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

Endpoint summary

Description of key information

For Isobornyl propionate the following results were derived:

Method	Test species	Endpoint	Result in mg/l	Remark
Read across from Isobornyl acetate, tested in an OECD TG 203 (Rel. 1)	Pimephales promelas	96-h LC50	8.3	Data are converted, considering log Kow and MW differences.
Read across from Isobornyl acetate, tested in an OECD TG 202, Rel.1)	Daphnia magna	48-h EC50	8.7	Data are converted, considering log Kow and MW differences.
Read across from Isobornyl acetate, which is tested in an OECD TG 201 (Rel.1)	Pseudokirchneriella subcapitata	72-h ErC50 72-h NOErC	> 18.7 9.87	Data are converted, considering log Kow and MW differences.
Read across from Isobornyl acetate, which was tested in an OECD TG 301F	Activated sludge, domestic	28-d NOEC	69.6	Data are converted, considering log Kow and MW differences.

Additional information

The aquatic toxicity of Isobornyl propionate is based on read-across from isobornyl acetate. The read-across documentation is for fish, daphnia, algae and microorganisms and is included in the study records of the respective endpoints. The read-across justification is also presented below:

Aquatic toxicity of Isobornyl propionate (CAS #2756-56-1) based on read-across from data available for Isobornyl acetate (CAS #125-12-2)

 

Introduction and hypothesis for the analogue approach

Isobornyl propionate has an exo-1,7,7-Trimethylbicyclo[2.2.1]heptane-2-ol (Isobornyl alcohol) backbone to which a propionic ester group is attached. For this substance no acute fish, Daphnia data and no algae and micro-organism data are available. In accordance with Article 13 data can be generated by means of, i.e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across. For assessing the aquatic toxicity of Isobornyl propionate, the analogue approach is selected because for closely related analogue, Isobornyl acetate reliable aquatic toxicity data are available.

Hypothesis: Isobornyl propionate has similar aquatic toxicity potential as Isobornyl acetate as these substances are similar in structures and related properties.

Available experimental information: For the source chemical Isobornyl acetate data are available from GLP guideline studies with fish, aquatic invertebrates, algae and activated sludge micro-organisms. The L(E)C50 values for fish, Daphnia and algae are 9.9, 10.5 and 24 mg/L, respectively. The NOEC value for algae and micro-organisms are 12 and 100 mg/L, respectively. The data are derived from OECD TG 203, 202, 201 and 301F (biodegradation test), respectively, and are reliable without restriction (Rel. 1).

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical(s) are shown in the data matrix, including relevant physico-chemical properties.

Purity / Impurities

Isobornyl propionate is a mono-constituent >=88%, with impurities similar to the parent substance and < 10%.

Analogue approach justification:

According to Annex XI 1.5 read-across can be used to replace testing when the similarity can be based on a common backbone and a common functional group.

Analogue selection: For Isobornyl propionate the one methyl shorter Isobornyl acetate was selected as an analogue being the closest analogue for which experimental aquatic toxicity information is available. E.g. for Isobornyl butyrate no such information was found on the ECHA dissemination site or in the RIFM database.    

Structural similarities and differences: Isobornyl propionate and Isobornyl acetate have the same backbone and functional ester group. The only difference between the two is the propionate and acetate group, respectively, which will result in a higher molecular weight for the propionate.

Bioavailability:Isobornyl- propionate and the acetate will be sufficiently bioavailable based on the similar (predicted) water solubility and log Kows.

Mode of Action:Isobornyl propionate and Isobornyl acetate have the same mode of action because of these substances almost the same, only differing in one methyl group in the alkyl chain.

Conversion of the short-term values to Isobornyl propionate from Isobornyl acetate:

The difference in log Kow and molecular weight between Isobornyl propionate and Isobornyl acetate will be used for conversion of the toxicity values. The toxicity is recalculated using moles/L and reported in mg/L. For conversion the difference in measured log Kows of Isobornyl-propionate and acetate are used, which is 0.7, because this is slightly higher than the calculated Kows is slightly lower (0.49) and therefore the measured log Kow difference is slightly more conservative.

The following conversion is used:

Log EC in mmol target= Log ECmmol x log Kow source/Log Kow target

First calculate log value of mg/l, thereafter / mw source then log Kow source/log Kow target

Secondly, multiply result with molecular weight target and anti-log the value for mg/l.

Uncertainty of the prediction:There is no remaining uncertainty other than already addressed above. The lower anticipated aquatic effect values for Isobornyl propionate are taking into account using the Isobornyl acetate converted values.

Data matrix

The relevant information on physicochemical properties and toxicological characteristics are presented in the data matrix below.

Conclusions for hazard and risk assessment

For Isobornyl propionate no aquatic toxicity information is available. Read-across is performed from the structural analogue Isobornyl acetate for which these data are available.

When using read across the result should be applicable for classification and labelling and risk assessment as well as presented with reliable and adequate documentation. This documentation is presented in the current document. For Isobornyl acetate the following acute aquatic toxicity data were found: 9.9, 10.5 and 24 mg/l for fish, Daphnia and algae. Long-term effects of algae and micro-organisms are 12 and 100 mg/l, respectively. These values are converted to Isobornyl propionate.

Final conclusion on hazard and risk assessment: Isobornyl propionate has acute fish, Daphnia and algae toxicity of 8.3, 8.7 and 18.7 mg/L, respectively. For long-term alga and for micro-organisms the values are 9.9 and 69.6 respectively.

 

Data matrix: Isobornyl propionate’s aquatic toxicity using read across from Isobornyl acetate, including conversion

Common names	Isobornyl propionate (IP)	Isobornyl acetate (IA)
Source/target	Target	Source
Chemical structures
CAS no.	2756-56-1	125-12-2
EINECS	220-410-5	204-727-6
REACH registration	2018	Registered
Empirical formula	C13H22O2	C12H20O2
Molecular weight	210.32	196.29
Phys-chem	EpiSuite	EpiSuite
Physical state	Liquid	Liquid
Log Kow	4.35 5.0 (IFF measured)	3.86 4.3 (Simonich, EpiSuite)
Acute aquatic toxicity
Fish 96-h LC50 in mg/L	8.3 (Read across using conversion)	9.9 (0.051mmol) (OECD TG 203)
Daphnia 48-h EC50 in mg/L	8.7 (Read across using conversion)	10.5 (0.054 mmol) (OECD TG 202)
Algae 72-h ErC50 in mg/L	18.7 (Read across using conversion)	24 (0.12 mmol) (OECD TG 201)
Algae 72-h NOEC in mg/L	9.9 (Read across using conversion)	12 (0.061 mmol) (OECD TG 201)
Micro-organisms 28-d NOEC in mg/L	69.6 (Read across using conversion)	100 (0.51 mmol) (OECD 301F)