Fatty acids, C16 and C18-unsaturated, methyl esters, chlorinated

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

The literature study "Bioconcentration of haloxyfop-methyl in bluegill (Lepomis macrochirus Rafinesque)" has been used to support the bioaccumulation potential of atty acids, C16-C18(even numbered) methyl esters, chlorinated.
Basing on similar structure of test material (RS)-2-[4-(3-Chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]propionic acid methyl ester and Fatty acids, C16-C18(even numbered) methyl esters, chlorinated is it possibile to assume a similar bioaccumulation behaviour.
Particularly, the Fatty acids, C16-C18(even numbered) methyl esters, chlorinated contains the same core structure with just an higher number of C atoms. The test item has a Log Kow between 5.41 and 6.41 while, the Fatty acids, C16-C18(even numbered) methyl esters, chlorinated has a Log Kow between 5.7 and 6.0. A lower Log Kow implies low bioaccumulation potential. Therefore, an extrapolation between study results is possible.
The presence of Cl does not increase or determine the bioaccumulation potential, considering the Log Kow.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

reference to other study

Radiolabelling:

yes

Key result

Type:

BCF

Value:

< 17 dimensionless

Basis:

not specified

Time of plateau:

28 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:0.29 µg/L

Metabolites:

Haloxyfop, polar metabolites 1 and 2.

Bluegill exposed to 14C haloxyfop-methyl for 28 days were found to rapidly absorb the ester from water which was then biotransformed at an extremely fast rate within the fish such that essentially no haloxyfop-methyl was detected in the fish. The estimated bioconcentration factor for the haloxyfop-methyl in whole fish was < 17, based upon the detection limit for ester in fish and the average concentration of haloxyfop-methyl in exposure water. The total 14C residue level within whole fish averaged about 0.27 µg/g equivalents over the course of the uptake phase. The principal component of the 14C residue was haloxyfop, which accounted for an average of about 60% of the radioactivity. Two other polar metabolites were detected in the fish which accounted for an average of about 14% of the radioactivity and an average of about 25% of the radioactivity. Once the fish were transferred to clean water, all metabolites cleared quickly with similar clearance rates. A simulation model estimated the uptake rate constant of haloxyfop-methyl from water to be about 720 mL/g/day. The rate constants for biotransformation of haloxyfop-methyl and the clearance of metabolites formed were estimated to be 200 days-1 (t1/2 = 5 min) and 0.82 day-1 (t1/2 = 0.8 days), respectively. The high rate of biotransformation of the parent compound within the fish demonstrates the importance of basing the bioconcentration factor upon the actual concentration of parent material within the organisms rather than the total radioactive residue levels for radiolabeled bioconcentration studies.

Validity criteria fulfilled:

yes

Conclusions:

The test substance turned out not to be bioaccumulable. Due to the structural similarity and consistent LogKow between the test substance and the target substance, "Fatty acids, C16-C18(even numbered) methyl esters, chlorinated" should not be considered as bioaccumulable.

Description of key information

BCF of in Bluegill exposed for 28 days is < 17 L/kg. Due to the structural similarity and consistent LogKow between the test substance and the target substance, "Fatty acids, C16-C18(even numbered) methyl esters, chlorinated" should not be considered as bioaccumulable.

Key value for chemical safety assessment

BCF (aquatic species):

17 dimensionless