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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

For aquatic bioaccumulation, several studies are available for the substance. The key study, a flow through study in rainbow trout conducted at the saturation concentration yielded a steady state BCF of 600 for the test substance and 1146 based on total radioactivity. However, other studies report BCFs of 4000 to 9000. The value of BCF from the key study has been taken as the key value for the chemical safety assessment.

Key value for chemical safety assessment

BCF (aquatic species):
600 L/kg ww

Additional information

For aquatic bioaccumulation, several studies are available for the substance. The key study, a flow through study in rainbow trout conducted at the saturation concentration yielded a steady state BCF of 600 for the test substance and 1146 based on total radioactivity. However, other studies report BCFs of 4000 to 9000 - but these are noted as being wholely unreliable studies with a Klimisch score of 4 in each case. As only one reliable study is available, the results of it should be taken as the key value for the chemical safety assessment for the the assessment of the aquatic bioaccumulation. Therefore, it can be concluded that, based on the reliable evidence presented, the BCF of the test substance is 600, and it does not meet the requirements for being considered as bioaccumulative in the aquatic compartment.

 

Additionally to this, a study conducted by Wildlife International (Project No.: 471A-126) assessed juvenile rainbow trout induced with 30 μg AN2/kg fish wet weight through intra-peritoneal injections at four time points over the course of a week. After the induction period, the livers were harvested, pooled and homogenized to allow for the hepatic microsomal fraction to be extracted for the assay. An assay was carried out to measure metabolism. A positive control of fluroxypyr-methylheptyl ester and three negative controls of heat-inactivated, no-NADPH, and buffer control groups were included. Samples were analysed using HPLC β-RAM. The results showed that there was no metabolism of the test substance, making bioaccumulation of the test substance possible as it is not being broken down within the liver. However, scientific literature indicates variable validity of hepatic microsomal fractions for indicating metabolic potential for some xenobiotics.