Fatty acids, tallow, zinc salts

Endpoint summary

Additional information

Justification for Read-across

There are no data available for the biodegradation of Fatty acids, tallow, zinc salts (CAS No. 68440-34-0). In order to fulfil the standard information requirements set out in Annexes VII - IX, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances and from surrogate substances was conducted.

In accordance with Article 13(1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human and environmental toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity and common physiological active moieties.

Fatty acids, tallow, zinc salts consist of approximately 10% zinc and 90% natural fatty acids, mainly of saturated C16 and C18 fatty acids and monounsaturated C18 fatty acid.

In the case of Fatty acids, tallow, zinc salts, read-across to Fatty acids, zinc salts and to inorganic zinc salts and zinc metal (as listed below) was used. Justification for both approaches is given below.

Fatty acids, zinc salts

The target substances Fatty acids, tallow, zinc salts and the source substances Fatty acids, C16-18, zinc salts (CAS No. 91051-01-3), zinc distearate (CAS No. 557-05-1), zinc bis[12-hydroxystearate] (CAS No. 35674-68-1) and zinc dicaprylate (CAS No. 557-09-5) are substances with a zinc moiety and a fatty acid moiety. The zinc content is considered to be similar. The fatty acid moiety is considered not being hazardous to humans and the environment. Fatty acids are natural constituents of the human body and the environment and essential components of a balanced nutrition for humans and animals. Fatty acids are generally judged as not representing a risk to human health (except the irritating/corrosive properties of short-chain fatty acids and the environment. Variability in the poorly soluble fatty acid moiety is not expected to have a relevant influence on the physiological activity of fatty acid zinc salts and therefore, read-across to another fatty acid zinc salts is justified without restrictions.

Inorganic zinc salts

A basic assumption for read-across made in this hazard assessment and throughout this CSR is that the biological activities of Fatty acids, tallow, zinc salts are expected to be mainly determined by ionic zinc, in case of dissociation. Since water solubility is the main determinant of bioavailability, read-across to source substances with higher water solubility and thus higher bioavailability of the zinc cation can be considered as worst-case for the target substance fatty acids, tallow, zinc salts.

This read-across approach is in accordance with the read-across approach applied in the course of the EU Risk assessments within the framework of EU Existing Chemicals Regulation (EEC) No 793/93 on substances zinc metal (CAS No. 7440-66-6), zinc oxide (CAS No. 1314-13-2), zinc chloride (CAS No. 7646-85-7), zinc sulphate (CAS No. 7733-02-0), trizinc bis(orthophosphate) (CAS No. 7779-90-0) and the structural analogue to Fatty acids, tallow, zinc salts being zinc distearate (CAS No. 557-05-1 / 91051-01-3).

For a comprehensive overview of the environmental fate properties and environmental and toxicological information of “Zinc” see the Chemical Safety Assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 in the technical dossier (see IUCLID Section 13).

 

Overview of source and target chemicals including CAS No./EC No.

Chemical Name	CAS No. / EC No.
Target substance
Fatty acids, tallow, zinc salts	68440-34-6 / 270-451-8
Source substances
Fatty acids, C14-18 and C16-18 unsatd., zinc salts	67701-12-6 / 266-936-9
Fatty acids, C16-18 and C18 unsatd., zinc salts	67701-13-7 / 266-937-4
Fatty acids, C16-18, zinc salts	91051-01-3 / 293-049-4
Zinc distearate	557-05-1 / 209-151-9
Zinc bis[12-hydroxystearate]	35674-68-1 / 252-669-5
Zinc dicaprylate	557-09-5 / 209-156-6
Zinc diacetate	557-34-6 / 209-170-2
Zinc dichloride*	7646-85-7 / 231-592-0
Zinc sulfate*	7733-02-0 / 231-793-3
Zinc nitrate*	7779-88-6 / 231-943-8
Zinc oxide*	1314-13-2 / 215-22-5
Zinc*#	7440-66-6 / 231-175-3

*) Surrogate substances (inorganic zinc salts)

#) The acceptance of zinc as surrogate refers to the cases where the specified CAS No. is given as test substance identity in the technical dossier with no further data on specification. In most cases this is presumably an ionic form, Zn²⁺.

A detailed read-across justification is provided in the technical dossier (see IUCLID Section 13).

Based on its physico-chemical properties the target compartments of Fatty acids, tallow, zinc salts in the environment would be soil and sediment. However, Fatty acids, tallow, zinc salts is readily biodegradable, poorly soluble in water and has potential to adsorb and is therefore expected to be eliminated in sewage treatment plants to a high extent. Significant release to surface waters and sediment is thus unlikely. In case of release, rapid elimination via biodegradation is also expected in aquatic and terrestrial environments.

An EU Risk Assessment Report is available for the structural analogue Zinc distearate (CAS No.: 557-05-1 and 91051-01-3.Commercially produced stearic acid is always a mixture of what chemically was called stearic acid (C18) and palmitic acid (C16). In practice, the description “Fatty acids, C16-18, zinc salts” registered under CAS no 91051-01-3 is a more exact fit with commercial zinc stearate, but it is only listed on EINECS and Chemical Abstracts have never indexed a single entry to this number. Based on these considerations, the CAS no 91051-01-3 was added. As stated in the Risk Assessment Report for Zinc distearate, Fatty acids, tallow, zinc salts is also assumed to partly dissociate into the zinc cation and the respective C16, C18 and C18:1 fatty acid anions, especially in an acidic environment (ECB, 2008). The further speciation of zinc, which includes complexation, precipitation and sorption, and the environmental fate of the fatty acids depend on the environmental conditions. In the presence of other cations such as calcium and magnesium, zinc distearate will partly form other “insoluble” fatty acid metal salts (e.g. Schmets, 1996). The fatty acids as such are readily biodegradable, although the degradability can be inhibited by the formation of insoluble salts (e.g. calcium, magnesium and zinc salts), that are not readily biodegradable (BKH, 1994; Schmets, 1996).