User:Elinf5/Drinking water quality in the United States

Original article link: Drinking water quality in the United States

Disinfectants
The EPA has released standards for many chemicals including disinfectants used to treat drinking water under the SDWA. Germs can contaminate water which puts public health at risk including carrying disease causing germs such as Salmonella, Campylobacter, and norovirus. These germs need to be killed off through a disinfect process that is usually done with chlorine or chloramine. Disinfection with chlorine is called chlorination and disinfection with chloramine is called chloramination. Both of these processes include disinfecting the water by adding the chemicals to it which is meant to destroy any germs or bacteria that came in contact with the water. Officials may switch off from chlorine and chloramine in an effort to decrease the risk of biofilm in pipes. Chlorine and chloramine are allowed at a level of up to 4 milligrams per liter (mg/L) or 4 parts per million (ppm) in drinking water. However, federal standards includes antimicrobials and any pesticide products and devices that make antimicrobial claims. Products that make such claims must be registered under the EPA before use and distribution. EPA has issued standards for chlorine, monochloramine and chlorine dioxide and ozone and/or ultraviolet light (UV). These chemicals must meet the regulations and standards of the SDWA and FIFRA before being released and approved for drinking water disinfection to the public.

Chromium
The United States Environmental Protection Agency’s implemented federal standards in 1991 to ensure that total chromium is limited to 0.1 milligrams per liter or 100 parts per billion in drinking water. It is an odorless and tasteless metal that can be naturally occurring in rocks, plants, soil and volcanic dust, and animals. It can also be introduced to the environment through man made processes such erosion of natural chromium deposits, leakage, poor storage, or inadequate industrial waste disposal practices. In large doses human consumption or exposure can lead to adverse health effects including cancer, eye, stomach, and respiratory tract issues. An example of this chemical causing adverse health issues is through a well-known Hexavalent chromium pollution event in Hinkley, CA. Hexavalent is a form of total chromium known as Chromium 6. Groundwater contamination in Hinkley, California was caused by water containing hexavalent chromium being dumped on the ground by Pacific Gas and Electric from 1952 to 1966. PG&E used this chemical to deter corrosion in their cooling towers. The use of this chemical in cooling towers lead to a wastewater leakage into unlined ponds at their cooling tower sites. This, in turn, turned into groundwater contamination which adversely affected the town of Hinkley, CA. The contamination resulted in a $333 million settlement in 1996. The clean-up process is still on-going through monthly monitoring reports by PG&E. This case has led to California being the only state in the US to adopt an MCL specifically for Hexavalent Chromium instead of relying on an overall total chromium count. California monitors chromium 6 in 10 ppb.

Organic chemicals
EPA has issued standards for 65 organic compounds, including benzene, dioxin (2,3,7,8-TCDD), PCBs, styrene, toluene, vinyl chloride and several pesticides. The presence of organic chemicals in water can cause an issues for human health and adverse effects on the environment will occur. This is especially because processes such as disinfection by chlorine can cause toxic chemical reactions to occur and leak out into the surrounding area. Some sources of these organic chemicals include pesticides and herbicides, polychlorinatedbyphenlys, industrial/commercial organics, and disinfection by products. Detection and regulation of these chemicals is key. Organic chemicals can be characterized in 3 separate categories including Inorganic Contaminants (IOCs) (including arsenic and nitrate), Volatile Organic Contaminants (VOCs), and Synthetic Organic Contaminants (SOCs). VOCs and SOCs do not reside naturally in drinking water and occur when they are improperly stored or leaked into the water systems through contamination. This is why it is important to pay attention to the improper and proper disposal techniques of even household cleaning chemicals.

Radionuclides
Radionuclides are reactive forms of elements that can be present in drinking water either through man made or natural processes. Every radionuclide has its own half life therefore has its own specific rate of measurement before decaying. There are some radionuclides that decay in seconds while others takes millions of years. Once it decays radionuclides turn into radioisotopes. This process emits radiation. Exposure to radiation to lead to acute and chronic consequences for human health including radiation sickness, cancer, and cardiovascular disease. The EPA has issued standards for alpha particles, beta particles and photon emitters, radium and uranium. There is a combined standard of 4 mrem/year for beta emitters, a gross alpha standard for all alphas of 15 pCi/L, and a combined radium 226/228 of 5 pCi/L. Uranium and radium are given a different standard of 30 µg/L. . The regulation of radionuclides began in 1977 and updated in 2000 to ensure that the maximum contaminant levels (MCL) are met according to the Radionuclides Rule in the state and public water systems.

Unregulated Contaminant Monitoring (UCMR)
There are certain chemicals in drinking water that are regulated because they do not have health based standards under the Safe Drinking Water Act. This is because they are flagged for being a risk to public safety due to its known adverse health effects in large quantities. Because of the cause for concern or potential risk for public safety a program was designed to keep track of whether or not these chemicals reside in water systems and at what level so that the federal government can decide if they need to be regulated in the future. This is done through the UCMR program which was established through amendments to the SDWA in 1996, 2018, and 2021. This program establishes priority chemicals that need to be monitored through data collection every 5 years through a regulation system using Maximum Contaminant Levels (MCLs). The UCMR program monitors a list of chemicals in water systems serving 3,300-10,000+ people and stores the data of the Contaminant Candidate List (CCL) chemicals in a National Contaminant Occurrence Database. UCMR 1 was released in 1990 and as of 2021, the EPA has released the Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) which has listed 30 contaminates they are watching and tracking across the country. These include 29 Per- and Polyfluoroalkyl Substances (PFAS) and lithium. The UCMR 5 includes an expanded list of PFAS constituents and additional public water systems.