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Iodine is a bluish-black, shiny solid that possesses an irritating odour and sublimes easily. Although it is never found as a free element, iodine is less reactive than other members of the halogen family. Iodine was named for the Greek "iodes," meaning violet. When dissolved in various solutions, this element imparts a marvellous purple colour to the liquid.

Iodine is essential for human health. A deficiency in the body can lead to goitre, also known as Derbyshire neck, whereby the thyroid gland becomes swollen. This condition is quite rare today in North America as iodine is a common additive to table salt. Many types of seaweed also contain relatively high concentrations of iodine. In collaboration with the National Research Council Canada (NRC), Acadian Seaplants Limited (ASL) has recently transformed Canadian seaweed into high-value products for international markets, such as Japan. The "Irish Moss" produced using technology developed by NRC and ASL serves as a source of iodine in the diet.

Iodine is an important element in forensics, where it can be used to develop fingerprints. In 1998, the NRC discovered a more efficient method of uncovering fingerprints on the bodies of homicide victims.

Traditional methods had involved fumigating a fingerprint with iodine vapour and then transferring it to a polished silver plate. However, this fingerprint development process posed a high risk of losing the print during the transfer step. NRC has adapted a British technology that was developed for use on paper. The victim's body is exposed to iodine fumes and then sprayed with another chemical (alpha-naphthoflavone). Fingerprints on the victim's skin turn a bright blue-black as a result of the reaction between the two chemicals. This method eliminates the need for a risky transfer of the fingerprint, yet still gives clear evidence of its presence. The technology is being used worldwide today.


Other Applications

  • Iodine compounds are dissolved in alcohol to disinfect wounds.
  • Isotopes of iodine serve as radioactive tracers in the study and treatment of thyroid cancer.