Inorganic Chemical Constituents with Health Significance
Constituent Remarks (Sources/Occurrence)
Antimony Antimony is a contaminant from pipe and fitting materials. It is not a raw water contaminant.
Arsenic For existing water supply systems.
Barium Barium occurs naturally as trace elements in both igneous and sedimentary rocks.
Boron Present in surface water due to discharge of treated sewage effluent, which still contains detergents; could be naturally occurring in certain areas. Maximum level has been elevated from 0.3 mg/L (PNSDW 1993) to 0.5 mg/L (PNSDW 2007) because it is difficult to achieve in areas with high natural levels and limited access to treatment technology.
Cadmium Cadmium is used in manufacture of steel, plastics and battery and released to the environment through wastewater or fumes. Cadmium is released in water supply as impurity of the zinc coating of galvanized pipes and solders and metal fittings.
Chromium (Total) Chromium is widely distributed in the Earth’s crust. Occurs in wastewater in certain industries such as chromium plating of bumpers, grills and ornaments.
Cyanide (Total) Cyanides are occasionally found in drinking water primarily as a consequence of industrial contamination.
Fluoride In areas where high natural fluoride levels occur, the maximum level may be difficult to achieve due to limited access to treatment technology.
Lead Lead may be present in water primarily from plumbing systems containing lead pipes, solder, fittings or the service connections to the homes. Although it may be found naturally occurring in certain areas, rarely is it present in water supply as a result of its dissolution from natural sources.
Mercury (Total) Mercury is used in industries such as in the electrolytic production of chlorine, in electrical appliances, in dental amalgams and as a raw material for various mercury compounds. Mercury occurs naturally in freshwater and groundwater in the inorganic form. Methylation of inorganic mercury occurs in freshwater and seawater.
Nickel Nickel is very toxic and usually occurs in water supply as a result of nickel or nickel-plated plumbing components. Although nickel could be naturally occurring in certain areas, it is not usually a raw water contaminant.
Nitrate Nitrate concentration in groundwater and surface water can reach high levels as a result of leaching or run-off from agricultural land or contamination from human or animal wastes. Anaerobic conditions may result in the formation and persistence of nitrite.
Nitrite
Selenium Selenium occurs naturally in groundwater sources.
Chlorate
Chloral hydrate (trichloroacetaldehyde) Chloral hydrate is formed as a by-product of chlorination when chlorine reacts with humic acids.
Dibromoacetonitrile Dibromoacetonitrile is produced during water chlorination from naturally occurring substances including algae, fulvic acid and proteinaceous material.
Dichloroacetic acid Chlorinated acetic acids are formed from organic material during water chlorination.
Dichloroacetonitrile Dichloroacetonitrile is produced during water chlorination from naturally occurring substances including algae, fulvic acid and proteinaceous material.
Formaldehyde Formaldehyde in drinking water results primarily from oxidation of natural organic matter during ozonation and chlorination.
Monochloroacetate Chlorinated acetic acids are formed from organic material during water chlorination.
Trichloroacetate Chlorinated acetic acids are formed from organic material during water chlorination.
2,4,6-trichlorophenol Chlorophenols are present in drinking water as a result of the chlorination of phenols, as by-products of hypochlorite with phenolic acid, as biocides or as degradation products of phenoxy herbicides.
Trihalomethanes
Bromoform Trihalomethanes are generated principally as by-products of chlorination of drinking water, being formed from naturally occurring organic compounds.
Dibromochloro-methane
Bromodichloro-methane
Chloroform

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