1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)propane-1,3-dione

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27.1.2009 - 7.4.2011

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study was performed corresponding to OECD Guidelines 305 under GLP like conditions in a laboratory which holds a GLP accreditation. Performance was done according to the pre-guidelines by a laboratory which participated in the ringtest for validation of the Draft OECD Guidelines 305: Performance of the study has been reported very detailed and comprehensively.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)

Version / remarks:

draft test guideline from before 2.10.2012

Principles of method if other than guideline:

Fish were exposed to the test substance via dietary exposure route.

GLP compliance:

yes

Remarks:

The study has been performed in a laboratory in Switzerland which has been found to be operating in compliance with GLP principles and holds a certificate for GLP accreditation (reference to ECHA's FAQ 11.6 ) .

Radiolabelling:

no

Details on sampling:

- Sampling intervals/frequency for test organisms:
- test organism were taken for analysis after 10 days of the uptake phase
- test organism taken during depuration phase on: 3d, 7d, 14d, 28d, 42d
- Sample storage conditions before analysis: freezer at approx -20 °C

Vehicle:

yes

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Oncorhynchus mykiss
- Weight at study initiation: 2.15 g
- Weight at termination: 16.69 ± 6.62 g
- Lenght at termination: 11.3 ± 1.3 cm
- Health status: checked regularly
- Description of housing/holding area: tank holding 135 L
- Feeding during test: daily feeding
- Food type: see below
- Amount: 3 % of average body weight of fish
- Frequency: daily

ACCLIMATION
- Acclimation period: two weeks in tap water under laboratory conditions
- Acclimation conditions: same as test
- Type and amount of food: Forellenfutter HOKOVIT
- Feeding frequency: daily
- Health during acclimation: no mortality observed

Route of exposure:

feed

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

10 d

Total depuration duration:

42 d

Hardness:

Total hardness: 11.2 °dH

Test temperature:

13.1 - 15.2 °C

pH:

0 - 10 d: 7.8 - 7.9
10 - 52 d: 7.8 - 7.9

Dissolved oxygen:

8.8 - 9.8 mg O2/L

Details on test conditions:

- Illumination: Photoperiod of 16h light, light intensity at light period: approx 300 - 400 Lux
- Average temperature: 13.1 - 15.2 °C
- Tap water: local tap water (non-chlorinated well water of drinking quality, reduced for total hardness by ion exchange).

Nominal and measured concentrations:

measured concentrations in fish:
Uptake phase (10d): 32.7 µg/kg fish (mean of 4 replicates)
Depuration phase (mean of 4 replicates):
day 3: 7.42 mg/kg
day 7: 5.12 mg/kg
day 14: 1.17 mg/kg
day 28: n.d. (LOD <0.02 mg/kg)

Reference substance (positive control):

yes

Lipid content:

63.7 other: mg/g

Time point:

start of exposure

Lipid content:

54 other: mg/g

Time point:

other: day 1 of depuration

Type:

BMF

Value:

0.032 dimensionless

Basis:

whole body w.w.

Time of plateau:

10 d

Calculation basis:

steady state

Key result

Type:

BMF

Value:

0.122 dimensionless

Basis:

normalised lipid fraction

Time of plateau:

10 d

Type:

BCF

Value:

1 807 L/kg

Basis:

other: BMF value, 5 % lipid

Key result

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

3.83 d

Details on kinetic parameters:

growth corrected rate constant K2 (depuration): 0.1811

Results with reference substance (positive control):

positive control: HCB= hexachlorobenzene
Results for HCB:
BMF: 2.3445
Lipid normalized BMF: 3.8474
DT50; depuration: 72.1 days

The experimentally determined BMF was translated into BCF values according to ECHA guidances and OECD calculation template. The BCF of BMDBM is considered to be in the range between 2000 and 3000, thus fulfilling the B criterion of BCF ≥ 2000, but not the vB criterion of BCF ≥ 5000. A detailed Weight of Evidence assessment for the bioaccumulation potential of the substance according to REACH Annex XIII criteria and ECHA guidance documents is attached to IUCLID Section 13.2.

Validity criteria fulfilled:

yes

Conclusions:

The substance is not considered to be a bioaccumulative substance as the calculated BMF is 0.032 or the lipid normalized BMF was calculated to be 0.1218 which is far below 1. The half-life (DT 50) for elimination of BMDBM during the depuration phase was 3.83 days. The growth corrected rate constant K2 for depuration was calculated to be 0.1811.

Executive summary:

The bioaccumulation potential of the test item was assessed in dietary study according to OECD TG 305 in a flow-through setup using rainbow trout (Oncorhynchus mykiss) as test species. The mean weight of fish at test start was measured to be 2.15 g. The uptake phase duration was 10 days. The growth rate k_g was calculated to be 0.0377 day^-1. A growth corrected depuration rate constant of 0.1811 was derived. The mean lipid fraction in fish was only measured at the end of the uptake phase (day 10), but not during the depuration phase of 42 days. The fish were fed daily (H.U. Hofmann AG, HOKOVIT, “Forellenfutter”, diet of known lipid and total protein content, spiked with test item or unspiked) based on about 3 % of the average fish body weight during acclimation and during the study, taking into account increasing body weights and decreasing number of fish per sampling interval. In OECD TG 305 it is stated that “…the feeding rate should be selected such that fast growth and large increase of lipid content are avoided”. For rainbow trout a range of 1-2% of body weight per day is proposed. It is therefore likely that the lipid content of fish slightly increased during the depuration phase. In this study the following kinetic biomagnification factors were determined:        

• The growth corrected biomagnification factor was: BMF_kg = 0.0324


• The BMF combined corrected for growth and lipid content was: BMF_kgl = 0.1218


• The growth corrected half-life was determined to be: t_1/2,g = 3.83 days

Following ECHA Guidance IR&CSA R.11 (2017) the dietary experimental data were translated to a tentative BCF for comparison against the BCF criteria outlined in REACH Annex XIII. An in-depth weight of evidence-assessment is attached to IUCLID section 13.2.

In compliance with the guidance document to OECD TG 305 (2^nd draft, 2016) the kinetic BMF value obtained from the OECD 305 study was translated into BCF values by using the excel spreadsheet published by OECD (version 2, as provided on 10 December 2020). Based on the experimental data and current guidance the BCF of the test item is considered to be in the range between 2000 and 3000.

Description of key information

In a dietary study according to OECD TG 305 under flow-through conditions with Oncorhynchus mykiss the lipid normalized BMF was calculated to be 0.1218. The half-life (DT 50) for elimination of BMDBM during the depuration phase was 3.83 days. The growth corrected rate constant K2 for depuration was calculated to be 0.1811.

Key value for chemical safety assessment

BMF in fish (dimensionless):

0.122

Additional information

The bioaccumulation potential of the test item was assessed in dietary study according to OECD TG 305 in a flow-through setup using rainbow trout (Oncorhynchus mykiss) as test species. The mean weight of fish at test start was measured to be 2.15 g. The uptake phase duration was 10 days. The growth rate k_g was calculated to be 0.0377 day^-1. A growth corrected depuration rate constant of 0.1811 was derived. The mean lipid fraction in fish was only measured at the end of the uptake phase (day 10), but not during the depuration phase of 42 days. The fish were fed daily (H.U. Hofmann AG, HOKOVIT, “Forellenfutter”, diet of known lipid and total protein content, spiked with test item or unspiked) based on about 3 % of the average fish body weight during acclimation and during the study, taking into account increasing body weights and decreasing number of fish per sampling interval. In OECD TG 305 it is stated that “…the feeding rate should be selected such that fast growth and large increase of lipid content are avoided”. For rainbow trout a range of 1-2% of body weight per day is proposed. It is therefore likely that the lipid content of fish slightly increased during the depuration phase. In this study the following kinetic biomagnification factors were determined:        

• The growth corrected biomagnification factor was: BMF_kg = 0.0324


• The BMF combined corrected for growth and lipid content was: BMF_kgl = 0.1218


• The growth corrected half-life was determined to be: t_1/2,g = 3.83 days

Following ECHA Guidance IR&CSA R.11 (2017) the dietary experimental data were translated to a tentative BCF for comparison against the BCF criteria outlined in REACH Annex XIII. An in-depth weight of evidence-assessment is attached to IUCLID section 13.2.

In compliance with the guidance document to OECD TG 305 (2^nd draft, 2016) the kinetic BMF value obtained from the OECD 305 study was translated into BCF values by using the excel spreadsheet published by OECD (version 2, as provided on 10 December 2020). Based on the experimental data and current guidance the BCF of the test item is considered to be in the range between 2000 and 3000.