Nitrates and nitrites stem from agricultural runoff, fertilizers, septic tanks and some industrial processing. Nitrate ingestion is the cause of oxygen deprivation in babies, called blue-baby syndrome. Synthetic organic chemicals are also prevalent in modern industry, used in everything from pesticides to cosmetics to common plastics. Despite their pervasiveness, little or no research has been conducted to determine their health risks and, consequently, their safety rating in water. Based on a 1995 study conducted by the nonprofit Environmental Working Group, one glass of tap water in Fort Wayne, Ind., contained nine different pesticides.
Radioactive materials are both natural and man-made.
Different parts of the country are susceptible to varying types of radioactive materials. Man-made radioactive materials originated with the introduction of nuclear energy and are all carcinogenic. Nuclear facilities, active or inactive, and mining areas carry high risks for contaminating water with radioactive materials. Additives , such as chlorine, are also included in drinking water. THMs have been associated with rectal and bladder cancers, as well as birth defects.