Iodine is among the body's essential trace elements. While a
          deficiency in iodine is both easy and inexpensive to
          prevent, IDD (iodine deficiency disorders) nevertheless
          continue to be a significant public health problem in 118
          countries.  An estimated 1571 million people live in
          iodine-deficient environments. A large proportion of the
          severely deficient are women in their reproductive years
          whose babies are at high risk of irreversible mental
          retardation unless they receive adequate amounts of iodine.
          Iodine deficiency not only causes goitre; it may also result
          in irreversible brain damage in the fetus and infant, and
          retarded psychomotor development in the child.  It is the
          most common cause of *preventable* mental retardation.  It
          also affects reproductive functions and impedes children's
          learning ability. Current estimates of daily iodine intakes
          in Canada and the USA, where IDD is no longer a public
          health problem, are substantially above physiological
          need--in the range of 460 microgrammes/day among
          9-16-year-old children, to greater than 1 mg among as many
          as 10-20% of adults. A generally accepted desirable adult
          intake is 100-300 microgrammes/day.  WHO recommends iodized
          salt for iodine supplementation to correct iodine
          deficiency. Iodized oil is the preferred interim measure in
          areas of moderate or severe deficiency that will not be soon
          be covered by iodized salt.  More information is available
          from: Dr Barbara Underwood, Nutrition unit, WHO, 1211 Geneva
          27, Switzerland, e-mail: [log in to unmask]

          Jim Akre, Nutrition unit, WHO