Naphtha (petroleum), steam-cracked, light hydrotreated, solvent refined

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non GLP, QSAR calculation, acceptable with restrictions.

Justification for type of information:

This endpoint is adapted in accordance with REACH Annex XI, Section 1.3 (QSAR). EPISuite and the BIOWIN models are well documented and commonly used QSARs for predicting the biodegradation potential of chemicals. Constituents within LOA streams fall within the applicability domain of these models and they have been recommended by ECHA in the Information Requirement Guidelines.

Reason / purpose for cross-reference:

assessment report

Reason / purpose for cross-reference:

(Q)SAR model reporting (QMRF)

Principles of method if other than guideline:

BIOWIN v4.1 in EPISuite 4.1 (2017). The Biodegradation Probability Program (Biowin) estimates the probability for the rapid aerobic biodegradation of an organic chemical in the presence of mixed populations of environmental microorganisms. As recommended in the ECHA guidance R.7b, BIOWIN 2, 3, 5 and 6 were used to predict the ready biodegradability of constituents of the category:

BIOWIN 2 =  nonlinear probability model
BIOWIN 3  =  expert survey ultimate biodegradation model
BIOWIN 5  =  MITI linear model
BIOWIN 6  =  MITI nonlinear model

Biodegradability estimates are based upon fragment constants that were developed using multiple linear or non-linear regression analyses, depending on the model. BIOWIN 2 is intended to convey a general indication of biodegradability under aerobic conditions, and not for any particular medium (Howard et al., 1992). BIOWIN 3 yield estimates for the time required to achieve complete ultimate and primary biodegradation in a typical or "evaluative" aquatic environment (Boethling et al., 1994). BIOWIN 5 and 6 are predictive models for assessing a compound’s biodegradability in the Japanese MITI (Ministry of International Trade and Industry) ready biodegradation test; i.e. OECD 301C (Tunkel et al., 2000).

The use of QSAR estimates to predict the biodegradability of hydrocarbons are included in the training sets of the BIOWIN. The databases were created using experimental biodegradation data for compounds found in crude oil and its products, with biodegradation references obtained for each of these compounds, mainly from the BIOLOG and DATALOG files of EFDB, TOXLINE and American Chemical Society Chemical Abstracts as well as literature searches.

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not applicable

Oxygen conditions:

aerobic

Inoculum or test system:

not specified

Details on inoculum:

Not applicable

Based on:

other: QSAR calculation

Parameter followed for biodegradation estimation:

other: QSAR calculation

Details on study design:

Not applicable

Preliminary study:

Not applicable

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

BIOWIN 2

Value:

>= 0.47 - <= 1

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Parameter:

calculated rating of total degradation time (QSAR/QSPR)

Remarks:

BIOWIN 3

Value:

>= 2.44 - <= 3.37

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

BIOWIN 5

Value:

>= 0.38 - <= 0.6

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

BIOWIN 6

Value:

>= 0.48 - <= 0.86

Remarks on result:

other: Result from QSAR prediction. Range based on the measured constituents in the streams.

Details on results:

BIOWIN 2, 5, and 6 Result Classification: A probability greater than or equal to 0.5 indicates “Biodegrades Fast” and a probability less than 0.5 indicates “Does NOT Biodegrade Fast”
BIOWIN 3 Result Classification (primary and ultimate): 5.00 - hours, 4.00 - days, 3.00 - weeks, 2.00 - months, 1.00 - longer. A probability greater than or equal to 2.75 indicates "Biodegrades Fast".

Details of the constituents and how their BIOWIN half-lives relate to their persistence assessment are found in the BIOWIN QMRF/QPRF, in the PBT report and in the Persistence Weight of Evidence Evaluation (see cross-references).

Results with reference substance:

Not applicable

 

Model	Biodegrades fast (No. of consituents)	Does not biodegrade fast  (No. of consituents)
BIOWIN 2	42	4
BIOWIN 3	45	1
BIOWIN 5	27	19
BIOWIN 6	42	4

Validity criteria fulfilled:

not applicable

Conclusions:

The BIOWIN models predict a high probability of ready biodegradability for a number of measured constituents of these streams. Out of the 46 constituents of the category, and according to the criteria in the R.7b Information Requirement Guidance from ECHA, the following is concluded:

- BIOWIN 2 predicted 42 constituents biodegrade fast
- BIOWIN 3 predicted 45 constituents biodegrade fast (within weeks)
- BIOWIN 5 predicted 27 constituents biodegrade fast
- BIOWIN 6 predicted 42 constituents biodegrade fast

Executive summary:

The ready biodegradability of measured constituents of this category (at equal or above 0.1% w/w) have been predicted using the EPISUITE v4.11 BIOWIN models (2017), which use methodology described by Howard et al. (1992), Boethling et al. (1994) and Tunkel et al. (2000). Of the 46 constituents, and according to the criteria set out in the ECHA R.7b Information Requirements Guidance, 42 (BIOWIN 2), 45 (BIOWIN 3), 27 (BIOWIN 5) and 42 (BIOWIN 6) were predicted to be readily biodegradable based on the different models, with all the constituents having at least one prediction of a high probability that it will biodegrade fast.

Description of key information

This endpoint is adapted in accordance with REACH Annex XI, Section 1.3 (QSAR). The ready biodegradability of measured constituents of this category (at equal or above 0.1% w/w) have been predicted using the EPISUITE v4.11 BIOWIN models (2017), which use methodology described by Howard et al. (1992), Boethling et al. (1994) and Tunkel et al. (2000). Of the 46 constituents, and according to the criteria set out in the ECHA R.7b Information Requirements Guidance, 42 (BIOWIN 2), 45 (BIOWIN 3), 27 (BIOWIN 5) and 42 (BIOWIN 6) were predicted to be readily biodegradable based on the different models, with all the constituents having at least one prediction of a high probability that it will biodegrade fast.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable