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Description of key information

Cyclacet and its terrestrial toxicity

Test species

Method

Result

EC10 / NOEC

Mg/kg soil dw

 

Remarks

Eisenia fetida

Read across

57 (EC10)

The value is converted from Verdox (tested in an OECD TG 222), for which an EC10 of 45 mg/kg soil dw is derived.

Plants

(6 species)

Read across

56 (EC10)

The value is converted from Verdox (tested in an OECD TG 208), for which an EC10 of 44 mg/kg soil dw is derived.

Soil micro-organisms

Read across

110 (NOEC)

The value is converted from Verdox (tested in an OECD TG 216), for which a NOEC of 100 mg/kg soil dw is derived.

Additional information

The PNEC soil for Cyclacet derived based on Equilibrium Partitioning from aquatic toxicity result in a value of 1.53 mg/kg dw soil, showing similar results as when the PNEC is derived from long-term terrestrial toxicity based on read across from Verdox, which results in a PNEC of 5.6 mg/kg soil dw. Cyclacet's terrestrial toxicity is derived from Verdox. The read across justification is presented below.

Cyclacet (EC no 911-369-0) and its terrestrial toxicity using read across from Verdox (Cas no 20298-69-5)

Introduction and hypothesis for the analogue approach

Cyclacet is an acetic ester attached to a tricyclodecenyl fused ring backbone. For this substance no experimental terrestrial toxicity information is available. In accordance with Article 13 of REACH,lacking information can be generated by means of applying alternative methods such as QSARs, grouping and read-across. For assessing the terrestrial toxicity Cyclacet the analogue approach is selected because for one closely related analogue reliable soil toxicity information is available.

Hypothesis: Cyclacet’s terrestrial EC10/NOEC values can be derived from Verdox after conversion using molecular weight and log Kow.

Available experimental information: For Verdox, long-term terrestrial toxicity information is available for earthworms (OECD TG 222), plants (OECD TG 208, 6 species) and on soil micro-organisms (OECD TG 216) performed according to current guidelines, which all receive Klimisch 1. The EC10/NOEC values are presented in the Data matrix.

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemicals are shown in the data matrix below. Physico-chemical properties thought relevant for aquatic and terrestrial toxicity are listed in the Data matrix.

Purity and impurities

Cyclacet is a reaction mass and is a mixture of two very similar isomers which differ in the position of the double bond at a 5yl or 6yl-position. The impurities are all below 1%.

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. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation, which is presented below.

Structural similarities and differences:Cyclacet and Verdox have a similar hydrocarbon backbone to which the same acetic ester functionality is attached. These backbones have the same number of carbons. The difference is that Cyclacet has an additional hydrocarbon ring structure in which an unreactive double bond is present, while Verdox has a hydrocarbon tert-butyl group attached to its cyclohexyl ring.

Bioavailability:Cyclacet (target) and Verdox (source) have somewhat similar bioavailability based on the similarity in chemical structure and molecular weight Cyclacet, the lower log Kow of Cyclacet compared to Verdox is not too different to present a difference in bioavailability.

Mode of action (MoA): Cyclacet and Verdox have both the same acetic ester as a functional group and therefore the MoA is the same based on the same acetic ester as the functional group. The difference in log Kow between Cyclacet and Verdox 3.9 and 4.75 are accounted for when deriving the terrestrial toxicity values for Cyclacet as presented in Table 1 using the following equation: (Log NOEC/EC10 target (mmol) = Log NOEC/EC10 source (mmol) x log Kow source/Log Kow target).

Uncertainty of the prediction: The lower log Kow of Cyclacet compared to Verdox will result in higher EC10/NOECs for terrestrial organisms. This is supported with information from aquatic toxicity where, after conversion for molecular weight and log Kow, these two substances have very similar aquatic toxicity (See Table 2). There are no other uncertainties than those already accounted for.

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented.Conclusions for terrestrial toxicity

For Cyclacet no terrestrial toxicity information is available, but for the related analogue Verdox long-term terrestrial toxicity is available and read across can be applied. When using read across information, the result derived should be applicable for risk assessment and it should be presented with adequate and reliable documentation, which is presented in the current document. For Verdox long-term terrestrial toxicity is available resulting in EC10/NOECs of 45.1, 44 and 100 mg/kg dw soil for earthworm, plants and micro-organisms. For Cyclacet these EC10/NOECs are converted using molecular weight and log Kow differences. Final conclusion: Cyclacet has EC10/NOEC values of 56, 57 and 110 mg/kg dw for earthworms, plants and micro-organisms.

 

Data matrix supporting the Cyclacet terrestrial toxicity information using read across from Verdox

Common names

Cyclacet

Verdox

 

Target

Source

Chemical structures

 

Cas no of the main isomer

Cas no of the generic

2500-83-6 (5-yl)

54830-99-8

20298-69-5

EINECS no

911-369-0

243-718-1

REACH registration

Registered

Registered

Empirical formula

C12H16O2

C12H22O2

Molecular weight

192

198

Physico-chemical data

 

 

Physical state

liquid

Liquid

Melting point (°C)

< -20

29.8

Boiling point (°C)

247

232

Vapour pressure (Pa at 23°C)

2.12

9.72

Log Kow

3.9

4.75

Fate

 

 

Log Koc

2.62

3.12

Aquatic toxicity

 

 

Acute fish LC50 mg/L

15.8 (OECD TG 203)

10.3 (RA from Verdox after conversion)

5.6 (OECD TG 203)

Acute invertebrates EC50) mg/L

25 (OECD TG 202)

25 (RA from Verdox after conversion_

17 (OECD TG 202)

Acute algae 72h-EC50 mg/L

3.7 (OECD TG 201)

8.11 (RA from Verdox after conversion)

4.2 (OECD TG 201)

Chronic algae EC10 72-h in mg/l

1.2 (OECD TG 201)

0.57 (OECD TG 201)

Chronic algae EC10 in mg/l

1.6 (RA from Verdox after conversion)

 

Terrestrial toxicity

 

 

Earthworm (EC10) mg/kg soil dw

57 (RA from Verdox after conversion*)

45.1 (OECD TG 222)

Terrestrial plants (EC10, average of 6 species) mg/kg soil dw

56 (RA from Verdox after conversion*)

44 ((OECD TG 208)

Micro-organisms (NOEC) mg/kg soil dw

110 (RA from Verdox after conversion*

100 (OECD TG 216)

*Conversion is necessary in view of the difference in log Kow exceeding 0.5 (3.9 and 4.75, for Cyclacet and Verdox, respectively).

 

Table 1 Terrestrial toxicity conversion table to Cyclacet from Verdox

Substance

Species

Effect in mg/l source

MW Source

Mmol/L Source

Log mMol/l Source

Log Kow source

Log Kow target

Convert to Log Mmol/l target

Convert to 10^

MW Target

EC50 value in mg/l Cyclacet

Cyclacet

Earthworm

45.1

198

0.2278

-0.64249

4.75

3,9

-0.52752

0.2968

192

56.988

Plant

44

198

0.2222

-0.65321

4.75

3,9

-0.53632

0.2909

192

55.844

Micro-org

100

198

0.5051

-0.29667

4.75

3,9

-0.24358

0.5707

192

109.58

 

 

Table 2 Aquatic toxicity conversion table to Cyclacet from Verdox

Substance

Species

Effect in mg/l source

MW Source

Mmol/L Source

Log mMol/l Source

Log Kow source

Log Kow target

Convert to Log Mmol/l target

Convert to 10^

MW Target

EC50 value in mg/l Cyclacet

Cyclacet

Algae EC50

4,2

198

0.0212

-1.,67342

4.75

3.9

-1.37396

0.0423

192

8.1159

Daphnia

17

198

0.0859

-1.06622

4.75

3.9

-0.87542

0.1332

192

25.579

Fish

5,6

198

0.0283

-1.54848

4.75

3.9

-1.27138

0.0535

192

10.278

Algae EC10

0,57

198

0.0029

-2.54079

4.75

3.9

-2.08612

0.0082

192

1.5746