Benzenesulfonic acid, di-C10-14-alkyl derivs., 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, di-C10-14-alkyl derivs., calcium salts

EC Number:

939-603-7

Cas Number:

1471316-72-9

Molecular formula:

not applicable (UVCB substance)

IUPAC Name:

Benzenesulfonic acid, di-C10-14-alkyl derivs., 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 6.91 and low water solubility (<0.1 mg/L)

Any other information on results incl. tables

In order to cross the skin, a compound must first penetrate into thestratum corneumand may subsequently reach the epidermis, the dermis and the vascular network. Thestratum corneumprovides 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. LogPow values between 1 and 4 favour dermal absorption (values between 2 and 3 are optimal; ECHA guidance R7c., TableR.7.12-2, 2012) particularly if water solubility is high. Above 4, the rate of penetration may be limited by the rate of transfer between thestratum corneumand the epidermis, but uptake into thestratum corneumwill 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. Additionally, vapours of substances with vapour pressures below 100 Pa are likely to be well absorbed and the amount absorbed dermally may be more than 10% 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, di-C10-14-alkylderivs., 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 (logPow of 6.91) of the substance and even though it will be absorbed into thestratum corneumit is unlikely to be transferred into the epidermis. Although the substance does show characteristics of a surfactant, benzenesulfonic acid, di-C10-14-alkylderivs., calcium salts 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). Repeated applications of the read-across substances to the skin of rats during 28 days resulted in NOAEL of 1000 mg/kg bw (no systemic effects were observed). Based on the high molecular weight, high logPow and on the results of dermal toxicity studies, 10% absorption is considered for the purposes DNEL derivation.

Applicant's summary and conclusion

Conclusions:

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

Executive summary:

The toxicology profile for benzenesulfonic acid, di-C10-14-alkylderivs., calcium salts and the calcium sulfonate read across substances indicate that oral and dermal absorption is expected to be limited. The in vitro and in vivo studies with DOBS and other related alkyl/aryl sulfates and sulfonates provide additional evidence that the skin absorption is expected to be low (Howes et al., 1975). No measurable skin penetration could be determined in the in vitro and in vivo studies in rats and/or humans.