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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
unknown
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study meets generally accepted scientific standards acceptable for assessment. Test water characteristics and test organism survival information is missing.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)
Deviations:
yes
Remarks:
tested only one concentration
Principles of method if other than guideline:
Not applicable
GLP compliance:
no
Remarks:
This is a published study which does not state the GLP status of the study or the laboratory, but the study is scientifically acceptable and is peer reviewed.
Specific details on test material used for the study:
No futher details provided
Radiolabelling:
yes
Details on sampling:
Water samples were collected daily.
Organism sampling occurred on days 2, 4, 8, 16, 18, 20, 24, 32, 48 and stored in glass jars at -20 °C until analysis.
Vehicle:
yes
Details on preparation of test solutions, spiked fish food or sediment:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (stock solution and final test solution(s) at different concentrations and in control(s)): 20 mg/L
Test organisms (species):
Gasterosteus aculeatus
Details on test organisms:
TEST ORGANISM
- Common name: stickleback
- Source: not provided
- Age at study initiation (mean and range, SD): not provided
- Feeding during test: yes
- Food type: mussels
- Frequency: once or twice a week

ACCLIMATION
- Acclimation period: not provided
Route of exposure:
aqueous
Test type:
flow-through
Water / sediment media type:
natural water: marine
Total exposure / uptake duration:
16 d
Total depuration duration:
32 d
Hardness:
not provided
Test temperature:
10-13 °C in Test 1
8-13 °C in Test 2
pH:
Not provided
Dissolved oxygen:
Not provided
TOC:
Not provided
Salinity:
Not provided
Conductivity:
Not provided
Details on test conditions:
TEST SYSTEM
- Test vessel: aquaria
- Material, size, headspace, fill volume: 10 L
- Type of flow-through (e.g. peristaltic or proportional diluter): not given
- Renewal rate of test solution (frequency/flow rate): 85 ml/min
- No. of organisms per vessel: 110
- No. of vessels per concentration (replicates): 3
- No. of vessels per control / vehicle control (replicates): not given


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: saltwater
- Intervals of water quality measurement: not provided


Nominal and measured concentrations:
Average measured cocentrations of 4.8 ug/L in Test 1 and 4.9 ug/L in Test 2
Reference substance (positive control):
not specified
Details on estimation of bioconcentration:
BCF was not estimated prior to testing.
BCF was calculated based on actual measurements from test.
Lipid content:
6.7 %
Time point:
other: on Day 8
Remarks on result:
other: for Test 1
Lipid content:
7.8 %
Time point:
other: on Day 8
Remarks on result:
other: for Test 2
Key result
Type:
BCF
Value:
1 200 dimensionless
Basis:
whole body w.w.
Time of plateau:
16 d
Calculation basis:
steady state
Remarks on result:
other: BCF determined by curves fitted by eye
Remarks:
Conc.in environment / dose:4.8 ug/L
Key result
Type:
BCF
Value:
1 300 dimensionless
Basis:
whole body w.w.
Time of plateau:
16 d
Calculation basis:
steady state
Remarks on result:
other: BCF determined by curves fitted by eye
Remarks:
Conc.in environment / dose:4.9 ug/L
Elimination:
yes
Parameter:
other:
Depuration time (DT):
32 d
Remarks on result:
not measured/tested
Details on kinetic parameters:
- Uptake rate constant (k1):not provided
- Depuration (loss) rate constant (k2):not provided
Metabolites:
not provided
Results with reference substance (positive control):
NA
Details on results:
Study does not give test organism survival.
Reported statistics:
BCF determinations were made by graphing results and fitting by eye.
Validity criteria fulfilled:
yes
Conclusions:
Study authors conclude provided BCF results for three saltwater organisms which are 5 to 340 times higher than other reported values. Mean BCF for Gasterosteus aculeatus based on whole body tissue wet weight caluclated at 1200 for Test 1 and 1300 for Test 2.
Executive summary:

The 16-day chronic toxicity and bioconcentration of nonylphenol to Gasterosteus aculeatus was studied under flow-through conditions in a laboratory. Fish were exposed to average measured concentration of 4.8 and 4.9 ug 14C-labeled nonylphenol/L for 16 days.  Fish whole body tissue and water column concentrations were measured at days 2, 4, 8, 16, 18, 20, 24, 32, and 48 (from the start of the exposure, including depuration) for mean BCF

determination. Steady state was reached after a few days, but by Day 16. Depuration stage was for 32 days.

 

This study is classified as acceptable and satisfies the guideline requirements for a bioconcentration test with Gasterosteus aculeatus.

 

Results Synopsis

 

Mean BCF based on whole body tissue wet weight = 1200 for Test 1 and 1300 for Test 2. The results have been lipid normalised based on the lipid values provided in the report, with calculated BCFs of 833 to 896. Results of this study show the BCF of valid fish bioconcentration studies are lower than the REACH bioaccumulation criterion of < 2,000. The BCF value of 896 is used for the purposes of risk assessment for nonylphenol.

 

Description of key information

A weight of evidence approach has been taken to the determination of the potential for nonylphenol to bioaccumulate in aquatic organisms and is described in a separate technical report in Section 13 of the CSA.

For the purposes of the risk assessment, the BCF from the Ekelund et al (1990) study with the fish Gasterosteus aculeatus is used. Based on whole body tissue wet weight the BCF is 1200 for Test 1 and 1300 for Test 2. The results have been lipid normalised based on the lipid values provided in the report, with calculated BCFs of 833 to 896. The highest value of 896 and most conservative value is used in the risk assessment. Results of this study show the BCF of valid fish bioconcentration studies are lower than the REACH bioaccumulation criterion of < 2,000.

Key value for chemical safety assessment

BCF (aquatic species):
896 dimensionless

Additional information

Determination of a bioconcentration factor (BCF) follows Guidance on Information Requirements and Chemical Safety Assessment Chapter R.16: Environmental Exposure Estimation (ECHA 2012) and Chapter R. 7c Endpoint Specific Guidance (ECHA 2014).  Chapter R.16.5.3.5 states that there may be bioaccumulation potential if log Kow is >3.  The log Kow of 4-nonylphenol as given by EU Risk Assessment – 4-Nonylphenol (branched) and Nonylphenol (EURAR, 2002) is 4.48.  Therefore, as per REACH Annex IX, bioaccumulation information preferably for fish must be presented for substances manufactured or imported in quantities of 100 t/y or more.

Chapter R.7c states that BCFs can be determined experimentally, by calculation using Kow, or by estimating using BCF models such as QSARs. But, since adequate reliable experimental data are available for the preferred organism (fish) BCFs for 4-nonylphenol are based on actual measured values from experimental tests. Where possible, experimental results have been normalised for a 5% lipid content, as described in the OECD 305 test guideline.

By way of an update and at the request of ECHA a weight of evidence (WoE) approach has been taken to the determination of the potential for nonylphenol to bioaccumulate in aquatic organisms and is described in a separate technical report in Section 13 of the CSA.

The conclusions are that the clear majority of data evaluated in the WoE assessment, particularly after consideration of many confounding factors, pointed towards the hypothesis that nonylphenol is not bioaccumulative. Based on the weighing of all the evidence, it is determined that nonylphenol does not fulfil the bioaccumulation criterion (>2,000) as defined in the PBT criteria in the REACH Regulation and ECHA guidance, in terms of bioaccumulation for fish. To be conservative, a worst case BCF value of 896 for fish (5% lipid normalised), based on Ekelund et al (1990) for stickleback (Gasterosteus aculeatus) is preferred for use in the risk assessment.

The potential for accumulation into other organisms, such as invertebrates, birds and mammals varies and may represent a broader range of concentrations factors than for fish species. The weight of this evidence does not generally indicate bioaccumulation or biomagnification for these species. It might be postulated that some very worst-case scenarios may occur for filter feeders, such as bivalves under certain unknown circumstances.