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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Administrative data

Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2009-07-30 to 2009-11-18
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study (with certain deviations), to GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)
Deviations:
yes
Remarks:
only one test concentration used and mean lipid content varied by more than 25%
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
Chlorinated tetradecane (C14) to 45% chlorine by wieght. Includes radiolabelled C14 also chlorinated to 45% Cl by weight.
Radiolabelling:
yes

Sampling and analysis

Details on sampling:
- Sampling intervals/frequency for test organisms: weekly (days 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70 and 77)- Sampling intervals/frequency for test medium samples: days -6, -3, -1, 0, 4, 7, 14, 21, 28 and 35- Sample storage conditions before analysis: no- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods):Test organism - whole organism combusted to 14CO2 and trapping solution counted by liquid scintillation counting (LSC)Test medium - Sample of test water (250 ml) extracted with hexane (5-10 ml); hexane extract counted by LSC

Test solutions

Vehicle:
yes
Details on preparation of test solutions, spiked fish food or sediment:
PREPARATION OF SPIKED WATER- Details of spiking: stock solution in DMF (129 mg/l) introduced in to mixing chamber at 0.004 ml/min- Controls: vehicle- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Dimethyl formamide (DMF) - Concentration of vehicle in final test solution: 0.004 ml/l

Test organisms

Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM- Common name: Rainbow trout- Source: Houghton Springs Fish Farm, Blandford Forum, Dorset, DT11 0PD, UK- Age at study initiation (mean and range, SD): no data- Length at study initiation (lenght definition, mean, range and SD): mean, range for 20 fish (mm) - 43.4, 38 to 50- Weight at study initiation (mean and range, SD): mean, range for 20 fish (g) - 1.21, 0.75 to 1.79 ; mean from bulk weight of all 89 fish - 2.68 g- Weight at termination : mean, range at day 77 (g) - solvent controls 12.24, 8.44 to 17.10 and test 17.45, 4.76 to 25.52- Method of breeding: no- Health status: no mortality during acclimatisation- Description of housing/holding area: glass tanks (max. capacity 120l) - Feeding during test: yes- Food type: Fish diet batch FF681- Amount: 2% total fish weight/day- Frequency: dailyACCLIMATION- Acclimation period: 7 days prior to study- Acclimation conditions (same as test or not): yes- Type and amount of food: as study- Feeding frequency: as study- Health during acclimation (any mortality observed): 2 fish damaged by dominant fish were removed

Study design

Route of exposure:
aqueous
Test type:
flow-through
Water / sediment media type:
natural water: freshwater
Total exposure / uptake duration:
35 d
Total depuration duration:
42 d

Test conditions

Hardness:
44.3 mg/l as CaCO3 (min/max 32.3/53.0)
Test temperature:
Solvent control - 14.9oC (range 14.8 to 15.5oC)Test - 14.9oC (range 14.8 to 15.4oC)
pH:
Solvent control - 7.14 to 7.42Test - 7.08 to 7.38
Dissolved oxygen:
Solvent control - 9.1 mg/l (range 8.6 to 9.8 mg/l)Test - 9.0 mg/l (range 8.4 to 9.8 mg/l)
TOC:
<3.0 mg/l
Salinity:
0.1%
Details on test conditions:
TEST SYSTEM- Test vessel: glass tank (120 L max. capacity)- Material, size, headspace, fill volume: size -915 x 305 x 465 mm; head space - 15 L; working vol - 105 L - Aeration: vigously stirred- Renewal rate of test solution (frequency/flow rate): 1000 ml/min (13.7 volume additions/24 h)- No. of organisms per vessel: 89 - No. of vessels per concentration (replicates): 1- No. of vessels per control / vehicle control (replicates): 1- Biomass loading rate: 2.1 (control) and 2.4 (test) g/LTEST MEDIUM / WATER PARAMETERS- Source/preparation of dilution water: dechlorinated tap water- Particulate matter: <3.0 mg/l- Metals: Cd, Ag, As, Co, Cu, Ni <1 µg/l; Al, Mn <10 µg/l; Hg < 0.01 µg/l; Cr <0.05 µg/l; Pb < 2 µg/l; Zn < 5 µg/l; Fe < 30 µg/l; B <100 µg/l- Pesticides: OC< 0.007 µg/l; OP < 0.01 µg/l; PCBs < 0.001 µg/l- Chlorine: < 0.002 mg/l- Alkalinity: 23.1 mg/l- Ca/Mg ratio: 4.02- Conductance: 213 µS/cm- Holding medium different from test medium:no- Intervals of water quality measurement: pH/conductivity - 5/wk; alkalinity/hardness/chlorine - weekly; others (including metals, pesticides, anions and cations, suspended solids, dissolved organic carbon, chemical oxygen demand) - onceOTHER TEST CONDITIONS- Adjustment of pH: no data- Photoperiod: 16 hours light/ 8 hours dark with 20 min transitions- Light intensity: no data
Nominal and measured concentrations:
Nominal - 0.5 µg/lMeasured - (days 0-35) : overall mean ± SD - 0.34 µg/l ± 0.06
Reference substance (positive control):
no
Details on estimation of bioconcentration:
BASIS FOR CALCULATION OF BCF- Estimation software: in house KINETICS v1.4- Whole body BCF at day 35 based on ratio of whole body concn to mean water concn- Kinetic BCF based on ratio of uptake to depuration rate constants

Results and discussion

Lipid content
Lipid content:
10.3 %
Time point:
other: days 0, 35 and 77
Remarks on result:
other: overall mean
Bioaccumulation factoropen allclose all
Type:
BCF
Value:
6 660 L/kg
Basis:
whole body w.w.
Remarks:
BCF based on total radioactivity
Time of plateau:
35 d
Calculation basis:
steady state
Remarks on result:
other: n-tetradecane (chlorinated to 45%)
Remarks:
Conc.in environment / dose:0.50 µg/l nominal
Type:
BCF
Value:
3 230 L/kg
Basis:
normalised lipid fraction
Remarks:
(5%); BCF based on total radioactivity
Time of plateau:
35 d
Calculation basis:
steady state
Remarks on result:
other: n-tetradecane (chlorinated to 45%)
Remarks:
Conc.in environment / dose:0.50 µg/l nominal
Type:
BCF
Value:
9 140 L/kg
Basis:
whole body w.w.
Remarks:
BCF based on total radioactivity
Time of plateau:
35 d
Calculation basis:
kinetic
Remarks on result:
other: n-tetradecane (chlorinated to 45%)
Remarks:
Conc.in environment / dose:0.50 µg/l nominal
Type:
BCF
Value:
4 440 L/kg
Basis:
normalised lipid fraction
Remarks:
(5%); BCF based on total radioactivity
Time of plateau:
35 d
Calculation basis:
kinetic
Remarks on result:
other: n-tetradecane (chlorinated to 45%)
Remarks:
Conc.in environment / dose:0.50 µg/l nominal
Type:
BCF
Value:
29 924 L/kg
Basis:
whole body w.w.
Calculation basis:
kinetic, corrected for growth
Type:
BCF
Value:
14 526 L/kg
Basis:
normalised lipid fraction
Remarks:
5%
Calculation basis:
kinetic, corrected for growth
Depurationopen allclose all
Elimination:
yes
Parameter:
DT50
Remarks:
based on total radioactivity
Depuration time (DT):
16 d
Elimination:
yes
Parameter:
other: DT95
Remarks:
based on total radioactivity
Depuration time (DT):
69 d
Details on kinetic parameters:
- Uptake rate constant (k1): 395/day- Depuration (loss) rate constant (k2): 0.0432/day- Indication of bi- or multiphasic kinetics: no- Computation / data analysis: KINETICS - first order
Metabolites:
no data
Results with reference substance (positive control):
none
Details on results:
- Mortality of test organisms: solvent control - 3; test - 4 (not considered treatment-related)- Behavioural abnormalities: none reported- Observations on body length and weight: Mean body weight of treated fish similar to solvent controls at day 0 (2.86 vs 2.50 g respectively); day 35 (5.52 vs4.63 g) and day 77 (17.45 vs 12.24 g).- Other biological observations: none- Organ specific bioaccumulation: no data- Bound residues forming a plateau: mean whole body concentration at day 35 - 2265 µg/kg - Mortality and/or behavioural abnormalities of control:none reported- Loss of test substance during test period: no- Results with vehicle control: yes
Reported statistics:
mean ± SD or mean with 95% confidence limits

Any other information on results incl. tables

Accumulation phase:

Mean body concentration of test substance on days 7, 14, 21, 28 and 35 was 1038, 1564, 1918, 2135 and 2265 µg/kg

BCF on days 7, 14, 21, 28 and 35 was 3050, 4060, 5640, 6280 and 6660

Depuration phase:

Mean body concentration of test substance on days 42, 49, 56, 63, 70 and 77 was 1648, 1405, 943, 870, 654 and 438 µg/kg

% depuration (from day 35) was 27.2, 38, 58.4, 61.6, 71.1 and 80.7 on those days

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In a guideline study to GLP, the whole body bioconcentration factor (BCF) for chlorinated n-tetradecane (45% chlorinated) in rainbow trout (Oncorhynchus mykiss) exposed to a nominal concentration of 0.5 µg/L for 35 days was 6660 and the kinetic BCF, based on the calculated uptake and depuration rate constants, was 9140. Normalised to 5% lipid content, these values would be 3230 and 4440, respectively, based on total radioactivity.
Executive summary:

In a GLP study conducted according to OECD Guideline 305, the bioaccumulation of 1-14C-labelled n-tetradecane (45% chlorinated) in rainbow trout (Oncorhynchus mykiss) was examined at a single exposure concentration of 0.5 µg/L (nominal), using a flow-through system. Seven fish died during the 35-day exposure period (3 solvent controls and 4 exposed); the deaths were considered to be due to natural/social factors unrelated to the test material. The treatment had no adverse effect on the growth of the fish; the mean body weight of exposed fish increased from 2.86 g on day 0 to 5.52 g at the end of the exposure period (day 35) and 17.45 g at the end of the depuration phase (day 77). The corresponding mean values for the solvent control fish were 2.50 g on day 0, 4.63 g on day 35 and 12.24 g on day 77.

During the accumulation phase, tissue levels of test material, measured by radiochemical analysis, increased to 2265 µg/kg bw (day 35) at a mean measured exposure concentrations of 0.34 µg/L. During the depuration phase, tissue levels declined to 438 µg/kg bw. The whole body bioconcentration factor (BCF) at the end of the exposure phase was 6660 (3230 normalised to 5% lipid content), based on total radioactivity .Based on the whole body concentration of test substance equivalents at day 35, the extent of depuration of test substance after 42 days was 81%.

Using a kinetic approach, the uptake rate constant (k1) was determined to be 395/day and the depuration rate constant (k2) 0.0432/day, giving a kinetic BCF of 9140 (4440 normalised to 5% lipid content). The kinetic data also allowed estimates to be made for the depuration half-life (16 days) and the time to 95% of steady state (69 days). Since all these calculations are based on radioactivity measurements, and therefore do not distinguish between parent compound and possible metabolites, these values represent the worst case values.

In conclusion, the whole body BCF for chlorinated n-tetradecane (45% chlorinated) in rainbow trout (Oncorhynchus mykiss) exposed to a nominal concentration of 0.5 µg/L for 35 days was 6660 and the kinetic BCF, based on the calculated uptake and depuration rate constants, was 9140. Normalised to 5% lipid content, these values would be 3230 and 4440, respectively.

[The BCF of 6660 appears to be unusually high compared with the other BCF values obtained to date,and the method employed may overestimate the BCF with decreasing chlorination content. Samples from this study were subjected to further analysis to determine the proportions of radioactivity present as parent compound or as polar or bound metabolites (Leonards and van Beuzekom, 2010). Only samples of fish at the end of the depuration phase were available. The results showed that no significant extractable metabolites of chlorinated tetradecane were present, but non-extractable tissue metabolites were found, which accounted on average for 21% of the total14C activity in the fish. It is considered likely that the proportion of metabolites present at the end of the uptake phase would have been different, and potentially higher, than those measured at the end of the depuration phase.]