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A to Z of Materials

"The aim of AZoM is to become the primary materials information source for the engineering and design community worldwide. It also aims to be the primary publicist of news, views and developments within the materials science community. However, unlike many other materials related organisations AZoM is totally focussed on the needs of the end users of materials. To achieve this aim, all of the educational, informative and news content on AZoM is easy to access and search and is provided on a free of charge, no subscription, no charge per article, totally free basis." (Source: AZoM website )


The process of taking in. For a person or an animal, absorption is the process of a substance getting into the body through the eyes, skin, stomach, intestines, or lungs. (Source: ATSDR Glossary of Terms  )



To take up and hold (a gas, liquid, or dissolved substance) in a thin layer of molecules on the surface of a solid substance. (Source: US EPA Acid Rain Glossary  )


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  )


Originating from the activity of humans. (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)  )


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)


The part of the Earth and its atmosphere in which living organisms exist or that is capable of supporting life. (Source: NRDC glossary  )

Canadian Centre for Occupational Health and Safety

"The Canadian Centre for Occupational Health and Safety (CCOHS) is a Canadian federal government agency based in Hamilton, Ontario, which serves to support the vision of eliminating all Canadian work-related illnesses and injuries."

"The mandate of CCOHS is to promote improvements in occupational health and safety by providing practical information to answer workplace concerns." (Source: CCOHS website )


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 )


A catalyst is substance which increases the rate of a chemical reaction without itself being used up in the reaction. (Source: Science@NASA NASA neurolab Glossary  )

Chlor-alkali process

The term chlor-alkali refers to the two chemicals (chlorine and an alkali) which are simultaneously produced as a result of the electrolysis of a saltwater. The most common chlor-alkali chemicals are chlorine and sodium hydroxide (caustic soda) but can include potassium hydroxide and muriatic acid. There are 3 types of electrolytic processes used in the production of chlorine and caustic soda: the diaphragm cell process, the mercury cell process, and the membrane cell process. In the mercury cell process, chlorine and sodium hydroxide are produced simultaneously by electrolyzing seawater (sodium saltwater or brine) in a mercury cell. Note that when a potassium brine is used, potassium hydroxide is produced instead of the more usual sodium hydroxide. (Source: GreenFacts)



HgS. Mercuric (mercury) sulphide. Most mercury mined comes from cinnabar ore (rock containing cinnabar mineralization). The colour of cinnabar ranges from cinnamon to brick and scarlet red, which explains its historic use as a pigment, mainly in paints but also as a traditional colorant for foods. (Source: GreenFacts)

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  )



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)


Controlled landfill(s)

A controlled landfill is a landfill whose operation is subject to a permit system and to technical control procedures in compliance with the national legislation in force. Includes specially engineered landfills. (Source: EEA Multilingual Environmental Glossary  )



The weight (mass) of a substance in a given volume (of that same substance). Examples of commonly used units are kg/m3 or g/cm3 for solids, and kg/l or g/ml for liquids and gases. Referring to a substance's density is to describe how heavy a substance is for its size. (Source: GreenFacts)


Dental amalgam

Dental amalgam is a combination of mercury with other metals and has been used for over 150 years for the treatment of tooth cavities because it is very strong and durable.

Dental amalgams are made by mixing one part of liquid mercury with one part of a mixture of other metals: mainly silver, but also tin, some copper and small amounts of zinc. (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  )


Hg(CH3)2. Dimethylmercury is a highly volatile colourless liquid at room temperature. As an organic mercury compound, it may form when mercury combines with carbon covalently (shares electrons forming a strong bond). Dimethylmercury is poisonous to the nervous system (a neurotoxin), it readily crosses the blood-brain barrier and causes a lack of coordination, sensory disturbance and changes in mental state. Dimethylmercury inhibits several stages of neurotransmission in the brain. (Source: GreenFacts)


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  )



The complex system of plant, animal, fungal, and microorganism communities and their associated non-living environment interacting as an ecological unit.

Ecosystems have no fixed boundaries; instead their parameters are set to the scientific, management, or policy question being examined. Depending upon the purpose of analysis, a single lake, a watershed, or an entire region could be considered an ecosystem. (Source: US EPA Glossary of Climate Change Terms   )

Elemental mercury

Hg. Mercury in its elemental (pure) form, that is, as a metal; hence the synonym metallic mercury. A shiny, silver-gray metal that is a liquid at room temperature. (Source: GreenFacts)


End of pipe techniques

Methods used to remove already formed contaminants from a stream of air, water, waste, product or similar. These techniques are called 'end-of-pipe' as they are normally implemented as a last stage of a process before the stream is disposed of or delivered. (Source: GreenFacts)


Environment Canada

"Environment Canada's mandate is to preserve and enhance the quality of the natural environment, including water, air and soil quality; conserve Canada's renewable resources, including migratory birds and other non-domestic flora and fauna; conserve and protect Canada's water resources; carry out meteorology; enforce the rules made by the Canada - United States International Joint Commission relating to boundary waters; and coordinate environmental policies and programs for the federal government." (Source: WHO website )

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 )


A protein that encourages a biochemical reaction, usually speeding it up. Organisms could not function if they had no enzymes. (Source: NHGRI NHGRI Talking Glossary of Genetic Terms  )


C2H5Hg+. Ethylmercury is a cation that forms organic mercury compounds such as ethylmercury chloride and ethylmercury urea. Thimerosal is also an ethylmercury salt: sodium ethylmercuric thiosalicylate. The term 'ethylmercury' is sometimes used as a generic term to describe ethylmercury compounds. (Source: GreenFacts)


EurActiv is the leading internet portal fully dedicated to European public affairs. It brings together daily EU news, weekly "Update" e-mails, in-depth analysis of selected policy topics, and a directory of 10,000 names of names of people and organizations acting on the EU level, the "Guide". All content is free of charge.

EurActiv aims to "facilitate efficiency and transparency (...) by providing news monitoring, policy positions, discussion forums and contacts on selected EU affairs topics, complementing the existing institutional websites."

(Source: EurActiv website )

European Food Safety Authority

"Following a series of food scares in the 1990s (eg BSE, dioxins…) which undermined consumer confidence in the safety of the food chain, the European Union concluded that it needed to establish a new scientific body charged with providing independent and objective advice on food safety issues associated with the food chain. Its primary objective as set out in the White Paper on Food Safety would be to: “…contribute to a high level of consumer health protection in the area of food safety, through which consumer confidence can be restored and maintained.” The result was the European Food Safety Authority (EFSA).

Set up provisionally in Brussels in 2002, EFSA provides independent scientific advice on all matters linked to food and feed safety - including animal health and welfare and plant protection - and provides scientific advice on nutrition in relation to Community legislation. The Authority communicates to the public in an open and transparent way on all matters within its remit. EFSA’s risk assessments provide risk managers (consisting of EU institutions with political accountability, i.e. European Commission, European Parliament and Council) with a sound scientific basis for defining policy driven legislative or regulatory measures required to ensure a high level of consumer protection with regards to food safety." (Source: EFSA 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)


EXtension TOXicology NETwork

"The EXTension TOXicology NETwork (EXTOXNET) is an effort of University of California, Davis, Oregon State University, Michigan State University, Cornell University, and the University of Idaho.

Some of the goals of EXTOXNET are to stimulate dialog on toxicology issues, develop and make available information relevant to extension toxicology, and facilitate the exchange of toxicology-related information in electronic form, accessible to all with access to the Internet.

The EXTOXNET InfoBase is accessible via the World Wide Web (WWW)." (Source: EXTOXNET website )

Food & Agriculture Organization

"The Food and Agriculture Organization of the United Nations leads international efforts to defeat hunger. Serving both developed and developing countries, FAO acts as a neutral forum where all nations meet as equals to negotiate agreements and debate policy. FAO is also a source of knowledge and information. We help developing countries and countries in transition modernize and improve agriculture, forestry and fisheries practices and ensure good nutrition for all. Since our founding in 1945, we have focused special attention on developing rural areas, home to 70 percent of the world's poor and hungry people. FAO's activities comprise four main areas:

  • Putting information within reach
  • Sharing policy expertise.
  • Providing a meeting place for nations.
  • Bringing knowledge to the field. "
Food Standards Australia New Zealand

"Food Standard Australia New Zealand ensures safe food by developing effective food standards for Australia and New Zealand."

Food web

The interconnected food chains (feeding relationships) in an ecosystem. Plants, herbivores, and carnivores all form parts of the food web. (Source: GreenFacts)


Fossil fuel(s)

A general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the Earth's crust over hundreds of millions of years. (Source: US EPA Glossary of Climate Change terms  )


Toxic (damaging) to DNA. Substances that are genotoxic may bind directly to DNA or act indirectly leading to DNA damage by affecting enzymes involved in DNA replication, thereby causing mutations which may or may not lead to cancer or birth defects (inheritable damage). Genotoxic substances are not necessarily carcinogenic. (Source: GreenFacts)

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  )


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 swallowing something through eating, drinking, or mouthing objects. A hazardous substance can enter the body this way. (Source: ATSDR Glossary of Terms  )


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 mercury compounds

Inorganic mercury compounds are formed when mercury (symbol Hg) combines with elements other than carbon, such as chlorine, sulfur, or oxygen. Elemental mercury is a form of inorganic mercury.

Mercury binds in two states:

  • Hg+ (mercurous or mercury I), and
  • Hg2+ (mercuric or mercury II).
(Source: GreenFacts)



Difficulty in going to sleep or getting enough sleep. (Source: NCI dictionary  )

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 Development Research Centre

"A public corporation, IDRC was created by the Parliament of Canada in 1970.

IDRC's mandate, as stated in the International Development Research Centre Act, is:

To initiate, encourage, support, and conduct research into the problems of the developing regions of the world and into the means for applying and adapting scientific, technical, and other knowledge to the economic and social advancement of those regions.

In doing so, the Centre helps developing countries use science and knowledge to find practical, long-term solutions to the social, economic, and environmental problems they face." (Source: IDRC Website )

International Food Information Council Foundation

The International Food Information Council Foundation (IFICF) is the educational arm of IFIC. IFIC's mission is to communicate science-based information on food safety and nutrition to health and nutrition professionals, educators, journalists, government officials and others providing information to consumers.

IFIC's purpose is to bridge the gap between science and communications by collecting and disseminating scientific information on food safety, nutrition and health and by working with an extensive roster of scientific experts and through partnerships to help translate research into understandable and useful information for opinion leaders and ultimately, consumers. (Source: IFICF 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:


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 )


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) 


Addition of a methyl group to a molecule or atom, often through bacterial action (Source: GreenFacts)


The term 'methylmercury' is commonly used as a generic term to describe (mono)methylmercury compounds. In fact, methylmercury is not a compound in itself but a cation, CH3Hg+, which forms one part of methylmercury compounds; usually methylmercury salts.

Dimethylmercury is one methylmercury compound that is not a salt. The methylmercury cation is normally associated with either a simple anion, like chloride (Cl-), or a large molecule (e.g. a protein) with negative and positive charges. The methylmercury cation is the most toxic form of mercury, able to inhibit fetal brain development, which results in the behavioural changes and reduced cognitive and motor ability. (Source: GreenFacts )


Minnesotans for an Energy-Efficient Economy (ME3)

"Minnesotans for an Energy-Efficient Economy (ME3) is a nonprofit organization leading the transition to a clean, efficient, and fair energy system."

"At the center of our mission are issues which include:

  • increasing renewable energy like wind and solar power
  • increasing energy efficiency in homes, government and business
  • protecting public health and our quality of life
  • promoting an energy-efficient economy. "

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   )

Neurological effects

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


Of, or relating to, nerves and the muscles they stimulate. (Source: Science@NASA NASA neurolab Glossary  )

Organic mercury compounds

Organic mercury compounds, sometimes called organomercurials, are those containing covalent bonds between carbon and mercury.

Examples are methylmercury, dimethylmercuryand methylmercury chloride (methylmercuric chloride). (Source: GreenFacts)

Pathogenic organisms

Organisms, including bacteria, viruses or cysts, capable of causing diseases (typhoid, cholera, dysentery) in a host (such as a person). There are many types of organisms which do NOT cause disease. These organisms are called non-pathogenic. (Source: US EPA US EPA Drinking Water Glossary, A Dictionary of Technical and Legal Terms Related to Drinking Water  )



Exposure pathway is the physical route by which a chemical substance transfers from a source to exposed organisms.

Potential pathways include air, surface water, groundwater, soil, plants, animals and humans. May not necessarily always refer to contaminants. (Source: GreenFacts)


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 )



Strictly speaking, phenylmercury is a cation, C6H5Hg+, that forms organic mercury compounds such as phenylmercury acetate and phenylmercury chloride, which have both been used as fungicides. The term 'phenylmercury' is sometimes used as a generic term to describe phenylmercury compounds. (Source: GreenFacts)


A group or number of people living within a specified area or sharing similar characteristics (such as occupation or age). (Source: ATSDR Glossary of Terms  )



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



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

Route of exposure

The way people [or other living organisms] come into contact with a hazardous substance. Three routes of exposure are breathing [inhalation], eating or drinking [ingestion], or contact with the skin [dermal contact]. (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)



A substance is soluble if it dissolves in certain fluids. The fluid [gas or liquid] (present in excess) is called the solvent and the substance dissolved in it is called the solute which together form a solution. The process of dissolving is called solvation. A solution that can not hold any more solute is said to be saturated. (Source: GreenFacts )

Standard IARC classification

Compounds or physical factors assessed by IARC (International Agency for Research on Cancer) are classified in four groups based on the existing scientific evidence for carcinogenicity.

Group 1: "Carcinogenic to humans" There is enough evidence to conclude that it can cause cancer in humans.
IARC definition and list of compounds

Group 2A: "Probably carcinogenic to humans" There is strong evidence that it can cause cancer in humans, but at present it is not conclusive.
IARC definition and list of compounds

Group 2B: "Possibly carcinogenic to humans" There is some evidence that it can cause cancer in humans but at present it is far from conclusive.
IARC definition and list of compounds

Group 3: "Unclassifiable as to carcinogenicity in humans" There is no evidence at present that it causes cancer in humans.
IARC definition and list of compounds

Group 4: "Probably not carcinogenic to humans" There is strong evidence that it does not cause cancer in humans.
IARC definition and compound listed

Standard IARC classification categorization descriptions

Group 1: "The agent (mixture) is carcinogenic to humans . The exposure circumstance entails exposures that are carcinogenic to humans."

"This category is used when there is sufficient evidence of carcinogenicity in humans. Exceptionally, an agent (mixture) may be placed in this category when evidence of carcinogenicity in humans is less than sufficient but there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent (mixture) acts through a relevant mechanism of carcinogenicity."

Examples include asbestos, benzene and ionizing radiation.
List of agents evaluated as group 1 to date. 

Group 2 (A and B): "This category includes agents, mixtures and exposure circumstances for which, at one extreme, the degree of evidence of carcinogenicity in humans is almost sufficient, as well as those for which, at the other extreme, there are no human data but for which there is evidence of carcinogenicity in experimental animals. Agents, mixtures and exposure circumstances are assigned to either group 2A (probably carcinogenic to humans) or group 2B (possibly carcinogenic to humans) on the basis of epidemiological and experimental evidence of carcinogenicity and other relevant data."

Group 2A: "The agent (mixture) is probably carcinogenic to humans . The exposure circumstance entails exposures that are probably carcinogenic to humans."

"This category is used when there is limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals. In some cases, an agent (mixture) may be classified in this category when there is inadequate evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals and strong evidence that the carcinogenesis is mediated by a mechanism that also operates in humans. Exceptionally, an agent, mixture or exposure circumstance may be classified in this category solely on the basis of limited evidence of carcinogenicity in humans."

Examples include diesel engine exhaust, Formaldehyde and PCBs.
List of agents evaluated as group 2A to date. 

Group 2B: "The agent (mixture) is possibly carcinogenic to humans. "

"The exposure circumstance entails exposures that are possibly carcinogenic to humans.

This category is used for agents, mixtures and exposure circumstances for which there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals. It may also be used when there is inadequate evidence of carcinogenicity in humans but there is sufficient evidence of carcinogenicity in experimental animals. In some instances, an agent, mixture or exposure circumstance for which there is inadequate evidence of carcinogenicity in humans but limited evidence of carcinogenicity in experimental animals together with supporting evidence from other relevant data may be placed in this group."

Examples include glass wool, styrene and gasoline exhaust.
List of agents evaluated as group 2B to date. 

Group 3: "The agent (mixture) is unclassifiable as to carcinogenicity in humans. "

"This category is used most commonly for agents, mixtures and exposure circumstances for which the evidence of carcinogenicity is inadequate in humans and inadequate or limited in experimental animals. Exceptionally, agents (mixtures) for which the evidence of carcinogenicity is inadequate in humans but sufficient in experimental animals may be placed in this category when there is strong evidence that the mechanism of carcinogenicity in experimental animals does not operate in humans.

Agents, mixtures and exposure circumstances that do not fall into any other group are also placed in this category."

Examples include anthracene, caffeine and fluorescent lighting.
List of agents evaluated as group 3 to date. 

Group 4: "The agent (mixture) is probably not carcinogenic to humans."

"This category is used for agents or mixtures for which there is evidence suggesting lack of carcinogenicity in humans and in experimental animals. In some instances, agents or mixtures for which there is inadequate evidence of carcinogenicity in humans but evidence suggesting lack of carcinogenicity in experimental animals, consistently and strongly supported by a broad range of other relevant data, may be classified in this group."

The only agent in that group is: Caprolactam (see Group 4 to date ) (Source: IUPAC Glossary of Terms Used in Toxicology Classification of carcinogenicity  )

Surface tension

The tension of a liquid's surface, due to the attraction of the liquid's molecules to each other. Liquids with a high surface tension are not attracted to other materials with which they have contact. For example, mercury will form beads if spilt onto a tile floor. Liquids with a low surface tension are attracted to other materials and will therefore be seen to 'soak' them. (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)


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


A substance that is harmful to living organisms as a result of physical or chemical interaction.


A toxicant produced by a living organism. (Source: IPCS )



Uncontrollable quivering, shaking or trembling. (Source: GreenFacts)

UK Committee On Toxicity

"The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) is an independent scientific committee that provides advice to the Food Standards Agency, the Department of Health and other Government Departments and Agencies on matters concerning the toxicity of chemicals."

The Committee on Toxicity of Chemicals (COT) is one of the independent committees that advise the UK Government's Food Standards Agency(FSA) and other UK Government departments. (Source: COT website )

UK Food Standards Agency

"The Food Standards Agency is an independent food safety watchdog set up by an Act of Parliament in 2000 to protect the public's health and consumer interests in relation to food.

Between 2001 and 2006, the Agency's key aims are to:

  • reduce foodborne illness by 20% by improving food safety right through the food chain.
  • help people to eat more healthily.
  • promote honest and informative labelling to help consumers.
  • promote best practice within the food industry.
  • improve the enforcement of food law.
  • earn people's trust by what we do and how we do it."
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
United Nations Environment Programme

"The United Nations Environment Programme (UNEP), established in 1972, works to encourage sustainable development through sound environmental practices everywhere. Its activities cover (...) the promotion of environmental science and information, to an early warning and emergency response capacity to deal with environmental disasters and emergencies."

See also UNEP.Net , which "delivers authoritative environmental information from a broad range of information and data providers (...)". (Source: UNEP website  )

US Center for Disease Control and Prevention

"As the Center for Disease Control and Prevention (CDC) is recognized as the lead federal agency for protecting the health and safety of people - at home and abroad, providing credible information to enhance health decisions, and promoting health through strong partnerships. CDC serves as the national focus for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States."

"CDC, located in Atlanta, Georgia, USA, is an agency of the Department of Health and Human Services." (Source: CDC 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 Food and Drug Administration

"The FDA is responsible for protecting the public health by assuring the safety, efficacy, and security of human and veterinary drugs, biological products, medical devices, our nation’s food supply, cosmetics, and products that emit radiation. The FDA is also responsible for advancing the public health by helping to speed innovations that make medicines and foods more effective, safer, and more affordable; and helping the public get the accurate, science-based information they need to use medicines and foods to improve their health." (Source: US FDA 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 )


Able to readily evaporate at normal temperatures and pressures. (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)
World Resource Institute

The World Resource Institute (WRI) is a moderate Green advocacy group. It defines itself as "an environmental think tank that goes beyond research to find practical ways to protect the earth and improve people's lives."

It publishes Earthtrends on the Internet, an excellent environmental database:  (Source: WRI website )

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