Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acrylate

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
1) The extended OECD 301F (GLP, 2021) showed a degradation of 73.9 % after 60 days without reaching a plateau phase. Following the Integrated assessment and testing of Persistence (ECHA Guidance Document R.11) these information are sufficient to conclude, that IBoA is not persistent (not P/ not vP).

2 and 3) Further, the results show an extensive biodegradability of IBoA, even though the criteria for 'readily biodegradability' are not met, due to not meeting the 10-day-window criteria. The label 'inherently biodegradable' is used for the exposure assessment calculations and which indicate no risk to aquatic organisms. As the emblem 'inherently biodegradable' is also given to substances with a degradation plateau slightly over 20 % after 28 days with no further degradation, the more than inherent biodegradability of IBoA suggests that the margin of safety calculated in the exposure assessment is conservative and protective for aquatic organisms.

4) Additionally, ester hydrolysis by carboxylesterases has been established as the primary step in the metabolism of esters of simple carboxyl acids like acryl acid. For IBoA, this hydrolytic step leads to the rapid degradation into Isoborneol (IBo, EC-No. 204-712-4) and Acrylic Acid (AA, EC-No. 201-177-9). The rapid metabolism of IBoA was shown in rats in a metabolism study with 1 % of the corresponding intravenous administered dose remaining in the blood after 10 min (DOW, 2019; see section metabolism). As carboxylesterases are documented for all major organism groups i.a. fish, mammals, plants, fungi and microorganisms, this metabolism pathway can be expected to be the major degradation pathway in the environment and in organisms.

5) The primary degradation products IBo and AA are both readily biodegradable in water fulfilling the 10-day-window criteria (biodegradation screening studies) and have a logKow < 3. Therefore, a bioaccumulation within the organism or an accumulation in the environment can be neglected for the primary metabolites of IBoA.

Results and discussion

Transformation products:

not measured

Remarks:

The hydrolysis of IBoA into its primary metabolites Isoborneol (IBO, EC-No. 204-712-4) and Acrylic Acid (AA, EC-No. 201-177-9) via carboxylesterases has been established. Please see the remark below for further information.

Identity of transformation products

Identity of transformation products 1

No.:

#2

Reference

Reference substance name:

Unnamed

IUPAC name:

prop-2-enoic acid

Inventory number:

InventoryMultipleMappingImpl [inventoryEntryValue=EC 201-177-9]

CAS number:

79-10-7

Molecular formula:

C3H4O2

Molecular weight:

72.063

SMILES notation:

OC(=O)C=C

InChl:

InChI=1/C3H4O2/c1-2-3(4)5/h2H,1H2,(H,4,5)

Identity of transformation products 2

No.:

#1

Reference

Reference substance name:

Unnamed

IUPAC name:

1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol

Inventory number:

InventoryMultipleMappingImpl [inventoryEntryValue=EC 204-712-4]

CAS number:

124-76-5

Molecular formula:

C10H18O

Molecular weight:

154.249

SMILES notation:

C[C@@]12CC[C@@H](C[C@@H]1O)C2(C)C

InChl:

InChI=1/C10H18O/c1-9(2)7-4-5-10(9,3)8(11)6-7/h7-8,11H,4-6H2,1-3H3

Details on transformation products:

- Ester hydrolysis by carboxylesterases has been established as the primary step in the metabolism of esters of simple carboxyl acids like acryl acid - including IBoA. For IBoA, this hydrolytic step leads to the degradation into Isoborneol (IBO, EC-No. 204-712-4) and Acrylic Acid (AA, EC-No. 201-177-9). The rapid metabolism of IBoA was shown in rats in a metabolism study with 1 % of the corresponding intravenous administered dose remaining in the blood after 10 min (DOW, 2019; see section metabolism). As carboxylesterases are documented for all major organism groups i.a. fish, mammals, plants, fungi and microorganisms, this metabolism pathway can be expected to be the corresponding major degradation pathway in the environment. IBO and AA are both readily biodegradable in water, fulfilling the 10-window criteria (biodegradation screening studies).
- The primary metabolites IBO and AA have a log Kow < 3 and are readily biodegradable (both meeting the 10-day-window criteria). Therefore, a bioaccumulation within the organism or an accumulation in the environment can also be neglected for the primary metabolites of IBoA.