Fatty acids, tallow, zinc salts

Endpoint summary

Additional information

Physico-chemical data for the substance fatty acids, tallow, zinc salts, CAS-No. 68440-34-6, were determined on the basis of data measured for close analogue substances:

Fatty acids, C14 -18 and C16 -18 unsatd., zinc salts, CAS-No. 67701 -12 -6

Fatty acids, C16 -18, zinc salts, CAS-No. 91051 -01 -3

Zinc distearate, CAS-No. 557 -05 -1

Fatty acids, C16 -18 and C18 unsatd., zinc salts, CAS-No. 67701 -13 -7

Fatty acid, tallow, zinc salts is a white, odourless solid with a melting point in the range from 101 °C (67701 -12 -6) to 121 °C (91051 -01 -3). As the analogue substance CAS No. 91051-01-3 started decomposing at approximately 330 °C before boiling, no boiling point could be determined, and the decomposition is assumed also for fatty acids, tallow, zinc salts. The relative density is in the range from 1.05 (CAS No. 67701 -12 -6) to 1.11 (CAS No. 91051-01-3) at 20°C. As the substance is a salt with a melting point of 101 -121°C, vapour pressure can be safely assumed to be negligible, i. e. below the level of relevance (10^-5 Pa).

The surface tension of a 90 % saturated aqueous solution of CAS No. 91051-01-3 was determined to be 64.56 mN/m, and it is concluded that also fatty acids, tallow, zinc salts is not surface active (surface tension > 60 mN/m).

The water solubility of fatty acids, tallow, zinc salts was determined in the weight of evidence approach, on the basis of results obtained for analogue substances with CAS Nos. 67701-12-6, 557-05-1 and 91051-01-3.

The solubility of these substances depends on several factors, including loading, solution matrix (pH, ionic strength, other salts) and exposure time.

In water, solubility ranges from 0.79 (CAS No. 557-05-1 at 15 °C) to 1.8 mg/L (CAS No. 557-05-1 at 20 °C, pH = 7.3) depending on test conditions. These calculations assume a 1:1 dissolution of zinc and a zinc content of ca. 10%. However, as stearate concentrations have not been experimentally confirmed, it may be more appropriate to express the solubility in resulting dissolved Zn concentrations (0.08 to 0.18 mg/L). Dissolved Zn concentrations for CAS No. 67701-12-6 (0.214 mg/L at 21 °C, pH = 6) and CAS No. 91051-01-3 (0.034 to 0.0608 mg/L at 30 °C) were also reported.

In more complex media simulating environmental solutions, solubility resulted in 0.02 to 0.9 mg/L dissolved zinc depending on test conditions. The following dissolved zinc concentrations have been measured in three different studies (most relevant for the classification of Fatty acids, C16-18, zinc salts are the data obtained by Schäfers (2010) in transformation dissolution studies (guideline conform and under GLP) for 7 and 28 days with loadings of 1, 10 and 100 mg/L):

Schäfers (2010), CAS No. 91051 -01 -3, guideline conform and under GLP:

ISO 6341 media at pH 8:

Loading 1 mg/L:

-after 7 days: 19 µg Zn/L

-after 28 days: 29 µg Zn/L

Loading 10 mg/L:

-after 7 days: 90 µg Zn/L

Loading 100 mg/L:

-after 7 days: 369 µg Zn/L

Bouwman (2003), CAS No. 557 -05 -1

ISO 6341 at pH 6:

Loading 100 mg/L:

-after 2 days: 208 µg Zn/L

ISO 6341 at pH 8

Loading 100 mg/L:

-after 2 days: 475 µg Zn/L

M7 at pH 6:

Loading 100 mg/L:

-after 2 days: 325 µg Zn/L

M7 at pH 8

Loading 100 mg/L:

-after 2 days: 900 µg Zn/L

Bowmer (2001), CAS No. 557-05-1

Modified ISO 6341 at pH 6.75:

Loading 10 mg/L:

-after 4 days: 241 µg Zn/L

Modified ISO 6341 at pH 6.75

Loading 100 mg/L:

-after 4 days: 431 µg Zn/L)

The partition coefficient of fatty acids, tallow, zinc salts is not considered to be relevant. This study generally does not need to be conducted for inorganic substances (cf. Annex VII, section 7.8, column 2 of Regulation (EC) No 1907/2006). The substance is a salt of fatty acids with an inorganic cation. It is similar to inorganic salts because of its ionic structure.

Based on data for analogue substances CAS Nos. 67701-13-7 and 91051-01-3, the substance fatty acids, tallow, zinc salts is non-flammable on ignition. Based on chemical structure, pyrophoric properties or flammability on contact with water are not to be expected.

Flash point, explosive properties, self-ignition temperature, oxidising properties, stability in organic solvents and identity of relevant degradation products as well as dissociation constant and viscosity are not relevant for this substance in accordance with column 2 of the respective sections of Regulation (EC) No 1907/2006, Annexes VII to IX or Annex XI, section 1.

The granulometry of representative test materials is summarized as follows:

CAS No. 91051-01-3:

D10 = 4.52µm

D50 = 27.43µm

D90 = 78.37µm

67701 -12 -6:

D10 = ca. 25 µm

D50 = ca. 310 µm

D90 = ca. 596 µm

Justification for classification or non classification

Substance fatty acids, tallow, zinc salts does not need to be classified for physico-chemical properties, neither according to Directive 67/548 EEC nor to CLP Regulation (EC) No 1272/2008. Fatty acids, tallow, zinc salts is not flammable, explosive properties are considered non-relevant based on lack of functional groups and oxidizing properties are considered non-relevant based on the chemical structure of the substance. In the long experience with the substance fatty acids, tallow, zinc salts, no indications on metal corrosivity became evident.

This conclusions on non classification is in line to conclusion from EU RAR “Zinc stearate (CAS# 91051-01-3, CAS# 557-05-1) Part I - Environment (Final report R074_0805_env, May 2008):

“Data on boiling point, vapour pressure, and surface tension were not provided. In view of the nature of the substance determination of these parameters is considered to be irrelevant. Information on flammability, explosive properties and oxidizing properties is not available. However, on theoretical considerations the compound is concluded to be not flammable, not explosive and not oxidizing."