Calcium

Endpoint summary

Description of key information

As testing of elemental calcium is not technically feasible because of its reactivity in air or water, acute toxicity was evaluated based on (1) the exposure considerations in its use industrial applications as well as based on (2) the read-across data from relevant calcium compounds.

1. Based on the Ca use in metallurgical use applications,
   a) acute oral toxicity was not considered to be relevant exposure route when assessing the human health hazard.
   b) acute dermal toxicity of elemental calcium in its industrial use applications, exposure potential is negligible and qualitative assessment of risk indicates that the risk is low, particularly as a result of the use of existing risk management measures in place (see chapter 9 and 10 in CSR).
   c) With respect to Ca use in its industrial applications, it appears that there is the possibility for inhalation exposure of the workers to Ca from the dust or fume. Therefore, inhalation was considered as relevant exposure route for acute toxicity, and the quantitative exposure assessment was considered necessary (see chapter 9 in CSR). However, the RCR with existing RMMs indicated low level of concern (see chapter 9 and 10 in CSR).


2. Testing of elemental Ca is not technically feasible because Ca metal reacts with water, evolving hydrogen gas. In powdered form the reaction with water is extremely rapid. In the Ca-water reaction calcium dihydroxide (Ca(OH) 2) is formed. Therefore, the acute toxicity was evaluated based on surrogate data from calcium dihydroxide (Ca(OH) 2). The subsequent reaction with air (calcium oxide) and moisture results in calcium hydroxide which is considered non-hazardous for human regarding acute toxicity, only exerting local irritative effects upon first contact on external surfaces of the human body. Upon this first contact exothermal reaction causes hydroxyl ion to liberate affecting skin and mucous membranes. Accidental exposure may cause desiccation of these tissues.

Additional information

Testing with metallic calcium is technically not possible due to its reactivity. Calcium is used in industrial settings and its life-cycle ends on these uses before it reaches general population, therefore only routes relevant for occupational exposure are assessed.

Based on the Ca use in metallurgical use applications, acute oral toxicity was not considered to be relevant exposure route when assessing the human health hazard. The acute oral toxicity was evaluated using supporting information from calcium dihydroxide in case of accidental ingestion. As a conclusion, calcium is an essential element which is regulated by homeostasis in the human body. Subsequent reaction product of calcium, calcium dihydroxide, has not shown any adverse effects in acute toxicity testing performed. In acute oral testing of calcium dihydroxide, no deaths occurred at the limit dose of 2000 mg/kg bw. Therefore the derived LD50 for calcium dihydroxide is >2000 mg/kg bw is considered as supportive information.

 

When considering the acute dermal toxicity of elemental calcium in its industrial use applications, exposure potential is negligible and qualitative assessment of risk indicates that the risk is low, particularly as a result of the use of existing risk management measures in place (see chapter 9 and 10 in CSR). Systemic effects were considered irrerelevant. However, the acute dermal toxicity was evaluated using supporting information from calcium dihydroxide in case of accidental exposure, no deaths occurred at the limit dose of 2500 mg/kg bw in acute dermal testing of calcium dihydroxide. Therefore the derived LD50 for calcium dihydroxide is >2500 mg/kg bw is considered as supportive information.

Acute inhalation testing is considered technically unfeasible because of the reactive nature of elemental calcium.With respect to Ca use in its industrial applications (e.g. raw material handling and Ca-wire production), it appears that there is the possibility for inhalation exposure of the workers to Ca from the dust or fume.Therefore, inhalation was considered as relevant exposure route for acute toxicity, and the quantitative exposure assessment was considered necessary (see chapter 9 in CSR). However, the RCR with existing RMMs indicated low level of concern according to quantitative assessment based on recommendations set for CaO/CaOH2 by Scientific Committee on Occupational Exposure Limits (2008), due to their irritative properties upon first contact on external surfaces of the body (see chapter 9 and 10 in CSR).

Justification for classification or non-classification

There is no need for calcium (metal form) to be classified as hazardous for acute toxicity.

(1)    Metallic calcium is not bioavailable.

(2)    Calcium and its subsequent reaction products (CaO and Ca(OH)2) have not exhibited toxicity in performed acute toxicity testing.