Official websites use. Share sensitive information only on official, secure websites. JavaScript appears to be disabled on this computer. Please click here to see any active alerts. Protection of our water resources is compromised by shortcomings in our abilities to adequately determine and reduce the full range of human and ecological health risks posed by waterborne contaminants, including chemicals and microbial pathogens.
EPA researchers are developing and evaluating effective tools to measure waterborne contaminants, which are essential for determining the risks these pollutants pose to people and the environment. With these tools, the source and level of contaminants can be evaluated, the risk posed to exposed communities can be characterized, and approaches for improving affected water resources can be developed. A key responsibility of the EPA under the Safe Drinking Water Act and the Clean Water Act is to develop methods to detect and quantitate waterborne contaminants, including microbes, that affect water systems.
Recent efforts in method development and application have focused on opportunistic pathogens, such as Legionella and Mycobatcteria , which are of particular concern for drinking water systems.
This work has provided more detail on the frequency and level of contamination of these microbes in commercial and residential water systems. In addition, methods for detecting several enteric viruses were used in a large virus occurrence study, and a comparison of staining kits used for detecting the protozoan pathogen Giardia in source water was conducted.
Advancements are also being made toward the development of rapid, nucleic acid based methods to detect somatic coliphages, which are alternative indicators of fecal pollution and an attractive surrogate for viral pathogens. These methods have the potential to provide evidence of fecal contamination in a matter of hours instead of days.
Developing and using methods and models to measure chemical contaminants is a critical responsibility of the Agency. One recent area of focus has been the development and use of occurrence methods to detect several different classes of contaminants of emerging concern CECs , including per- and polyfluoroalkyl substances PFAS and algal toxins.
Collectively this work has helped characterize the level of chemical contamination across the Nation. Tools that enable EPA to measure the impact of contaminants on human health and the environment are essential for determining the risk posed by pollutants. Recent efforts have focused on the use of novel bioassays, such as those based on Adverse Outcome Pathways AOPs or metabolomic techniques, to assess the risk posed by various chemical pollutants.
Chromium III is a nutritionally essential element. Chromium VI is much more toxic than Chromium III and causes liver and kidney damage, internal hemorrhaging, respiratory damage, dermatitis, and ulcers on the skin at high concentrations. Copper Enters environment from metal plating, industrial and domestic waste, mining, and mineral leaching.
Can cause stomach and intestinal distress, liver and kidney damage, anemia in high doses. Imparts an adverse taste and significant staining to clothes and fixtures. Essential trace element but toxic to plants and algae at moderate levels. Cyanide Often used in electroplating, steel processing, plastics, synthetic fabrics, and fertilizer production; also from improper waste disposal.
Poisoning is the result of damage to spleen, brain, and liver. Dissolved solids Occur naturally but also enters environment from man-made sources such as landfill leachate, feedlots, or sewage. A measure of the dissolved "salts" or minerals in the water. May also include some dissolved organic compounds.
May have an influence on the acceptability of water in general. May be indicative of the presence of excess concentrations of specific substances not included in the Safe Water Drinking Act, which would make water objectionable. High concentrations of dissolved solids shorten the life of hot water heaters. Fluoride Occurs naturally or as an additive to municipal water supplies; widely used in industry. Decreases incidence of tooth decay but high levels can stain or mottle teeth.
Causes crippling bone disorder calcification of the bones and joints at very high levels. Hardness Result of metallic ions dissolved in the water; reported as concentration of calcium carbonate.
Calcium carbonate is derived from dissolved limestone or discharges from operating or abandoned mines. Decreases the lather formation of soap and increases scale formation in hot-water heaters and low-pressure boilers at high levels.
Iron Occurs naturally as a mineral from sediment and rocks or from mining, industrial waste, and corroding metal. Imparts a bitter astringent taste to water and a brownish color to laundered clothing and plumbing fixtures. Lead Enters environment from industry, mining, plumbing, gasoline, coal, and as a water additive. Affects red blood cell chemistry; delays normal physical and mental development in babies and young children.
Causes slight deficits in attention span, hearing, and learning in children. Can cause slight increase in blood pressure in some adults. Probable carcinogen. Manganese Occurs naturally as a mineral from sediment and rocks or from mining and industrial waste. Causes aesthetic and economic damage, and imparts brownish stains to laundry. Affects taste of water, and causes dark brown or black stains on plumbing fixtures.
Relatively non-toxic to animals but toxic to plants at high levels. Mercury Occurs as an inorganic salt and as organic mercury compounds.
Enters the environment from industrial waste, mining, pesticides, coal, electrical equipment batteries, lamps, switches , smelting, and fossil-fuel combustion. Causes acute and chronic toxicity. Targets the kidneys and can cause nervous system disorders.
Nickel Occurs naturally in soils, groundwater, and surface water. Often used in electroplating, stainless steel and alloy products, mining, and refining. Damages the heart and liver of laboratory animals exposed to large amounts over their lifetime. Nitrate as nitrogen Occurs naturally in mineral deposits, soils, seawater, freshwater systems, the atmosphere, and biota.
More stable form of combined nitrogen in oxygenated water. Found in the highest levels in groundwater under extensively developed areas. Enters the environment from fertilizer, feedlots, and sewage. Toxicity results from the body's natural breakdown of nitrate to nitrite.
Causes "bluebaby disease," or methemoglobinemia, which threatens oxygen-carrying capacity of the blood. Selenium Enters environment from naturally occurring geologic sources, sulfur, and coal. Causes acute and chronic toxic effects in animals--"blind staggers" in cattle.
Nutritionally essential element at low doses but toxic at high doses. Silver Enters environment from ore mining and processing, product fabrication, and disposal. Often used in photography, electric and electronic equipment, sterling and electroplating, alloy, and solder. Because of great economic value of silver, recovery practices are typically used to minimize loss. Can cause argyria, a blue-gray coloration of the skin, mucous membranes, eyes, and organs in humans and animals with chronic exposure.
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Araya R. Bacterial activity and community composition in stream water and biofilm from an urban river determined by fluorescent in situ hybridization and DGGE analysis. In: Haggblom M. Aerobic bacteria can only convert compounds when plenty of oxygen is present, because they need it to perform any kind of chemical conversion.
Usually the products they convert the contaminants to are carbon dioxide and water. When bacteria are used for water purification there are two sorts of conversion; one of these is anaerobic transfer. This means, that bacteria that are NOT oxygen dependent are converting the contaminants in the water. Anaerobic bacteria can only convert when oxygen levels are low, because they use other sorts of substances to perform chemical conversion. Anaerobic bacteria do not just develop carbon dioxide and water during conversion, but also methane gas.
This can be used to keep the machinery that supports the purification going. The anaerobic conversion of a substance requires more steps than aerobic conversion, but the final result is often less satisfactory. After anaerobic conversion usually aerobic bacteria bacteria that do use oxygen still need to finish the process, because the water is not clean enough yet.
Fertilizers such as phosphate are removed through addition of another chemical, usually iron. The substances than become solid precipitates, that can be filtered from the water. The removal of ammonium and nitrates is a little bit more complicated; it is a purification process that takes both aerobic and anaerobic conversion to remove them.
In the aerobic conversion stage there are two bacterial species involved. Nitrosomonas bacteria that convert ammonia to nitrite and Nitrobacter bacteria that convert nitrite to nitrate after that.
Although nitrate does not represent a direct health threat to most fish, high levels are still undesirable.
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