Benzenesulfonic acid, mono- and dialkylation products with C16-20 (even numbered, branched and linear) olefins, barium salts, barium carbonate, overbased, including distillates (petroleum), hydrotreated, solvent-refined, solvent-dewaxed, or catalytic dewaxed, light or heavy paraffinic C15-C50

Categories

Category name:

Benzenesulfonic acid, mono- and dialkylation products with C16-20 (even numbered, branched and linear) olefins, with and without Group II metal salts Mammalian Toxicity Category

Justifications and discussions

Category definition:

Benzenesulfonic acid, mono- and dialkylation products with C16-20 (even numbered, branched and linear) olefins, with and without Group II metal salts Mammalian Toxicity Category

Category rationale:

REPORTING FORMAT FOR THE CATEGORY APPROACH
Please note that several studies are currently in progress that will determine the appropriate hypothesis for read-across. Therefore a read-across justification docment has not yet been prepared. However, a preliminary document of intent has been provided. On completion of these intial studies to determine the appropriateness of each potential hypothesis, a strategy will be developed, with appropriate study plans to fulfil the requirements of read-across according to the RAAF. In light of animal welfare considerations, the current gaps in the data will not be fulfilled until the approaches for read-across have been adequately investigated.

The substances in this category are UVCBs, they are considered structurally similar due to the commonality of their manufacturing processes. All the substances considered within this assessment utilise the same starting olefin in their manufacturing process, and consequently all form the same alkylbenzene sulfonic acid (ABSA). This ABSA is one of the substances and the main starting material for all the other substances in the category. The other members of the category are either:
a. ABSA neutralised with calcium salt, or
b. ABSA neutralised with either calcium, magnesium or barium salt and overbased in mineral oil.

Therefore, there is structural similarity between members of the category. However, investigations are in progress to determine if there is metabolic similarity.

1. READ-ACROSS HYPOTHESIS
This read-across hypothesis is based on a category approach. This category is still in development, and as such, a formal hypothesis has not yet been prepared. To that end, work is currently in progress to determine if all members of the category will have similar, or dissimilar toxicokinetic properties. Once this has been established, a read-across hypothesis will be proposed, and a plan will be developed for addressing the data gaps in the category.

No tests are proposed prior to the completion of the toxicokinetic work to ensure minimal use of animals for testing, i.e., due to animal welfare considerations.

2. CURRENT AND ON-GOING ACTIVITIES
2.1. ECOTOXICOLOGICAL AND ENVIRONMENTAL FATE READ-ACROSS
A category has already been developed for the ecotoxicological and environmental fate endpoints. Whilst there are still several studies outstanding for these endpoints, the data collated to date indicate strong similarity between all members of the category. This supports the appropriateness of using these substances in a category for mammalian toxicity endpoints (see ‘Interim Benzenesulfonic acid, mono- and dialkylation products with C16-20 (even numbered, branched and linear) olefins Ecotoxicity Read-Across Justification-October 2022’ for further details). That document should be consulted for a detailed demonstration of the process by which a robust read-across assessment has been conducted. A similar process will be conducted for the mammalian toxicity endpoints once sufficient data are available.

2.2. DETERMINATION OF TOXICOKINETIC PROPERTIES OF PROPOSED MEMBERS OF THE CATEGORY
Prior to developing a category hypothesis, it is necessary to obtain an understanding of the toxicokinetic similarities and differences between members of the categories. This will inform if the category hypothesis will be either be Scenario 3 or 5, or if the category will either be Scenario 4 or 6. To that end, the following activities are currently in progress:

• Experimental work is in progress using the ToxTraker® assay. These assays are in progress; however, no results are currently available.
• Toxicokinetic modelling is in progress using TIMES. This information will support the experimental studies currently in progress.

On completion of these assays, an initial read-across hypothesis will be developed, and a plan will be developed that will address data gaps in the experimental dataset, with consideration to minimisation of animal use.

2.3. PLANNING OF EXPERIMENTAL STUDIES TO FUFIL DATA GAPS
Once the toxicokinetic studies are complete, it will be clear which scenario is appropriate for the category read-across. It is recognised that there are several data gaps in this category, and therefore, a plan will be developed to fill these data gaps. It is not appropriate to undertake such preparation until the toxicokinetic data are available, as this may result in unnecessary animal testing.

2.4. DEVELOPMENT OF A COMPLETE READ-ACROSS JUSTIFICATION
Upon completion of the necessary studies, a read-across justification will be developed (with appropriate assessment elements), according to the previously determined category hypothesis. Whilst it is too early to address the assessment elements at the present time (as some will be determined by the scenario hypothesis), the following chapters provide some information of the category, which would meet the criteria of some of the common assessment elements.