Zinc selenite

Endpoint summary

Description of key information

Acute toxicity, oral: LD50 of zinc selenite between 50 and 500 mg/kg bw for males/females (200 and 500 mg/kg bw for males and between 50 and 200 mg/kg bw  for females) (study report)
Acute toxicity, inhalation: LC50 of zinc selenite = > 1 - 5 mg/L air, cut-off value 5 mg/L air (study report)
Acute toxicity, dermal: derogation statement included; no testing required since inhalation route is the more likely route of exposure

Additional information

General

A literature search and evaluation programme on animal and human acute toxicity data of zinc selenite has been conducted. All data sources were assessed by expert toxicologists for quality and reliability, as well as relevance for regulatory risk assessment under REACH. The documentation of the literature search is attached to the technical dossier.

Acute toxicity, oral:

The study report (Prinsen, 1996) was conducted according to GLP and OECD guidelines and is considered to be reliable. Thus, the resulting LD50 values (LD50 between 50 and 500 mg/kg for males and females) is used for classification of zinc selenite for acute oral toxicity.

Acute toxicity, inhalation:

The test data (GLP, OECD guideline conform) is reliable without restrictions.

Acute toxicity, dermal:

No relevant data on acute dermal toxicity are available for zinc selenite. However, according to the data requirements as outlined in section 8.5, Column 2, Annex VIII, of Regulation (EC) 1907/2006 the choice for the second route of exposure shall depend on the nature of the substance and the likely route of human exposure. The inhalation route is considered as the major route of exposure. Furthermore, the physicochemical and toxicological properties do not suggest potential for significant rate of absorption through the skin. Following the HERAG guidance for metals and metal salts (see section 7.1.2 of the technical dossier, dermal absorption), 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”.

Justification for classification or non-classification

Acute toxicity, oral:

The reference Prinsen (1996) is considered as the key study for acute oral toxicity and will be used for classification. On the basis of the mortality observed, the oral LD50 of zinc selenite is considered to be between 50 and 500 mg/kg body weight for males and females. Thus, a classification and labelling as "acute tox 3"; H301 (toxic if swallowed) is required for zinc selenite according to Regulation (EC) 1272/2008 and subsequent regulations.

This classification is in accordance with the harmonised classification of zinc selenite (as a group entry: selenium compounds except cadmium sulphoselenide) as laid down in regulation (EC) 1272/2008 and subsequent regulations.

 

Specific target organ toxicant (STOT) – single exposure: oral

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, oral are not met for zinc selenite.

Acute toxicity, inhalation:

The study report by Leuschner (2010) is considered as the key study for acute inhalation toxicity and will be used for classification. The test result, (LC50 of zinc selenite: > 1 - 5 mg/L air, with a cut-off value 5 mg/L air) leads to a classification as “acute toxic cat. 4”, H332 (harmful if inhaled) according to regulation (EC) 1272/2008 and subsequent regulations.

 

The current classification for zinc selenite is “acute toxic cat. 3“, H331 (toxic if inhaled) and is based on a group entry for “selenium compounds except cadmium sulphoselenide“ (Index No. 034-002-00-8) in regulation (EC) 1272/2008. However, the new experimental data (reliable without restrictions) for zinc selenite resulting in an LC50 >1 – 5 mg/l air, leads to a less severe classification as “acute toxic cat. 4”, H332 (harmful if inhaled). Since this test result is based on a substance specific study it is proposed to correct the classification of zinc selenite according to the study result by replacing the classification H331 by the new classification H332 in accordance with Regulation (EC) 1272/2008 and subsequent regulations.

 

Specific target organ toxicant (STOT) – single exposure: inhalation

Slight ataxia, slight to moderate tremor and slight dyspnoea were observed among the test animals only on day 1 after exposure. No other clinical signs were noted. It can be concluded that the classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure are not met for zinc selenite.

Acute toxicity, dermal:

No relevant data is available for zinc selenite. Following the HERAG guidance for metals and metal salts (see section 7.1.2 of the technical dossier, dermal absorption), 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”. In conclusion, testing for acute toxicity of zinc selenite via the dermal route is not required according the criteria laid down in Annex VIII, point 8.5.

Thus, concerning dermal toxicity of zinc selenite, following the criteria specified in Regulation (EC) 1272/2008 and subsequent regulations, the test item shall not be classified as acutely toxic via the dermal route.