Water Quality Standards

Nickel is used mainly in the production of stainless steel and nickel alloys. Food is the dominant source of nickel exposure in the non-smoking, non-occupationally exposed population; water is generally a minor contributor to the total daily oral intake. However, where there is heavy pollution or use of certain types of kettles, of non-resistant material in wells, or of water that has stood for an extended time in water pipes, the nickel contribution from water may be significant.

As regards health risks, inhalation is an important route of exposure to nickel and its salts; IARC concluded that inhaled nickel compounds are carcinogenic to humans (Group 1) and metallic nickel is possibly carcinogenic (Group 2B). However, there is a lack of evidence of a carcinogenic risk from oral exposure to nickel.

In several limited studies in rats, the NOAEL was approximately 5 mg of nickel per kg of body weight per day. In a recent careful two-generation study in rats, dose-related increases in perinatal mortality were observed, giving a LOAEL of 1.3 mg/kg of body weight per day in the second litter, whereas the LOAEL in the first litter was 31.6 mg/kg of body weight per day. These variations in response between successive litters make it difficult to draw firm conclusions from this study. In addition, a NOAEL of 7 mg of nickel per kg of body weight per day was derived from a more limited two-generation study in rats.

The guideline value for nickel of 0.02 mg/litre is maintained because, on the basis of the available data, it is considered to provide sufficient protection for individuals who are sensitive to nickel. Owing to uncertainties about the effect level for perinatal mortality, however, the value is considered to be provisional.