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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 )

Absorption

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  )

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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  )

American Council on Science and Health

"The American Council on Science and Health, Inc. (ACSH) is a consumer education consortium concerned with issues related to food, nutrition, chemicals, pharmaceuticals, lifestyle, the environment and health. ACSH is an independent, nonprofit, tax-exempt organization.

The nucleus of ACSH is a board of 350 physicians, scientists and policy advisors - experts in a wide variety of fields-who review the Council's reports and participate in ACSH seminars, press conferences, media communications and other educational activities." (Source: ACSH website )

Arsenic Crisis Information Centre

"Online focal point for the environmental health disaster in Bangladesh and West Bengal, India, where millions of people are drinking ground water heavily contaminated with arsenic. Site includes infobank of news articles, scientific papers, comprehensive links to other relevant sites, online forum, email newsletter, and local site search." (Source: ACIC website )

Arsenic trioxide

As2O3: an inorganic arsenic compound; a by-product of metal smelting operations. (Source: GreenFacts)

Arsenopyrite

FeAsS, Iron Arsenide Sulfide, an inorganic arsenic compound. This mineral is a major ore of arsenic. (Source: GreenFacts)

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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

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 )

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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 )

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Blackfoot disease

Blackfoot disease (BFD) is a severe form of peripheral vascular disease (PVD), in which the blood vessels in the lower limbs are severely damaged, resulting eventually in progressive gangrene. It has been observed in Taiwan. (Source: GreenFacts)

Cancer

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 )

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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  )

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Carcinogen

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

Cell

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)

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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  )

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Chromosome

One of the threadlike "packages" of genes and other DNA in the nucleus of a cell. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes, 46 in all: 44 autosomes and two sex chromosomes. Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mothers and half from their fathers. (Source: NHGRI Talking Glossary of Genetic Terms  )

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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  )

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Concentration

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)

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Dartmouth College

"Dartmouth, a member of the Ivy League, is a private, four-year, coeducational undergraduate college with graduate schools of business, engineering and medicine and 16 graduate programs in the arts and sciences.

The Dartmouth Toxic Metals Research program includes more than 60 faculty scientists and physicians; postdoctoral, graduate and undergraduate students; and associated technical and support staff from Dartmouth College and Dartmouth Medical School in Hanover, New Hampshire, and from the Veterans Affairs Medical Center in White River Junction, Vermont. We also collaborate with researchers at other universities and government agencies." (Source: Dartmouth website )

DNA

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

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Dose

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  )

Elemental Arsenic

The element with the symbol "As" and the atomic number 33. Its molecular weight is 74.92160 g. It can be classified as semi metallic and its colour is observed to be metallic grey. (Source: GreenFacts)

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Enzyme(s)

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  )

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  )

Exposure

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)

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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  )

Genes

The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein. (Source: NHGRI Talking Glossary of Genetic Terms  )

Groundwater

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

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: www.hc-sc.gc.ca/english  (Source: Health Canada website )

Immune system

The immune system is a network of cells, tissues, and organs that work together to defend the body against attacks by “foreign” invaders. (Source: NIAID Immune System   )

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Ingestion

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  )

Inhalation

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

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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 www.inchem.org, "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:

London Arsenic Group

"The London Arsenic Group brings together expertise from the fields of sedimentary geochemistry, hydrochemistry, environmental mineralogy and analytical geochemistry. We seek to understand the source, mobility, and fate, of arsenic in the environment. We exist to bring a multi-disciplinary approach to this issue and provide a focus for exchange of views."

(Source: LAG website )

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) www.bipm.org/en/si/ 

Metabolism

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

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Metabolite

A substance that is the product of biological changes to a chemical. (Source: US EPA Glossary  )

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Methyl group

In chemistry a methyl-group is an alkyl functional group with the formula -CH3 .

This hydrocarbon unit can be found in many organic compounds, like biodiesel (methyl ester). (Source: GreenFacts )

Methylation

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

National Pure Water Association

"National Pure Water Association is a not-for-profit organisation founded in 1960 by Lord Douglas of Barloch, KCMG, to campaign for safe drinking water." (Source: NPWA website )

Neurological effects

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

Organic arsenic compounds

Arsenic compounds containing carbon. They are mainly found in sea-living organisms, although some of these compounds have also been found in species living on land. (Source: GreenFacts)

Pigment

A substance that gives colour to tissue. Pigments are responsible for the colour of skin, eyes, and hair. (Source: NCI cancer.gov dictionary  )

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Soluble

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  )

Standard IARC degrees of evidence of carcinogenicity

which are the basis for the Standard IARC Classification

Carcinogenicity in humans

Sufficient evidence of carcinogenicity:

The Working Group considers that a causal relationship has been established between exposure to the agent, mixture or exposure circumstance and human cancer. That is, a positive relationship has been observed between the exposure and cancer in studies in which chance, bias and confounding could be ruled out with reasonable confidence.

Limited evidence of carcinogenicity:

A positive association has been observed between exposure to the agent, mixture or exposure circumstance and cancer for which a causal interpretation is considered by the Working Group to be credible, but chance, bias or confounding could not be ruled out with reasonable confidence.

Inadequate evidence of carcinogenicity:

The available studies are of insufficient quality, consistency or statistical power to permit a conclusion regarding the presence or absence of a causal association between exposure and cancer, or no data on cancer in humans are available.

Evidence suggesting lack of carcinogenicity:

There are several adequate studies covering the full range of levels of exposure that human beings are known to encounter, which are mutually consistent in not showing a positive association between exposure to the agent, mixture or exposure circumstance and any studied cancer at any observed level of exposure. A conclusion of 'evidence suggesting lack of carcinogenicity' is inevitably limited to the cancer sites, conditions and levels of exposure and length of observation covered by the available studies. In addition, the possibility of a very small risk at the levels of exposure studied can never be excluded.

In some instances, the above categories may be used to classify the degree of evidence related to carcinogenicity in specific organs or tissues.

Carcinogenicity in experimental animals

Sufficient evidence of carcinogenicity:

The Working Group considers that a causal relationship has been established between the agent or mixture and an increased incidence of malignant neoplasms or of an appropriate combination of benign and malignant neoplasms in (a) two or more species of animals or (b) in two or more independent studies in one species carried out at different times or in different laboratories or under different protocols.

Exceptionally, a single study in one species might be considered to provide sufficient evidence of carcinogenicity when malignant neoplasms occur to an unusual degree with regard to incidence, site, type of tumour or age at onset.

Limited evidence of carcinogenicity:

The data suggest a carcinogenic effect but are limited for making a definitive evaluation because, e.g. (a) the evidence of carcinogenicity is restricted to a single experiment; or (b) there are unresolved questions regarding the adequacy of the design, conduct or interpretation of the study; or (c) the agent or mixture increases the incidence only of benign neoplasms or lesions of uncertain neoplastic potential, or of certain neoplasms which may occur spontaneously in high incidences in certain strains.

Inadequate evidence of carcinogenicity:

The studies cannot be interpreted as showing either the presence or absence of a carcinogenic effect because of major qualitative or quantitative limitations, or no data on cancer in experimental animals are available.

Evidence suggesting lack of carcinogenicity:

Adequate studies involving at least two species are available which show that, within the limits of the tests used, the agent or mixture is not carcinogenic. A conclusion of evidence suggesting lack of carcinogenicity is inevitably limited to the species, tumour sites and levels of exposure studied. (Source: IARC Preamble to the IARC Monographs  )

Sustainable Development Networking Program

"The Sustainable Development Networking Program (SDNP) is a global catalytic initiative launched by the United Nations Development Program (UNDP) in response to Agenda 21, which articulated the need for improved information dissemination to support sustainable development. The program is geared towards facilitating communication between users and suppliers of sustainable development information in developing countries.

Bangladesh is intensely reliant on environmental and natural resources. Some times Natural calamity seriously wrinkled the natural resource base of the country, which could have serious adverse impact on output, income and employment. Efforts are being made to address these issues by the Government, donors, political parties, NGOs and other advocacy groups. The Government has been giving some attention to this sector. Among others it has approved the National Environment Management Action Plan (NEMAP) in 1996. Sustainable environment Management Programme (SEMP) is an out come of NEMAP in Bangladesh.

SDNP in Bangladesh is acting as a non-profitable organization that affianced in network development programme for environment awareness, education, health care and countryside development projects in the rural areas of Bangladesh.

SDNP defines as its community mission to contribute to national development by providing services in (1) information and communication technology and (2) Internet connectivity to rural communities for the enhancement of delivery of education, health care and livelihood programs of government agencies, multi-lateral and other concerned institutions." (Source: SDNP website )

Tissue

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

Toxic

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

Toxicity

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

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Tumour

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)

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."
UN Economic and Social Commission for Asia and the Pacific

"The regional arm of the United Nations Secretariat for the Asian and Pacific region is the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP). It is located in the United Nations Building, Ratchadamnoen Nok Avenue, Bangkok, Thailand. The functions of UNESCAP have been defined by the Secretary- General as follows:

Promoting economic and social development through regional and subregional cooperation and integration;
Serving as the main economic and social development forum within the United Nations system for the UNESCAP region;
Formulating and promoting development assistance activities and projects commensurate with the needs and priorities of the region while acting as an executing agency for relevant operational projects;
Providing substantive and secretariat services and documentation for the Commission and its subsidiary bodies;
Carrying out studies, research and other activities within the terms of reference of the Commission;
Providing advisory services to governments at their request;
Developing and executing programmes of technical cooperation;
Coordinating UNESCAP activities with those of the major departments/offices of the United Nations at Headquarters and specialized agencies and intergovernmental organizations."

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 )

Valency

The numerical value of the charge on an ion (cation or anion), describing the number of bonds which can be formed by the ion. Valencies may be respresented in different ways, that is, descriptively (e.g. divalent), with numbers (e.g. 2-) or with roman numerals (e.g. II) and may or may not include description of the charge (- or +).

Examples of valancies are sodium (Na+) which is monovalent or univalent and the carbonate ion (CO32-) which is divalent. Chrome can occur in -(II) to +(VI) valencies, but is most common in the elemental (0), divalent (II), trivalent (III) and hexavalent (VI) forms. (Source: GreenFacts)

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Volatile

Able to readily evaporate at normal temperatures and pressures. (Source: GreenFacts)

Winsconsin Department of Natural Resources

"The Department of Natural Resources is dedicated to the preservation, protection, effective management, and maintenance of Wisconsin's natural resources. It is responsible for implementing the laws of the state and, where applicable, the laws of the federal government that protect and enhance the natural resources of our state. It is the one agency charged with full responsibility for coordinating the many disciplines and programs necessary to provide a clean environment and a full range of outdoor recreational opportunities for Wisconsin citizens and visitors." (Source: WDNR website )

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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