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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Cyclacet has a BCF of 156 l/kg based on read across from Verdox, which are experimentally tested in OECD TG 305 (Klimisch 1).

Key value for chemical safety assessment

BCF (aquatic species):
156 L/kg ww

Additional information

The BCF of Cyclacet is derived by using read across from Verdox which documentation is presented below. This section starts, however, with the executive summaries of the BCFs of Verdox.

Bioaccumulation of Cyclacet (EC no. 911-369-0) using read across from Verdox (CAS no. 20298-69-5).

Introduction and hypothesis for the analogue approach

Cyclacet has a tricyclodecenyl type backbone to which an acetic ester is attached. For this substance no experimental bioaccumulation test (OECD TG 305) is available. In view of its log Kow of 3.9, further BCF information is relevant because this value of 3.9 is higher than the cut off of 3 presented in Annex IX and therefore further information is needed. In accordance with Article 13 of REACH, lacking information can be generated by i.e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across. For assessing the bioaccumulation potential of Cyclacet the analogue approach is selected because for the analogue Verdox in vivo experimental bioaccumulation information is available, which can be used for read across.

Hypothesis: Cyclacet has the same bioaccumulation potential as Verdox.

Available information: For Verdox the BCF is 156 l/kg (including 5% lipid normalisation), based on OECD TG 305 test (GLP and Kl. 1, respectively).

Target chemical and source chemical

Chemical structures of Cyclacet and analogue Verdox is shown in the data matrix, including physico-chemical properties thought relevant for bioaccumulation and read across.

Purity / Impurities

Cyclacet is a reaction mass containing a mixture of two very similar isomers differing only the site of the double bond which can be at the 5-yl or 6-yl position. All impurities are <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.

Analogue justification: For Cyclacet the substance Verdox is selected because of the structural similarity and for Verdox experimental BCF information is available.

Structural similarities and differences: Cyclacet has a similar hydrocarbon backbone and acetic ester functionality as Verdox. Cyclacet has the hydrocarbons somewhat differently organised, it has an extra bridge on the cyclohexyl ring and a pentene ring, while Verdox has an additional tert-butyl group to the cyclohexyl ring.

Bioavailability: Cyclacet and Verdox have similar bioavailability based on chemical structures and similar molecular weight. Cyclacet has a somewhat lower log Kow compared to Verdox but the log Kow is still in the range of being bioavailable.

Metabolism: Cyclacet and Verdox will be similarly metabolised because both are acetic esters and these ester group will be readily cleaved by the carboxyl-esterases in fish into the respective alcohols (Wheelock et al. 2008). The respective alcohols will be conjugated and excreted via the kidneys.

Uncertainty of the prediction:There or no remaining uncertainties other than those already addressed above.

Data matrix

The relevant information on physico-chemical properties and other environmental fate properties are presented in the Data Matrix below.

Conclusions for Bioaccumulation

For Cyclacet no experimental BCF is available. For the analogue Verdox such information is present, which can be used for read across. When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation. The current document fulfils this documentation. Verdox has an experimental steady state BCF values of 156 l/kg (5% lipid normalised, OECD TG 305 test, Kl. 1), which can be directly applied to Cyclacet because the molecular weight of both is almost the same: 192 for Cyclacet and 196 for Verdox.

Final conclusion: Cyclacet is not bioaccumulating and has a BCF of 156 l/kg.

 

Data matrix to support the read across to Cyclacet from Verdox on bioaccumulation

Common name

Cyclacet

Verdox

Target / Source

Target

Key Source

Molecular structure

CAS

 

2500-83-6 (5-yl)

54830-99-8 (Generic)

20298-69-5

Einecs number

911-369-0

243-718-1

REACH registered

Registered

Registered

Empirical formula

CH12O2

C12H20O2

Molecular weight

192

196

Physico-chemical properties

 

 

Appearance

Liquid

Handled as liquid

Water solubility in mg/l

186

10

Log Kow

3.9

4.75

Environmental Fate

 

 

Bioaccumulation in l/kg

156

RA from Verdox

156

(OECD TG 305, Kl. 1)

 

Reference to support ester cleavage

Wheelock, C.E., Philips, B.M., Anderson, B.S., Miller, J.L., Miller, M.J., and Hammock, B.D., 2008, Application of carboxylesterase activity in environmental monitoring and toxicity identification evaluations, (TIEs), in Reviews of Environmental Contamination an Toxicology, ed. Whitacre, 117-178, D.M., Springer.