Changes in bromide concentrations have been observed in the source waters due to natural and anthropogenic changes in watersheds.  Bromide in source water can react with the applied disinfectant (e.g., free chlorine) to form brominated disinfection by-products (DBPs) in drinking water treatment plants.  Brominated-DBPs are more carcinogenic than chlorinated-DBPs, and thus are more of a concern for consumers of treated drinking water.  The formation of DBPs in drinking water depends on source water quality and drinking water treatment plant operations.