The health-based value relates to total cyanide concentration at the tap, including
cyanide from cyanogen chloride in drinking-water as a by-product of disinfection with
chlorine. Cyanogen chloride rapidly breaks down to cyanide in the distribution system
or when ingested. As the low levels of cyanide normally found in drinking-water
are mostly a consequence of the presence of cyanogen chloride, it is not considered
necessary to develop a guideline value for long-term exposure to cyanide.