Benzene, mono-C11-13-branched alkyl derivs.

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

other: Publication: similar substances, BABs

Adequacy of study:

weight of evidence

Study period:

2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test:
Exposure of M. edulis to BABs: Mussels were exposed for 72 h to produce a mean tissue concentration of approximately 50 microg/g dry weight (similar to somewild M. edulis populations) Exposure was static renewal with 24-h water exchange.
Exposure of C. maenas to contaminated mussels: The crabs were each fed two BAB-contaminated mussels per day for 7 d, with seawater exchanged every 48 h. Following exposure to the mussels, the crabs were not fed for 2 d and were observed afterwards.
- Parameters analysed / observed: the crabs were observed for behavioural response and physiological response. Hemolymph and urine were extracted from crabs and analysed. The cellullar response (hemocytes) was tested. Midgut tissue was also analysed.

GLP compliance:

no

Radiolabelling:

not specified

Test organisms (species):

other: Carcinus maenas

Route of exposure:

feed

Total exposure / uptake duration:

7 d

Type:

BCF

Remarks on result:

not measured/tested

Remarks:

not the objective of the study

Validity criteria fulfilled:

not applicable

Conclusions:

The study proved that C12-C14 BAB was transferred to the crabs when they were fed with mussels contaminated with BAB. But the concentration of BAB found in the crab tissue was lower than expected. This fact suggested to the authors of the study that BAB was metabolized, excreted or both.
The analysis of the urine of crabs exhibited elevated UVF, which according to the conclusions by the authors could be consistent perhaps, with the presence of fluorescent BABs metabolites.
The authors concluded that the results of the study results did not support the hypothesis that BABs are likely to biomagnify in crabs and perhaps other marine organism.

Reference 2

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

other: Publication: similar substance

Adequacy of study:

weight of evidence

Study period:

2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Mussels were exposed to 5 microg/L of a complex mixture of C12–14 BABs for 14 d. Feeding rates and the viability of hemocytes were measured immediately after exposure and again after 5 d depuration. Tissues were extracted, analyzed and alkylbenzenes quantified by both GC-MS and GC * GC-ToF-MS.

GLP compliance:

no

Radiolabelling:

no

Test organisms (species):

other: Mytilus edulis

Route of exposure:

aqueous

Test type:

static

Total exposure / uptake duration:

14 d

Total depuration duration:

5 d

Conc. / dose:

5 µg/L

Type:

BCF

Value:

794 dimensionless

Basis:

not specified

Calculation basis:

steady state

Validity criteria fulfilled:

not applicable

Conclusions:

In this publication the authors reported that mussels bioaccumulate BAB. The tissue concentrations of the mussels exposed to 5 µg/L for 14 d were measured to be 46 to 47 µg/g dry weight by GC-MS. A log BCF=2.9, meaning a BCF of 794 (dimensionless), was calculated.

Description of key information

Literature studies support a BCF of 794 for BAB. This is consistent with Arnot-Gobas QSAR modeling (including biotransformation) results fromUS EPA’s EPIsuite v4.10,BCFBAFv3.01. The weight of evidence therefore suggests that BAB does not satisfy the B (BCF of ≥2000 to <5000) or vB (BCF ≥5000) criteria.

 

As described in the attached assessment, the physicochemical properties of BAB preclude testing via OECD 305 or comparable test method.

 

Review of available information:

 

There is apublication (Scarlett et al, 2008) conducted with mussels, withthe main purpose to see the effect of long-term exposure to low aqueous concentration of BABs andmussels’ ability to recover, following a previous study done by Booth et al 2007. In the study of Scarlett,using a C12-C14 BAB mixture, the authors calculated a log BCF of 2.9 (BCF 794) and a log Kow of 4.2. Another well documented study (Scarlett et al, 2009) conducted on crabs fed with contaminatedmussels, suggested that the substance could be metabolised or excreted in the urine or both, and theresults did not support the hypothesis that BABs are likely to biomagnify in crabsorothermarine organisms.

 

QSAR results are consistent with the literature studies. US EPA’s EPIsuite v4.10,BCFBAFv3.01 test module was used to model the BCF of several branched-alkyl structures, with C9, C12 and C14 alkyl groups. The Arnot-Gobas model (including biotransformation) provided BCF values ranging from 58 to 1208 for these structures, across the upper, middle and lower trophic levels. The inclusion of biotransformation rates in the model is supported by the observations of Scarlett et. al. that shows low levels of BAB in crabs after feeding on BAB-exposed mussels.

Key value for chemical safety assessment

BCF (aquatic species):

794 dimensionless