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WHO Guidelines 2006

Copper (Cu)

Guideline value 2 mg/litre
Occurrence Concentrations in drinking-water range from £0.005 to >30 mg/litre,
primarily as a result of the corrosion of interior copper plumbing.
Basis of guideline To be protective against acute gastrointestinal effects of copper and
derivation provide an adequate margin of safety in populations with normalcopper homeostasis
Limit of detection 0.02–0.1 mg/litre by ICP/MS; 0.3 mg/litre by ICP/optical emission
spectroscopy; 0.5 mg/litre by FAAS
Treatment achievability Copper is not removed by conventional treatment processes. However,
copper is not normally a raw water contaminant.
Additional comments • For adults with normal copper homeostasis, the guideline value
should permit consumption of2 or 3 litres of water per day, use of
a nutritional supplement and copper from foods without
exceeding the tolerable upper intake level of 10 mg/day or eliciting
an adverse gastrointestinal response.
• Staining of laundry and sanitary ware occurs at copper
concentrations above 1 mg/litre. At levels above 2.5 mg/litre,
copper imparts an undesirable bitter taste to water; at higher
levels,the colour of water is also impacted.
• In most instances where copper tubing is used as a plumbing
material, concentrations of copper will be below the guideline
value. However, there are some conditions, such as highly acidic or
aggressive waters, that will give rise to much higher copper
concentrations, and the use of copper tubing may not be
appropriate in such circumstances.Toxicological review

IPCS concluded that the upper limit of the acceptable range of oral intake in adults
is uncertain but is most likely in the range of several (more than 2 or 3) but not many
milligrams per day in adults. This evaluation was based solely on studies of gastrointestinal
effects of copper-contaminated drinking-water. The available data on toxicity
in animals were not consideredhelpful in establishing the upper limit of the acceptable
range of oral intake due to uncertainty about an appropriate model for humans,
but they help to establish a mode of action for the response. The data on the gastrointestinal
effects of copper must be used with caution, since the effects observed
are influenced by the concentration of ingested copper to a greater extent than the
total massor dose ingested in a 24-h period. Recent studies have delineated the threshold
for the effects of copper in drinking-water on the gastrointestinal tract, but there
is still some uncertainty regarding the long-term effects of copper on sensitive populations,
such as carriers of the gene for Wilson disease and other metabolic disorders
of copper homeostasis.

History of guideline developmentThe 1958 WHO International Standards for Drinking-water suggested that concentrations
of copper greater than 1.5 mg/litre would markedly impair the potability of the
water. The 1963 and 1971 International Standards retained this value as a maximum
allowable or permissible concentration. In the first edition of the Guidelines for Drinking-
water Quality, published in 1984, a guideline valueof 1.0 mg/litre was established
for copper, based on its laundry and other staining properties. The 1993 Guidelines
derived a provisional health-based guideline value of 2mg/litre for copper from the
PMTDI proposed by JECFA, based on a rather old study in dogs that did not take into
account differences in copper metabolism between infants and adults. The guideline
value was consideredprovisional because of the uncertainties regarding copper toxicity
in humans. This guideline value was retained in the addendum to the Guidelines
published in 1998 and remained provisional as a result of uncertainties in the
dose–response relationship between copper in drinking-water and acute gastrointestinal
effects in humans. It was stressed that the outcome of epidemiological studies
in...