Most trace elements in drinking water are of concern
from a public health point of view because of
potential for excess above recommended limits.
However, some trace elements are essential to health
and so are required to be present at certain
concentrations in drinking water or food. Iodine is
one such essential element. Deficiency in dietary
iodine can lead to a number of iodine-deficiency
disorders (IDDs) in humans. No regulations or
recommendations are placed on concentrations of
iodine in drinking water because such standards are
imposed to regulate upper rather than lower limits.
Iodine may also be potentially detrimental to health at
high concentrations, but the element usually behaves
in a similar way to chlorine in nature and hence
iodine-rich waters are likely to be rendered unfit for
potable use due to high salinity before iodine becomes
a significant problem
