Select the first letter of the word from the list above to
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the entry or uptake of a substance into the body, either
across a tissue or cells.
Daily Intake (ADI)
The maximum amount of a substance that can be taken into
the body daily over the course of a lifetime without
posing a health risk.
The buildup of a substance in the body due to either long
term (chronic) exposure or repeat exposure.
A compound is considered acidic when its pH is below 7.
An example would be lemon juice or vinegar.
- Action Level
The concentration of lead or copper in water which
determines the treatment requirements that a water system
is required to complete.
- Acute Exposure
Either a single or short term exposure to a compound.
The condensation of gases, liquids, or dissolved
substances on the surfaces of solids.
- Adverse Health Effect
An effect that causes functional impairment, or a
pathological lesion which may affect how the organism
performs, or reduce its ability to respond to new changes
in the environment.
A compound that counteracts or neutralizes the effect of
A process that requires oxygen to continue or persist. An
example would be aerobic bacteria which require oxygen to
A compound is considered alkaline or basic when its pH is
above 7. An example would be bleach or baking soda.
The metabolism of substances by bacteria that do not
require oxygen to live.
A rheumatism of the joints, which could be any of a variety of
disorders marked by inflammation, degeneration, or metabolic
derangement of the connective tissue structures of the body.
- Background level
The normal concentration of a chemical in the
A microscopic organism that consists of a single cell
Alkaline; a compound with a pH above 7.
The accumulation within living organisms of toxic
substances occuring in the environment.
A disease that tends to have rapid, uncontrolled growth of cells
A cancer causing substance.
The development of cancer
Tending to induce the formation of cataracts
The part of the nervous system that contains the brain and the
A process of adding chlorine to water to disinfect it, to aid in
coagulation, or to remove odors and smells. See also disinfection.
A long term exposure to a chemical, either continuously or
periodically through that period of time.
The clumping together of fine particles into larger particles,
caused by the use of chemicals. the larger particles are then
easier to separate from the water.
The amount of the compound present in a specified quantity of
dilutant (i.e. water). Can be expressed as ml/L, oz/gallon, etc.
Any impurity or substance that pollutes another; an agent of
contamination accidently or inadvertantly introduced into food,
water, soil, or air, that may or may not be harmful or
Pertaining to the skin. Some chemicals can be absorbed
through or by the skin.
The movement of a chemical from a high concentration area
to a low concentration area. Eventually, an equilibrium
is reached where chemical is in equal concentrations
throughout the system.
The process in which most microorganisms are killed,
especially pathogenic microbes. See chlorination.
The total amount of the compound given to or taken by an
- Efflux pump
Located in the cell membrane are pumps made of proteins,
which transport molecules in and out of the cell. An
efflux pump would be one that transports molecules out of
- Enteric Virus
A virus of intestinal origin.
- Environmental Fate
The fate of the chemical after it has been released into
the environment. The fate depends upon the specific
characteristics of the chemical and the physical and
biological forces which may act upon that chemical, such
as heat, water or soil microorganisms among others.
Coming into contact with a compound which may or may not
result in a toxic effect. The main routes of exposure are
by mouth, skin and by breathing.
A process of removing particles from water by passing it
through a porous media such as a filter.
A process of gathering fine particles in the water into
larger particles by the addition of a chemical agent. See
Toxic action occurring among the heritable chromosomes.
Heritable chromosomes can be transmitted from parent to
Water which is located in zones below the soil surface.
Wells and springs can be fed by groundwater.
Groundwater residue guidance level.
The potential that the use of a compound could result in
a toxic effect.
- Health Advisory (HA)
A non-enforceable guideline set by the EPA used to
evaluate the health significance of a contaminant in
drinking water when no MCL has been set for that
contaminant by the EPA.
Substances or compounds that do not contain
carbon and are generally not derived from plants and
animals, such as minerals, salts, and metals.
The amount of a compound that is inhaled, ingested, or
absorbed over a certain period of time.
An electrically charged atom, formed by the loss or gain
of one or more electron.
A biological process made to occur in a laboratory vessel or
other controlled experimental environment rather than within a
living organism or natural setting.
Having an affinity for fat.
Contaminant Level (MCL)
A drinking water standard which is set by the EPA. The
MCL is the maximum amount of a compound that can be
present in drinking water at any given time.
Tolerated Dose (MTD)
The highest dose of a chemical that does not shorten the
organism's lifespan or cause severe damage to the
One millionth of a gram i.e. 10-6 g. Also is one
thousandth of a milligram i.e. 10-3 g. Is often
designated by the symbol µg.
- Minimata Disaster
In 1953, an epidemic hit fishermen and their families in
villages on Japan's Minamata Bay. A number of people who
were highly dependent on seafood showed signs of brain
damage. Some of these cases were fatal. An investigation
revealed that a local chemical plant was discharging
organic mercury into the bay, and the fish in the area
had absorbed the mercury and eventually passed it on to
- Muscular dystrophy
A group of genetic degenerative myopathies characterized
by weakness and atrophy of muscle without involvement of
the nervous system.
A substance that causes permanent damage to genes, that
would not normally occur.
Observable Effect Level (NOEL)
The highest dose given which does not show an observable
adverse effect to the organism.
A substance that will not become a gas or vaporize into
Any gene that is a causative factor in the initiation of
cancerous growth. When activated these genes can
transform the cell from normal to one which does not have
regulated cell growth.
Capable of inducing tumor formation
Egg like forms of a parasite such as cryptosporidium
which are infectious.
Carbon containing compounds including those existing in
or derived from plants and animals, also including
man-made carbon based compounds.
A treatment process in which ozone is applied to the
water for disinfection, or for taste and odor control.
A substance or mixture of substances used to prevent,
destroy, or repel a pest.
Parts per billion; This is a measure of the concentration
of a compound. 1 ppb is equal to one microgram per
kilogram. An example of this would be one ppb is equal to
one second in thirty-two years.
Parts per million; This is a measure of concentration of
a compound. 1 ppm is equal to one mg per kg. An example
of this would be one ppm is equal to one minute in two
- Priority Pollutants
A group of toxic chemicals or classes of chemicals listed
under section 307(a)(1) of the Clean Water Act of 1977
(U.S.C. 466). This list was established for the purpose
of providing guidelines for regulating industrial
effluent discharge with the primary goal of protecting
A unicellular microorganism that has the means to move
around either by cilia or a flagella.
A tranquilizer, sedative, antidepressant or mood altering drug.
Dysfunction of the lungs.
- Reference Dose (RfD)
A level of exposure that is considered acceptable or
safe. Also known as the "acceptable daily
The possibility that an adverse effect will occur.
A water treatment in which solid particles are
settled out of the water in a sedimentation basin or
The concentration of a compound that dissolves in a
solvent (i.e. water).
- Surface Water
Water at the soil surface. Examples include oceans,
lakes, streams, rivers, etc.
Any chemical which can produce toxic effects; includes
toxins which are toxicants produced by living organisms.
Example: DDT and PCBs are toxicants, strychnine and
pyrethrins are toxins produced by plants.
The smallest microorganism that is capable of causing a disease.
Revised: May 04, 1998.