MeSH

A naturally radioactive element with atomic symbol Rn, and atomic number 86. It is a member of the noble gas family found in soil, and is released during the decay of RADIUM.

Year introduced: ACTINON was see RADON 1978-1993

Carcinogenic substances that are found in the environment.

Year introduced: 1975

Pollutants present in air which exhibit radioactivity.

Year introduced: 1991(1975)

Isotopes that exhibit radioactivity and undergo radioactive decay. (From Grant and Hackh's Chemical Dictionary, 5th ed and McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Atomic species differing in mass number but having the same atomic number. (Grant and Hackh's Chemical Dictionary, 5th ed)

Year introduced: 1974

A broad class of substances encompassing all those that do not include carbon and its derivatives as their principal elements. However, carbides, carbonates, cyanides, cyanates, and carbon disulfide are included in this class.

Year introduced: 1998

Elements that constitute group 18 (formerly the zero group) of the periodic table. They are gases that generally do not react chemically.

Year introduced: 1994

The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant and Hackh's Chemical Dictionary, 5th ed)

Unstable elements with atomic numbers greater than 83 that exist in nature solely as radioisotopes.

Year introduced: 1998

Substances that comprise all matter. Each element is made up of atoms that are identical in number of electrons and protons and in nuclear charge but may differ in mass or number of neutrons.

Mixtures of many components in inexact proportions, usually natural, such as PLANT EXTRACTS; VENOMS; and MANURE. These are distinguished from DRUG COMBINATIONS which have only a few components in definite proportions.

Year introduced: 2004

A group of pharmacologic activities, effects on living systems and the environment, and modes of employment of drugs and chemicals. They are broken into actions, which describe their effects, and uses, which describe how they are employed.

Year introduced: 1999

Radioactive substances which act as pollutants. They include chemicals whose radiation is released via radioactive waste, nuclear accidents, fallout from nuclear explosions, and the like.

Year introduced: 1975

Agents capable of exerting a harmful effect on the body.

Year introduced: 1998

A broad category of chemical actions with harmful or deadly effect on living organisms.

Year introduced: 2004(1998)

Substances or energies, for example heat or light, which when introduced into the air, water, or land threaten life or health of individuals or ECOSYSTEMS.

Year introduced: 1975

Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.

Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or materials. Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS.

Year introduced: 1975