<unk> is used to treat and prevent<unk> deficiency and as an antiseptic. For<unk> deficiency it can be given by mouth or injection into a muscle. As an antiseptic it may be used on wounds that are wet or to disinfect the skin before surgery. Common side effects when applied to the skin include irritation and discoloration. When taken by mouth or injection side effects may include allergic reactions, goitre, and thyroid dysfunction. Use during pregnancy is recommended in regions where deficiency is common, otherwise it is not recommended.<unk> is an essential trace element. In 1811, Bernard Courtois isolated<unk> from seaweed while in 1820 Jean-Francois Coindet linked<unk> intake to goiter size. It initially came into use as a disinfectant and for goiter. It is on the World Health Organization's List of Essential Medicines. Table salt with<unk>  known as<unk> d salt, is available in more than 110 countries.
Iodine 
Lindane
Copper 
Chorus
Fluoride
Amine fluoride
Hydrogen fluoride
Sodium fluoride