Some experts estimate 50 ppb may pose as much as a 1 in 50 risk of cancer. Nonmetallic inorganics include asbestos, cyanide, and nitrates and nitrites. The carcinogen asbestos is quite prevalent throughout the country due to the presence of asbestos-cement in water mains. Cyanide enters the water system through insecticides and plastics manufacturing. 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.