Humans are exposed to disinfection by-products , or DBPs, through drinking-water and oral, dermal, and inhalational contact with chlorinated water ⁶. In populations that take hot showers or baths, inhalation and dermal absorption in the shower accounts for more exposure than drinking water.  Chlorine remains the most widely used chemical for water disinfection in the United States.

Animal research has shown that exposure to high concentrations of DBPs can increase the risk of cancer. There is particular concern about bladder cancer. However, these studies were conducted using DBP concentrations that are much higher than those found in drinking water.

Over the past several years, a handful of studies have also shown a possible link between high levels of DBPs in tap water and adverse effects on reproductive health, including low birth weight and miscarriage. Other studies have failed to demonstrate such a linkage. Experts agree that the research on DBPs and health effects is preliminary and inconclusive, so research is ongoing.

For more on DBPs, see this page on the CDC (Centers for Disease Control) website.