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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:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented peer-reviewed publication
Justification for type of information:
Category Approach; test material (C12-2 LAS) is major component of reference substance LAS. LAS provides suitable read across for LAB Sulfonic Acids as both form the identical chemical species in aqueous solutions at neutral (physiological) pH, namely, the LAS ion (C10-13linear alkyl benzene-SO3-) and would be expected to have similar bioaccumulation properties.
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Bioconcentration of LAS: Experimental determination and extrapolation to environmental mixtures.
Author:
Tolls, J., Haller, M., DeGraaf, I., Thijssen, M.A.T.C. and Sijm, D.T.H.M.
Year:
1997
Bibliographic source:
Environ. Sci. Technol. 31:3426-3431.

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 305 A (Bioaccumulation: Sequential Static Fish Test)
Deviations:
no
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
Analytical Purity: all test materials in this study are >97.4% purity.
Radiolabelling:
not specified

Sampling and analysis

Details on sampling:
Water samples (~40 ml) were taken at least once per day, and extracted immediately or preserved with 10% vol MeOH and stored under N2 in a refrigerator for no more than 2 days. Fish were sacrificed by immersion in liquid N2, and stored at -20 degrees C until analysis. 2-4 replicates of fish samples were taken.

Test solutions

Vehicle:
not specified
Details on preparation of test solutions, spiked fish food or sediment:
To address differences in composition of mixtures, bioconcentration potential was calculated for
1) mixtures typical of LAS in European detergent formulations (C10 12%, C11 29%, C12 34%, C13 24%; average alkyl chain length = C11.6) and
2) mixtures typical of LAS in filtered Mississippi river water (C10 45%, C11 23%, C12 23%, C13 2%; average chain length = C10.8).
Stock solutions were kept under N2 to prevent aerobic biodegradation.

Test organisms

Test organisms (species):
Pimephales promelas
Details on test organisms:
Common name: Fathead Minnow
- Source: Utrecht University hatchery
- Weight at study initiation (mean and range, SD): 0.5-1 g
- Health status: free from observable diseases and abnormalities
- Feeding during test
- Amount: 1 % body weight per day, in order to minimize suspended solids, fish were fed for 30 min in a separate aquarium

ACCLIMATION
- Acclimation period: 1 week

Study design

Route of exposure:
aqueous
Test type:
other: measured flow-through
Water / sediment media type:
natural water: freshwater
Total exposure / uptake duration:
> 48 - < 192 h

Test conditions

Hardness:
1.21 mM
Test temperature:
20.7-22.5°C
Details on test conditions:
When tested by itself: The exposure phase in Experiment A was 48 hours. The exposure phase in Experiments B-D ranged from 168 to 192 hours. Due to the rapid equilibrium demonstrated in these studies, a longer exposure period was not needed. Fish were then transferred to untreated water for the depuration phase (duration not stated).

TEST SYSTEM
- Test vessel: aquaria
- Type of flow-through (e.g. peristaltic or proportional diluter): peristaltic
- Renewal rate of test solution (frequency/flow rate): 1 L/day g fish

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted H2O
Nominal and measured concentrations 2.7 and 4.1 µM
Reference substance (positive control):
not specified
Details on estimation of bioconcentration:
The calculation of BCF for the typical mixtures was done using the following equation developed in the above testing:
(∑Cf,i/∑Cw,i)rel = ∑(øi,w · BCFi,rel)

Results and discussion

Lipid content
Remarks on result:
other:
Remarks:
The BCF value was not normalized to a fish with a lipid content of 5%. However, in accordance with Tolls and Sijm (1999) the rate of biotransformation of LAS is high enough for the resulting BCF not to change significantly with the lipid content. Hence, the normalization to 5% lipid was not needed, nor appropriate. An entire section, “Lipid content”, within the Discussion section of Tolls and Sijm (1999) was summarized as follows: “No dependency (of tissue concentration on lipid content) is apparent”. Because C12-2-LAS is biotransformed at an appreciable rate, it is probably not sequestered into storage tissues that are rich in lipids.” Publications by Dyer et al. (2008) have shown that LAS also undergoes efficient in vitro biotransformation in S9 extracts from carp and rainbow trout, as well as an immortalized hepatic cell line (PLHC-1) and primary hepatocytes from carp. Biotransfromation rate constants are provided in this paper. Tolls J, Lehmann MP, Sijm DTHM. 2000. Quantification of in vivo transformation of the anionic surfactant C12-2-linear alkylbenzene sulfonates in fathead minnows. Environ. Toxicol. Chem. 19: 2394–2400. Tolls, J. and Sijm, D. T.H.M. (1999), Bioconcentration and biotransformation of the nonionic surfactant octaethylene glycol monotridecyl ether 14C-C13EO8. Environmental Toxicology and Chemistry, 18: 2689–2695. doi:10.1002/etc.5620181206 Dyer et al. (2008). In vitro biotransformation of surfactants in fish. Part I: Linear alkylbenzene sulfonate (C12-LAS) and alcohol ethoxylate (C13EO8). Chemosphere 72, 850 -862.
Bioaccumulation factor
Type:
BCF
Value:
>= 2 - <= 1 000 L/kg
Details on results:
The BCFs were 87 L/kg for a standard mixture typical of LAS in European detergent formulations (average alkyl chain length = C11.6) and 22 L/kg for a representative environmental sample (filtered Mississippi river water, average alkyl chain length = C10.8). The BCF for the most lipophilic homologue (C13-2) tested was 987.2 L/kg.

Any other information on results incl. tables

When tested by itself:

Values of Steady-State Bioconcentration Factor (BCFss) and Average Length of Alkyl Chain (nC,Av) are shown in the following table.

 

Experiment

Compound

BCFss (L kg -1)

nC, Av

A

C10-2

1.7

10.8

 

C11-2

5.8

 

 

C12-2

47.6

 

 

C13-2

353.8

 

B

C11-5

6.1

11.7

 

C12-2

99.1

 

 

C12-5

10.0

 

 

C13-5

34.0

 

C

C11-5

9.8

11.4

 

C12-2

168.4

 

 

C12-3

42.1

 

 

C12-6

31.9

 

D

C10-2

6.0

10.6

 

C11-2

31.9

 

 

C12-2

211.5

 

 

C13-2

987.2

 

 

C10-in

3.0

 

 

C11-in

9.1

 

 

C12-in

29.9

 

 

C13-in

112.4

 

*In the format Cn-m, n and m are the length of the alkyl chain and the position at which the sulfophenyl moiety is substituted to the alkyl chain, respectively. As shown in the table, BCF values ranged between 2-1000 L/kg. Experiments A, B and D showed that BCFs increase with increasing alkyl chain length for a given isomer. In addition, the results of Experiments B and C demonstrate that the closer the p-sulfophenyl moiety is positioned to the terminal carbon of the alkyl chain, the higher the BCF. However, alkyl chain length has a much bigger effect than does the phenyl position.

Applicant's summary and conclusion

Conclusions:
BCF values ranged from between 2 and <1000 L/kg, with BCFs increasing with increasing alkyl chain lengths. Steady-State Bioconcentration Factors (BCFss) for C10-2 LAS (CAS# 65185-98-0) were 1.7 and 6.0 L/kg in two experiments.
Executive summary:

The bioaccumulation potential of a series of LAS substances was evaluated in flow-through studies with fathead minnows. Results show that the bioconcentration potential of LAS is low, likely due to rapid biotransformation and is decreased by external environmental processes such as biodegradation and absorption/settling, which reduce aquatic concentrations.