Gastrointestinal effects associated with soluble and insoluble copper in drinking water

The aim of this study was to determine whether total copper or soluble copp er concentration is associated with gastrointestinal signs and symptoms. Fo rty-five healthy adult women (18-55 years of age), living in Santiago, Chil e, ingested tap water with 5 mg/L of copper containing different ratios of soluble copper (copper sulfate) and insoluble copper (copper oxide) over a 9-week period. Three randomized sequences of the different copper ratios (0 :5, 1:4, 2:3, 3:2, and 5:0 mg/L) were followed. Subjects recorded their wat er consumption and gastrointestinal symptoms daily on a special form. Mean water consumption was similar among groups. Serum copper levels, ceruloplas min, and activities of liver enzymes were within normal limits. No differen ces were detected between the means of biochemical parameters at the beginn ing and at the end of the study. Twenty subjects presented gastrointestinal disturbances at least once during the study, 9 suffered diarrhea (with or without abdominal pain and vomiting), and the other 11 subjects reported ab dominal pain, nausea, or vomiting. No differences were found in incidence o f abdominal pain, nausea, vomiting, and diarrhea regardless of the ratio of copper sulfate to copper oxide. In conclusion, both copper sulfate (a solu ble compound) and copper oxide (an insoluble compound) have comparable effe cts on the induction of gastrointestinal manifestations, implying that simi lar levels of ionic copper were present in the stomach.