ethyl N,S-bis(4-oxo-4-(2,6,6-trimethylcyclohex-3-en-1-yl)butan-2-yl)cysteinate

Bioaccumulation: aquatic / sediment

Administrative data

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September to November, 2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Test Method Relating to New Chemical Substances “Bioconcentration test of chemical substances in fish and shellfish” (Japanese notification, Yakushokuhatsu 0331 No.7, Heisei 23.03.29 Seikyoku No.5, Kanpokihatsu No.110331009, March 31, 2011)

Version / remarks:

Latest revision, 01 July, 2019

Deviations:

no

Principles of method if other than guideline:

Japanese fish bioconcentration test guideline similar to that of OECD 305.

A single exposure concentration was performed in the definitive study based on the Following :
Overview of Rational for Using a Single Exposure Concentration :
a) SCENTAURUS BERRY is a non-polar organic substance and is expected to behave and bioaccumulate in a linear fashion across a broad range of environmentally relevant exposure concentrations.
b) No concentration effects were expected because the test concentration (2 µg/L) was much lower than its water solubility (0.0567 mg/L), and, no acute toxic effect was observed in fish toxicity studies (96 hr LC50 >2 mg/L for Medaka).
c) Low BCF values were observed in the pre-study with common carp (< 100 L kg-1 wet wt), and, the BCF values observed at the two exposure levels in the pre-study were equivalent.
d) Reduction in the number of vertebrate animals employed in testing, conform with good animal welfare practice.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

ethyl N,S-bis(4-oxo-4-(2,6,6-trimethylcyclohex-3-en-1-yl)butan-2-yl)cysteinate

EC Number:

866-600-7

Cas Number:

2173997-41-4

Molecular formula:

C31H51NO4S

IUPAC Name:

ethyl N,S-bis(4-oxo-4-(2,6,6-trimethylcyclohex-3-en-1-yl)butan-2-yl)cysteinate

Test material form:

liquid

Radiolabelling:

no

Sampling and analysis

Details on sampling:

Following a pre-study performed at 2 exposure concentrations, a single exposure concentration plus a Control was performed for the definitive study (based on the justification provided, above).

Sampling of Aqueous Phase for Analysis :
Exposure Concn. (2 ppb, nominal) : Day 0 (prior to introduction of fish), Day 5, 8, 14, 21 and 28.
Control : Day 0, Day 28

Sampling of Fish for Analysis :
Exposure Concn. (2 ppb, nominal) : Day 5, 8, 14, 21 and 28.
Control : Day 0, Day 28

Test solutions

Vehicle:

yes

Remarks:

Dimethyl sulfoxide 50 ppm (v/v)

Details on preparation of test solutions, spiked fish food or sediment:

Test substance concentrations in test water (nominal concentrations)
Concentration level: 0.002 mg/L (measured time-weighted average = 0.00170 mg/L)
Control: 0 mg/L (measured < LOD)

Vehicle in test water
Concentration level: Dimethyl sulfoxide 50 ppm (v/v)
Control: Dimethyl sulfoxide 50 ppm (v/v)

Test organisms

Test organisms (species):

Cyprinus carpio

Details on test organisms:

Source: Kitamura-yourijou
12-388, Gunchiku, Yatsushiro, Kumamoto 866-0001, Japan
Date of purchase: December 18, 2018
Lot number: 18-K-1218

Pre-acclimation: At the start of acclimation, abnormal fish were removed upon visual inspection. The remaining normal fish were then reared in an aquarium with flowing water.
Total length: 8 ± 4 cm
Body weight: Approximately 5 g
Age: Yearling fish

Acclimation
Aquarium number: A-11
Water temperature: 24 ± 2°C
Period: August 14, 2019 to September 26, 2019
Food: Babygold, Kyorin Co., Ltd.
Feeding: The food was given daily equivalent to approximately 1.5% of the body weight.
Mortality during the 1 week before testing: <5%
Medication during acclimation: None

Study design

Route of exposure:

aqueous

Justification for method:

aqueous exposure method used for following reason: No concentration effects were expected because the test concentration (2 µg/L) was much lower than its water solubility (0.0567 mg/L), and, no acute toxic effects was observed in fish toxicity studies (96 hr LC50 >2 mg/L for Medaka)

Test type:

flow-through

Total exposure / uptake duration:

28 d

Test conditions

Hardness:

52 - 55 mg CaCO3/L

Test temperature:

24.1 - 24.4 °C

pH:

pH 6.5 - 6.8

Dissolved oxygen:

7.3 - 8.4 mg O2/L

TOC:

18.0 - 19.4 mg C/L, including 17.1 mg C/L from co-solvent (Di-Methyl Sulfoxide).

Thus maximum TOC related to other sources during the exposure period was 2.3 mg C/L.

Details on test conditions:

Supply of test water: Continuous flow-through dilution system
Exposure level (nominal concentrations of the test substance)
Concentration level: 0.002 mg/L
[Vehicle concentration: Dimethyl sulfoxide 50 ppm (v/v)]
Control: 0 mg/L
[Vehicle concentration: Dimethyl sulfoxide 50 ppm (v/v)]
Supply of dilution water: 800 L/day (Turnover rate: 16 times/day)
Supply of feed solution: 40 mL/day
(test item concentration = 40 mg/L)
Number of fish (at the start of the exposure period):
Concentration level: 28 fish in 50 L test water (>1 L/day/g)
Control: 16 fish in 50 L test water (>1 L/day/g)
Water temperature: 24 ± 2°C
Dissolved oxygen: >60% of the saturation (>5 mg/L at 24°C)
Aeration: Continuous
pH: 6.0 to 8.5
Lighting: Approx. 16 hr/day, Hf fluorescent lamp
(wavelength 400-700 nm) )
Exposure period: 28 days
Reason: The steady-state was reached within 28days

Nominal and measured concentrations:

The nominal exposure concentration was 2 ppb.
The time-weighted average exposure concentration was 1.7 ppb

Reference substance (positive control):

no

Results and discussion

Lipid content

Lipid content 1

Lipid content:

5.1 %

Time point:

end of exposure

Lipid content 2

Lipid content:

5 %

Time point:

start of exposure

Lipid content 3

Lipid content:

5.1 %

Time point:

other: Average value for entire expsoure period

Bioaccumulation factor

Bioaccumulation factor 1

Key result

Conc. / dose:

1.7 µg/L

Temp.:

24 °C

pH:

6.5

Type:

BCF

Value:

63 L/kg

Basis:

normalised lipid fraction

Remarks:

BCF on day 28 of exposure normalised to 5% lipid content

Time of plateau:

5 d

Calculation basis:

other: Value at end of 28 day exposure period

Remarks on result:

other: BCF range in fish samples over 28 day exposure period was 41 - 123 L/kg (wet wt.)

Bioaccumulation factor 2

Conc. / dose:

1.7 µg/L

Temp.:

24 °C

pH:

6.5

Type:

BCF

Value:

64 L/kg

Basis:

whole body w.w.

Time of plateau:

5 d

Calculation basis:

other: Value at end of 28 day exposure period

Remarks on result:

other: BCF range in fish samples over 28 day exposure period was 41 - 123 L/kg (wet wt.)

Details on results:

The concentration in test water at concentration level was close to the nominal concentration, and the variation of the test substance concentrations in the water was within ±20% of the measured mean values.

No occurrence of mortality or abnormality was observed. Surviving fish showed no abnormality in appearance, swimming or feeding behavior. Therefore, test fish were confirmed to be reared and maintained appropriately.

The mean weight of test fish was 5.67 g at the start of the exposure (fish for lipid contents measurement) and 6.38 g at the end of the exposure (all fish taken from the concentration level and control level on day 28).

A steady-state was considered to have been reached at the concentration level, since all the obtained BCF (mean) at each measurement during the exposure period were less than 100 L/kg. A mean BCF of 64 L/kg was determined on Day 28 of the exposure. No depuration-phase was necessary.

The mean BCF value at the end of the 28-day exposure period was 64 L/kg (wet wt.), 63 L/kg (wet wt.) when normalised to 5% lipid content.

All BCF values observed over the 28 day exposure duration were < 100 L/kg (wet wt.), except for one sample on Day 14 which showed a BCF value of 123 L/kg. SCENTAURUS BERRY has a very low potential to bioconcentrate.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

A steady-state was considered to have been reached at the concentration level, since all the obtained BCF (mean) at each measurement during the exposure period were less than 100 L/kg. A mean BCF of 64 L/kg was determined on Day 28 of the exposure. No depuration-phase was necessary.

The mean BCF value at the end of the 28-day exposure period was 64 L/kg (wet wt.), 63 L/kg (wet wt.) when normalised to 5% lipid content.

All BCF values observed over the 28 day exposure duration were < 100 L/kg (wet wt.), except for one samaple on Day 14 which showed a BCF value of 123 L/kg. SCENTAURUS BERRY has a very low potential to bioconcentrate.