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Environmental fate & pathways

Biodegradation in water: screening tests

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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:
2012-02-23 to 2012-03-22
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Read across to the analogous substance.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Read across is based on structural and physico chemical similarity of 1,4BDDMA and 1,3-BDDMA

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Substance name 1,4-Butanediol dimethacrylate 1,3-Butanediol dimethacrylate

EC-Number 218-218-1 214-711-0
CAS-Number 2082-81-7 1189-08-8

Purity: 90-100 % Purity: 90-100 %
Reactive ester content: >= 98 % Reactive ester content: >= 98 %
1,4-Butane diol, CAS 110-63: 0-1 % 1,3-Butane diol, CAS 107-88-0 0-1 %
Methyl methacrylate, CAS 80-62-6: 0-1 % Methyl methacrylate, CAS 80-62-6 0-1 %
4-Methoxyphenol, CAS 150-76-5 0.009 – 0.011 % 4-Methoxyphenol, CAS 150-76-5 0.018 – 0.022 %


3. ANALOGUE APPROACH JUSTIFICATION
see attached document
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Version / remarks:
adopted 23 March 2006
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
certificate dated 2010-10-20
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): Municipal sewage treatment plant, Hildesheim, Germany
- Preparation of inoculum for exposure:
Activated sludge was washed twice with autoclaved tap water. After the second washing the settled sludge was resuspended in mineral salts medium and was maintained in an aerobic condition by aeration for 2-4 hours. Thereafter the sludge was homogenized with a blender. The supernatant was decanted and was maintained in an aerobic condition by aeration with CO2-free air for 6 days. 10 mL/L were used to initiate inoculation.
- Initial cell/biomass concentration: 10E05 - 10E08 CFU/L in the test solution
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
test mat.
Initial conc.:
12.6 mg/L
Based on:
other: TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral salts medium acc. to OECD 310 / 80 mL
- Additional substrate: no
- Test temperature: 20 - 22°C
- pH: no data
- Continuous darkness: low light conditions
- Other: agitation on shaker 150-200 rpm

TEST SYSTEM
- Culturing apparatus: Headspace flasks / 120 mL, headspace-to-liquid-ratio 1:2
- Number of culture flasks/concentration: triplicates (test end 5 replicates)
Measurement of the increase of the inorganic carbon (IC) concentration during the incubation: Sodium hydroxide solution (0.74 mL 7 mol/L solution to 80 mL medium) was injected to each vessel sampled. The vessels were shaken on an overhead shaker (100 rpm) for 1 h at test temperature. Suitable volumes of the liquid phase were analysed.

SAMPLING
- Sampling frequency: day 0, 4, 8, 11, 14, 21, 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: mineral salts medium + inoculum
- Toxicity control: test item in test concentration + 30 mg/L reference item
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (CO2 evolution)
Value:
84
Sampling time:
28 d
Remarks on result:
other: 95% c.i. 76 - 92%
Parameter:
% degradation (CO2 evolution)
Value:
27
Sampling time:
4 d
Parameter:
% degradation (CO2 evolution)
Value:
68
Sampling time:
11 d
Details on results:
The 10% level (beginning of biodegradation) was reached after 2 d. The pass level of 60% was reached after 9 d and the biodegradation came to 84% after 28 d.

The biodegradation of the toxicity control reached 83% within 14 d and it came to 89% after 28 d. The biodegradation of the reference item was not inhibited by the test item in the toxicity control. The 95% confidence interval on day 28 was 86 - 93%
Results with reference substance:
The adaptation phase of the functional control changed after 1 day into the degradation phase (degradation > 10%). The course of the degradation phase was rapid and the pass level of 60% was reached after 3 days. The biodegradation came to 91% after 28 days. The validity criterion degradation > 60% after 14 d is fulfilled. The 95% confidence interval on day 28 was 90 - 93%.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
In this headspace test, 1,4-BDDMA was readily biodegradable fulfilling the 10-day window criterion.
Executive summary:

The ready biodegradation of 1,3 -BDDMA was assed by read across with structurally very similar substance 1,4 -BDDMA on structural analog approach.

The ready biodegradation of 1,4-BDDMA was investigated in a study conducted according to OECD Guideline 310 (Headspace Test), adopted 23 March 2006, over a period of 28 days and using predominantly domestic non-adapted activated sludge as inoculum. The biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank, toxicity control and procedural/functional control with the reference substance sodium benzoate were performed.

 

The functional control reached the pass level pass level of 60% after 3 days. 

The 10% level (beginning of biodegradation) was reached after 2 days. The pass level of 60% was reached after 9 days and the biodegradation came to 84 % after 28 days. The 95% confidence interval on day 28 was 76 - 92% 

The biodegradation of the toxicity control reached 83% within 14 days and 89% after 28 days. The biodegradation of the reference item was not inhibited by the test itemin the toxicity control.The 95% confidence interval on day 28 was 86 - 93%

 

1,4-BDDMA was readily biodegradable fulfilling the 10-d window criterion.

 

 

 

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

 

Description of key information

1,3-BDDMA proved to be readily biodegradable and fulfilling the 10-d window criterion.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

One study on biodegradation of 1,3-BDDMA as well as one study on biodegradation of the structural analogue 1,4-BDDMA are available, which are both considered as reliable without restrictions (Klimisch score 1):

The ready biodegradation of the structural analogue 1,4 -BDDMA was investigated in a study conducted according to OECD Guideline 310 (Headspace test) , adeopted 23 March 2006, over a period of 28 days and using predominantly domestic non-adapted activated sludge as

inoculum. The biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank, toxicity control and procedural/functional control with the reference substance sodium benzoate were performed.The functional control reached the pass level pass level of 60% after 3 days. 

The 10% level (beginning of biodegradation) was reached after 2 days. The pass level of 60% was reached after 9 days and the biodegradation came to 84 % after 28 days. The 95% confidence interval on day 28 was 76 - 92% 

The biodegradation of the toxicity control reached 83% within 14 days and 89% after 28 days. The biodegradation of the reference item was not inhibited by the test item in the toxicity control.The 95% confidence interval on day 28 was 86 - 93%

1,4-BDDMA was readily biodegradable fulfilling the 10-d window criterion.

 

In a supporting study 1,3-BDDMA has been tested for biodegradation: 

The ready biodegradation of 1,3-BDDMA was investigated in a study conducted according to OECD Guideline 301 B (CO2 evolution test), adopted 17th July 1992, and EU Method C.4-C, 31 July 1992, over a period of 28 days and using domestic sewage as inoculum. The biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank and procedural/functional control with the reference substance sodium acetate were performed.

The functional control reached the pass level >60% after 14 d (68.5%).

The 10-day window started on day 6. Biodegradation achieved 57% at the end of the 10 day window (day 16) and 74% at the end of the test period.

A degradation of 60% has to be reached in a 10-day window within 28 days in order to classify the test substance as readily biodegradable. Based on this criterion, 1,3-BDDMA is not readily biodegradable. But as the pass level is almost fulfilled (degradation slightly below 60%), the test substance can be considered as inherently biodegradable.

Due to a ceratin vapor pressure indicating that 1,3 -BDDMA is a volatile substance, the OECD 301B is most likely not suitable and therefore the results underestimate the biodegardability. In this case the choice of the OECD 310 seems more reasonable.

Considering close structural similarity to the isomer 1,4 -BDDMA (see also the attached document "Phys-chem properties 1,3 -BDDMA and 1,4 -BDDMA), and the fact that the structural constituents of the ester - 1,3 -butanediol as well as methacrylic acid (MAA) - are both readily biodegradable, 1,3 -BDDMA is judged to be readily biodegradable.