Quaternary ammonium compounds, C12-14-alkyl[(ethylphenyl)methyl]dimethyl, chlorides

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

KL2 due to RA

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

EPA OPP 165-4 (Laboratory Studies of Pesticide Accumulation in Fish)

Deviations:

no

GLP compliance:

yes

Radiolabelling:

yes

Details on sampling:

- A stock solution of 2.4 mg/mL was formulated by mixing radiolabeled test substance with unlabeled test substance and diluting with water.
- Following dilution with unlabeled test substance, the percent radiolabeled test substance in the mixture was 0.337 or 0.00337 as a decimal. On a combined test substance basis (both labeled and unlabeled) the calculated specific activity was 227013 dpmug x 0.00337 = 765.03 dpm/ug

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

Test organism:
- Common name: Bluegill
- Strain: SLS Lot 88A9
- Source: Froma culture maintained at Springborn Life Sciences, Inc.
- Length at study initiation (lenght definition, mean, range and SD): 65 mm
- Weight at study initiation (mean and range, SD): 3.6g
- Health status: Normal and healthy
- Frequency: Daily

Acclimation:
- Acclimation period: 14d prior to test initiation
- Acclimation conditions (same as test or not): Yes
- Type and amount of food: Dry pelleted food, ad libitum, daily throughout the 14d period, except 24h before testing.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

35 d

Total depuration duration:

21 d

Hardness:

22-32 mg/L CaCO3

Test temperature:

16-21°C

pH:

6.7-7.6

Dissolved oxygen:

6.2 -10.1 mg/L (64-94% of saturation)

Details on test conditions:

Test system
- Test vessel: 76 x 40 x 30 cm aquaria
- Type (delete if not applicable): Open
- Material, size, headspace, fill volume: 75L
- Renewal rate of test solution (frequency/flow rate): 4-4.7 tank volume replacements/d; 2L water to each aquaria at an average rate of 375 times/d
- No. of organisms per vessel: 190
- Biomass loading rate: 0.91 g/L/day

Test medium / Water parameters:
- Source/preparation of dilution water: Dilution water used for this test was from the same source as the water which flowed into the fish holding tank and was characterised weekly.
- Alkalinity: 21-24 mg/L CaCO3
- Conductance: 100-130 umhos/cm

Other test conditions:
- Photoperiod: 16h light/ 8h dark

Sampling period:
- To monitor initial concentration of 14C residues in water: 5 mL of samples were collected on Days 4, 3, 2, and 1 before introduction of fish
- To monitor concentration of 14C residues in water during the test: 5 mL of samples were collected on Days 1, 3, 7, 8, 9, 10, 14, 21, 23, 28 and 35 of exposure
- To quantify the accumulation and elimination of 14C residues in the edible, non-edible tissue of fish: 5 fish were collected, eviscerated and filleted on Day 1, 3, 7, 10, 14, 21, 28 and 35 of exposure.
- To quantify background 14C residues of test substance: 5 control fish were also collected, eviscerated and filleted on Day 35 of exposure and Day 21 of depuration.
- To estimate the half-life of the accumulated 14C residue present in the fish during depuration period: Water and tissue samples were collected from the tankon Day 1, 3, 7, 10, 14, 16 and 21 of depuration. Five fish were collected at each interval for analysis.

Others:
- Steady state was determined by measuring 14C residue conc. for 3 consecutive sampling intervals.
- After 35d of exposure, 35 of remaining fish in the treatment aquarium were transferred to a clean aquarium into which untreated dilution water was introduced at a rate equal to flow rate during exposure.
- Triplicate edible fish tissue samples from Day 35 of exposure were prepared for a hexane and methanol extraction procedure.
- To estimate the amount of 14C residues bound to the external surface of the skin of fish: 10 fish were removed after 35 d of exposure, eviscerated, filleted and the muscle portions were scraped off the skin. The skin portions were subsequently combustible to determine the residue conc. of the test substance.

Nominal and measured concentrations:

Nominal concentration: 0.05 mg/L
Measured concentration: 0.076 mg/L

Details on estimation of bioconcentration:

BCF factors for edible, non-edible and whole body fish tissue were determined by dividing the mean measured equilibrium 14C tissue concentration for each tissue type by the mean measured water concentration for the entire exposure period.

For comparison, an additonal method of calculating BCF factors wher the ratio of the uptake constant (Ku) to the depuration constant (Kd) was utilized. i.e.,
BCF = Ku/Kd

Key result

Type:

BCF

Value:

79 dimensionless

Basis:

whole body w.w.

Calculation basis:

other: mean

Remarks on result:

other: predicted BCF (calculated using uptake and depuration constants) = 110

Remarks:

conc. in environment / dose: 0.076 mg/L

Key result

Type:

BCF

Value:

160 dimensionless

Basis:

non-edible fraction

Calculation basis:

other: mean

Remarks on result:

other: predicted BCF = 190

Remarks:

conc. in environment / dose: 0.076 mg/L

Key result

Type:

BCF

Value:

33 dimensionless

Basis:

edible fraction

Calculation basis:

other: mean

Remarks on result:

other: predicted BCF = 50

Remarks:

conc. in environment / dose: 0.076 mg/L

Key result

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

21 d

Details on results:

- Mortality of test organisms: two treated fish (in a population of 190) died
- Behavioural abnormalities: None

Exposure phase:
- The mean 14C residues measured in the edible tissue reached steady state on Day 14 and remained relatively constant throughout the remainder of the exposure (mean range 2.10-3.36 mg/kg).
- Mean steady state conc. in edible tissue and mean conc. in the water during the period 0-35d: 2.54±0.67 mg/kg and 0.076±0.024 mg/L. The mean steady state BCF factor in the edible tissue during the 35d of exposure was determined to be 33X.
- The mean 14C residues measured in the non-edible tissue reached steady state on Day 14 and ranged from 11-13 mg/kg during the remainder of the 35-d exposure.
- Mean steady state in non-edible tissue and mean conc. in the water during the period 0-35 d: 12±2.3 mg/kg and 0.076±0.024 mg/L. The mean steady state BCF factor in the non-edible tissue during the 35d of exposure was determined to be 160X.
- The mean steady state conc. of 14C residue conc. in whole fish and mean conc. in the water during the period 0.35 d: 6±1.5 mg/kg and 0.076±0.024 mg/L.. The mean steady state BCF factor in the whole body of fish during the 35d of exposure was determined to be 79X.
- The residues in control were below the detectable level; small residues seen were due to contamination.
- Analytical results of the polar (methanol) solvent and non-polar (hexane) solvent extractions of edible tissue samples revealed 11% of the 14C residues accumulated in the exposure were extractable with methanol, 2.4% with hexane and 75% were not extractable with either solvent.

Depuration phase:
- Analyses of the tissues during the depuration phase indicated that in each case there was a continuous elimination of 14C residues from the respective tissues over the course of the 21d depuration period.
- Concentration of 14C residues present in the water of the depuration aquarium remained <= 0.014 mg/L, the limit of radiometric detection throughout the 21d depuration period.
- Half-life for non-edible tissue was: Between Days 14 and 21. By Day 21, the fish had eliminated 29%, 60% and 44% of the 14C residues that had been present on the last day of exposure on each of the tissues (i.e., edible, non-edible and whole body tissues respectively).
- Half-life based on model calculations (using 1st order kinetics) were: 16, 10 and 12d for edible, non-edible and whole body tissues respectively.
- The conc. of the residual test substance on the skin was observed to be higher than those found in the total edible tissue (skin and muscle combined) indicating significant binding of the test substance to skin and scales of fish.

Given the known strong affinity for the cationic compounds like the test substance to bind to essentially all surfaces, a logical explanation for the observed slow depuration is that the 14C residues are strongly bound to surfaces exposed to the treated water, e.g., gills, skin and intestine. The phenomenon has been clearly demonstrated with other quarternary ammonium compounds.

Validity criteria fulfilled:

not specified

Conclusions:

Based on the results of the read-across study, the whole body BCF of the test substance, C12 -14 ADEBAC, can also be considered to be 79, indicating a low potential to bioaccumulate.

Executive summary:

A study was conducted to determine the aquatic bioaccumulation of the read across substance, C12 -16 ADBAC (active: 98.9%), according to EPA OPP 165-4, in compliance with GLP. The bioaccumulation potential was evaluated inLepomis macrochirus(bluegill fish). The fish were continuously exposed to a nominal concentration of 0.050 mg/L of the read across substance (equivalent to a measured concentration of 0.076 mg/L) in well water for 35 days, after which 35 fish were transferred to flowing, uncontaminated water for a 21 day depuration period. Sampling intervals were Days 0, 1, 3, 7, 9, 10, 14, 21, 23, 28 and 35 for the exposure period and Days 1, 3, 7, 10, 14 and 21 for the depuration period. Water samples were collected on Day 8 of the exposure period and Day 16 of the depuration for analytic determination of the read across substance concentration. Radiometric analyses of the water and selected fish tissues revealed that the mean steady state BCF factors in the edible, non-edible and whole body tissue during the 35 days of exposure were 33, 160 and 79, that the half-life for non-edible tissue was attained between Days 14 and 21 (by Day 21, the fish had eliminated 29, 60 and 44% of the 14C residues that had been present on the last day of exposure in each of the tissues (i.e., edible, non-edible and whole body tissues respectively), and that the concentration of residual read across substance on the skin was higher than the one found in the total edible tissue (skin and muscle combined) indicating significant binding of the read across substance to skin and scales of fish. Under the study conditions, the whole body BCF of the read across substance was determined to be 79 indicating low potential to bioaccumulate (Fackler, 1989). Based on read across approach, a similar BCF value of 79 can be considered for the test substance, C12-14 ADEBAC.

Description of key information

Based on the results of the read-across study, the whole body BCF of the test substance, C12-14 ADEBAC, is considered to be 79, indicating a low potential to bioaccumulate. This is supported by a QSAR based estimated BCF value of 70.80 L/kg ww (log BCF =1.85) determined for the test substance.

Key value for chemical safety assessment

BCF (aquatic species):

79 dimensionless

Additional information

A study was conducted to determine the aquatic bioaccumulation of the read across substance, C12 -16 ADBAC (active: 98.9%), according to EPA OPP 165-4, in compliance with GLP. The bioaccumulation potential was evaluated inLepomis macrochirus(bluegill fish). The fish were continuously exposed to a nominal concentration of 0.050 mg/L of the read across substance (equivalent to a measured concentration of 0.076 mg/L) in well water for 35 days, after which 35 fish were transferred to flowing, uncontaminated water for a 21 day depuration period. Sampling intervals were Days 0, 1, 3, 7, 9, 10, 14, 21, 23, 28 and 35 for the exposure period and Days 1, 3, 7, 10, 14 and 21 for the depuration period. Water samples were collected on Day 8 of the exposure period and Day 16 of the depuration for analytic determination of the read across substance concentration. Radiometric analyses of the water and selected fish tissues revealed that the mean steady state BCF factors in the edible, non-edible and whole body tissue during the 35 days of exposure were 33, 160 and 79, that the half-life for non-edible tissue was attained between Days 14 and 21 (by Day 21, the fish had eliminated 29, 60 and 44% of the 14C residues that had been present on the last day of exposure in each of the tissues (i.e., edible, non-edible and whole body tissues respectively), and that the concentration of residual read across substance on the skin was higher than the one found in the total edible tissue (skin and muscle combined) indicating significant binding of the read across substance to skin and scales of fish. Under the study conditions, the whole body BCF of the read across substance was determined to be 79 indicating low potential to bioaccumulate (Fackler, 1989). Based on read across approach, a similar BCF value of 79 can be considered for the test substance, C12-14 ADEBAC.