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Occurring over a short time [compare with chronic]. (Source: ATSDR Glossary of Terms  )


An aerosol is a collection of microscopic particles, solid or liquid, suspended in a gas.

In the context of air pollution, an aerosol refers to fine particulate matter, that is larger than a molecule, but small enough to remain suspended in the atmosphere for at least several hours.

The term aerosol is also commonly used for a pressurized container (aerosol can) which is designed to release a fine spray of a material such as paint. It has also come to be associated, erroneously, with the gas (propellant) used to expel materials from an aerosol can. (Source: GreenFacts )


Alternating current & Direct current

Alternating Current (AC) is a type of electrical current, in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current flowing in power lines and normal household electricity that comes from a wall outlet is alternating current. The standard current used in the U.S. is 60 cycles per second (i.e. a frequency of 60 Hz); in Europe and most other parts of the world it is 50 cycles per second (i.e. a frequency of 50 Hz.).

Direct current (DC) is electrical current which flows consistently in one direction. The current that flows in a flashlight or another appliance running on batteries is direct current.

One advantage of alternating current is that it is relatively cheap to change the voltage of the current. Furthermore, the inevitable loss of energy that occurs when current is carried over long distances is far smaller with alternating current than with direct current. (Source: GreenFacts)



The largest artery in the body.

It carries oxygen-rich blood away from the heart to vessels that reach the rest of the body. (Source: St. Jude Children's Research Hospital  )



An arrhythmia (also called dysrhythmia or irregular heart rhythm) is an irregular or abnormal heartbeat.

An arrhythmia can involve a change in the rhythm, producing an uneven heartbeat, or a change in the rate, causing a very slow or very fast heartbeat. (Source: Cleveland Clinic Heart Center Treating the Heart, Blood Vessels and Circulation  )



The mass of air surrounding the Earth.

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

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



The study of the chemical processes and compounds occurring in living organisms. (Source: American Institute for Medical and Biological Engineering Glossary  )

Blood serum

Clear, watery fluid of the blood that separates when blood clots. (Source: GreenFacts)



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



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)


Cell membrane

The cell membrane is a fine structure that envelops a cell, separating the content of the cell from its surroundings.

It regulates the substances that can enter and leave the cell.

The membrane consists of a double layer of lipids in which proteins are embedded. (Source: GreenFacts)


An electric charge (q or Q) is the quantity of unbalanced electricity in an object (either positive or negative). It is interpreted as an excess or deficiency of electrons. Matter that possesses a charge is influenced by and produces electromagnetic fields.

Electrons, by convention have an elementary charge of -1. Ions are either positively or negatively charged. The unit of measurement of the charge of an object is the coulomb, which represents 6.24 x 1018 elementary charges. (Source: GreenFacts)


Occurring over a long period of time, either continuously or intermittently; used to describe ongoing exposures and effects that develop only after a long exposure. (Source: US EPA Thesaurus  )

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  )

Cohort study

A type of epidemiological study which observes a large number of individuals in a population over a period of time.

It compares individuals who are exposed for instance to a certain chemical to others without the exposure or with a different level of exposure. These two groups are called cohorts and are followed over time to determine the differences in the health outcomes between the exposure subjects. (Source: GreenFacts)

Confounding factor

A confounding factor in a study is a variable which is related to one or more of the variables defined in a study. A confounding factor may mask an actual association or falsely demonstrate an apparent association between the study variables where no real association between them exists. If confounding factors are not measured and considered, bias may result in the conclusion of the study. (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  )

DG Health and Consumers

"The Health and Consumers DG (formally known as Health and Consumer Protection DG) is one of 36 Directorates-General (DGs) and specialised services which make up the European Commission."

The mission statement of the Health and Consumers DG is: "to promote a better quality of life by ensuring a high level of protection of consumers' health, safety and economic interests as well as of public health"

"This overall goal is addressed through legislative and non-legislative actions in three inter-related policy areas: 1. Consumer policy (...), 2. Public Health (...), 3. Food safety, animal health, animal welfare and plant health (...)". (Source: DG Health and Consumers website  )

Electric current

The electrical current is a physical phenomenon caused by the displacement of electrons or ions that induce electric fields. By convention, current is considered to be a flux of positive charges.

The intensity of the current is the quantity of charge which passes in a conductor per unit of time. The intensity of the current is measured in Amperes (A). (Source: Belgian BioElectroMagnetic Group Dictionary   )


Electric field

An electric field is an invisible force field created by the attraction and repulsion of electrical charges (the cause of electric flow), and is measured in Volts per meter (V/m).

The intensity of the electric field decreases with distance from the field source.

A static electric field (also referred to as electrostatic field) is an electric field that does not vary with time (frequency of 0 Hz). Static electric fields are created by electrical charges that are fixed in space. They are different from fields that change over time, such as electromagnetic fields generated by appliances using alternating current (AC) or by cell phones etc. (Source: GreenFacts )



A solution capable of conducting electricity, usually a solution of a salt in water.

Alternately, a substance capable of conducting an electric current, such as a molten salt. (Source: Physchem Glossary of scientific terms  )


Electromagnetic fields (EMF)

Electromagnetic fields (EMF) are a combination of invisible electric and magnetic fields of force. They occur both naturally and due to human activity. (Source: GreenFacts)


Endocrine system

A network of glands distributed throughout the body forms the endocrine system. These glands produce hormones that are released into the circulation and distributed to distant target sites via the blood. Hormones produced by these glands act as chemical messengers to control body functions such as growth, metabolism, sexual development, and egg and sperm production. (Source: EMCOM Glossary  )



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  )

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  )


A portable monitoring instrument used to measure the exposure to a physical hazard a person has received over a period of time.

Such instruments are designed to measure the accumulated exposure to factors such as radiation, electric and magnetic fields, or noise. (Source: GreenFacts)


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)


Exposure assessment(s)

Quantitative or qualitative evaluation of the contact of a chemical [or a physical factor] with the outer boundary of the human body, which includes consideration of the intensity, frequency and duration of contact, the route of exposure (e.g. dermal, oral or respiratory), rates (chemical intake or uptake rates), the resulting amount that actually crosses the boundary (dose), and the amount absorbed (internal dose) (WHO 1999). (Source: EMCOM Glossary  )


One of the strongest forms of magnetism which is the basis for all permanent magnets.

Ferromagnetism refers to the phenomenon by which ferromagnetic metals such as iron, nickel, cobalt and certain alloys become magnetized in a magnetic field and retain their magnetism when the field is removed. (Source: GreenFacts)



The embryo is referred to as a foetus after it has reached a certain stage of organ development (in humans this is eight weeks after conception). (Source: CSIRO Glossary of terms  )

Free radical

A free radical is an atom or molecule that is highly reactive because it contains an unpaired electron in the outer shell.

Free radicals are formed as necessary intermediates in a variety of normal biochemical reactions, but can damage important cellular molecules such as DNA or lipids.

Radicals can have positive, negative or neutral charge. (Source: GreenFacts)


Frequency is the measurement of the number of times that a repeated event occurs per unit of time.

The frequency of wave-like patterns including sound, electromagnetic waves (such as radio or light), electrical signals, or other waves, expresses the number of cycles of the repetitive waveform per second.

In SI units, the result is measured in Hertz (Hz), named after the German physicist, Heinrich Rudolf Hertz. 1 Hz means one cycle (or wave) per second.

Frequency has an inverse relationship to the concept of wavelength (the distance between two peeks) such that the frequency is equal to the velocity divided by the wavelength. (Source: GreenFacts)


Gene expression

The process by which a gene is "turned on" to produce the specific biological molecule encoded by that gene (usually protein or RNA). (Source: GreenFacts )

Genetic material

Any material of plant, animal, microbial or other origin that carries genetic information and that passes it from one generation to the next.

The information contained controls reproduction, development, behaviour, etc. (Source: GreenFacts )


Geomagnetic field

The geomagnetic field is the magnetic force field that surrounds the Earth. It is attributed to the combined effects of the planetary rotation and the movement of molten iron in the Earth's' core.

Compasses, instruments that align themselves with the magnetic poles of the Earth, have been used in navigation for centuries. Some birds (particularly migratory species) and other animals rely on the geomagnetic field to orient themselves. (Source: GreenFacts)


In vitro

In an artificial environment outside a living organism or body. For example, some toxicity testing is done on cell cultures or slices of tissue grown in the laboratory, rather than on a living animal. (Source: ATSDR Glossary of Terms  )

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 Commission on Non-Ionizing Radiation Protection

"ICNIRP is the International Commission on Non-Ionizing Radiation Protection. It is a body of independent scientific experts consisting of a main Commission of 14 members, 4 Scientific Standing Committees covering Epidemiology, Biology, Dosimetry and Optical Radiation and a number of consulting members. This expertise is brought to bear on addressing the important issues of possible adverse effects on human health of exposure to non-ionising radiation.

ICNIRP's principal aim is to disseminate information and advice on the potential health hazards of exposure to non-ionizing radiation to everyone with an interest in the subject. ICNIRP's information and advice covers all of the non-ionizing radiations including, the optical radiations (ultraviolet, visible and infrared - and lasers), static and time-varying electric and magnetic fields and radiofrequency (including microwave) radiation, and ultrasound. Much of the information that ICNIRP provides is published in the form of scientific reviews and reports and the proceedings of scientific meetings. The results of these reviews combined with risk assessments carried out in collaboration with the World Health Organization, WHO, result in the publication by ICNIRP of Exposure Guidelines. Examples of these are guidelines limiting exposure to electromagnetic fields, to laser radiation, to ultraviolet radiation, to incoherent optical radiation and to ultrasound."


An ion is an atom or molecule that is not electrically neutral, but instead carries a positive or negative electrical charge, which is due to the loss or gain of one or more electrons.

An anion is a ion with a negative electrical charge, e.g. chloride (CI-), as opposed to a cation which is an ion with a positive electrical charge, e.g. sodium (Na+). (Source: GreenFacts)

Magnetic field

A magnetic field is an invisible force field created by a magnet or as a consequence of the movement of electric charges (flow of electricity).

The magnitude (intensity) of a magnetic field is usually measured Tesla (T or in mT), but it can also be measured in Gauss (G).

The intensity of the field decreases with distance from the field source. (Source: GreenFacts)


Magnetic Resonance Imaging (MRI)

A technique that uses a strong circular magnet in combination with pulses of radio waves to produce detailed images of internal organs. MRI is especially useful for imaging spine, joints, and inside bones and also soft tissue such as the brain.

Physicians can use MRI to see for instance the difference between normal and diseased brain tissue or which parts of the brain are active when you perform certain tasks or feel certain emotions and sensations.

MRI is one of several Nuclear Magnetic Resonance techniques. (Source: GreenFacts, based on Institute of Physics Inside story: MRI scans   )


Magnetic Resonance Spectroscopy (MRS)

A technique that uses a strong circular magnet for instance to identify the chemical composition of diseased tissue.

MRS is one of several Nuclear Magnetic Resonance techniques. It is somewhat different from MRI because it uses a continuous band of radio wave frequencies to excite hydrogen atoms.

Physicians mainly use MRS to study the brain and disorders such as epilepsy, Alzheimer's disease, brain tumors, and the effects of drugs on brain growth and metabolism. The technique is also useful in evaluating metabolic disorders of the muscles and nervous system. (Source: GreenFacts )



A class of physical phenomena that include being able to attract iron.

Magnetism is associated with moving electricity, is exhibited by both magnets and electric currents, and involves force ["magnetic"] fields. (Source: Glossary  )



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


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



Any permanent change in the DNA of a cell.

Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment.

Mutations can be harmful, beneficial, or have no effect. If they occur in cells that make eggs or sperm, they can be inherited; if mutations occur in other types of cells, they are not inherited.

Certain mutations may lead to cancer or other diseases. (Source: NCI dictionary   )

Nervous system

The nervous system is a complex, sophisticated system that regulates and coordinates body activities.

It is made up of:

  • the central nervous system, consisting of the brain and spinal cord, and
  • the peripheral nervous system which includes, the eyes, the ears, the sensory organs of taste and smell, as well as the sensory receptors located in the skin, joints, muscles, and other parts of the body.

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

Nuclear Magnetic Resonance (NMR)

A physical phenomenon based upon the magnetic property of the nuclei of certain atoms.

The term is often used to describe a series of techniques that make use of this phenomenon to determine the structure of molecules, by placing them in a strong magnetic field.

Applications in medical imaging include Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS). (Source: GreenFacts)


A small battery-operated electronic device that is surgically implanted under the skin and joined to the heart by wires, and that measures the pulse and corrects too fast or too slow heart rhythms. (Source: GreenFacts)



Visual sensations, such as flashes of light, that are not caused by an external source of light entering the eye, but arise as a result of mechanical, electrical or magnetic stimulation of the eyeball.

They don't impair vision and they are transitory.

They can occur for instance when a person is moving in a strong static magnetic field. (Source: GreenFacts)

Pregnancy outcomes

Results of conception and ensuing pregnancy, such as sex ratio, birth weight, spontaneous abortion, congenital malformations, lower birth weight, preterm delivery or stillbirth. (Source: GreenFacts)

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)


Spark discharge

A momentary electric discharge between two differently charged objects. Sparks cross the air-gap between the objects along a narrow channel, which is visible as a light flash.

Small painful spark discharges can occur when a person who is well insulated from the ground through wearing shoes with plastic soles touches an object that is electrically connected to the ground. If the electric currents are very small (microshocks of less than 1mA) they are usually not perceived.

A lightning discharge can be considered a large-scale spark discharge. (Source: GreenFacts)



A group of organisms that differ from all other groups of organisms and that are capable of breeding and producing fertile offspring. This is the smallest unit of classification for plants and animals. (Source: OceanLink Glossary of Common Terms and Definitions in Marine Biology  )



Superconductors are materials that, at very low temperatures, conduct electricity with no resistance.

This means that, unlike the more familiar conductors such as copper or steel, a superconductor can carry a current indefinitely without losing any energy in the form of heat, light, or sound.

Another important property is that no magnetic field can exist within a superconductor. This property has been exploited in the creation of maglev (for magnetic levitation) high-speed trains. This property is also used, paradoxically, in the creation of very strong magnets used in research and in medical applications such as magnetic resonance imaging (MRI). (Source: GrenFacts, based on Superconductor week Glossary   )


Measures taken to treat a physical or mental disease.

First-line therapy is the first type of therapy given for a condition or disease.

Second-line therapy is the treatment that is given when initial treatment (first-line therapy) doesn't work, or stops working. (Source: based on St Jude Hospital Medical Terminology & Drug Database )


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

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 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 )

Ventricular fibrillation

Ventricular fibrillation is a heart condition which consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart. The ventricular muscle twitches randomly, because the contraction of the muscle cells is not synchronized and as a result the ventricles fail to pump blood into the arteries. (Source: GreenFacts based on Medical Emergencies )



A dizzying sensation of the environment spinning, often accompanied by nausea and vomiting. (Source: National Multiple Sclerosis Society Glossary of MS terms )


The difference in electrical charge between two points in a circuit expressed in volts which makes electrical charges flow through a closed circuit. (Source: GreenFacts)


World Health Organization

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

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

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

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

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

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