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Disinfection by-product
 
 
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Disinfection by-products (DBPs) form when organic materials in source water react with chemical treatment agents
Chlorination

Chlorination is the process of adding the element chlorine to water as a method of water purification to make it fit for human consumption as drinking water....
 at the drinking water treatment
Water purification

This article discusses large scale, municipal water purification. For portable/emergency water purification, see Portable water purification.Water purification is the process of removing undesirable chemical and biological contaminants from raw water....
 plant . Since chlorination is the most widely form of disinfection, DBPs may also be referred to as chlorination by-products (CBPs).

For example, chlorinated disinfectants (e.g. free chlorine, chlorine dioxide) introduced into the water to destroy pathogenic microbes and form a residual chlorine component such that drinking water may reach the consumer tap safe from microbial contamination, may react with naturally present fulvic and humic
Humic acid

Humic acid is one of the major components of humic substances which are dark brown and major constituents of soil organic matter humus that contributes to soil chemical and physical quality and are also precursors of some fossil fuels....
 acids to produce a range of DBPs including trihalomethanes, haloacetic acids
Haloacetic acids

Haloacetic acids are carboxylic acids in which a halogen atom takes the place of a hydrogen atom in acetic acid. Thus, in a monohaloacetic acid, a single halogen would replace a hydrogen atom....
 and many others.






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Disinfection by-products (DBPs) form when organic materials in source water react with chemical treatment agents
Chlorination

Chlorination is the process of adding the element chlorine to water as a method of water purification to make it fit for human consumption as drinking water....
 at the drinking water treatment
Water purification

This article discusses large scale, municipal water purification. For portable/emergency water purification, see Portable water purification.Water purification is the process of removing undesirable chemical and biological contaminants from raw water....
 plant . Since chlorination is the most widely form of disinfection, DBPs may also be referred to as chlorination by-products (CBPs).

For example, chlorinated disinfectants (e.g. free chlorine, chlorine dioxide) introduced into the water to destroy pathogenic microbes and form a residual chlorine component such that drinking water may reach the consumer tap safe from microbial contamination, may react with naturally present fulvic and humic
Humic acid

Humic acid is one of the major components of humic substances which are dark brown and major constituents of soil organic matter humus that contributes to soil chemical and physical quality and are also precursors of some fossil fuels....
 acids to produce a range of DBPs including trihalomethanes, haloacetic acids
Haloacetic acids

Haloacetic acids are carboxylic acids in which a halogen atom takes the place of a hydrogen atom in acetic acid. Thus, in a monohaloacetic acid, a single halogen would replace a hydrogen atom....
 and many others. Residual chlorine may also react further within the distribution network if it comes into contact with organic material accumulated there e.g. as biofilms. In addition to being highly influenced by the types of organic and inorganic matter in the source water, the different species and concentrations of DBPs vary according to e.g. chlorine dosing at the drinking water disinfection stage, the time since dosing, temperature, pH of the water . Ozone reacts with bromide
Bromide

A bromide ion is a bromine atom with electric charge of -1.Compounds with bromine in formal oxidation state -1 are called bromides, and each individual chemical in this class can be called a bromide, as well....
 (oxidization
Oxidization

Oxidization may refer to:* Oxidation* Beta oxidation* RustSee also * Redox...
) to create hypohalous acids, aldehyde
Aldehyde

An aldehyde is an organic compound containing a terminal carbonyl group. This functional group, which consists of a carbon atom bonded to a hydrogen atom and double bond to an oxygen atom , is called the aldehyde group....
s and carboxylic acid
Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
s.. Ozone is not as common due to the high costs. Data on it's DBPs is not sufficiently researched.

Occurrence

DBPs are present in most drinking water supplies that have been subject to chlorination, chloramination or ozonation. Many hundreds of DBPs exist in treated drinking water and while the exact figure is not known, at least 600 have been identified. The low levels of many of these DBPs, coupled with the analytical costs in testing water samples for them, means that in practice only a handful of DBPs are actually monitored.

Health effects

Exposure to DBPs in drinking water has been associated through epidemiological studies with cancers, adverse birth outcomes and some birth defects. The exact putative agent remains unknown, however, in the epidemiological studies since the number of DBPs in a water sample are high and exposure surrogates such as monitoring data of a specific by-product (often total trihalomethanes) are used in lieue of more detailed exposure assessment. The World Health Organization
World Health Organization

The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health....
 has stated that "the risk of death from pathogens is at least 100 to 1000 times greater than the risk of cancer from disinfection by-products (DBPs) the risk of illness from pathogens is at least 10 000 to 1 million times greater than the risk of cancer from DBPs"