Evaluating factors that affect copper tasting sensitivity in drinking water
Corrosion of household copper plumbing infrastructure can cause pipe failure and lead to elevated levels of copper in drinking water which can exceed the USEPA health based standard for copper in drinking water of 1.3 mg/L Cu. The purpose of this study was to determine taste thresholds of copper in different types of water, analyze how copper chemistry can affect tasting, determine if common disinfectants influence the taste of copper and evaluate genetic links to copper sensitivity. A one-out-of-five test was used to define thresholds, evaluate disinfectant influences, and examine copper chemistry differences. A difference from control test was used to analyze soluble copper tasting and a one solution test with visual classification was used to discriminate 6-n-propylthiouracil (PROP) taster status.
Solutions containing copper sulfate (0.05 – 8 mg/l Cu) were prepared in distilled water, mineral water of varying pH and mineral water with disinfectant added. Geometric mean copper taste thresholds were 0.48 mg Cu/l and 0.41mg Cu/l in distilled and mineral water pH 7.4 respectively. Logistic regression copper taste thresholds were 1.50 mg Cu/l and 1.96 mg Cu/l in distilled and mineral water pH 7.4 respectively. Soluble copper was readily tasted while particulate copper was poorly tasted. Chlorine and chloramines dosed at typical tap water levels had no significant effect on panelists' tasting abilities for water containing 1 mg/l total copper. Geometric mean copper thresholds values did not correlate with (PROP) status so PROP sensitivity would not be a good indicator for copper sensitivity.