Phenol, heptyl derivs.

Bioaccumulation: aquatic / sediment

Administrative data

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Peer-reviewed publication provided sufficient detail of experimental conditins and data to conclude the study was performed according to acceptable guidelines

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

Acute Toxicity and Toxicokinetics of 4-Heptylphenol in Juvenile Atlantic Doc (Gadus Morhua L.)

Author:

Tollefsen KE, Ingerbrigtsen K, Olsen AJ, Zachariassen, KE & Johnsen S

Year:

1998

Bibliographic source:

Environmental Toxicology and Chemistry, Vol. 17, No. 4, pp 740-746, 1998

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

not specified

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Phenol, heptyl derivs.

EC Number:

276-743-1

EC Name:

Phenol, heptyl derivs.

Cas Number:

72624-02-3

Molecular formula:

C13H20O

IUPAC Name:

4-(2-methylhexyl)phenol; 4-heptylphenol

Radiolabelling:

yes

Sampling and analysis

Details on sampling:

- At the end of the exposure period (192 h) the fish were transferred to clean seawater for the elimination period (192 h). Quadruple samples of fish and seawater were taken during both phases of the experiment for analysis by liquid scintillation counting.

Test solutions

Vehicle:

yes

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

4-[14C]heptylphenol (1 Ci/mol) was synthesized at the University of Stockholm, Sweden. The fish were exposed to 15.5 nmol/L of 4-[14C]HP by first dissolving the compound in microfiltered (0.45um) autoclaved seawater with the use of methanol as solvent and then diluting the stock solution in filtered seawater (5 um).

Test organisms

Test organisms (species):

other: Atlantic Cod (Gadus morhua L.)

Details on test organisms:

TEST ORGANISM
- Common name: Cod
- Strain: Gadus Morhua L.
- Source: Juvenile Atlantic code were obtained from Naeroysund Norway as post yolk sac fry and reared in the testing laboratory for 4 months prior to the experiments.

- Age at study initiation (mean and range, SD): about 4 months
- Weight at study initiation (mean and range, SD): 4.6 + 0.51 g
- Weight at termination (mean and range, SD): no data
- Method of breeding: fish hatchery.
- Health status: The fish in good health were selected for the test.
- Description of housing/holding area: Commercial 128 L aquaria under flow through conditions
- Feeding during test Feeding occurred daily with commercial cod pellets from Trondheim Norway in amounts corresponding to a maximum 1% of total body mass


ACCLIMATION
- Acclimation period: 4 months
- Acclimation conditions (same as test or not): same
- Health during acclimation (any mortality observed): Healthy.

Study design

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: marine

Total exposure / uptake duration:

196 h

Test conditions

Hardness:

no data

Test temperature:

7.7 + 0.2 degrees C

pH:

7.9 + 0.1

Dissolved oxygen:

85% + 9% saturation

TOC:

no data

Salinity:

33.6 + 0.4 ‰

Details on test conditions:

TEST SYSTEM
- The experiments were conducted in commercial 128-L aquaria under flow-through conditions
- Biomass loading rate: 3.5 g fish/L


OTHER TEST CONDITIONS
- Photoperiod: The aquaria received artificial illumination at 50 lux for 12 hr a day.
- Light intensity: 50 lux


RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations:
- Results used to determine the conditions for the definitive study: 96 hr LC50= 2.9 umol/L

Nominal and measured concentrations:

The final exposure concentration was 15.5 nmol/L of 4-[14C]heptylphenol and 2.4 umol/L of methanol solvent.

Reference substance (positive control):

not specified

Details on estimation of bioconcentration:

The bioconcentration process was described by a 1-compartment first order kinetic model. Steady state concentrations in the whole animal and rate constants for uptake (k1) and elimination (k2) were estimated by nonlinear regression analysis according to OECD guidelines. The time required to reach apparent steady state (t95) and the biological half life (t1/2) were calculated using the elimination rate constant. The BCF was calculated using the relationship where BCFss is the steady state and BCFk is the kinetic BCF.

BCFss = [x]f / [x]w
and
BCFk = k1 / k2

Results and discussion

Bioaccumulation factor

Type:

BCF

Value:

555 dimensionless

Basis:

not specified

Time of plateau:

58 h

Calculation basis:

steady state

Remarks on result:

other: Based on the steady state conc, mean BCFss for samples collected at 96 &192 h = 555 +/- 16. Rate const for uptake and elimin = 29.94 +/- 1.83 & 0.052 +/- 0.011/hr, respectively. Values correspond to a kinetic BCFk of 578 +/- 127.

Remarks:

Conc.in environment / dose:15.5 nmol/L

Depuration

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

13 h

Details on kinetic parameters:

Rate constants for uptake and elimination was 29.94 + 1.83 and 0.052 + 0.011/hr, respectively.

Metabolites:

No data

Results with reference substance (positive control):

not applicable

Details on results:

No data

Reported statistics:

Results are expressed as mean with standard deviation and were subjected to a nonparametric one way analysis of variance between different groups (Mann Whitney U test). Differences were considered statistically significant at the p<0.05 level.

Any other information on results incl. tables

Based on the steady state concentrations the mean BCFss for samples collected at 96 and 192 hours was 555+16. Rate constants for uptake and elimination was 29.94 + 1.83 and 0.052+0.011/hr, respectively. The values correspond to a kinetic BCFk of 578+127.

The distribution of 4-heptylphenol at steady state displayed a heterogenous pattern dominated by the gastrointestinal system. Bile, liver, and intestinal contents accumulated the test item from seawater higher than other organs and media measured (i.e., spleen, kidney, heart, stomatch content, brain, gills, skin, blood stomach). The relatively high concentrations in liver, bile and intestinal contents as well as the relatively low activity in the stomach contents indicate a rapid uptake and elimination of 4-heptylphenol and its potential metabolites via the liver and subsequent excretion through the biliary system.

 

Elimination of 4-heptylphenol occurred rapidly following first order kinetics with an estimated biological half life of 13 hours. Substantial radioactivity was detected in seawater during the initial part of the elimination period but no radioactivity was detected in water after more than 96 hr recovery in clean seawater.

No radioactivity was detected in tissues of cod at the end of the elimination period, indicating a lack of retention in specific tissues. Radioactivity in autoradiograms extracted with nonpolar and polar solvents was not observed, giving additional support to the conclusion that 4-heptylphenol and metabolites do not bind to specific macromolecules or tissue structures in cod.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The bioaccumulation potential of 4-heptylphenol was evaluated during a 192 hour exposure period and 192 hour elimination period in atlantic cod at a concentration of 15.5 nmol/L of 4-[14C]heptylphenol. The steady state BCF was 555 and the kinetic BCF was 578. Rate constants for uptake and elimination were 29.94 and 0.052/h respectively. Elimination of 4-heptylphenol followed first order kinetics with an estimated biological half life of 13 hours.

Executive summary:

Test Guidance

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

Method and materials

In a bioaccumulation test consisting of a 192 hour exposure period and a 192 hour elimination period, Atlantic cod were exposed to 4-hepthylphenol at a concentration of 15.5 nmol/L (as 4-[14C]heptylphenol) under flow-through conditions according to procedures similar to that described in OECD 305.  

Results

The steady state BCF was 555 and the kinetic BCF was 578. Rate constants for uptake and elimination were 29.94 and 0.052/h respectively. 

 

Elimination of 4-heptylphenol occurred rapidly following first order kinetics with an estimated biological half life of 13 hours. Substantial radioactivity was detected in seawater during the initial part of the elimination period but no radioactivity was detected in water after more than 96 hr recovery in clean seawater.

No radioactivity was detected in tissues of cod at the end of the elimination period, indicating a lack of retention in specific tissues. Radioactivity in autoradiograms extracted with nonpolar and polar solvents was not observed, giving additional support to the conclusion that 4-heptylphenol and metabolites do not bind to specific macromolecules or tissue structures in cod.

Conclusions

The test material does not bioaccumulate in aquatic organisms.