Fluoride in drinking water is a case where the dose determines the effect. At low concentrations (0.7 mg/L — the current US public water fluoridation…

Nitrates are one of the most common groundwater contaminants in the United States, particularly in agricultural regions where nitrogen fertilizers and animal waste enter the

Lead doesn’t belong in drinking water at any concentration. The EPA’s current action level is 15 parts per billion (ppb), but the agency’s own Maximum