Chlorine and sodium hypochlorite hazards and risks: no need for further risk reduction measures


Glossary over Chlorine and sodium hypochlorite hazards and risks: no need for further risk reduction measures

Adverse health effect

A change in body function or cell structure that might lead to disease or health problems. (Source: ATSDR Glossary of Terms  )


A usually chronic inflammatory disorder of the airways characterized by intermittent episodes of wheezing, coughing, and difficulty in breathing, sometimes caused by an allergy to inhaled substances. (Source: American Lung Association Appendix 4: Glossary  )


The mass of air surrounding the Earth.

The atmosphere consists of nitrogen (78%), oxygen (21%), and traces of other gases such as argon, helium, carbon dioxide, and ozone.

The atmosphere plays an important role in the protection of life on Earth; it absorbs ultraviolet solar radiation and reduces temperature extremes between day and night. (Source: GreenFacts)



Bacteria are a major group of micro-organisms that live in soil, water, plants, organic matter, or the bodies of animals or people. They are microscopic and mostly unicellular, with a relatively simple cell structure.

Some bacteria cause diseases such as tetanus, typhoid fever, pneumonia, syphilis, cholera, and tuberculosis.

Bacteria play a role in the decomposition of organic matter and other chemical processes. (Source: GreenFacts)



Bioaccumulation is used to describe the increase in concentration of a substance in an organism over time.

Bioaccumulative substances tend to be fat soluble and not to be broken down by the organism. (Source: GreenFacts )



According to the Biocides Directive (98/8/EC), biocidal products are those that are intended to destroy, render harmless, prevent the action of, or otherwise exert a controlling effect on any harmful organism by chemical or biological means. Examples include disinfectants, preservatives, antiseptics, pesticides, herbicides, fungicides and insecticides.

Biocidal products mentioned in the Biocides Directive are listed in the following table: (Source: GreenFacts, based on the Biocides Directive (98/8/EC)  )



Br-. An inorganic bromide anion. Also used to describe any compound (usually a bromide salt) that contains the Br- ion, such as sodium bromide (NaBr). (Source: GreenFacts)



Any one of a group of diseases that occur when cells in the body become abnormal and have the potential to spread and establish growth in nearby tissues and other parts of the body (malignancy). (Source: GreenFacts )



A substance, factor or situation that causes or induces cancer. (Source: GreenFacts )

Chemical element

A substance which cannot be separated into its constituent parts and still retains its chemical identity. For example, sodium (Na) is an element. (Source: US EPA Drinking Water Glossary  )



The treatment of drinking water with a chloramine disinfectant. Both chlorine and small amounts of ammonia are added to the water one at a time which react together to form chloramine (also called combined chlorine), a long lasting disinfectant. As such, chloramine disinfection is sometimes used in large distribution systems. Chloraminated water is toxic to fish and must not be used for kidney dialysis. (Source: GreenFacts)



Chlorine (Cl2) is produced in large amounts and widely used both industrially and domestically as a disinfectant and bleach. In particular, it is widely used in the disinfection of swimming pools and is the most commonly used disinfectant and oxidant for drinking-water treatment. In water, chlorine reacts to form hypochlorous acid and hypochlorites. (Source: WHO  Guidelines for drinking water quality )

Chlorine dioxide

ClO2: Chlorine dioxide is a strong oxidizing agent that is added to water as a disinfectant and to control taste and odour. Chlorine dioxide rapidly decomposes into chlorite, chloride, and chlorate. (Source: WHO Guidelines for drinking water quality  )



CHCl3: Chloroform is an organic compound part of the trihalomethane. It is colorless and has a pleasant, nonirritating odor with a slightly sweet taste. Chloroform evaporates easily into the air and dissolves easily in water. It is derived primarily from various industrial and chemical processes, or as a by-product of disinfecting water with chlorine. Chloroform is largely present in drinking water. Although it is both a man-made and a naturally occurring compound, human activity is responsible for most of the chloroform found in the environment. (Source: GreenFacts)



The clumping together of very fine particles to form larger particles; caused by the use of chemicals (coagulants). The chemicals neutralize the electrical charges of the fine particles and cause destabilization of the particles. The clumping together makes it easier to separate the solids from the water by settling, skimming, draining or filtering. (Source: US EPA Drinking Water Glossary  )


A material made up of two or more elements combined in a fixed ratio. (Source: CoRIS glossary  )



The amount of a chemical or substance present in a particular quantity of soil, water, air, food, blood, hair, urine, breath, or any other media. (Source: GreenFacts)


Degradation of ecosystems

A persistent reduction in the capacity to provide ecosystem services. (Source: MA  Glossary )



A chemical or physical process that kills or inactivates microorganisms such as bacteria, viruses, and protozoa. (Source: US EPA US EPA Drinking Water Glossary  )


Dutch National Institute for Public Health and the Environment

RIVM works to prevent and control outbreaks of infectious diseases.

We promote public health and consumer safety, and we help to protect the quality of the environment.

RIVM collects and collates knowledge and information from various sources, both national and international.

We apply this knowledge ourselves, and we place it at the disposal of policy-makers, researchers, regulatory authorities and the general public.

Each year, RIVM produces numerous reports on all aspects of public health, nutrition and diet, health care, disaster management, nature and the environment. (Source:  )


The study of the patterns, causes, and control of disease in groups of people. (Source: NCI NCI dictionary  )

European Chemicals Agency

"ECHA is the driving force among regulatory authorities in implementing the EU's groundbreaking chemicals legislation for the benefit of human health and the environment as well as for innovation and competitiveness. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern." (Source:   )

European Union

"The European Union (EU) is a family of democratic European countries, committed to working together for peace and prosperity. It is not a State intended to replace existing states, but it is more than any other international organisation. The EU is, in fact, unique. Its Member States have set up common institutions to which they delegate some of their sovereignty so that decisions on specific matters of joint interest can be made democratically at European level.This pooling of sovereignty is also called "European integration". " (Source: EU website  )


Contact of the cells of an organism with a substance, micro-organism or radiation. In the case of humans, this may involve contact with a substance or agent by swallowing, breathing, or through the skin or eyes. Exposure may be short-term [acute exposure], of intermediate duration, or long-term [chronic exposure].

Exposure can be divided into external and internal.

External exposure refers to the whole dose to which an organism is exposed.

Internal exposure refers only to that fraction of the initial chemical dose that is absorbed and distributed throughout the body via systemic circulation. (Source: GreenFacts)


Granular activated carbon

A highly porous adsorbent material, produced by heating organic matter, such as coal, wood and coconut shell, in the absence of air, which is then crushed into granules. Activated carbon is positively charged and therefore able to remove negative ions from the water such as ozone, chlorine, fluorides and dissolved organic solutes by absorption onto the activated carbon. The activated carbon must be replaced periodically as it may become saturated and unable to absorb. Activated carbon is not effective in removing heavy metals. (Source: GreenFacts )


Haloacetic acids

A family of organic compounds based on the acetic acid molecule (CH3COOH) where one or more hydrogen atoms attached to carbon atoms are replaced by a halogen (chlorine, bromine, fluorine and/or iodine). There are nine species of HAAs including monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), and dibromoacetic acid (DBAA). HAAs are colourless, have a low volatility, dissolve easily in water and are fairly stable. (Source: GreenFacts)


Human health

A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.

The health of a whole community or population is reflected in measurements of disease incidence and prevalence, age-specific death rates, and life expectancy. (Source: MA Glossary  )


The frequency of a disease may be measured in two (standard) ways:

- Incidence is the number of new cases detected in the population at risk for the disease during a specific period.

- Prevalence (Source: Health canada Diabetes in Canada  )


The act of breathing.

A hazardous substance can enter the body by inhaling an airborne substance or contaminant in the form of gas, fumes mists, vapors, dusts, or aerosols. Once inhaled, contaminants can be deposited in the lungs and/or transported into the blood. (Source: GreenFacts)

Inorganic arsenic compound(s)

Sometimes referred to in short as inorganic arsenic, inorganic arsenic compound contain arsenic (As) and at least one other element, but no carbon (C). Inorganic arsenic exists in four main chemical forms known as valency or oxidation states. Valency is a measure of the ability of a compound to combine with other elements, such as hydrogen.

The dominant forms are:

  • Arsenite, with a valency of 3, also referred to as trivalent arsenic (As (III), As+3), and
  • Arsenate, with a valency of 5, also referred to as pentavalent arsenic (As (V), As+5


International Programme on Chemical Safety

The International Programme on Chemical Safety (IPCS) was established in 1980 by the WHO, the UNEP and the ILO (International Labour Organisation) "for the early warning and prevention of harmful effects of chemicals to which humans were being increasingly exposed, and for the assessment of the potential risks to human health."

It has collaborated to and published many highly recognized scientific publications.

Most publications are availaible from the INCHEM website, "a means of rapid access to internationally peer reviewed information on chemicals commonly used throughout the world, which may also occur as contaminants in the environment and food." Publications include:


Cancerous. Progressive and uncontrolled growth. Malignant neoplasms or tumours can invade and destroy other tissues and spread to other parts of the body via the bloodstream or lymphatics (metastasis). (Source: GreenFacts )

Membrane filtration

Water under high pressure is forced through a membrane, a thin material with very small pores, stopping small particles (including bacteria). (Source: GreenFacts )



A molecule is the smallest part of any chemical compound composed of two or more atoms and which has the qualities of that substance and can exist alone in a free state. As an example, a molecule of water (H2O) consists of two atoms of hydrogen and one of oxygen. (Source: GreenFacts, based on Helios Glossary   )


A substance or physical agent that causes mutations, i.e. permanently alters the DNA of a cell. (Source: GreenFacts)


Natural organic matter

Organic matter originating from plants and animals present in natural (untreated or raw) waters, for example, in lakes, rivers and reservoirs. (Source: GreenFacts)


Oxidizing agent

Any substance, such as oxygen (O2) or chlorine (Cl2), that will readily add (take on) electrons. The opposite is a reducing agent. (Source: US EPA Drinking Water Glossary   )



Ozone is a form of oxygen having the molecular form of O3. It is a bluish, unstable gas with a pungent odour, found in two parts of the atmosphere: the stratosphere and the troposphere.

The ozone layer: The stratosphere contains a layer in which the concentration of ozone is greatest, the so called ozone layer. The layer extends from about 12 to 40 km. It shields the Earth from ultraviolet radiation's harmful health effects on humans and the environment. This layer is being depleted by human emissions of chlorine- and bromine-containing compounds.

Ground-level ozone: At ground level (in the troposphere), ozone is considered an air pollutant that can seriously affect the human respiratory system. It is a chemical oxidant and a major component of photochemical smog. (Source: GreenFacts)


Ozone biofiltration

A combined water treatment process to reduce natural organic matter (NOM) which is a water disinfectant byproduct precursor. Water is first ozonated (ozone is mixed into the water flow to oxidize organic matter, cyanide, iron and manganese) and then passed through a biofilter (a filter bed laden with microorganisms that break down organic matter into carbon dioxide, water and salts). (Source: GreenFacts)


Persistent organic pollutants

Persistent organic pollutants (POPs) are chemical substances that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the environment. This group of priority pollutants consists of pesticides (such as DDT), industrial chemicals (such as polychlorinated biphenyls, PCBs) and unintentional by-products of industrial processes (such as dioxins and furans).

Persistent Organic Pollutants are transported across international boundaries far from their sources, even to regions where they have never been used or produced. (Source: European Commission Environment DG POPs  )


A toxic chemical product that kills harmful organisms (e.g., insecticides, fungicide, weedicides, rodenticides, acaricides). (Source: FAO Glossary of biotechnology & genetic engineering  )



pH is a measure of the concentration of protons (H+) in a solution and, therefore, its acidity or alkalinity. The concept was introduced by S.P.L. Sørensen in 1909. The p stands for the German "Potenz", meaning power or concentration, and the H for the hydrogen ion (H+). In layman's terms , the "pH" value is an approximate number between 0 and 14 that indicates whether a solution is acidic (pH < 7), basic (pH > 7) or neither (pH = 7) [neutral]. (Source: GreenFacts )



A polymer is a high-molecular-weight organic compound, natural or man-made, consisting of many repeating simpler chemical units or molecules called monomers.

Examples of natural polymers are proteins (polymer of amino acids) and cellulose (polymer of sugar molecules).

An example of synthetic polymer is PVC (a polymer of vinyl chloride). (Source: GreenFacts)



A precursor is a chemical which precedes and is the source of another. (Source: GreenFacts)


Respiratory tract

The organs that are involved in breathing.

These include the nose, throat, larynx, trachea, bronchi, and lungs. Also known as the respiratory system. (Source: St. Jude Children's Research Hospital Glossary   )


Risk assessment

A scientifically based process consisting of four steps:

  • hazard identification,
  • hazard characterization,
  • exposure assessment and
  • risk characterization
(Source:   Official Journal of the European Communities 2002 L 31 )



Sewage refers to waste-water from homes and industry which is collected and carried away in sewers (pipes or tunnels). When raw waste-water is cleaned in treatment plants the waste product is sewage sludge, which can be used as a fertiliser under certain conditions or deposited in landfills. (Source: GreenFacts )


Sodium is an essential element (chemical formula: Na) that the body needs to function properly, in order to regulate blood pressure and blood volume and for the functioning of muscles and nerves.

Sodium occurs naturally in most foods, mainly as sodium chloride (NaCl), but also in other forms such as sodium nitrate, sodium phosphate, or sodium glutamate. (Source: GreenFacts)



The production of a substance by either joining chemical elements, groups, and/or simpler compounds or breaking down a complex compound. (Source: GreenFacts )

The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection

The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) is an advisory body, established in 1969, that advises the United Nations (UN) system on the scientific aspects of marine environmental protection.

At present GESAMP is jointly sponsored by nine UN organizations with responsibilities relating to the marine environment, and they utilize GESAMP as a mechanism for coordination and collaboration among them. GESAMP functions are to conduct and support marine environmental assessments, to undertake in-depth studies, analyses, and reviews of specific topics, and to identify emerging issues regarding the state of the marine environment. GESAMP itself today consists of 16 experts, drawn from a wide range of relevant disciplines, who act in an independent and individual capacity. Studies and assessments are usually carried out by dedicated working groups, most of whose members are not sitting members of GESAMP but part of the broader GESAMP network.


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The capacity or property of a substance to cause adverse effects. (Source: GreenFacts)



The study of the harmful effects of substances on humans or animals. (Source: ATSDR Glossary of Terms  )


A class of organic compounds, based on the methane molecule (CH4) where the hydrogen atoms normally present are replaced by three halogen atoms (chlorine, bromine, fluorine and/or iodine). Examples include chloroform and dibromochloromethane. (Source: GreenFacts)



An abnormal mass of tissue resulting from uncontrolled and excessive cell division.

Tumours can be either benign (localised, without the invasion of other tissues) or malignant (showing progressive invasion of other tissues). (Source: GreenFacts)

World Health Organization

"The World Health Organization  (WHO) is the directing and coordinating authority on international health within the United Nations’ system. WHO experts produce health guidelines and standards, and help countries to address public health issues. WHO also supports and promotes health research. Through WHO, governments can jointly tackle global health problems and improve people’s well-being.

193 countries and two associate members are WHO’s membership. They meet every year at the World Health Assembly in Geneva to set policy for the Organization, approve the Organization’s budget, and every five years, to appoint the Director-General. Their work is supported by the 34-member Executive Board, which is elected by the Health Assembly. Six regional committees focus on health matters of a regional nature."

WHO's scientific publications are widely recognized as a reference source.

The WHO has a number of regional offices which address the specific issues of those regions.

WHO World Regional Offices
  WHO African Region  (46 countries)
  WHO European Region  (53 countries)
  WHO Eastern Mediterranean Region  (21 countries)
  WHO Region of the Americas  (35 countries)
  WHO South-East Asia Region  (11 countries)
  WHO Western Pacific Region  (27 countries)

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