Home » Dioxins » Glossary



Glossary over Dioxins

Acute exposure

Contact with a substance that occurs once or for only a short time (up to 14 days [for humans]). (Source: ATSDR Glossary of Terms  )

Adverse health effect

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

Agency for Toxic Substances and Disease Registry

The Agency for Toxic Substances and Disease Registry (ATSDR) is an agency of the U.S. Department of Health and Human Services (HHS). As mandated by the federal superfund law, the agency assesses health risks from hazardous waste sites on the EPA's National Priorities List. ATSDR determines if additional health studies are needed at these sites, provides health advisories and publishes toxicological profiles on chemicals found at hazardous waste sites.

ATSDR also maintains exposure registries of people exposed to certain substances. (Source: ATSDR website  )

Agent Orange

Toxic chemical defoliant [that strips trees and plants of their leaves] used by American military in Vietnam to deprive the enemy of food and of hiding places in the jungles, by killing all vegetation.

Nicknamed “Agent Orange” because of the identifying orange stripe on its steel drum containers. It was sprayed over large areas by aircraft and over smaller areas by hand. It was supposed to have been diluted 20:1, but it was used full strength. Many Vietnam Veterans suffer from health problems caused by exposure to Agent Orange. (Source: New Jersey Vietnam Veterans' Memorial Foundation Vietnam Glossary  )


Ah receptor

Aryl hydrocarbon receptor. A protein within the cell that binds to aryl hydrocarbons forming a complex that moves into the nucleus of the cell. In the nucleus, this complex controls the onset of a series of biotransformation processes for the excretion of hydrocarbon compounds. Ah-receptor binding, may, however also result in the synthesis of other proteins, some of which may interfere adversely with cellular growth and differentiation (specialization). (Source: GreenFacts)


American Chemical Society

"The American Chemical Society (ACS) is a self-governed individual membership organization that consists of more than 159,000 members at all degree levels and in all fields of chemistry. The organization provides a broad range of opportunities for peer interaction and career development, regardless of professional or scientific interests. The programs and activities conducted by ACS today are the products of a tradition of excellence in meeting member needs that dates from the Society's founding in 1876." (Source: ACS website )

Background level(s)

Levels of chemical or physical agents that are normally found in the environment.

Two types of background levels may exist for chemical substances or physical agents: (a) Naturally occurring levels: ambient concentrations of substances or agents present in the environment, without human influence; (b) Anthropogenic levels: Concentrations of substances or agents present in the environment due to human-made, non-site sources (e.g., automobiles, industries). (Source: US EPA Glossary of IRIS Terms  )


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 )


Biologic intake

The process by which a substance crosses the outer boundary of an organism without passing an absorption barrier, e.g. through ingestion or inhalation. (Source: US EPA glossary )


Biologic uptake

The transfer of substances from the environment to plants, animals, and humans. (Source: ATSDR Glossary of Terms )



The term biomagnification refers to the progressive build up of persistent substances by successive trophic levels - meaning that it relates to the concentration ratio in a tissue of a predator organism as compared to that in its prey. (Source: GreenFacts)

Body burden

The total amount of a substance in the body. Some substances build up in the body because they are stored in fat or bone or because they leave the body very slowly. (Source: ATSDR Glossary of Terms  )



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 )


Cancer risk

A theoretical risk for getting cancer if exposed to a substance every day for 70 years (a lifetime exposure). The true risk might be lower. (Source: ATSDR Glossary of Terms  )



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


The basic subunit of any living organism; the simplest unit that can exist as an independent living system. There are many different types of cells in complex organisms such as humans, each with specific characteristics. (Source: GreenFacts)



Chloracne is a rare acne-like skin condition caused by exposure to halogenated aromatic hydrocarbons (such as dioxins). (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 Chemistry Council

"The Chlorine Chemistry Council (CCC), a business council of the American Chemistry Council, is a national trade association based in Arlington, representing the manufacturers and users of chlorine and chlorine-related products.

To fulfill this mission, CCC:

  • Serves as a credible source of information and expertise on chlorine and chlorine-based product.
  • Promotes the use of sound science and comparative risk assessment in public policies affecting chlorine chemistry.
  • Sponsors and conducts research into the potential health and environmental effects of chlorine and the products of chlorine chemistry.
  • Creates better understanding of chlorine's health and safety benefits among customers, policy-makers and the public."
Chronic exposure

Contact with a substance that occurs over a long time (more than 1 year [for humans]). (Source: ATSDR Glossary of Terms  )

Circulatory system

The system that contains the heart and the blood vessels and moves blood throughout the body. This system helps tissues get enough oxygen and nutrients, and it helps them get rid of waste products. The lymph system, which connects with the blood system, is often considered part of the circulatory system. (Source: NCI Dictionary of cancer terms  )



Having to do with the ability to think and reason. This includes the ability to concentrate, remember things, process information, learn, speak, and understand. (Source: NCI dictionary  )


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)



Congener is a term in chemistry that refers to one of many variants or configurations of a common chemical structure. (Source: GreenFacts)



The inflammation of the mucous membrane covering the outer (exposed) part of the eyeball and the inner surface of the eyelids.

It is the most common infection of the eye in children. (Source: GreenFacts)


A substance that is either present in an environment where it does not belong or is present at levels that might cause harmful effects to humans or the environment. (Source: GreenFacts)

Developmental effects

Effects in the developing offspring due to exposure before conception (either parent), prenatally, or postnatally to the time of sexual maturation. Developmental effects may be expressed at any time in the life span of the organism. Developmental effects are a subset of reproductive effects. (Source: CSIRO CSIRO biological effects and safety of EMR Glossary  )


"Dioxins" refers to a group of chlorinated organic chemicals with similar chemical structures.

In all GreenFacts publications the term "dioxins" is used to cover both polychlorinated dibenzo-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs). Other sources may refer to these compounds as "dioxins and furans".

Some dioxins have harmful properties, depending on the number and position of chlorine atoms. One of the most toxic dioxin is known as TCDD (2,3,7,8 tetrachlorodibenzo-p-dioxin). Some PCBs which have similar properties are considered "dioxin-like". (Source: GreenFacts)



Chlorinated chemicals with comparable structural and biochemical properties to dioxins. There are 12 PCBs that are considered dioxin-like. (Source: GreenFacts)


DNA constitutes the molecules inside cells that carry genetic information and pass it from one generation to the next. (Source: NCI dictionary  )



The amount of a substance to which a person is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time) when people eat or drink contaminated water, food, or soil. In general, the greater the dose, the greater the likelihood of an effect. An "exposure dose" is how much of a substance is encountered in the environment. An "absorbed dose" is the amount of a substance that actually got into the body through the eyes, skin, stomach, intestines, or lungs. (Source: ATSDR Glossary of Terms  )

Dose-response relationship

The relationship between the amount of exposure [dose] to a substance and the resulting changes in body function or health (response). (Source: ATSDR Glossary of Terms  )



A benign condition in which tissue that looks like endometrial tissue grows in abnormal places in the abdomen [outside the uterus]. (Source: NCI dictionary  )


Environment DG

"The Environment DG is one of 36 Directorates-General (DGs) and specialised services which make up the European Commission. Its main role is to initiate and define new environmental legislation and to ensure that measures, which have been agreed, are actually put into practice in the Member States."

The mission statement of the Environment DG is: "to promote Sustainable Development, preserving the rights of future generations to a viable environment; to work towards a high level of environmental and health protection and improvement of the quality of life; to promote environmental efficiency; to encourage the equitable use, as well as the sound and effective management, of common environmental resources" (Source: EC DG ENVI website )

Environmental Health Perspectives

"The mission of Environmental Health Perspectives (EHP), the journal of the National Institute of Environmental Health Sciences, is to serve as a forum for the discussion of the interrelationships between the environment and human health by publishing in a balanced and objective manner the best peer-reviewed research and most current and credible news of the field."

Epidemiological studies

Studies on human populations, which attempt to link human health effects (e.g. cancer) to a cause (e.g. exposure to a specific chemical). (Source: GreenFacts)


European Commission

"The European Commission (EC) embodies and upholds the general interest of the [European] Union and is the driving force in the Union's institutional system. Its four main roles are to propose legislation to Parliament and the Council, to administer and implement Community policies, to enforce Community law (jointly with the Court of Justice) and to negotiate international agreements, mainly those relating to trade and cooperation."

The Commission's staff is organised into 36 Directorates-General (DGs) and specialised services, such as the Environment DG and the Research DG. (Source: EC 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)


Female urogenital malformations

Abnormal formation of the organs involved in reproduction and the formation and release of urine, including the kidneys, ureters, bladder, urethra, ovaries, uterus, fallopian tubes, vagina, and clitoris. (Source: GreenFacts)

French Food Safety Agency

The French Food Safety Agency (AFSSA, Agence Française de Sécurité Sanitaire des Aliments) is a public institution created in April 1999.

AFSSA's mission is to asses sanitary and nutrional risks of foods destined for human and animal consumption in France. (Source: AFSSA website )

Gamma GT

A specific enzyme. Gamma GT plays a key role in the formation and breakdown of glutathione, which is a chemical made by the body to protect cells from many toxins. (Source: GreenFacts)



Glucose is naturally occurring sugar and a primary source of energy for living organisms, including humans. Its chemical formula is C6H12O6. (Source: GreenFacts)


Water beneath the Earth's surface in the spaces between soil particles and between rock surfaces. (Source: ATSDR Glossary of Terms  )

Half life

The term which is used for the time required for the amount of a particular substance to be reduced to one half of its value when the rate of decay is exponential.

Radioactive half-life refers to the decay of radioactive substances. Iodine-131, for instance, has a half-life of 8 days whereas that of Plutonium-239 is more than 23 000 years.

Biological half-life refers to decay by biological processes. Substances with a long biological half-life will tend to accumulate in the body and are, therefore, particularly to be avoided. Substances with a short biological half-life may accumulate if some becomes tightly bound, even if most is cleared from the body rapidly. There is also the possibility of cumulative effects of chemicals which have a short residence time in the body. (Source: GreenFacts)


Health canada

"Health Canada is the federal department responsible for helping the people of Canada maintain and improve their health ."

"In partnership with provincial and territorial governments, Health Canada provides national leadership to develop health policy, enforce health regulations, promote disease prevention and enhance healthy living for all Canadians."

See also the Health Canada Environment page:  (Source: Health Canada website )

Heavy metals

Metallic elements with high atomic weights, e.g. mercury, chromium, cadmium, arsenic, and lead.

They can damage living things at low concentrations and tend to accumulate in the food chain. (Source: US EPA Drinking Water Glossary  )


Appearance of thickened, horny, verruca-like scales (for example, warts and calluses) over the entire body, concentrated in flexural areas. (Source: GreenFacts)


Abnormally increased pigmentation (colouration). (Source: GreenFacts)

Incomplete combustion process(es)

A reaction or process which entails only partial burning of a fuel. This may be due to a lack of oxygen or low temperature, preventing the complete chemical reaction. Carbon monoxide is produced as a byproduct from incomplete combustion of carbon.


International Agency for Research on Cancer

"The International Agency for Research on Cancer (IARC) is part of the World Health Organization (WHO).

IARC's mission is to coordinate and conduct research on the causes of human cancer, the mechanisms of carcinogenesis, and to develop scientific strategies for cancer control. The Agency is involved in both epidemiological and laboratory research and disseminates scientific information through publications, meetings, courses, and fellowships."

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

Most publications are availaible from the webpage IARC Monographs Programme on the Evaluation of Carcinogenic Risks to humans , "The IARC Monographs series publishes authoritative independent assessments by international experts of the carcinogenic risks posed to humans by a variety of agents, mixtures and exposures."

IARC distinguishes between four groups of compounds or physical factors based on the existing scientific evidence for carcinogenicity: Standard IARC classification (Source: IARC website )

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:


An area of abnormal tissue. A lesion may be benign (non-cancercous) or malignant (cancerous). (Source: NCI dictionary  )


An essential structural component of living cells, lipids are a class of oily organic compounds which are insoluble in water but soluble in fats and oils. The lipid class of molecules mainly consists of fats, oils and waxes. (Source: GreenFacts)



Lipophilic or 'lipid-loving' molecules are attracted to lipids. A substance is lipophilic if it is able to dissolve much more easily in lipid (a class of oily organic compounds) than in water. (Source: GreenFacts )


Lowest Observed Adverse Effect Level

The lowest tested dose of a substance that has been reported to cause harmful (adverse) health effects on people or animals. (Source: ATSDR glossary  )


Mass (weight) Units

The Metric System of Measurements uses the mass units: gram (g), kilogram (kg) and tonne (t).

1000 g = 1 kg
1000 kg = 1 tonne

Adding prefixes of the International System of Units (SI) allows to express weight as multiples or fractions of 1 gram:

1 gigatonne (Gt) =1 000 000 000 000 000 g
1 megatonne (Mt) =1 000 000 000 000 g
1 tonne (t) =1 000 000 g
1 kilogram (kg) =1 000 g
1 gram (g) =1 g
1 milligram (mg) =0.001 g
1 microgram (µg) =0.000 001 g
1 nanogram (ng) =0.000 000 001 g
1 picogram (pg) =0.000 000 000 001g

Imperial and US weight units can also be expressed as metric units:

Metric units
1 US ton (ton) =0.907 tonne
1 UK ton (ton) =1.016 tonne
1 lb (pound) =453.59 g
1 oz (ounce) =28.35g

Further information on the International System of Units (SI) is provided by the International Bureau of Weights and Measures (BIPM) 


The conversion or breakdown of a substance from one form to another by an enzyme. (Source: GreenFacts, based on ATSDR Glossary of Terms )



Mathematical representation or simulation of an actual situation. (Source: GreenFacts)


Having to do with the way the brain affects emotion, behavior, and learning. (Source: NCI dictionary   )

Neurobehavioural test(s)

Standard tests designed to evaluate different aspects of the functioning of the central nervous system, including attention, motor performance, perceptual coding, learning, memory and affect. (Source: GreenFacts)

Neurodevelopmental delays

Delays in the development of the nervous system. (Source: GreenFacts)

Neurological effects

Effects to nervous system especially regarding structure, functions, and abnormalities. (Source: GreenFacts)

No Observed Adverse Effect Level

The highest tested dose of a substance that has been reported to have no harmful (adverse) health effects on people or animals. (Source: ATSDR Glossary of Terms   )


Non toxic

Not harmful or destructive. (Source: NCI dictionary  )


The term organic has different meanings (depending on the context):

In chemistry, "organic" refers to a chemical compound based on a hydrocarbon, i.e. a chain or a ring of carbon atoms onto which hydrogen atoms are bonded.

In agriculture, "organic" refers to a production system that excludes or limits the use of chemicals



Polychlorinated biphenyls (PCBs) are a family of 209 congeners of structurally similar organic chemicals, ranging from oily liquids to waxy solids. There are 12 PCBs that are dioxin-like and can similarly be toxic and non-toxic. One dioxin-like PCB is 3,4,4',5-Tetrachlorobiphenyl.

PCBs are synthetic and produced either as a singular congener, as a homogeneous group or as a mixture. They are non-flammable, stable, have a high boiling point and exhibit electrical insulating properties. As such, PCBs have been used as coolants and lubricants in transformers and other electrical equipment, as hydraulic fluids, and as plasticizers, pigments, dyes and carbonless copy paper ink. They are also generated and released into the environment as waste byproducts of chemical manufacturing and incineration. (Source: GreenFacts)



A large molecule composed of one or more chains of amino acids in a specific order, formed according to genetic information.



A molecule on the surface of a cell that serves as a recognition or binding site for antigens, antibodies or other cellular or immuniologic components. (Source: NIAID HIV vaccine Glossary   )

Rice oil

In Asia, rice oils are used as common cooking oils. In the rest of the world, rice oil is used as an ingredient in some baby foods and can be found for sale in specialized food shops. Produced from the bran of rice, it is a by-product of milled white rice. (Source: GreenFacts )


The probability that something will cause injury or harm. (Source: ATSDR Glossary of Terms  )


A portion or piece of a whole. A selected subset of a population or subset of whatever is being studied. For example, in a study of people the sample is a number of people chosen from a larger population [see population]. An environmental sample (for example, a small amount of soil or water) might be collected to measure contamination in the environment at a specific location. (Source: ATSDR Glossary of Terms   )

Scientific Consensus

The Scientific Consensus represents the position generally agreed upon at a given time by most scientists specialized in a given field. (Source: GreenFacts)


Sebaceous cyst(s)

A cyst on the skin resulting from a blocked sebaceous gland (gland producing sebum) which has consequently filled the sac with fatty matter. (Source: GreenFacts )


Seveso is a small city in northern Italy where on 10th July 1976, after an explosion at a TCP (trichlorophenol) manufacturing plant, a cloud of chemicals travelled over parts of the city and some adjacent communities who were exposed to the chemicals in cloud. 2,3,7,8-TCDD was one chemical in this cloud. (Source: GreenFacts)


C12H4Cl4O2. TCDD or 2,3,7,8-TCDD is one of the most potent toxic dioxins and used as a reference for all other dioxins. 1,2,3,7,8-Pentachlorodibenzodioxin is of a similar potency, while the other members of the subset are 10–10 000 times less toxic. (Source: GreenFacts)


Thyroid gland

The thyroid gland consists of two bodies like small walnuts; they are connected by an isthmus beside the larynx (voice box). The thyroid gland produces thyroid hormones T3 and T4 which regulate the metabolism of all cells in the body. Disorders of the thyroid gland are characterized by the inability to produce or release sufficient thyroid hormones (hypothyroidism) or the overactivity of the thyroid gland (hyperthyroidism). (Source: EMCOM Endocrine Disruptors Glossary  )



A group of cells joined to perform a set of functions. (Source: GreenFacts)

Tolerable Daily Intake

A TDI is an estimate of the amount of a substance in air, food or drinking water that can be taken in daily over a lifetime without appreciable health risk. TDIs are calculated on the basis of laboratory toxicity data to which uncertainty factors are applied.

TDIs are used for substances that do not have a reason to be found in food (as opposed to substances that do, such as additives, pesticide residues or veterinary drugs in foods- see ADI). (Source: GreenFacts)



Able to poison or harm an organism. Toxic substances can cause adverse health effects. (Source: GreenFacts)


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



Made up of 3 fatty acid molecules attached to a gyclerol molecule, tryglyceride is a type of fat found in the blood and stored in the body. Most fats in foods are triglycerides. Humans can obtain triglycerides from food but the liver produces it too. (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)

Uncertainty factor

A number (equal or greater than 1) used to divide NOAEL or LOAEL values derived from measurements in animals or small groups of humans, in order to estimate a NOAEL or LOAEL value for the whole human population; also called margin-of-safety. (Source: IPCS )


Unit prefixes of the International System of Units (SI)

In order to keep figures short and presentable, SI prefixes are often attached to units such as m (meter) or g (gram).

For example, a substance weighing 0.000 000 001 g may be described more simply as 1 ng (nanogram) or as 1000 pg (picograms).

Common prefixes of the International System of Units (SI) are:

p pico = 1 000 000 000 000th = 10-12
n nano = 1 000 000 000th = 10-9
µ micro = 1 000 000th = 10-6
m milli = 1 000th = 10-3
no prefix = 1
k kilo = 1 000 = 103
M Mega = 1 000 000 = 106
G Giga = 1 000 000 000 = 109
T Tera = 1 000 000 000 000 = 1012
US Department of Health and Human Services

The Department of Health and Human Services (HHS) is the United States government's principal agency for protecting the health of all Americans and providing essential human services, especially for those who are least able to help themselves. (Source: HHS website )

US Environment Protection Agency

The Environment Protection Agency's of the USA was founded in 1970. It's "mission is to protect human health and to safeguard the natural environment — air, water, and land — upon which life depends."

The EPA enforces federal environmental protection laws. It registers and regulates pesticides, enforces laws covering outdoor air and drinking water quality and regulates the disposal of hazardous and solid wastes.

It has now grown into a big and powerful administration: "18,000 people in Headquarters program offices, 10 regional offices, and 17 labs across the country, EPA employs a highly educated, technically trained staff, more than half of whom are engineers, scientists, and environmental protection specialists. A large number of employees are legal, public affairs, financial, and computer specialists."

U.S. EPA's scientific publications are widely recognized as reference materials. (Source: US EPA website  )

US National Institute of Environmental Health Sciences

The US National Institute of Environmental Health Sciences (NIEHS) is one of 27 Institutes and Centers  of the National Institute of Health (NIH) , which is a component of the Department of Health and Human Services (DHHS) .

The National Institute of Environmental Health Sciences tries to reduce human illness from environmental causes by understanding environmental factors, individual susceptibility and age.

It conducts biomedical research programs, prevention and intervention efforts, and education.

It has collaborated to and published many highly recognized scientific publication. (Source: NIEHS website )

Uterine disease(s)

Abnormal health conditions in, or related to, the uterus (womb). These may include fibroids (non-cancerous growths), endometriosis and cancer of the uterus (uterine cancer). (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)

Other articles you might like...
Acrylamide in food home
Is there a risk to health?
Aluminium exposure home
Does aluminium pose a health risk?
Pesticides occupational risks home
We review the scientific literature regarding the health risks associated with occupational exposure to pesticides.
A-Z List
    Themes covered
    Publications A-Z