2,2-dimethylbutane

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Calculation of bioconcentration factors to determine the potential for bioaccumulation of chemicals is acceptable provided that a recognised and scientifically robust method is used. The TGD includes two methods for calculation of a BCF QSAR depending on the molecular weight and log Kow. This approach is considered to be acceptable with restrictions.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Principles of method if other than guideline:

BCF was calculated using Log Kow of 3.6 and the equation defined in the TGD (Log BCF fish = 0.85 . Log Kow -0.7). This is the TGD guideline QSAR

GLP compliance:

not specified

Remarks:

Calculated value therefore this is not applicable.

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
not applicable

Details on sampling:

not applicable

Vehicle:

not specified

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

not applicable

Test organisms (species):

Pimephales promelas

Details on test organisms:

not applicable because this is a calculated value.

Route of exposure:

other: not applicable

Test type:

other: QSAR

Water / sediment media type:

not specified

Hardness:

not applicable

Test temperature:

not applicable

pH:

not applicable

Dissolved oxygen:

not applicable

TOC:

not applicable

Salinity:

not applicable

Details on test conditions:

not applicable

Nominal and measured concentrations:

not applicable

Details on estimation of bioconcentration:

BASIS FOR CALCULATION OF BCF
- Result based on measured log Kow of:4

Key result

Type:

BCF

Value:

501.187 dimensionless

Remarks on result:

other: Temperature and pH not specified

Details on kinetic parameters:

not applicable

Metabolites:

not applicable

Results with reference substance (positive control):

not applicable

Details on results:

not applicable

Reported statistics:

not applicable

Validity criteria fulfilled:

not applicable

Remarks:

This is a calculated value

Conclusions:

The BCF of isohexane was calculated to be 501.187. This calculation indicates that isohexane does not greatly bioaccumulate in the lipids of ecological receptors.

Executive summary:

The QSAR used to calculated the BCF of n-hexane followed the TGD guideline and so is deemed suitable for the assessment of bioconcentration. The calculated BCF of 501.187 indicates that iso-hexane does not greatly bioaccumulate in the lipids of ecological receptors.

Description of key information

A QSAR prediction for 2,2 -dimethylbutane indicates a bioconcentration factor of 154 L/kg w/w.

This is supported by data available for isohexane, which can be used to read-across to 2,2 -dimethylbutane.

The BCF of Isohexane was calculated using a QSAR (Veith and Broderius, 1987), based on a log Kow of 3.6. The QSAR used to calculated the BCF of Isohexane followed the TGD guideline and so is deemed suitable for the assessment of bioconcentration. The calculated BCF of 501.187 indicates that Isohexane does not greatly bioaccumulate in the lipids of ecological receptors.

Key value for chemical safety assessment

BCF (aquatic species):

154 L/kg ww