Acute gastrointestinal effects of graded levels of copper in drinking water

The objective of this study was to determine the acute gastrointestinal eff ects caused by the consumption of drinking water containing graded levels o f added copper. Sixty healthy, adult women were randomly assigned to receiv e copper [Cu(II)] at four concentrations in their drinking water following a Latin-square design. Each group (n = 15) received tap water with no added copper, 1, 3, and 5 mg Cu/l of added copper sulfate for a 2-week study per iod, followed by 1 week of standard tap water. The subjects recorded their water consumption and gastrointestinal symptoms daily on a special form. Th e average daily consumption of water was 1.64 liters per subject, regardles s of the amount of copper added. Final serum copper, ceruloplasmin, and liv er enzymes were measured in all subjects and were not different from baseli ne concentrations. Twenty-one subjects (35%) recorded gastrointestinal dist urbances sometime during the study, 9 had diarrhea, some with abdominal pai n and vomiting, and 12 subjects presented abdominal pain, nausea, or vomiti ng. There was no association between copper levels in drinking water and di arrhea. However, nausea, abdominal pain, or vomiting were significantly rel ated to copper concentrations in water. The recorded incidence rate of thes e symptoms was 5, 2, 17, and 15% while ingesting water with 0, 1, 3, and 5 mg Cu/l, respectively (overall chi(2) = 11.3, p<0.01; Cu less than or equal to 1 mg/l versus Cu greater than or equal to 3 mg/l, chi(2), p<0.01). When subjects interrupted their consumption of drinking water with added copper , most symptoms disappeared. We conclude that under the conditions of the s tudy, there was no association between aggregate copper in drinking water w ithin the range of 0-5 mg/l and diarrhea, but a greater than or equal to 3 mg Cu/l level of ionized copper was associated with nausea, abdominal pain, or vomiting. Additional studies with sufficient numbers of subjects are ne eded to define thresholds for specific gastrointestinal symptoms with preci sion and to extrapolate these results to the population at large.