Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Parent substance

The substance is not readily and poorly biodegradable in a study according to OECD criteria (CIBA-GEIGY 1985, OECD 301B-testing).

Significant elimination (DOC-removal of 45%) was observed in a simulation test according to OECD 303A (CIBA-GEIGY 1986). However, as the substance is poorly soluble and very adsorptive it can be assumed that adsorption is a major factor for elimination.

Additional QSAR calculations with Catalogic v5.11.19, Catalogic 301C v09.13 revealed a degradation of 2% after 28d. The predicted primary half-life of the substance was 6.03 days and the ultimate half-life 2y 11m 11d. It is assumed that the parent compound undergoes a certain degree of primary degradation, i.e. primarily ester hydrolysis resulting in the corresponding benzenepropanoic acid (metilox acid, CAS 20170-32-5). In total, the model identified 23 metabolites. This can be regarded as clear worst case as the model lists the complete degradation map which also contains metabolites at very low quantities as well as metabolites that are subject to further degradation. Metilox acid (CAS 20170-32-5) was predicted to have the highest quantity.

Degradation products were also assessed by the ECB PBT working group (PBT List No 77) in the available PBT assessment of CAS 6683-19-8. The PBT working group identified two potential degradation products which were also predicted by Catalogic 301C.

(1)  benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy- (metilox acid; CAS 20170-32-5)

(2)  pentaerythritol (CAS 115-77-5)

The assumed formation of these degradation products by the ECB working group is based on data on a structural analogue (CAS 2082-79-3). They are in line with the before-mentioned results of CATALOGIC which predicted metilox acid to be the main metabolite as well. Concerning pentaerythritol CATALOGIC assumed that this compound is subject to further degradation processes and therefore its quantity is rather low. The detailed assessment of the ECB PBT working group on CAS 6683-19-8 is attached in IUCLID section 13.

Based on experimental data and modelled data it can be concluded that CAS 6683 -19 -8 is not readily biodegradable. it cannot be confirmed whether the parent compound fulfills the persistence criteria or not, but as a worst case it is assumed that it is persistent in the environment with half lives in fresh water >40d. This assumption seems reasonable regarding the high molecular weight of the compound and the resulting limitations due to mass-transfer.

Additional information

Degradation product Metilox acid (CAS 20170-32-5)

Metilox acid was identified as the main metabolite in CATALOGIC 301C v.09.13. Furthermore, the assessment of the ECB PBT working group also identified metilox acid as one of the main metabolites according to the data on a structural analogue.

Experimental data available for metilox acid show that the compound is not readily biodegradable. In a study according to OECD TG 301B the substance degraded by 7% and 3%, respectively. CATALOGIC 301C v.09.13 predicted a BOD of 0%. It is therefore assumed that metilox acid fulfills the persistence criteria set out in Regulation (EC) No 1907/2006.

Degradation product Pentaerythritol (CAS 115-77-5)

Pentaerythritol was identified by the ECB PBT working group as major metabolite of CAS 6683-19-8.The ECB PBT working group assessed it as not readily biodegradableand hydrolytically stable.This substance was also identified by CATALOGIC 301C as degradation product which will be further degraded. Based on more recent disseminated data (ECHA, CAS 115 -77 -5, accessed Januray 29, 2018), pentaerythritol is readily biodegradable, which is in line with the Catalogic predictions.The predicted quantity in the model was below 0.1% mol/mol parent and the logKow-1.77. As a consequence, pentaerythritol is not further assessed in the PBT assessment.

The complete list of metabolites derived by the CATALOGIC 301C model was screened for relevant metabolites for the subsequent PBT/vPvB assessment. Only metabolites with a quantity ≥0.1% and a logKow value ≥4 were taken into account (besides the parent substance).

According to Regulation (EC) No 1907/2006 a PBT/vPvB assessment needs to be conducted for substances at concentrations >0.1%. Furthermore, according to ECHA’s Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.11: PBT/vPvB assessment, section R.11.4.1.2, it is assumed for organic substances with a logKow value below 4.5 that the affinity for the lipids of an organism is insufficient to exceed the B criterion, i.e. a BCF value of 2000. Deviating from this screening criterion BASF decided to further tighten the trigger criterion to a logKow of ≥4 as a worst case. Taking both the quantity and the logKow trigger of 4 into account, 9 metabolites could be identified which are assessed for their bioaccumulation potential (see table and also IUCLID chapter 5.3.1, endpoint summary).

Further metabolites identified with CATALOGIC 301C

In the absence of experimental data on the degradability and bioaccumulation the CATALOGIC 301C v.09.13 was used to predict the BOD, logKow and the quantity. Relevant metabolites and information on quantity, BOD and logKow can be found in the table. In general, the identified metabolites consist of pentaerythritol as a core and 2 to 4 metilox acid groups (in some cases slightly modified at the tert butyl group or the propane chain) attached to it. In dependence of the amount of metilox groups the logKow values range from 7.02 to 18.06.

According to the (Q)SAR results none of the metabolites can be classified as readily biodegradable. Due to the high structural similarity to the parent compound this assumption seems reasonable. Details on the modelling can be found in the attached QPRF documents in the corresponding endpoint study records. As a worst case, the metabolites are regarded as persistent or very persistent in the environment.

Parent and metabolites at a quantity ≥0.1% (mol/mol parent) and a logKow ≥4.

Quantity [%] mol/mol parent (1)

LogKow (1)

BOD Catalogic [%](1)

Remarks

SMILES Code

4.01

19.60

2.00

Parent (CAS 6683-19-8)

CC(C)(C)c1cc(CCC(=O)OCC(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C)c1O

230.20

4.77

0.00

Metabolite (Metilox acid; CAS 20170-32-5)

CC(C)(C)c1cc(CCC(O)=O)cc(C(C)(C)C)c1O

10.38

13.91

2.00

Metabolite (triester of CAS 6683-19-8)

CC(C)(C)c1cc(CCC(=O)OCC(CO)(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C)c1O

0.37

18.06

2.00

Metabolite

CC(C)(C)c1cc(CCC(=O)OCC(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)COC(=O)CC(O)c2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C)c1O

24.37

8.62

2.00

Metabolite (diester of CAS 6683-19-8)

CC(C)(C)c1cc(CCC(=O)OCC(CO)(CO)COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C)c1O

0.51

12.77

2.00

Metabolite

CC(C)(C)c1cc(CCC(=O)OCC(CO)(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)COC(=O)CC(O)c2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C)c1O

0.73

18.00

2.00

Metabolite

CC(C)(C)c1cc(CCC(=O)OCC(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C(O)=O)c1O

2.38

7.08

2.00

Metabolite

CC(C)(C)c1cc(CCC(=O)OCC(CO)(CO)COC(=O)CC(O)c2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C)c1O

1.03

12.30

2.00

Metabolite

CC(C)(C)c1cc(CCC(=O)OCC(CO)(COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C(O)=O)c1O

4.76

7.02

2.00

Metabolite

CC(C)(C)c1cc(CCC(=O)OCC(CO)(CO)COC(=O)CCc2cc(C(C)(C)C)c(O)c(C(C)(C)C)c2)cc(C(C)(C)C(O)=O)c1O

(1)Catalogic v5.11.19, CATALOGIC 301C v.09.13