Reaction products of acrylic acid with 2,2'-[oxybis(methylene)]bis[2-ethylpropane-1,3-diol]

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Assessed composition(s):

Reaction products of acrylic acid with 2,2’-[oxybis(methylene)]bis[2-ethylpropane-1,3-diol] (legal entity composition)

Reaction products of acrylic acid with 2,2’-[oxybis(methylene)]bis[2-ethylpropane-1,3-diol] (boundary composition)

PBT status:

the substance is not PBT / vPvB

Justification:

The test substance and its degradation products may be potentially persistent but they are not bioaccumulative or toxic. Therefore, the test substance as well as its degradation products cannot be classified as PBT and vP/vB.

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Based on the results of the modified Sturm test as well as closed bottle test, the test substance is not readily biodegradable. However, extension of the close bottle test up to Day 60, resulted in 46% degradation, indicating an inherent biodegradation potential of the test substance. This is further supported by the primary half-life QSAR predictions for the different constituents and their degradation products, which indicates that the test substance is overall not persistent in the environment, except for two degradation products.

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater

Experimental data:

A study was conducted to determine the ready biodegradability potential of the test substance in a CO2 evolution (modified Sturm) test, according to OECD Guideline 301B, in compliance with GLP. In addition, the procedures were designed to meet the test methods of the Commission Regulation (EC) No. 440/2008 of 30 May 2008, Publication No. L142, Part C.4-C and the ISO International Standard 9439, 1999 and ISO Standard 10634, 1995. The substance was tested in duplicate at approximately 17.5 mg/L, corresponding to 12 mg total organic carbon (TOC)/L, during 28 d. Based on the TOC content, the theoretical CO2 demand (ThCO2) of the test substance was calculated to be 2.52 mg CO2/mg. The relative biodegradation values revealed 4 and 14% biodegradation of the test substance for the duplicate bottles tested. Thus, the criterion for ready biodegradability was not met. In conclusion, the test substance is considered to be not readily biodegradable in this study (Desmares-Koopmans, 2012).

Another study was conducted to determine the ready and inherent biodegradability of the test substance in a prolonged close bottle test, according to an extended version of OECD Guideline 301D, in compliance with GLP. The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers. There were 10 bottles containing only river water, 6 bottles containing river water and sodium acetate, 10 bottles containing river water with test substance and surfactant, and 10 bottles containing river water with surfactant. The concentrations of test substance, surfactant and sodium acetate in the bottles were 4.0, 4.0 and 6.7 mg/L, respectively. No reduction in the endogenous respiration was observed at Day 7. The test substance was therefore considered to be non-inhibitory to the inoculum. The test was valid, as shown by an endogenous respiration of 1.5 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 83% of its theoretical oxygen demand after 14 d. Oxygen concentrations remained >0.5 mg/L in all bottles during the test period. The test substance was biodegraded by 25% at Day 28 and by 46% at Day 60. Under the conditions of the study, the test substance is not readily biodegradable, but can be considered inherently biodegradable (Ginkel, 2014).

QSAR predictions:

The ready biodegradation and half-life of the test substance was predicted using the CATALOGIC 301C v.12.17. Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) primary and ultimate half-life values were predicted for the individual constituents followed by the determination of an overall weighted average using the mole fractions. SMILES codes were used as the input parameter. The predicted primary half-life values of the individual constituents ranged from 1 to 6.51 days, leading to a weighted average half-life value of 4.5 days for the test substance. Whereas the predicted ultimate half-life values of the individual constituents ranged from 39 to 113 days, leading to a weighted average half-life value of 54.5 days for the test substance. All the QSAR predictions were within the domain of the QSAR model (LMC, 2018). According to the ECHA Guidance Chapter R.11, June 2017,the primary half-life values for the different constituents indicates that the test substance is not persistent.[OAT1] [SM2] 

The ready biodegradation and half-life of the test substance was predicted using the CATALOGIC Kinetic 301F v.15.18. Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) half-life values were predicted for the individual constituents followed by the determination of an overall weighted average using the mole fractions. SMILES codes were used as the input parameter. The predicted primary half-life values of the individual constituents ranged from <1 to 1.13 days, leading to a weighted average half-life value of 1 day for the test substance. Whereas the predicted ultimate half-life values of the individual constituents ranged from 30 to 3650 days, leading to a weighted average half-life value of 155.8 days for the test substance. Except the trimers (which exceeded the molecular weight parameter), all other constituents were within the domain criteria defined in the QSAR model. Therefore, the predictions for the trimers are considered to be less accurate or reliable with restrictions (LMC, 2022). According to the ECHA Guidance Chapter R.11, June 2017, the primary half-life values for the different constituents indicates that the test substance is not persistent.

The primary half-life of 12 degradation products of the test substance identified and predicted using CATALOGIC 301C v.12.17 model, ranged from <1 day to 240 days. Except for two degradation products, the predicted half-life values for most of the degradation products were below 40 days.Further, none of the degradation products was assessed to be bioaccumulative or toxic, suggesting that they have no PBT concerns(see Annex 7 for further details).

Therefore, taking into consideration the primary half-life QSAR predictions for the different constituents and their degradation products indicates that, the test substance is overall not persistent in the environment, except for two degradation products.

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Based on the available weight of evidence i.e., experimental log Kow values of the major constituents, predicted BCF values of the constituents (combined with high MW and Dmax values for the out of domain constituents), together with the absence of systemic effects in repeated dose study in mammals, overall indicate a low bioaccumulation potential for the test substance. As a conservative approach, the higher weighted average BCF value from EPISuite has been considered further for risk assessment.

BCF (aquatic species):

9.38 L/kg ww

The test substance is an UVCB with severalconstituents, varying mainly in the number of acrylates attached totrimethylolpropane(TMP) backbone as well as adducts formation.The experimental log Kow values for the major constituents of the test substance were determined to be 4.14 and 3.05 (respectively representing 81% and 10% of total base peak area) and were between -0.10 and 3.8 for the minor constituents (representing together <10% peak area). Based on this information, the test substance cannot be considered B or vB as it is below the log Kow ≤ 4.5 threshold, according to the REACH criteria.

This is further supported by the QSAR based BCF predictions for individual constituents using BCF base-line (LMC) and Arnot Gobas model of BCFBAF (EPISuite):

The bioaccumulation factor (BCF) of the test substance was predicted using the BCF base line model v.05.12 program of LMC. Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) log BCF values were predicted for the individual constituents followed by the determination of an overall weighted-average value using mole fractions. SMILES codes were used as the input parameter. The predicted log BCF of the individual constituents ranged from 0.61 to 0.88, leading to a weighted average log BCF value of 0.78 (i.e., BCF = 6.03 L/Kg wet-wt for the test substance (LMC, 2018). Based on the BCF predictions, the test substance can be considered to have a low bioaccumulation potential.

The bioaccumulation factor (BCF) of the test substance was predicted using the BCFBAF v.3.01 program (EPISuite v4.11). Since the test substance is a UVCB with similar constituents (varying mainly in the number of acrylates TMP backbone as well as adduct formation) BCF values were predicted for the individual constituents followed by the determination of an overall weighted-average value based on mole fractions. SMILES codes were used as the input parameter. Using the Arnot Gobas method,which uses mitigating factors (e.g., growth dilution and metabolic biotransformations), the upper trophic BCF value for the constituents was predicted to range from 0.9 to 12.59 L/kg, leading to a weighted average BCF value of 9.38 L/kg (log BCF: 0.97) for the test substance (US EPA, 2018). With regard to the domain evaluations for both the QSAR models, most of the constituents meet the respective domain criteria, i.e., log Kow and molecular weight (MW) cut offs as defined in the BCFBAF user guide of EPISuite and general properties (log Kow, WS and MW), structural and mechanistic criteria as defined in the BCF base-line QSAR model. Only, the trimers (present at <15% of composition) due to their higher MW exceed the maximum MW of the training set (1100 g/mol). However, these constituents in general can be expected to have low permeability across membranes, considering their big size, high MW and predicted log Kow >10 (refer to Annex 5), all of which support a low bioaccumulation potential in accordance with the ECHA Guidance Chapter R.11. Therefore, the QSAR predictions from the two models can be considered to be reliable with low degree of uncertainty.

Overall, based on the available weight of evidence i.e., experimental log Kow values of the major constituents, predicted BCF values of the constituents (combined with high MW and Dmax values for the out of domain constituents), together with the absence of systemic effects in repeated dose study in mammals, overall indicate a low bioaccumulation potential for the test substance. As a conservative approach, the higher weighted average BCF value from EPISuite has been considered further for risk assessment.

Results and discussion

Transformation products:

not specified