Benzenesulfonic acid, 4-(branched alkyl derivs.) and benzenesulfonic acid, 4-(linear alkyl dervis.), calcium salts

Dermal absorption

Administrative data

Endpoint:

dermal absorption

Type of information:

other: assessment of dermal absorption based on physico-chemical properties

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: An assessment of the toxicokinetic behaviour of calcium sulfonate target substance was performed, taking into account the chemical structure, the available physico-chemical-data and the available toxicological data.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

other: Expert statement

Title:

Unnamed

Year:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Technical guidance document, Part I, 2003

Deviations:

no

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Benzenesulfonic acid, mono-C15-36 branched alkyl derivs., C24 rich and Octadecylbenzenesulfonic acid,calcium salts

IUPAC Name:

Benzenesulfonic acid, mono-C15-36 branched alkyl derivs., C24 rich and Octadecylbenzenesulfonic acid,calcium salts

Test material form:

other: liquid

Results and discussion

Percutaneous absorption

Parameter:

percentage

Absorption:

10 %

Remarks on result:

other: The calcium sulfonate target substance is expected to be poorly absorbed following dermal exposure into the stratum corneum, due to its LogPow of 6.65 and low water solubility (1.69 mg/L)

Any other information on results incl. tables

In order to cross the skin, a compound must first penetrate into the stratum corneum and may subsequently reach the epidermis, the dermis and the vascular network. The stratum corneum provides its greatest barrier function against hydrophilic compounds, whereas the epidermis is most resistant to penetration by highly lipophilic compounds. Substances with a molecular weight below 100 are favourable for penetration of the skin and substances above 500 are normally not able to penetrate. The substance must be sufficiently soluble in water to partition from the stratum corneum into the epidermis. Therefore if the water solubility is below 1 mg/L, dermal uptake is likely to be low. Additionally LogPow values between 1 and 4 favour dermal absorption (values between 2 and 3 are optimal; TGD, Part I, Appendix IV). Above 4, the rate of penetration may be limited by the rate of transfer between the stratum corneum and the epidermis, but uptake into the stratum corneum will be high. Above 6, the rate of transfer between the stratum corneum and the epidermis will be slow and will limit absorption across the skin. Uptake into the stratum corneum itself may be slow. Vapours of substances with vapour pressures below 100 Pa are likely to have enough contact time to be absorbed and the amount absorbed dermally is most likely more than 10% and less than 100 % of the amount that would be absorbed by inhalation. If the substance is a skin irritant or corrosive, damage to the skin surface may enhance penetration. During the whole absorption process into the skin, the compound can be subject to biotransformation.

In the case of benzenesulfonic acid, mono-C15-36 branched alkyl derivs., C24 rich and Octadecylbenzenesulfonic acid, calcium salts, the molecular weight is above 500, which indicates already a marginal potential to penetrate the skin. This is accompanied by a low hydrophilicity of the substance and even though the stratum corneum is open for lipophilic substances, the epidermis is very resistant against penetration by highly lipophilic substances. However, the amount of benzenesulfonic acid, mono-C15-36 branched alkyl derivs., C24 rich and Octadecylbenzenesulfonic acid, calcium salts, which is absorbed following dermal exposure into the stratum corneum is unlikely to be transferred into the epidermis. Although the substance does show characteristics of a surfactant, the calcium sulfonate target substance is not irritating to skin and eyes, and therefore this does not enhance dermal absorption.

In support of this hypothesis (the low dermal absorption), the systemic toxicity of the calcium sulfonate read across substance CAS 70024-69-0 and of 115733-09 -0 via the skin is low (acute dermal toxicity, LD50 value of > 2000 and > 5000 mg/kg bw for rats, respectively).

In conclusion, the evaluation of all the available indicators and the results of toxicity studies allow the allocation of the chemical in question into the group of chemicals with a low dermal absorption. In detail, due to it’s molecular weight and the results for acute toxicity, the use of a factor of 10 % for the estimation of dermal uptake for benzenesulfonic acid, mono-C15-36 branched alkyl derivs., C24 rich and Octadecylbenzenesulfonic acid, calcium salts is justified (Schuhmacher –Wolz et al.,2003; TGD, Part I, 2003).

Applicant's summary and conclusion

Conclusions:

No significant dermal absorption is expected for the calcium sulfonate target substance.

Executive summary:

In order to assess the toxicological behaviour of benzenesulfonic acid, mono-C15-36 branched alkyl derivs., C24 rich and Octadecylbenzenesulfonic acid, calcium salts, the available physico-chemical and toxicological data for it and its near calcium read across substances have been evaluated. The calcium sulfonate target substance is expected to be absorbed to a limited extent after oral exposure, based on its high molecular weight, its low water solubility and its high LogPow. Concerning the absorption after exposure via inhalation, as the chemical is considered to have a low vapour pressure, is highly lipophilic, has a high LogPow, and has a rather high molecular weight, it is clear, that the substance is poorly available for inhalation and will not be absorbed significantly.The calcium sulfonate target substance is also not expected to be absorbed following dermal exposure into the epidermis, due to its low water solubility and its fairly high molecular weight. Concerning its distribution in the body the calcium sulfonate target substance is expected to be distributed into the intravasal compartment and possibly also into the intracellular compartment. The substance does not indicate a significant potential for accumulation, when taking into account the predicted behaviour concerning absorption and metabolism. The calcium sulfonate target substance is expected to be extensively metabolised (metabolism by cytochrome P450 enzymes, followed by omega- and beta-oxidation and cleavage of the aromatic ring and desulfonation) and to be eliminated mainly via the urine and also via the bile.