environment under aerobic conditions. Although it did not meet the 10 -day window requirement, it is characterized as readily biodegradable because the criteria is not applied to multi-component substances when assessing their ready biodegradability.

Description of key information

There is no data available for Hydrocarbons, C12-C18, isoalkanes, cyclics, 2-30% aromatics. However, key data is available for the structural analogue, Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, aromatics (2-30%) and presented in the dossier. This data is read across to Hydrocarbons, C12-C18, isoalkanes, cyclics, 2-30% aromatics based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

 

Data read-across from the source substance showed that it biodegraded to an extent of 61% after 28 days in an OECD 301F study. The data support characterizing the source substance substance (Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, aromatics (2-30%)) as rapidly biodegradable, readily biodegradable, not expected to persist in the environment under aerobic conditions. Although it did not meet the 10 -day window requirement, it is characterized as readily biodegradable because the criteria is not applied to multi-component substances when assessing their ready biodegradability.