Registration Dossier

Administrative data

Description of key information

The slightly soluble and insoluble zinc compounds (i.e., zinc oxide, zinc hydroxide,  zinc phosphate, zinc carbonate, zinc metal, zinc sulphide as well as Fatty acids, C14 -18 and C16 -18 -unsatd., zinc salts ) are of low acute, dermal and inhalation toxicity not requiring a classification for acute toxicity according to the EC criteria.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
5 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
Value:
50 000 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
Value:
2 000 mg/kg bw

Additional information

FATTY ACIDS, C14 -18 AND C16 -18- UNSATD.,ZINC SALTS:

Fatty acids, C14-18 and C16-18-unsatd., zinc salts (CAS 67701-12-6) is a zinc salt of a fatty acid containing 14-18 C-atoms. Thus, read-across of data available for zinc salts of shorter-chained (C8, 12) and similar chained (C16-18) fatty acids based on structural similarity, water solubility and zinc content in a conservative, worst-case approach is assumed to adequately describe the toxicological potential of Fatty acids, C14-18 and C16-18-unsatd., zinc salts. The read-across to "Zinc", based on the assumption that after intake Fatty acids, C14-18 and C16-18-unsatd., zinc salts is changed (at least in part) to ionic zinc and that only ionic zinc is determining biological activities results in similar or higher effect levels except for inhalation.

Acute toxicity is addressed with substance-specific information and data read-across from relevant zinc soaps (zinc salts of shorter-chained (C8, C12) and similar chained (C16-18) fatty acids) as well as supporting information from slightly soluble/insoluble zinc compounds. Thus, read-across of toxicological data of (i) zinc oxide; (ii) octanoic acid, zinc salt, basic; (iii) zinc dilaurate; and (iv) Fatty acids, C16-18, zinc salts is applied to Fatty acids, C14-18 and C16-18-unsatd., zinc salts. Regarding acute oral toxicity, substance specific data as well as read-across data from different reliable studies conducted with (i) zinc oxide; (ii) Fatty acids, C16-18, zinc salts; and (iii) octanoic acid, zinc salt, basic; are addressed. The LD50 for Fatty acids, C14-18 and C16-18-unsatd., zinc salts was estimated to be greater than 2000 mg/kg bw. Regarding acute inhalative toxicity, different reliable studies conducted with different zinc compounds are read-across to address this endpoint, including (i) zinc oxide; (ii) Fatty acids, C16-C18, zinc salts; and (iii) zinc dilaurate. Based on the lack of an acute inhalative toxicity potential of zinc salts of similar chained (C16-18) and shorter-chained (C12) fatty acids, a similar lack of acute inhalative toxicity is considered for Fatty acids, C14-18 and C16-18-unsatd., zinc salts. The LC50 for Fatty acids, C16-18, zinc salts was estimated to be greater than 50 mg/L and is thus magnitudes higher than the value reported for metal fume fever. A similar conclusion can be drawn for the structural analogue zinc dilaurate for which a LC50 of greater than 5.08 mg/L (actual concentration) was determined. In sum, metal fume fever is not relevant for zinc salts of fatty acids at all.

Regarding acute dermal toxicity, a study is available. Further, following the HERAG guidance for metals and metal salts (see section 7.1.2 of the technical dossier: dermal absorption), negligible percutaneous uptake based on minimal penetration, i.e. a dermal absorption rate in the range of maximally 0.1 - 1.0 %, can be anticipated. Dermal absorption in this order of magnitude is not considered to be “significant”. Furthermore, the LD50 of Fatty acids, C16-18, zinc salts has been estimated to be greater than 2000 mg/kg bw. In sum, acute oral and dermal LD50values exceed 2,000 mg/kg bw.

Conclusions 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 (http://echa.europa.eu/documents/10162/08799aec-42c5-44e0-9969-baa022c66db1):"Zinc distearate does not need to be classified on the basis of its acute toxicity according to the EC criteria."

A similar lack of acute toxicity is considered for Fatty acids, C14-18 and C16-18-unsatd., zinc salts.

Conclusions: Based on substance-specific data and applying read-across, Fatty acids, C14-18 and C16-18 -unsatd., zinc salts does not need to be classified on the basis of its acute toxicity.

ZINC:

With LD50values consistently exceeding 2,000 mg/kg bw, slightly soluble or insoluble zinc compounds such as zinc oxide (LD50ranges between 5,000 and 15,000mg/kg bw), zinc phosphate (LD50is >5,000mg/kg bw), zinc metal (LD50 >2,000mg/kg bw) or zinc sulphide (LD50is >15,000mg/kg bw), show level of acute oral toxicity. Moreover, zinc oxide and zinc metal were further shown to be of low acute inhalation toxicity (i.e., LC50 values of > 5.41 and 5.7 mg/L/4hrs). Given the common characteristics shared via their solubility characteristics, the remaining slightly soluble zinc compounds are also considered to be of low acute inhalation toxicity.

Of significance for humans from an acute toxicity standpoint is the occurrence of metal fume fever following exposure to ultrafine particles of special grades of zinc oxide in context of very specific operations. According to the response from 11 zinc companies to a questionnaire, there have been no observations of zinc metal fume fever over the last decade and in recent occupational practice. However in light of responsible care and since no studies are available that allow the establishment of a NOAEL for metal fume fever with a reasonable degree of certainty, a LOAEL (5 mg ZnO/m3) for 2 hours (showed the typical metal fume fever symptoms beginning 4 to 8 hours after exposure and disappearing within 24 hours) can be used for metal fume fever based on the study by Gordon et al.(1992).

Justification for classification or non-classification

The slightly soluble and insoluble zinc compounds (i.e., zinc oxide, zinc hydroxide, zinc phosphate, zinc carbonate, zinc metal, zinc sulphide as well as

Fatty acids, C14-18 and C16-18-unsatd., zinc salts) are of low acute,dermal and inhalation toxicity not requiring a classification for acute toxicity according to the EC criteria.