bis(branched-alkyl) 2-{[(1-phenylethyl)amino]methyl}alkanedioate

Endpoint summary

Description of key information

Dietary exposure of fish

Bluegill were exposed to a control and treatment feed for 14 days. Mean measured concentration of the treatment diet was 497 μg/g test item. The growth and lipid corrected BMF value was 0.0032 in analytically determined whole fish tissues in the treatment group. The measured time zero concentration (tissue concentration at Day 14 uptake) in whole fish tissue was 3.10 μg/g, while the derived time zero concentration in whole fish tissue was 0.268 μg/g suggesting the presence of undigested food in the gut tract. When whole fish tissues were analyzed without the gut tract, the mean measured concentration in fish tissue was 1.15 μg/g (OECD 305).

Exposure of sediment organisms

The Day 28 bioaccumulation factor (BAF) for oligochaetes (Lumbriculus variegatus) exposed to sediment spiked with the test item at a nominal concentration of 100 mg test substance/kg dry sediment (mean measured concentration during the uptake phase of 92.1 mg the test item equivalents/kg dry sediment) was 6.40. The accumulation in tissue was swift and the elimination was quick but variable. The non-eliminated residue content on Day 10 of the elimination phase was 34.9%. The uptake rate was 0.670 and the elimination rate was 0.105. The BAFK was 6.35 mg/kg. The lipid content from the organisms found in the four negative control replicates on Day 28 of the uptake phase was determined to be 2.17%. The percent organic carbon in the sediment was 1.5%. The normalized Day 28 BAF, based on the lipid content and percent organic carbon in the sediment was 4.42 (OECD 315).

Additional information

Dietary exposure of fish

GUIDELINE

The objective of this study was to obtain laboratory data characterizing the bioaccumulation potential of test item in the bluegill, Lepomis macrochirus. The protocol was based on procedures outlined in OECD Guidelines for Testing of Chemicals, Guideline 305: Bioaccumulation in Fish: Aqueous and Dietary Exposure.As the BMF is a comparison of the concentration of a substance in an organism with that in the organism’s food, lipid is taken into account by correcting for the contents of lipid in the organism and in the food.

METHODS

The test was divided into two phases: uptake and depuration. During the uptake phase, bluegill were exposed an isotopic mixture of test item in diet at a sub-lethal concentration. The bluegill in the control group were exposed to an untreated diet. The nominal concentration of 500 μg/g test item was selected in consultation with the Sponsor. Each group consisted of one test chamber with 70 fish in each chamber. During the depuration phase, fish were exposed to an untreated diet only. The duration of the uptake phase was 14 days and the depuration phase was 12 days. During both phases of the test, test organisms and water samples were collected and analyzed for 14C radioactivity. These values were used to determine the growth-corrected substance-specific half-life (t1/2g, from the growth-corrected elimination rate constant,k2g), the assimilation efficiency (absorption across the gut; α), the kinetic biomagnification factor (BMFK) and the lipid-corrected kinetic biomagnification factor (BMFKL) for whole fish tissues.

RESULTS

Bluegill were exposed to a control and treatment feed for 14 days. Mean measured concentration of the treatment diet was 497 μg/g test item. The growth and lipid corrected BMF value was 0.0032 in analytically determined whole fish tissues in the treatment group. The measured time zero concentration (tissue concentration at Day 14 uptake) in whole fish tissue was 3.10 μg/g, while the derived time zero concentration in whole fish tissue was 0.268 μg/g suggesting the presence of undigested food in the gut tract. When whole fish tissues were analyzed without the gut tract, the mean measured concentration in fish tissue was 1.15 μg/g.

Exposure of sediment organisms

GUIDELINE

The objective of this study was to determine the bioaccumulation potential of the test item in the oligochaete, Lumbriculus variegatus, through sediment exposure. The protocol was based upon the OECD Guidelines for Testing of Chemicals, Guideline 315: Bioaccumulation in Sediment-dwelling Benthic Oligochaetes

 

METHODS

An initial trial was conducted but was terminated early and repeated due to high mortality in the treatment group. The test concentration was lowered for the definitive test.

 

The test was divided into two phases: the uptake (exposure) phase and the elimination (post-exposure) phase. During the uptake phase, oligochaetes were exposed to one sub-lethal test concentration and a negative and solvent control. The nominal test concentration selected in consultation with the sponsor was 100 mg the test item mg/kg of sediment based on the dry weight of the sediment. Oligochaetes in the solvent control group were exposed under identical conditions without test substance, but with the same amount of solvent used in the treatment group. Oligochaetes in the negative control group were exposed without test substance or solvent. Each test chamber contained the same quantities of sediment and overlying water. Thirty-six replicate test chambers were prepared for both the treatment group and the solvent control group for exposure of the test organisms (i.e. 18 replicates for sampling during the uptake phase plus 18 replicates for sampling during the elimination phase). An additional three replicates were prepared without organisms for the treatment group and the solvent control group for analytical sampling on Day 0. Four replicate test chambers were prepared for the negative control group for sampling at the end of the uptake phase.

 

The results of the study are based on the mean measured test concentrations in the sediment during the uptake phase. The duration of the uptake phase typically will vary according to the time required to reach steady-state, but was not to exceed 28 days. Sediment and overlying water samples were collected and analyzed from three sacrificed replicates of the treatment group and solvent control group on Days 0, 1, 3, 7, 14, 21 and 28 of the uptake phase. Results of the analyses in the sediment were used to verify the exposure over time. Additionally, sediment and overlying water samples were collected on Days 0, 1, 3, 5, 7 and 10 of the elimination phase. The duration of the elimination phase typically will vary according to the time required to reach 10% of the concentration measured in tissues at the end of the uptake phase, but was not to exceed 10 days. Worm tissue samples were collected from the culture on Day 0 and from three replicates from the treatment group and solvent control group on days 1, 3, 7, 14, 21 and 28 of the uptake phase and on days 0, 1, 3, 5, 7 and 10 of the elimination phase. An additional four replicates from the negative control group were sacrificed at the end of the uptake phase for the determination of lipid content in the tissue. The tissue concentrations were used to calculate the uptake rate constant (ks), the elimination rate constant (ke), and the kinetic bioaccumulation factor (BAFK). The bioaccumulation factor (BAF) was calculated, based on the concentration of the test item in the oligochaetes compared to the concentration of the test item in the sediment. Additionally, the residue level in the oligochaetes at the end of the elimination phase (non-eliminated residue; NER) was also determined.

 

RESULTS

The Day 28 bioaccumulation factor (BAF) for oligochaetes (Lumbriculus variegatus) exposed to sediment spiked with the test item at a nominal concentration of 100 mg test substance/kg dry sediment (mean measured concentration during the uptake phase of 92.1 mg the test item equivalents/kg dry sediment) was 6.40. The accumulation in tissue was swift and the elimination was quick but variable. The non-eliminated residue content on Day 10 of the elimination phase was 34.9%. The uptake rate was 0.670 and the elimination rate was 0.105. The BAFK was 6.35 mg/kg. The lipid content from the organisms found in the four negative control replicates on Day 28 of the uptake phase was determined to be 2.17%. The percent organic carbon in the sediment was 1.5%. The normalized Day 28 BAF, based on the lipid content and percent organic carbon in the sediment was 4.42.