Fatty acids, tallow, zinc salts

Endpoint summary

Description of key information

The read-across substance fatty acids, C16-18, zinc salts was without any effect to skin and eyes in tests according to Draize.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

No studies are available on acute toxicity of fatty acids, tallow, zinc salts. In accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5, a read across to the structural analogue fatty acids, C16-18, zinc salts (CAS No. 91051-01-3) and zinc dicaprylate (CAS No. 557-09-5) was conducted. Based on similar structure, physico-chemical properties (i.e. water solubility) and zinc content, the toxicological profile of the substances is expected to be comparable. Further justification is given within the CSR chapter 5 and the read-across justification. The data available for fatty acids, zinc salts and the supporting data available for inorganic zinc salts are discussed below.

Fatty acids, zinc salts

Skin

In two available studies according to Draize fatty acids, C16-18, zinc salts was not irritating in a test when applied as a single dose of 0.5 g (100%) to the skin of 6 rabbits under occlusive conditions for 4 or 24 hours, respectively (Penick et al., 1977). The reported primary irritation index was 0, which was translated into an overall irritation score of 0 according to OECD 404.

 

In two other publications, the local action of fatty acids, C16-18, zinc salts was studied for 10 days after its application in a paste form on the shorn surface of the fur skin of rats and rabbits (Tarasenko et al., 1976). In both animals no irritation potential was noted.

No corrosion was found in an in vitro test performed mainly similar to EU method B.46 (Gay et al., 1992). However, due to some methodological deficiencies the result could not be used for assessment.

Additionally, fatty acids, C16-18, zinc salts has a long history of use in a wide range of pharmaceutical and cosmetic preparations, at concentrations up to 50%. It has been used as a mild antiseptic and to sooth inflammation and irritation (CIR, 1982). Apparently these uses have not been associated with irritation.

 

Eye

No eye irritation was found on days 1, 2, and 3 after instillation, when 0.1 g of pure fatty acids, C16-18, zinc salts was applied into the eyes of 6 rabbits according to Draize (Penick et al., 1977). The primary irritation index was 0, which was translated into a score of 0 according to OECD 405 (2002).

Primary irritation indices of 2 on day 1 and 0 on day 2 after instillation of 100% fatty acids, C16-18, zinc salts was found in another eye irritation study according to Draize (Avon products, 1976). Thus, fatty acids, C16-18, zinc salts caused minimal eye irritation which was reversible within 2 days.

 

Fatty acids, C16-18, zinc salts as formulation (10% in undiluted eye shadow form) was applied into the eyes of six rabbits (CTFA, 1976). The irritation score was 0 in all animals at 24, 48, and 72 hours after test substance application.

The effect of another fatty acid, zinc salt, namely zinc dicaprylate on mucous membranes was studied via insufflating 50 mg of powder into the conjunctival sac of the rabbits (Tarasenko et al, 1974). Zinc caprylate produced a more pronounced effect on the mucouse membranes of the eye. However, by day 4 essentially all the irritation phenomena had disappeared: the eye was clear, there was no discharge, only weak hyperaemia remained. Due to insufficient documentation the study cannot be used for hazard assessment.

 

The substance fatty acids, C16-18, zinc salts was without any effect to skin and eyes in reliable, adequate and relevant tests according to Draize. Thus, data on fatty acids, C16-18, zinc salts do not indicate a skin or eye irritating or corrosive potential. Also, the use of fatty acids, C16-18, zinc salts in pharmaceutical and cosmetic preparations is not associated with irritation in humans. Other slightly soluble zinc compounds (i.e. zinc phosphate and zinc oxide) are not eye irritating and zinc oxide is not skin irritating. It is consequently concluded by read-across that the substance fatty acids, tallow, zinc salts does not have an irritating or corrosive potential to skin or eyes either.

This conclusion is in line with the conclusion for the structural analogue (i.e. Fatty acids, C16 -18, zinc salts) from EU RAR “Zinc stearate (CAS# 91051-01-3, CAS# 557-05-1) Part II – Human Health. EUR 21168 EN:"It is consequently concluded that zinc distearate is not likely to have eye and skin irritation potential and, therefore does not need to be classified/labelled... Zinc distearate is not corrosive to skin or eyes."

A similar lack of skin and eye irritancy is considered for Fatty acids, tallow, zinc salts.

 

For a comprehensive overview of the (non) irritancy of zinc, refer to the hazard assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 in the technical dossier (see IUCLID Section 13).

 

Inorganic zinc salts

Based on the available information it appears that the slightly soluble zinc oxide and insoluble zinc sulphide are not skin irritants and therefore slightly soluble zinc hydroxide, zinc phosphate, zinc carbonate and zinc metal are also expected to be not irritating to skin. Zinc oxide, zinc phosphate, zinc metal and zinc sulphide are not eye irritants and therefore zinc carbonate and zinc hydroxide are also expected to be not irritating to eyes. None of the slightly soluble or insoluble zinc compounds appear to cause respiratory tract irritation.

 

 

Justification for selection of skin irritation / corrosion endpoint:

Hazard assessment is conducted by means of read-across from structural analogues using a weight of evidence approach from available studies.

Justification for selection of eye irritation endpoint:

Hazard assessment is conducted by means of read-across from structural analogues using a weight of evidence approach from available studies.

Justification for classification or non-classification

Fatty acids, tallow, zinc salts as slightly soluble zinc compound is not irritating or corrosive based on the available irritation data of fatty acids, C16-C18, zinc salts. Thus, based on read-across from the structurally similar substances, the available data on skin and eye irritation do not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.

Other slightly soluble and insoluble zinc compounds (zinc oxide, zinc hydroxide, zinc phosphate, zinc carbonate, zinc metal and zinc sulphide) are not irritating or corrosive based on the available irritation data and therefore no classification is required according to EC criteria either for irritation or corrosion.