Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM) 

Cadmium Toxicity
What is Cadmium?

Learning Objectives

Upon completion of this section, you should be able to:

• identify the chemical properties of cadmium.

Definition

Cadmium is an element. Its most abundant naturally-occurring isotope is non-radioactive. It is found in nature in mineral forms and is obtained for commercial uses principally from cadmium ore, called greenockite, which is commonly found in association with zinc ore. Commercial production of cadmium ore depends on the mining of zinc (ATSDR 1999).

Cadmium is commercially available as an oxide, chloride, or sulfide. Cadmium metal (Cd²⁺) refined from the ore is a silver-white, blue-tinged lustrous heavy metal solid at room temperature (National Toxicology Program [NTP] 2004).

Chemical Properties

Cadmium is an element and is classified as a transition metal.

• Cadmium has a vapor pressure of 1 mmHg at 394ºC and is odorless.
• Cadmium is resistant to corrosion.
• Cadmium metal and its oxides are insoluble in water.
• Occurs in an oxidation state of +2.
• Solid cadmium is inflammable but powdered cadmium will burn and release corrosive and toxic fumes (Harbison 1998; NTP 2004; HSDB 2006; ATSDR 1999).
• Some cadmium salts are water soluble such as cadmium chloride, cadmium sulfate and cadmium nitrate; other insoluble salts can become more soluble by interaction with acids, light or oxygen.
• The melting point of cadmium is 321۫ C.

Key Points

• Cadmium, a heavy metal, is produced by refining zinc ores.
• Cadmium metal is practically insoluble in water but some cadmium salts are water soluble.
• Powdered cadmium will burn and can release corrosive fumes.

Progress Check