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Ecotoxicological information

Toxicity to terrestrial arthropods

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Description of key information

The PNEC of Cyclacet is derived using the EP method, being a valid method with a reliable result, because no excess soil toxicity is expected compared to aquatic organisms and the exposure to soil organisms from Cyclacet will be via the pore water in view of its water solubility and its Koc (407). 

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:
2.12 mg/kg soil dw

Additional information

The following WoE is presented to justify the PNEC for earthworms and terrestrial arthropods being 2.12 mg/kg bw:

- In view of the low acute hazard of Cyclacet for aquatic organisms (E(L)C50 > 10 mg/l (R 7c, page 125), no short-term toxicity to soil invertebrates is anticipated.

-The EP method may be applied according to REACH regulation Annex IX. Though the EP method may be considered a rough estimate for predicting terrestrial toxicity it is considered a valid method for a broad spectrum of organic type of substances and present mostly a conservative approach as identified by van Beelen et al. (2001), Sijm et al. (2007, pg. 148) and Hartmann et al. (2014) (see Overall Endpoint Summary for references). It is also a valid method for substances which will be mainly exposed via the pore water (Sijm et al., 2007). Therefore for Cyclacet, being an unreactive ester the EP method can be applied.

-Using the EP method a NOEC for Cyclacet of > 10 mg/kg soil dw (PNEC 2.12) is calculated which is also considered conservative because primary degradation in soil is anticipated as well as some volatilisation in view of its Henry coefficient being 2.4.

In view of the low adsorption potential Cyclacet will dissipate from soil because of the Log Koc < 3. It is anticipated that Cyclacet is biodegraded in a water-screening system because the alkyl chains of esters are readily biodegraded, firstly in the sludge. This means that in case of application of the sludge on land minimal or no Cyclacet is expected. Even if some Cyclacet is remaining also by soil organisms will degrade the Cyclacet into the respective alcohols and acids (Wheelock et al. 2008) (see for references Overall Endpoint Summary). The alcohol is the Cyclacet-alcohol and has a determined log Kow of 2.4. The acetic acid will be consumed by the bacteria. This alcohol is less toxic and has lower adsorption potential compared to Cyclacet because of the lower log Kow.