The Primary Drinking Water Standards are the parameters or contaminants that have a specific health concern. Typically, these health specific concerns can occur before the parameter causes or is associated with an aesthetic problem with the water and are associated with the long-term consumption or use of the water as a drinking water source.
They are categorized as a primary contaminant because they can directly impact your health, but, in some cases, they may also be associated with aesthetic problems. They can be characterized as pathogenic or disease-causing or can serve as vectors that facilitate the spread of disease or other disorders.
Inorganics can include a combination of metals, salts, compounds, particles, and mineral complexes and are regulated under both Primary and Secondary Drinking Water Standards. They can pose an acute or chronic health risk or concerns and include Antimony, Arsenic, Barium, Beryllium, Cadmium, Chromium, Copper, Cyanide, Fluoride, Lead, Mercury, Nitrates / Nitrites, Selenium, and Thallium.
Volatile Organic Compounds (VOCs) include a group of organic compounds that have a high vapor pressure and low solubility in water, i.e., chemicals that would prefer to volatilize into the atmosphere then to stay dissolved in the water. Common VOCs include Benzene, Carbon Tetrachloride, Chloroform and Trichloromethane, Ethylbenzene, Methylene Chloride- Dichloromethane (DCM), MTBE- Methyl tert-butyl ether, Tetrachloroethylene, Trichloroethylene, Toluene, and Xylenes.
Synthetic Organic Compounds (SOCs) are man-made compounds that are less volatile, i.e., less likely to escape into the atmosphere, when compared to the volatile organic compounds (VOCs). Most of the SOCs are represented by a combination of Herbicides, Insecticides, Pesticides, and/or Fungicides that can be commonly found in agricultural areas, urban development, and recreational areas.
The most common semi-volatile synthetic organic compounds found in shallow groundwater systems include, Atrazine (trade names AAtrex and Gesaprim) and other trazines, Alachlor (trade names Lasso and Alanox), Metolachlor, Glyphosate (trade names Roundup and Rattler) , 2,4-D (trade names Weed-B-Gon and Chloroxone), Bis (2-Ethylhexyl) phthalate, and gamma-Hexachlorocyclohexane (Lindane).
Disinfection By-products form when disinfecting agents react with naturally-occurring organic compounds in the drinking water when the water is being treated. The reaction of the oxidizing chemicals and the natural organics can create a combination of Trihalomethanes (THMs), Haloacetic Acids (HAA5), Chlorite, and Bromate depending on the type and quantity of the disinfection agent. Common Disinfection By-products regulated by the drinking water standards include: Trihalomethanes, Haloacetic Acids, Chlorite and Bromate.
Radioactive isotopes include both natural and man-made unstable elements and their decay products. As the radioactive isotope decays, depending on the specific isotope, it can emit radiation in a number of forms (alpha, beta, gamma) and generate daughter isotopes which may also be radioactive. Radioactive isotopes which can be important in water include: Uranium (U-238), Plutonium (Pu-239), Radon (Rn-222), and fission reactor products such as Iodine (I-131), Cobalt (Co-60), and (Strontium) Sr-90.