Potassium 3-sulphopropyl methacrylate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

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:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Remarks:

The value is not an experimental result, however the QSAR model is recommended by the ECHA guidance document on information requirements, is well documented with regard to validation parameters according to OECD principles. Only for 2 of the 7 models, the criteria of the applicability domain are not met completely.

Justification for type of information:

1. SOFTWARE
EPIWIN software by US-EPA

2. MODEL (incl. version number)
BIOWIN v4.10

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
C(=C)(C)C(=O)OCCCS(=O)(=O)OK (with potassium)
C(=C)(C)C(=O)OCCCS(=O)(=O)O (without potassium)


4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- The model and the training and validation sets are published by US Environmental Protection Agency (USA). Details in addition to the summary provided here can be found in the program.

The Biowin program is part of the Estimation Programs Interface (EPI) Suite© and contains six models whose purpose is to provide screening-level estimates of aerobic biodegradability for organic chemicals:
Biowin1 = linear probability model;
Biowin2 = nonlinear probability model;
Biowin3 = expert survey ultimate biodegradation model;
Biowin4 = expert survey primary biodegradation model;
Biowin5 = Japanese Ministry of International Trade and Industry (MITI) linear model; and
Biowin6 = MITI nonlinear model.
Biowin1 and 2 constitute the original Biodegradation Probability Program and were the first two models developed (Howard et al., 1992). Biowin3 and 4 estimate the time required to achieve complete ultimate (Biowin3) or primary (Biowin4) biodegradation in a typical, or ‘evaluative’, aquatic environment. They were developed from estimates of biodegradability for 200 substances, provided by a panel of experts (Boethling et al., 1994). The output of the model for any given chemical is a number from one to five (continuous scale; fractional values permitted) that either can be used as it is, or if desired can be related to the words (e.g. ‘days’, ‘weeks’) used in the expert survey. In Biowin3 values N2.75 and b=3.25 are assigned the term ‘weeks’. Here 2.75 was used as the criterion for ready biodegradability, so that a calculated value N2.75 is a prediction of RB and is equivalent to a prediction of ‘weeks’ or an even shorter timeframe. For Biowin4 a criterion of 3.6 (i.e., b=3.6 is NRB) yielded a reasonable separation of RB and NRB compounds. Biowin5 and 6 are linear and nonlinear probability models developed exclusively from the MITI data (MITI, 2014). Biowin5/6 classify a substance as either RB or NRB based on the MITI ready biodegradation test (OECD 301C).
Characteristics of this test, as well as details of model development and validation, are given by Tunkel et al. (2000). The model estimates the likelihood that a chemical will degrade under the test conditions. Values of the dependent variable N0.5 usually are taken as predicting that the chemical will be RB in the OECD 301C test, but as with other Biowin models the user can set the RB/NRB criterion at any value desired.

Predicting Ready Biodegradability
The following line appears at the end of the Biowin prediction results: Ready Biodegradability Prediction:  (YES or NO)
The criteria for the YES or NO prediction are as follows:  If the Biowin3 (ultimate survey model) result is "weeks" or faster (i.e. days, days to weeks, or weeks) AND the Biowin5 (MITI linear model) probability is >= 0.5, then the prediction is YES (readily biodegradable).  If this condition is not satisfied, the prediction is NO (not readily biodegradable).
This method is based on the application of Bayesian analysis to ready biodegradation data for US Premanufacture Notification (PMN) chemicals, derived collectively from all six OECD301 test methods plus OECD310.  The approach is fully described in Boethling et al. (2004).
The linear and nonlinear MITI models (Biowin5 and 6) also predict ready biodegradability, but for degradation in the OECD301C test only, and based exclusively on data from the Chemicals Evaluation and Research Institute Japan (CERIJ) database (http://www.cerij.or.jp/ceri_en/otoiawase/otoiawase_menu.html).

5. APPLICABILITY DOMAIN
The EPI Suite data files are files containing the experimental data sets used to derive and validate program methodologies or test program accuracy.  In EPI Suite v4.00, the data files were available in either the appendices of the individual program help files or via Internet download from: http://esc.syrres.com/interkow/EpiSuiteData.htm
For Biowin they are listed in Appendix D, which gives for each fragment the maximum number of instances of that fragment in any of the 200 training set compounds (the minimum number of instances is of course zero, since not all compounds had every fragment). The minimum and maximum values for molecular weight are also given. Currently there is no universally accepted definition of model domain. However, users may wish to consider the possibility that biodegradability estimates are less accurate for compounds outside the MW range of the training set compounds, and/or that have more instances of a given fragment than the maximum for all training set compounds.  It is also possible that a compound may have a functional group(s) or other structural features not represented in the training set, and for which no fragment coefficient was developed; and that a compound has none of the 36 fragments in the model’s fragment library.  In the latter case, predictions are based on molecular weight alone.  These points should be taken into consideration when interpreting model results.
 In addition to the above, the maximum and minimum values of the dependent variable (i.e. the averaged expert ratings) in the regressions, for both ultimate and primary degradation, may help characterize model domain.  They are:
Model                Min        Compound                        Max        Compound
Biowin3          1.44        pentabromoethylbenzene      3.89        ethylene glycol diacetate
Biowin4          2.37        pentabromoethylbenzene      4.57        ethylene glycol diacetate

6. ADEQUACY OF THE RESULT
The accuracy of the models is described in detail in the program itself and e.g. by Boethling (Science of the Total Environment 497–498 (2014) 60–67) and suffices to give suitable predictions for substances falling into the applicability domain of the model.

Two independent training sets were used to develop four mathematical models for predicting aerobic biodegradability from chemical structure.  All four of the models are based on multiple regressions against counts of 36 preselected chemical substructures plus molecular weight.  Two of the models, based on linear and nonlinear regressions, calculate the probability of rapid biodegradation and can be used to classify compounds as rapidly or not rapidly biodegradable.  The training set for these models consisted of qualitative summary evaluations of all available experimental data on biodegradability for 295 compounds.  The other two models allow semi-quantitative prediction of primary and ultimate biodegradation rates using multiple linear regression.  The training set for these models consisted of estimates of primary and ultimate biodegradation rates for 200 compounds, gathered in a survey of 17 biodegradation experts.  The two probability models correctly classified 90% of the compounds in their training set, whereas the two survey models calculated biodegradation rates for the survey compounds with R2 = 0.7.  These four models are intended for use in chemical screening and in setting priorities for further review.

The organic substance lies within the applicability domain with a molecular weight of 247.33. Regarding the fragments including the maximum number of instances, it also lies within the applicability domain except for model Biowin 6 & 7 (not relevant for overall prediction). Hence, the results could still be considered as adequate.

Guideline:

other: REACH guidance on QSARs Chapter R.6

Version / remarks:

May 2008

Principles of method if other than guideline:

The estimation for biodegradability of the test material was performed with US-EPA software EPWIN/BIOWIN v4.10. Seven different models are used by this tool to predict the overall biodegradability potential. Anaerobic conditions are considered as well.

GLP compliance:

no

Remarks:

(not applicable)

Specific details on test material used for the study:

SMILES
C(=C)(C)C(=O)OCCCS(=O)(=O)OK (with potassium)
C(=C)(C)C(=O)OCCCS(=O)(=O)O (without potassium)

Oxygen conditions:

other: aerobic (Biowin 1-6) and anaerobic (Biowin 7)

Inoculum or test system:

other: QSAR calculation

Details on study design:

Using the computer tool BIOWIN v4.10 by US-EPA (EPIWIN) the aerobic as well as the anaerobic biodegradability of the test material can be estimated. The following seven different models are used by the tool: Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called Biowin 1-7, respectively). Due to these results the overall prediction of readily biodegradability is done for the chemical.

Key result

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks on result:

readily biodegradable based on QSAR/QSPR prediction

Details on results:

Two calculations have been performed (with and without potassium). Both calculations led to the same result.
According to the Linear and also Non-linear Model the substance will biodegrade fast. The Ultimate Biodegradation Timeframe is given in weeks, whereas the Primary Biodegradation Timeframe shows as result a time period of days. Both MITI Models predict that the substance is readily degradable, which is also the overall prediction result. Also under anaerobic conditions the substance is suspected to be biodegraded fast.

Validity criteria fulfilled:

yes

Remarks:

(A scientifically accepted calculation method was used.)

Interpretation of results:

readily biodegradable

Conclusions:

The study report describes a scientifically accepted calculation method for the biodegradability prediction using the US-EPA software BIOWIN v4.10.No GLP criteria are applicable for the usage of this tool and the QSAR estimation is easily repeatable. The substance falls within the applicability domain of the QSAR model, hence, the result can be considered as reliable. The result is adequate for the regulatory purpose.

Executive summary:

The ready biodegradability of the substance potassium 3-(methacryloyloxy)propane-1-sulfonate was determined by the QSAR program BIOWIN v1.40 (EPIWIN software) by US-EPA.

BIOWIN estimates the probability of rapid aerobic and anaerobic biodegradation of an organic compound in the presence of mixed populations of environmental microorganisms. Two independent training sets were used to develop four mathematical models for predicting aerobic biodegradability from chemical structure.  All four of the models are based on multiple regressions against counts of 36 preselected chemical substructures plus molecular weight.  Two of the models, based on linear and nonlinear regressions, calculate the probability of rapid biodegradation and can be used to classify compounds as rapidly or not rapidly biodegradable.  The training set for these models consisted of qualitative summary evaluations of all available experimental data on biodegradability for 295 compounds.  The other two models allow semi-quantitative prediction of primary and ultimate biodegradation rates using multiple linear regression.  The training set for these models consisted of estimates of primary and ultimate biodegradation rates for 200 compounds, gathered in a survey of 17 biodegradation experts.  The two probability models correctly classified 90% of the compounds in their training set, whereas the two survey models calculated biodegradation rates for the survey compounds with R2= 0.7. In this case, the substance was estimated to be readily biodegradable.

Adequacy of the QSAR:

- QSAR model is scientifically valid.

- The substance falls within the applicability domain of the QSAR model (except for model BIOWIN 6 & 7, which are not relevant for the overall prediction of biodegradability).

- The prediction is fit for regulatory purpose.

Reference 2

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 - 30 January 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Deviations:

not specified

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge : Sewage treatment plant Birsfelden
- Concentration of sludge : 0.2 g dry substance/L
- Date of sampling: 09.01.1996

Duration of test (contact time):

14 d

Initial conc.:

167 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

no details available

Reference substance:

ethylene glycol

Remarks:

125 mg/L

Key result

Parameter:

% degradation (DOC removal)

Value:

> 99

Sampling time:

14 d

Results with reference substance:

The reference substance is degraded at least 70% within the 14d-window, confirming the inoculum and the test set-up to be appropriate .

Validity criteria fulfilled:

yes

Remarks:

The reference substance is degraded at least 70% within the 14d-window, therefore the test is considered valid.

Interpretation of results:

inherently biodegradable

Conclusions:

It can be concluded that the test substance is inherently biodegradable. Based on the available results, i.e. >99% biodegradation after 14 days, although under less stringent conditions compared to a testing for ready biodegradability, it can be concluded that the test item is easily biodegradable, which is supported by QSAR estimation indicating that the substance is readily biodegradable.

Executive summary:

The biodegradability of the test substance was investigated according to OECD guideline 302 B. The degradation parameter was the DOC removal in the samples. After 14 days incubation >99 % degradation had occurred. Due to this result SPM can be considered as inherently biodegradable. Ethylene glycol was used as reference substance. After 14 days incubation the reference substance is degraded at least 70% within the 14d-window, confirming the inoculum and the test set-up to be appropriate.

Description of key information

OECD Guideline 302 B, 1996: inherently biodegradable (> 99% after 14 days).

Calculation with BIOWIN v4.10 (EPIWIN software by US-EPA): readily biodegradable (overall prediction)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Inherent biodegradability of the test substance was investigated according to OECD guideline 302 B. The degradation parameter was the DOC removal in the samples. After 14 days incubation >99 % degradation had occurred. Due to this result SPM can be considered as inherently biodegradable. Ethylene glycol was used as reference substance. After 14 days incubation the reference substance is degraded at least 70% within the 14d-window, confirming the inoculum and the test set-up to be appropriate. Based on the available results, although under less stringent conditions compared to a testing for ready biodegradability, it can be concluded that the test item is easily biodegradable.

The ready biodegradability of the substance potassium 3-(methacryloyloxy)propane-1-sulfonate was determined by the QSAR program BIOWIN v1.40 (EPIWIN software) by US-EPA.

BIOWIN estimates the probability of rapid aerobic and anaerobic biodegradation of an organic compound in the presence of mixed populations of environmental microorganisms. Two independent training sets were used to develop four mathematical models for predicting aerobic biodegradability from chemical structure.  All four of the models are based on multiple regressions against counts of 36 preselected chemical substructures plus molecular weight.  Two of the models, based on linear and nonlinear regressions, calculate the probability of rapid biodegradation and can be used to classify compounds as rapidly or not rapidly biodegradable.  The training set for these models consisted of qualitative summary evaluations of all available experimental data on biodegradability for 295 compounds.  The other two models allow semi-quantitative prediction of primary and ultimate biodegradation rates using multiple linear regression.  The training set for these models consisted of estimates of primary and ultimate biodegradation rates for 200 compounds, gathered in a survey of 17 biodegradation experts.  The two probability models correctly classified 90% of the compounds in their training set, whereas the two survey models calculated biodegradation rates for the survey compounds with R2= 0.7. In this case, the substance was estimated to be readily biodegradable.

Adequacy of the QSAR:

- QSAR model is scientifically valid.

- The substance falls within the applicability domain of the QSAR model (except for model BIOWIN 6 & 7, which are not relevant for the overall prediction of biodegradability).

- The prediction is fit for regulatory purpose.