Cadmium

CHEMICAL SUBSTANCE IDENTIFICATION

Chemical name

Cadmium (elemental) [1]

Main ions of the substance

Key isotopes

Cadmium ⁺²

¹¹⁴Cd

Synonyms

Cadmium metal, Cadmium cation, Cadmium ion

IUPAC name

CAS No

 7440-43-9

REACH registration number

EC No

231-152-8 [2]

Molecular formula

Cd

Substance group/chemical family

Inorganic substances/transition metal

Appearance

Physical state

Odour

Form

Colour

solid

odourless

silvery-white, bluish white [1]

USES AND HANDLING ISSUES

Relevant identified uses

manufacture of batteries, electrical conductors and metal plating [2]. 

Handling considerations

 Processes and operations which may release cadmium fumes or dust should be enclosed and fitted with exhaust ventilation if practicable. Workers should wear a high efficiency particulate filter respirator or self-contained breathing apparatus in activities where over-exposure is possible. Protective clothing and gloves also should be worn, and these should be removed before leaving work. If contact should occur, immediately wash contaminated skin with large amounts of water. Do not eat, smoke, or drink in work areas.  Cadmium should be stored in closed containers, away from sources of physical damage. [1]

PHYSICO-CHEMICAL PROPERTIES

Molecular weight

112.41 g/mol [1] (Cd elemental)

Bulk density/Specific gravity

8.69 g/cm³ at 25 °C [1]

pH

EC

Melting point

309 - 326 °C @ 101.325 kPa [6], 321°C [1]

Boiling point

767 °C (Cd elemental) [1]

Flash point

Flammability

Non-combustible solid in bulk form, but will burn in powder form. 250°C (cadmium metal dust) [2]

Vapour density

Vapour pressure

0 mmHg (approx) [8] 

Solubility in water

insoluble (Cd elemental) [1]

2.3 - 8.7 mg/L @ 20 °C and pH 7.23 - 8.94 [6]

Solubility in organic solvents

Hydrolysis

Ionicity in water

Surface tension

Dispersion properties

Simple Compounds

Nitrides (Cd₃N₂), Sulfides (CdS), Selenides (CdSe), Tellurides (CdTe), Hydrides (CdH₂), Fluorides (CdF₂), Chlorides (CdCl₂), Iodides (CdJ₂), Oxides (CdO, CdO₂) [12]

Stability and reactivity

Chemical stability

Slowly oxidized by moist air to form cadmium oxide [2].

Reactivity hazards

Cd reacts with acids. This produces flammable/explosive gas (hydrogen). The dust reacts with oxidants, hydrogen azide, zinc, selenium and tellurium. This generates fire and explosion hazard [2].

Corrosivity

Corrosion resistance poor in industrial atmosphere [1]

Polimerization

Incompatibility with various substances

Strong oxidizers; elemental sulfur, selenium & tellurium

Physical, chemical and biological coefficients

Koc

Kow

pKa

Henry-constant

ENVIRONMENTAL FATE AND BEHAVIOUR

Artificial pollution sources

Liberation during smelting and refining of ores where it is a by-product of zinc, lead and copper bearing ores. Liberation during recovery of metal by processing scrap; during melting and pouring of cadmium metal; during casting of alloys for cadmium-copper, cadmium-lead, cadmium-bismuth, cadmium-silver, cadmium-nickel, cadmium-lead-silver, cadmium-lead-silver-nickel, cadmium-lead-bismuth-tin, and cadmium-gold products used for coating telephone cables, trolley wires, welding, electrodes, automatic sprinkling systems, steam boilers, fire alarms, high pressure/temperature bearings, starting switches, aircraft relays, light duty circuit breakers, low temperature solder, and jewellery. Liberation during fabrication of metal, alloys, or plated steel. Liberation during casting and use of solders; during melting of cadmium ingots for paint and pigment manufacture used for colouring of plastics and ceramic glazes, electroplating, and in chemical synthesis. Liberation during coating of metals by hot dipping or spraying. Liberation during manufacture of nickel-cadmium batteries for use in radio portable telephones, convenience appliances, and vented cells used in airplanes, helicopters, and stand-by power and lighting [1].

General terrestrial fate

In all soil types, Cd activity is strongly affected by pH; it is more mobile in acidic soil within the pH range of 4.5 to 5.5, and its solubility is largely controlled by organic matter and sesquioxides. In alkaline soil, Cd is rather immobile and precipitation of Cd compounds occur. The critical acidity in mineral soil is between pH 4.0 to 4.5, at which a drop in pH of merely 0.2 units results in a 3 to 5 times increase of Cd concentration in soil solutions. Cd readily forms complexes in solution with halides, cyanides and ammonium species, and has a strong affinity for organic matter [10].

General aquatic fate

high mobility especially during conditions of elevated flow, when pH is lower [10].

General atmospheric fate

General persistence and degradability

Abiotic degradation and metabolites

Biodegradation and metabolites

Volatilization

Photolysis

Hydrolysis

Soil adsorption and mobility

In the surface environment, Cd is most mobile under oxidising conditions at pH levels below 8.

Measured data

Cadmium is a widely but sparsely distributed element found in the earth's crust at concentrations ranging from 0.1 to 0.5 ppm, primarily as sulfide minerals in association with zinc ores, zinc-bearing lead ores, and complex copper-lead-zinc ores. Greenocktite (CdS) is found associated with zinc ore, sphalerite (ZnS); zinc carbonate contains otavite (CdCO3) in small amounts. Cadmium abundance in seawater is estimated as 0.11 ug/L[1]. Cadmium values in stream water range from <0.002 to 0.53 μg /L. The median Cd content is 0.09 mg kg-1 in subsoil and 0.145 mg/kg in topsoil; the range varies from < 0.01 to 14.2 mg/kg in subsoils and up to 14.1 mg/kg in topsoils. The average ratio topsoil/subsoil is 1.477. The median Cd content in stream sediment is 0.29 mg/kg, and the range varies from <0.02 to 43.1 mg/kg [10].

ECOTOXICOLOGICAL INFORMATION

General adverse effects on ecosystem

Acute toxicity (LC50, EC50)

Aquatic systems

Terrestrial systems

LC50=16 µg Cd/L, (96 hr) (flow system) Mortality, Mysidopsis bahia (adult shrimp) [4]

LC50=1.62 mg Cd/L, (96 hr) (static) Mortality, Mytilus edulis planulatis (mussel) [4]

LC50<1 mg Cd/L, (8 hr) Tetrahymena pyriformis (freshwater protozoan) [4]

LC50 (24 days) 34 - 2 300 µg/L (fish) [6]

LC50 (4 days) 748 - 6 470 µg/L (fish) [6]

EC50 (24 h) 1.9 mg/L (aquatic invertebrates) [6]

LC50 (48 days) 110 - 750 µg/L (aquatic invertebrates)[6]

LC50 (4 days) 5 - 1 820 µg/L (aquatic invertebrates)[6]

LC50 (72 h) 8.88 µg/L (aquatic invertebrates)[6]

LC50 (60 h) 15.8 µg/L (aquatic invertebrates)[6]

EC50 (72 h) 18 - 120 µg/L aq. algae & cyanobacteria [6]

Routes of human exposures

inhalation from ambient air and working environment;

the smoking of tobacco;

ingestion from drinking water and food;

hand-to-mouth route for children;

absorption via skin;

absorption via intestinal tract;

absorption via inhalation [3].

General effects

pulmonary edema, dyspnea (breathing difficulty), cough, chest tightness, substernal (occurring beneath the sternum) pain; headache; chills, muscle aches; nausea, vomiting, diarrhea; anosmia (loss of the sense of smell), emphysema, proteinuria, mild anemia [8].

Endocrine disruption

Mutagenicity

Genotoxicity

Cadmium, when given at a dose of 10µmol/l or 1.83 µg/ml for 2 weeks, can induce malignant transformation of human or rat prostatic epithelial cells in vitro [7]

Carcinogenicity

Cadmium and cadmium compounds are carcinogenic to humans (Group 1) [1].

Reprotoxicity

Developmental toxicity

Teratogenicity

Skin, eye and respiratory irritations

It is irritating to the nose and throat [1].

Metabolism:

absorption, distribution & excretion

The absorption or bioavailability of cadmium from the gastrointestinal tract is generally considered to be slightly lower in experimental animals than in humans. For the majority of species tested, the absorption of cadmium can range from 0.5% to 3.0% of the dose administered, while in humans a range of 3.0–8.0% can be found [7].

Exposure limits

(DNEL) 4 µg/m³ (inhalation) (repeated dose toxicity, workers) [6]

(DNEL) 1 µg/kg bw/day (oral) (repeated dose toxicity, general population) [6]

(TWA) 0.005 mg/m³ [8]

Drinking water MAC

Other information

Animal toxicity data

Acute toxicity (LD50)

LD50 63 - 2 330 mg/kg bw (rat) (oral)[6]

LD50 63 - 890 mg/kg bw (mouse) (oral) [6]

LC50 (3 h) 4.6 - 8.4 mg/m³ air (rat) (inhalation)[6]

LC50 (2 h) 4.5 - 132 mg/m³ air (rat) (inhalation)[6]

LC50 (30 min) 8.63 mg/m³ air (rat) (inhalation)[6]]

LC50 (15 min) 9.02 mg/m³ air (mouse) (inhalation)[6]

LC50 (2 h) 4.5 mg/m³ air (inhalation)[6]

Chronic toxicity (NOEL, LOEL)

NOAEL (rat): 0.2 - 3 mg/kg bw/day (oral) [6]

NOAEL (dog): 0.75 mg/kg bw/day (oral) [6]

LOAEL (rat): 0.5 mg/kg bw/day (oral) [6]

NOAEL (rat): 25 µg/m³ air (inhalation) [6]

NOAEL (hamster): 10 µg/m³ air (inhalation) [6]

LOAEL (rat): 50 µg/m³ air (inhalation) [6]

EINECS regulation

̵ 231-152-8

OSHA regulations etc.

NIOSH

OSHA has set the permissible exposure limit (PEL) for cadmium at a time-weighted average (TWA) [8]

The National Institute for Occupational Safety and Health (NIOSH)  has not set a recommended exposure limit (REL) and has designated cadmium as a known human carcinogen [8]

REACH regulation

COMMISSION REGULATION (EC) No 1881/2006 of 19 December 2006

The supply and use of cadmium is restricted in Europe [5]

Current maximum levels for cadmium in certain foods are laid down [11]

Classification and proposed labelling with regard to toxicological data

According to the classification provided by companies to ECHA in REACH registrations this substance is fatal if inhaled, is very toxic to aquatic life, is very toxic to aquatic life with long lasting effects, may cause cancer, causes damage to organs through prolonged or repeated exposure, is suspected of causing genetic defects, is suspected of damaging fertility or the unborn child and catches fire spontaneously if exposed to air [5].

CREATED, LAST UPDATE

Created

4^th of July, 2018

Last update

6^th of July, 2018

REFERENCES

[1] TOXNET – Toxicology Data Network. Available from: https://toxnet.nlm.nih.gov/cgi-bin/sis/search2/f?./temp/~6wVkBb:3, Accessed: 4^th of July, 2018

[2] PUBCHEM - NIH, US National Library of Medicine, National Center for Biotechnology Information, Open Chemistry Database, Available from: https://pubchem.ncbi.nlm.nih.gov/compound/cadmium#section=Canonical-SMILES, Accessed: 4^th of July, 2018

[3] INCHEM - International Programme on Chemical Safety, Environmental Health Criteria 134, Available from: http://www.inchem.org/documents/ehc/ehc/ehc134.htm, Accessed: 4^th of July, 2018.

[4] INCHEM - International Programme on Chemical Safety, Environmental Health Criteria 135,  Available from: http://www.inchem.org/documents/ehc/ehc/ehc135.htm, Accessed: 5^th of July, 2018

[5] European Chemicals Agency (ECHA). Substance information. Available from: https://echa.europa.eu/hu/substance-information/-/substanceinfo/100.028.320, Accessed: 5^th of July, 2018.

[6] European Chemicals Agency (ECHA). Substance information. Available from: https://echa.europa.eu/hu/brief-profile/-/briefprofile/100.028.320, Accessed: 5^th of July, 2018.

[7] INCHEM - International Programme on Chemical Safety, Environmental Health Criteria,  Available from http://www.inchem.org/documents/jecfa/jecmono/v52je22.htm#gen, Accessed: 5^th of July, 2018.

[8] NIOSH. NIOSH Pocket Guide to Chemical Hazards. Cadmium dust (as Cd), Available from: https://www.cdc.gov/niosh/npg/npgd0087.html, Accessed: 5th of July, 2018.

[9] 2002/95/EC (RoHS) - European Commission Decision of 12 October 2006 amending, for the purposes of adapting to technical progress, the Annex to Directive 2002/95/EC of the European Parliament and of the Council as regards exemptions for applications of lead and cadmium (notified under document number C(2006) 4790)". Journal of the European Union. 14 October 2006. Available from: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:283:0048:0049:EN:PDF, Accessed: 5^th of July, 2018.

[10] Cadmium, Available from: http://weppi.gtk.fi/publ/foregsatlas/text/Cd.pdf  , Accessed: 5^th of July, 2018.

[11] Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs, Available from: http://data.europa.eu/eli/reg/2006/1881/2015-05-21,  Accessed: 6^th of July, 2018.

[12] The Mineralogy of Cadmium, Available from: https://www.mindat.org/element/Cadmium, Accessed: 6^th of July, 2018.