Registration Dossier

Administrative data

Endpoint:
bioaccumulation in aquatic species: invertebrate
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1985-12-17 to 1986-01-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
EPA OPPTS 850.1710 (Oyster Bioconcentration Test)
Deviations:
yes
GLP compliance:
yes
Remarks:
Deviations did not impact the outcome of the test.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
The test material was supplied to the testing facility in 2 forms; bis (ethylhexyl) terephthalate and bis (2-ethylhexyl) (hexyl-2-14C)

Bis (2-ethylhexyl) terephthalate:
Purity of the sample: 100 %
Storage conditions of test material: room temperature
Lot/Batch No.: 84-6-20
Physical appearance: clear viscous liquid

Bis (2-ethylhexyl) terephthalate (hexyl-2-14C):
Purity of sample: >98.5%
Storage conditions of test material: refrigerated in radioactive materials section of the testing facility
Lot/Batch No.: 1249-297
Physical appearance: clear liquid dissolved in methanol

Both materials were used to prepare the primary stock and dosing material for the test.
Radiolabelling:
yes

Sampling and analysis

Details on sampling:
Duplicate 1-mL water samples were taken from the middle of the exposure and solvent control aquaria on Days 1, 3, 6, 10, 14, 17, 21, and 24 of the bioconcentration phase, and on Days 1, 3 , 7, 11, and 14 of the depuration phase.

Test organisms

Test organisms (species):
other aquatic mollusc: Crassotrea virginica
Details on test organisms:
TEST ORGANISM
Common name: Eastern Oyster
Supplier: Aquatic Research Corporation, East Dennis, MA
Age at study initiation: prespawning condition
Length at study initiation: 3.5 - 5.6 cm
Health: free of disease through histological examination

ACCLIMATION/TEST CONDITIONS
Acclimation Period: All oysters were held in unfiltered Duxbury Bay seawater for 12 d prior to testing. At that time, thery were moved to a tray receiving test dilution water, which was coarsely (30 µm) filtered Duxbury Bay seawater.
Photoperiod: 14 h daylight/10 h darkness with a 30-min phase-in period
Feeding: Saltwater alga, Isochrysis galbana, used as a food supplement
Culture Water: Coarsely filtered (30 µm) Duxbury Bay seawater

Study design

Route of exposure:
aqueous
Test type:
flow-through
Water / sediment media type:
natural water: marine
Total exposure / uptake duration:
24 d
Total depuration duration:
14 d

Test conditions

Test temperature:
19.4 - 22.7 °C
pH:
7.86 - 8.07
Dissolved oxygen:
6.8 - 8.9 mg/L
Salinity:
32.5-34.0 ‰
Details on test conditions:
One hundred twenty (120) individual oysters were cleaned and measured prior to test initiation. Sixty (60) organisms were randomly placed in each container. Two glass 20-gallon aquaria were used in the test. Each aquarium was fitted with a stand-pipe drainage system to maintain a water depth of 15 cm and test solution volume of approximately 40 L. During the exposure period, one aquarium received 50 µg of 14C-DOTP /L salt water and the other aquarium (solvent control) received a combination of solvent and salt water. Both aquaria received dilution water at a continuous flow rate of 60 L/h.

The 14C-DOTP was dissolved in distilled-in-glass acetone and metered to the test aquarium at a rate of 0.057 mL/L salt water using a peristaltic pump. Similarly, 838 mL of acetone was combined with 162 mL of deionized water and metered to the solvent control at a rate of 0.068 mL/L salt water. The 14C-DOTP was allowed to equilibrate with the physical system for a 3-d period prior to test initiation. After equilibration, duplicate 1-mL water samples were taken to verify that the exposure concentration was within 30% of nominal. Exposure of the oysters to 14C-DOTP at a nominal concentration of 50 µg/L was continuous for 24 d. After 24 d of exposure, all remaining oysters from the test aquaria were transferred to clean aquaria in which toxicant-free salt water was introduced at a rate equal to the flow rate during exposure. The depuration period continued for 14 d to estimate half-life.
Nominal and measured concentrations:
Nominal concentration: 50 µg/L 14C-DOTP
Measured concentration: 48.4 ± 7.56 µg/L (97% of nominal)

Results and discussion

Bioaccumulation factor
Type:
BCF
Value:
393
Basis:
whole body w.w.
Remarks:
at equilibrium
Time of plateau:
14 d
Calculation basis:
steady state
Remarks on result:
other: Statistical analysis (ANOVA) performed on the results of tissue analyses from Days 14, 17, and 21 suggested equilibrium had been attained.
Depuration
Elimination:
yes
Parameter:
DT50
Depuration time (DT):
5 d
Metabolites:
72.9 to 75.5% of the residues remaining in the tissues after 14 d of depuration was parent compound and the remaining 24.5 to 27.1% were metabolites and/or degradation products.
Details on results:
The concentration of 14C-residues measured in the homogenized oyster tissues increased substantially during the first 3 d of exposure. This was the period of maximum accumulation of 14C-residues. The mean measured concentration of 14C-DOTP on Day 3 of exposure represented a maximum BCF of 790X. Between days 3 and 10, the 14C-residue concentration in tissues decreased substantially (50%). At Day 10 and throughout the remaining 14 days of exposure, an apparent equilibrium between the rates of accumulation and elimination of 14C-residues in oyster tissues existed. The mean BCF at equilibration was 393X.

Any other information on results incl. tables

Bioconcentration of 14C-DOTP Residues in Soft Tissues of Oysters during 24 Days Exposure to 50 µg/L DOTP
Concentration of 14-C Residues
Exposure Period Day Salt Water (µg/L) Cumulative Mean Salt Water (µg/L) Oyster Tissue (µg/kg) BCF*
0 45.9
1 46.6 46.2 5720 124
3 44.8 45.8 36200 790
6 44.8 45.6 27200 596
10 52.4 46.9 18400 392
14 34.6 44.9 22200 494
17 52.0 45.9 21000 458
21 57.5 47.3 17600 372
24 56.5 48.4 15600 322
Notes:
Cumulative mean concentration is based on progressive data (days 0-24)
*Bioconcentration Factor (BCF) is the mean measured 14C-residues of DOTP in tissues divided by the cumulative mean measured concentration in exposure water

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The BCF of 14-C DOTP in oyster tissues at equilibrium was 393X. Half-life of the accumulated 14C-residues in oyster tissues was between days 3 and 7 of the depuration period. Most of the 14C-residues remaining in the tissues after 14 days of depuration were the parent material. There were metabolites and/or degradation products present in the soft tissues.
Executive summary:

A 38-d study was performed to investigate the bioconcentration and elimination of 14C-DOTP in the soft tissues of eastern oysters, Crassostrea virginica, continuously exposed to 14C-DOTP at a nominal concentration of 50 µg/L. The maximum bioconcentration factor for 14C-DOTP in oyster tissue was 790X and was observed on Day 3 of the exposure period. Apparent equilibrium was established between days 10 and 24. The BCF at equilibrium was 393X. Half-life of the accumulated 14C-residue content present in oyster tissues occurred between days 3 and 7 of the depuration period. Most of the 14C-residues (72.9 to 75.5%) remaining in the tissues of oysters after 14 days of depuration were the parent DOTP. The remaining 24.5 to 27.1% were metabolites and/or degradation products.