Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2019
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
other: OECD319b
Deviations:
yes
Remarks:
See below
Principles of method if other than guideline:
The aim of the OECD 319B is to determine the in vitro intrinsic clearance (CL in vitro int) of a test chemical using the substrate depletion approach. This can be applied to increase modelled predictions of bioaccumulation in fish. In short the clearance rate can be inputted into toxicokinetic models for fish bioaccumulation or extrapolated to a whole body biotransformation rate. See test guideline. The aim of this assay is to ultimately reduce animal testing in groups of similar substances, by more extensive use of such alternative tests. In addition the assay can be implemented in a simpler fashion to determine if a product is transformed and can be useful to aid degradation product identification. In this memo the
implementation of the assay for Trout and Rat liver is summarized and one test chemical was tested using the assay in order to establish if biotransformation occurred. No intrinsic clearance rate was calculated at this stage.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): [1,3(or 1,4)-Phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide
- Molecular formula (if other than submission substance): C20H34O4
- Molecular weight (if other than submission substance): 338.49
- Smiles notation (if other than submission substance): CC(c1ccc(cc1)C(OOC(C)(C)C)(C)C)(OOC(C)(C)C)C
- Substance type: Organic peroxide
Analytical purity: 97.6%
- Purity test date: 28 July 2009
- Lot/batch No.: 307090713
- Expiration date of the lot/batch: July 2010
- Storage condition of test material: Room temperature in the dark
- Other: Date received 22 September 2009
Radiolabelling:
no

Results and discussion

Applicant's summary and conclusion

Conclusions:
No metabolic activity was observed for the test chemical.
Executive summary:

The test chemical was used during the implementation of the OECD 319B assay. Performance of the assay was assessed using testosterone as a standard to demonstrate activity using both trout and rat liver S9 fractions. Multiple tests were conducted to establish an optimal concentration for use in subsequent tests as a positive control. After which, both rat and trout liver fractions gave an acceptable levels of testosterone metabolism and showed a sufficient level of reproducibility. Should definitive tests

take place an additional standard for phase II enzyme activity and day to day test variation still requires validation.

The test substance di(tert-butylperoxyisopropyl)benzene was tested with a rat liver S9 fraction at 50 and 200 μ/moles. No metabolic activity was observed for the test chemical. The meta isomer only was quantified. The reference material at 50 μ/moles performed normally demonstrating sufficient phase 1 activity in the cell line used.