[4-[α-[4-(dimethylamino)phenyl]benzylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium acetate

Bioaccumulation: aquatic / sediment

Description of key information

Non-bioaccumulable

Key value for chemical safety assessment

BCF (aquatic species):

91 L/kg ww

Additional information

No reliable BCF was found; two studies report by Dystar, 1998, provides a BCF estimated from logPow of >36 - <91 for Malachite Green (MG) hydrochloride and states that no bioaccumulation is expected. This result is consistent with the proposal of the Committee for Risk Assessment RAC of no considering MG as a non bioaccumulative substance based on a logKow < 3.

Notwithstanding, after waterborne exposure of channel catfish to 14C labelled MG, MG and its metabolites can be traced in all studied fish tissues. Blood, plasma, tank water, bile, urine and tissue extracts were sampled. MG was rapidly and extensively metabolized to its reduced form, Leucomalachite Green (LG), which was slowly eliminated from the tissues. Elimination of the parent compound from plasma was triphasic with a terminal half-life of 4.7 h. In muscle, the half-life of the parent compound was approximately 67 h and the half-life of LG was estimated to be 10 days (Plakas et al. 1995).

The study by Allen (1990) showed that the mean concentrations of MG in salmon tissue, eggs and offspring after 24 and 33 days were: 0.43μg/g (muscle); 0.173μg/g (eggs); 0.14μg/g (fry) after treatment of Atlantic salmon and Chinook salmon according to common fish hatchery practise. Long-term bioaccumulation studies have shown that the total MG (MG and metabolites) has a longer elimination, predominantly governed by LG, which varies in different organs.

Bilandzic et al. (2010) studied residue levels of MG in carp and rainbow trout after treatment with MG in Croatian fish farms, using an in-house enzyme linked immunoassay (ELISA) validated to the criteria of Commission Decision 2002/657/EC with an LOD of 0.31 µg/kg. The highest concentration of MG residue was determined in rainbow trout at a concentration of 1.07 µg/kg. No information regarding treatment was provided in this study however, tissue residues are roughly a factor 1000 lower as those observed by Allen, 1990.

Schuetze et al. (2008), determined residue levels of MG and LG in wild eels caught in catchment areas after municipal sewage treatment plants (STP) in Berlin, Germany. LG was the dominating residue with LG:MG ratios varying between 5:1 and 7:1, which would confirm the conclusion by Plakas et al, 1995. MG and its metabolite LG were detected with total concentrations up to 0.765 µg/ kg fresh weight (similar to Bilandzic et al, 2010) in the tissues of 25 out of 45 eels caught from different lakes, a river and a canal. In all cases, the occurrence of the residues could directly be linked to the presence of discharges by municipal STPs into the receiving surface waters.

 

While no BAF/BCF values could be determined in these studies, it is established that the bioaccumulation of MG and its metabolite LG in fish is possible, also due to municipal releases i.e. by wash off from clothes or paper towels coloured with MG. Elimination from fish tissue appears to be slowest for LG.