Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Based on the results of three OECD guideline screening studies for biodegradation Dantocol DHE cannot be classified as readily or inherently biodegradable (Clarke, 2007; Zhao, 2008; and Xue, 2015). The adsorption coefficient (Koc) of Dantocol DHE is <17.8 with a Log Koc <1.25 (Fox and Mullee, 2007). In addition, the Log Kow of Dantocol DHE was measured as -1.32. The need for bioaccumulation testing is waived on the basis of the Log Kow and a very low potential to accumulate.

Additional information

Three reliable OECD guideline screening studies for biodegradation are available for Dantocol DHE and are included in the dossier. The test substance showed a maximum degradation of 17.7%, achieved after 28 days in one of the Ready Biodegradation OECD 301B tests (Zhao 2008), therefore not meeting the criteria for ready biodegradability and indicating a potential persistence in the environment. An inherent biodegradability test (OECD 302C) was also carried out, which provides optimal conditions for degradation. In this study, the test substance demonstrated a maximum of 1.4% degradation after 28 days. Based on these results Dantocol DHE cannot be classified as inherently biodegradable under the conditions of the test. In accordance with ECHA Guidance R.11 Figure R.11 -3, where the result of a MITI II (OECD 302C) Inherent Biodegradability test demonstrates the test substance does not fulfill the inherent biodegradability criteria, this indicates the test substance will not degrade and must be classified as Persistent.

The adsorption coefficient (Koc) of Dantocol DHE has been determined in according to the HPLC Screening OECD 121 guideline method. This method uses the retention times of reference standards to generate a calibration curve for determination of the adsorption characteristics of the test substance. The retention time of the test substance was less than all of the reference standards, with resulting calculated Koc and Log Koc of <17.8 and <1.25 respectively. These values indicate that Dantocol DHE will be unlikely to adsorb to soil and sludge and is likely to have a very high mobility in the environment.

ECHA guidance states that where the Log Kow of the test substance is ≤3, the requirement for bioaccumulation testing can be waived as the test substance has a low potential to bioaccumulate. The Log Kow of Dantocol DHE was measured as -1.32 and therefore the potential for bioaccumulation is considered very low.