1-isopropyl-2,2-dimethyltrimethylene diisobutyrate

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: Guideline study conducted under GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

2000

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

: Propanoic acid, 2-methyl-, 1,1'-[2,2-dimethyl-1-(1-methylethyl)-1,3-propanediyl] ester

IUPAC Name:

: Propanoic acid, 2-methyl-, 1,1'-[2,2-dimethyl-1-(1-methylethyl)-1,3-propanediyl] ester

Constituent 2

Reference substance name:

1-isopropyl-2,2-dimethyltrimethylene diisobutyrate

EC Number:

229-934-9

EC Name:

1-isopropyl-2,2-dimethyltrimethylene diisobutyrate

Cas Number:

6846-50-0

Molecular formula:

C16H30O4

IUPAC Name:

trimethoxy[3-(oxiran-2-ylmethoxy)propyl]silane

Constituent 3

Reference substance name:

2,2,4-Trimethylpentanediol-1,3-diisobutyrate

IUPAC Name:

2,2,4-Trimethylpentanediol-1,3-diisobutyrate

Constituent 4

Reference substance name:

Texanol isobutyrate; TXIB

IUPAC Name:

Texanol isobutyrate; TXIB

Details on test material:

no data

Radiolabelling:

yes

Sampling and analysis

Details on sampling:

- Sampling intervals/frequency for test organisms: 5 fish collected and analized by LCS on days 1,3,6,9,14,17,21 and 23 of exposure, and days 1,3,7,10 and 14 of depuration
- Sampling intervals/frequency for test medium samples: Triplicate 5 mL water samples collected and analized by LCS on days 1,3,6,9,14,17,21 and 23 of exposure, and days 1,3,7,10 and 14 of depuration
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods): Each 5-mL water sample was collected from the approximate midpoint of the aquarium and transferred into a scintillation vial to which 15 mL of Monophase S® was added prior to analysis by LSC. LSC analysis was performed with a Beckman Instruments LS5000TD, LS3801 or LS1801 liquid scintillation counter.
For fish samples entire individual tissue portions for each of the fish were placed in pre-tared Combusto-Cones® (a pressed cellulose-based material, Packard Instrument Company) and weighed. Two cones per fish were used; the cones were labeled edible and nonedible. Each tissue sample was air-dried for at least 24 hours, at ambient temperature prior to combustion. To aid combustion, approximately 0.2 g of cellulose powder (Whatman CC41) was added to each cone containing the dry fish tissue. A Combusto-Pad® (Packard Instrument Company) was placed on top of each cone and then the cones were placed in a Packard Model 307 Sample Oxidizer and combusted. The resulting 14C02 was trapped as a carbonate salt in Carbosorb® (a basic amine) and flushed into a glass scintillation vial with Permafluo~E+ (a toluene-based scintillation fluid). Each vial was then placed in a liquid scintillation counter and the radioactivity (counts per minute) determined. Disintegrations per minute were calculated by LSC after background subtraction. LSC analysis was performed with a Beckman Instruments LS5000TD liquid
scintillation counter.

Test solutions

Vehicle:

yes

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

PREPARATION OF SPIKED WATER
- Details of spiking: A 1.59 mg/mL radiolabeled stock solution was prepared. The diluter stock solution for the bioconcentration exposure (0.0060 mg/L, nominal) was prepared by combining 16.35 mL of the 1.59 mg/mL C14[test substance] stock solution with 120 mg (119 mg as active ingredient) of nonradiolabeled [test substance] and diluting to 600 mL with acetone. The diluter stock solution for the bioconcentration exposure (0.060 mg/L, nominal) was prepared by combining 58.65 mL of the 1.59 mg/mL C14[test substance] stock solution with 2810 mg (active ingredient) nonradiolabeled [test substance] and diluting to 1200 mL with acetone. The toxicant delivery system for the bioconcentration and metabolite exposure solutions
(both at a nominal concentration of 0.060 mg/L) consisted of a Sage® syringe pump equipped with two 20 mL gas-tight glass syringes calibrated to deliver 0.0104 mL/min of the appropriate stock solution into the appropriate mixing cell. These cells received a flow of 420 mL/min of dilution water. This delivery rate provided a turnover rate equivalent to 8 aquarium volumes per 24 hours and 90% aquarium volume replacement every 6.5-hour period. A second (identical) toxicant delivery system was used to deliver the stock solution to prepare the 0.0060 mg/L exposure solution.
- Controls: An additional toxicant delivery system was used to deliver the acetone for the solvent control solution. The resulting concentration of acetone was equivalent to the solvent concentration in the exposure aquaria.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in final test solution: 25 uL/L

Test organisms

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: Bluegill sunfish
- Source: Osage Catfish Hatchery, Osage Beach, Missouri
- Length at study initiation (lenght definition, mean, range): 51 mm (range 47 to 55 mm}
- Weight at study initiation (mean and range): 1.8 g (range 1.5 to 2.1 g)
- Description of housing/holding area: Prior to testing, the fish were held in a 500-L fiberglass tank under a photoperiod of 16 hours of light and 8 hours of darkness. The well water which flowed into this holding tank was drawn from a 1OO-meter bedrock well into a concrete reservoir where it was aerated and supplemented with well water supplied by the Town of Wareham, Massachusetts. During the acclimation period, the water was characterized as "soft", having a total hardness (as CaC03 ) range of 43 to 47 mg/L, a total alkalinity (as CaC03) range of 25 to 34 mg/L and a specific conductivity range of 115 to 130 umhos/cm. Other parameters determined in the holding tanks were a pH range of 6.9 to 7.1, a dissolved oxygen concentration range of 81 to 98% saturation, and a flow rate range of 9.8 to 15 tank volume replacements/day. The test fish were maintained under these conditions for a minimum of 14 days prior to test initiation.
- Feeding during test
- Food type: commercial flaked food
- Amount: approximately 2.0% of their total biomass per feeding
- Frequency: daily except fish were not fed at least 24 hours prior to analytical sampling


ACCLIMATION
- Acclimation period: 14 days
- Acclimation conditions (same as test or not): Same
- Type and amount of food: commercial flaked food
- Feeding frequency: ad libitum
- Health during acclimation (any mortality observed): No mortality was observe in the test fish population during the 48 hours prior to testing

Study design

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

23 d

Total depuration duration:

14 d

Test conditions

Hardness:

32 mg/L CaCO3

Test temperature:

Continuous monitoring of the temperature (in the solvent control aquarium) throughout the test resulted in a temperature range of 21 to 24°C.

pH:

The measured pH range was 6.9 to 7.6.

Dissolved oxygen:

7.3 - 8.3 mg/L. Dissolved oxygen remained above 60% saturation in aquaria during the exposure and depuration periods.

TOC:

TOC measured weekly throughout the exposure phase ranged from 10 to 12 mg/L. During the depuration phase, the TOC ranged from 0.39 to 1.9 mg/L, indicating that nearly all of the TOC was contributed by the test substance and solvent.

Salinity:

Specific conductance 115 - 125 umhos/cm

Details on test conditions:

TEST SYSTEM
- Test vessel:aquaria
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass, 75 x 39 x 30 cm(length x width x height), filled to 25 cm, 73 liters
- Type of flow-through (e.g. peristaltic or proportional diluter): continuous flow diluter
- Renewal rate of test solution (frequency/flow rate): 0.0104 mL/min of the appropriate stock solution into the appropriate mixing cell. These cells received a flow of 420 mL/min of dilution water. This delivery rate provided a turnover rate equivalent to 8 aquarium volumes per 24 hours
and 90% aquarium volume replacement every 6.5-hour period.
- No. of organisms per vessel: 90 bluegill into each test aquarium
- No. of vessels per concentration (replicates): 1
- No. of vessels per control / vehicle control (replicates): 1
- Biomass loading rate: 162 g (0.27 g/L of the 24-hour flow-through volume of the aquaria)


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Well water from a 1OO-meter bedrock well supplemented with well water supplied by the Town of Wareham, Massachusetts.
- Metals: None detected
- Pesticides: None detected
- Alkalinity: 25-29 mg/L
- Conductance: 115-125 umhos/cm
- Holding medium different from test medium: no
- Intervals of water quality measurement: Temperature and dissolved oxygen concentration were measured daily in each test aquarium. Temperature was continuously monitored in the solvent control aquarium. Measurements of pH were performed daily. Total organic carbon (TOC) was measured in each test aquarium twice prior to test initiation and weekly during the in-life phase. Total hardness (as CaC03) was measured at test initiation in each aquarium.



OTHER TEST CONDITIONS
- Photoperiod: 16 hours light - 8 hours dark/day


RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Toxicity study @ nominal [test substance] concentrations of 0.65, 1.1, 1.8,3.0 and 5.0 mg/L during the 96-hour study. The mean measured concentrations defined the exposure levels as 0.24,0.37,0.74,3.0 and 6.0 mg a.i./L.
- Results used to determine the conditions for the definitive study: BCF conducted at 1/1000 and 1/100 of the NOEC (and estimated water solubility) of the substance in the toxicity study.

Nominal and measured concentrations:

Nominal 0.0060 and 0.060 mg/L
Mean Measured 0.00519 and 0.0517

Reference substance (positive control):

not required

Details on estimation of bioconcentration:

BASIS INFORMATION
- Results from residue study: Bioconcentration factors (BCF) for edible and non-edible tissue types at both exposure levels were calculated using the mean measured exposure water concentrations and the mean measured steady state tissue concentrations (based on total C14 residues).

Results and discussion

Lipid content

Lipid content 1

Lipid content:

3.63 %

Time point:

start of exposure

Remarks on result:

other: lipid wet weight

Lipid content 2

Lipid content:

16.2 %

Time point:

start of exposure

Remarks on result:

other: lipid dry weight

Bioaccumulation factor

Bioaccumulation factor 1

Type:

BCF

Value:

1.95

Basis:

whole body w.w.

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: based upon parent compound

Remarks:

Conc.in environment / dose:0.0491

Bioaccumulation factor 2

Type:

BCF

Value:

46

Basis:

edible fraction

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:0.00519 mg/L and 0.0517 mg/L

Bioaccumulation factor 3

Type:

BCF

Value:

364

Basis:

non-edible fraction

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:0.00519 mg/L

Bioaccumulation factor 4

Type:

BCF

Value:

343

Basis:

non-edible fraction

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:0.0517 mg/L

Bioaccumulation factor 5

Type:

BCF

Value:

194

Basis:

whole body w.w.

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:0.00519 mg/L

Bioaccumulation factor 6

Type:

BCF

Value:

183

Basis:

whole body w.w.

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:0.0517

Bioaccumulation factor 7

Type:

BCF

Value:

1 200

Basis:

total lipid content

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: whole body BCF - dry weight lipid content (16.2%)

Remarks:

Conc.in environment / dose:0.00519 mg/L

Bioaccumulation factor 8

Type:

BCF

Value:

1 130

Basis:

total lipid content

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: whole body BCF - dry weight lipid content (16.2%)

Remarks:

Conc.in environment / dose:0.0517 mg/L

Bioaccumulation factor 9

Type:

BCF

Value:

5 340

Basis:

total lipid content

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: whole body BCF - wet weight lipid content (3.63%)

Remarks:

Conc.in environment / dose:0.00519 mg/L

Bioaccumulation factor 10

Type:

BCF

Value:

5 030

Basis:

total lipid content

Time of plateau:

3 d

Calculation basis:

steady state

Remarks on result:

other: whole body BCF - wet weight lipid content (3.63%)

Remarks:

Conc.in environment / dose:0.0517

Depuration

Depuration 1

Elimination:

yes

Parameter:

other: 67.9 % elimination

Depuration time (DT):

24 h

Depuration 2

Elimination:

yes

Parameter:

other: 87.3 % elimination

Depuration time (DT):

14 d

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

Total [14C] residue concentrations in all fish tissue portions (based on wet weights) reached steady state (equilibrium) by Day 3 at both exposure concentrations. The whole body BCF for fish exposed to a mean measured steady state concentration of 0.00519 mg/L was 194X. The whole body BCF for fish exposed to 0.0517 mg/L was 183X. The rate of elimination was initially rapid. The biological half-life of the total [14C]residues was < 24 hours. After 24 hours, > 70% of the whole body residues present on the last day of exposure had been eliminated from the fish exposed at both test concentrations. [14C]Residue representing parent compound was determined in an extracted whole body fish tissue sample, collected from the metabolite aquarium at the end of the uptake phase of the study. The mean measured exposure concentration in this test aquarium was 0.0491 mg/L. The analysis of this sample revealed that the test substance was extensively metabolized. Approximately 1.0% of the total residues represented parent compound. The measured concentration of 0.0956 mg/kg was used to calculate a BCF of 1.95X.