Biomonitoring Glossary

At a glance

List of terms commonly used in the field of biomonitoring.

Lab tech handling samples



The process of a substance getting into the body through the eyes, skin, stomach, intestines, or lungs.


Occurring over a short time.

Acute exposure

Contact with a substance that occurs once or for a short time.

Acute toxicity

Adverse effects that occur shortly after an exposure, within a few hours to several days.

Adverse health effect

A change in body function or cell structure that may lead to disease or health problems.


A substance measured in a sample (for instance, water, air, or blood) by laboratory analysis.

Analytical method

Laboratory procedure using various methods and instruments to measure the amount of a chemical in a human specimen.

Blood lead level

A measure of lead in the body usually reported as micrograms of lead per deciliter of blood (µg/dL).


An unintentional or secondary product created when an intended product or chemical is created.


A substance that can cause cancer.

CAS registry number

A unique number assigned to a substance or mixture by the Chemical Abstracts Service of the American Chemical Society.

Childbearing age

Range of ages during which a woman may become pregnant. For example, can be defined as 16-49 years of age.

Chronic (health) effect

A health condition that lasts a long time. For example, a health condition with symptoms that do not start immediately. Could also be symptoms that stay a long time (several weeks or more) or symptoms that stop and then come back.

Chronic exposure

Contact with a substance that occurs for a long time, typically more than one year.

Clinical Laboratory Improvement Amendments (CLIA)

Federal requirements established to ensure the accuracy, reliability, and timeliness of laboratory test results. CLIA regulations apply to all facilities in the U.S. that perform laboratory testing on human specimens. This testing must assess health, diagnosis disease, or measure results of methods to prevent or treat disease. All laboratories, including those at CDC, that perform these types of testing must meet requirements.


Substance created by combining more than one part or element (or chemical if a "chemical compound").


Amount of a substance in a specific amount of any media (for instance, soil, water, air, food, blood, hair, urine, breath).


A substance found in an environment where it does not belong. Can also be a substance that is present at levels that might cause bad health effects.


Statistical measurement that describes the form, direction, and strength of a relationship between two things.


A substance that is a breakdown product of energy usage in muscle. The substance is filtered from the blood by the kidneys and eliminated from the body in urine.

Creatinine corrected

A technique used to calculate urine measurement results that can indicate whether urine was diluted or concentrated.


A metabolite (resulting product) formed when the body breaks down (metabolizes) nicotine.



For chemicals that are not radioactive:

Amount of a toxic substance taken into the body from contaminated water, food, or soil over a period of time. A measurement of exposure often expressed as milligram (amount) per kilogram (body weight) per day (a measure of time).

For radioactive chemicals:

The radiation dose is the amount of energy from radiation that is actually absorbed by the body. This measurement is not the same as the amount of radiation in the environment.


Naturally occurring substance (for instance, sodium, lead, arsenic, cadmium) that cannot be broken down by using chemical methods.

Environmental chemicals

Chemical compounds or elements in the air, water, food, soil, or dust, or from other sources such as consumer products.

Environmental media

Soil, water, air, plants, animals, or any other part of the environment that can contain contaminants.

Environmental tobacco smoke

Tobacco smoke in the environment that comes from the burning end of a cigarette or cigar or smoked pipe tobacco. This is combined with the smoke exhaled by a smoker from any of these sources. Also referenced as second-hand smoke.


Protein that starts or speeds up a chemical reaction.

Epidemiologic investigation

Collection and analysis of data related to the cause or spread of a disease, or health effects from a disease.


Process of eliminating a substance from the body.


Swallowing, breathing, or touching a substance. Exposure duration may be immediate, short term (14 days or fewer), intermediate, or long term (more than 1 year).


Geometric mean

Mathematical average calculated by taking the average of log-transformed data. Geometric mean is often used to describe data sets that are not normally distributed.


The time needed for half of the original amount of a substance to disappear. The substance may disappear by being changed to another chemical by bacteria, sunlight, or other chemical processes. In the human body, the substance may disappear by being changed to another substance and then leaving the body. The substance may also simply leave the body.


A chemical, substance, or an exposure that can adversely affect health.

Human biomonitoring

Assessing human exposure to environmental chemicals by measuring chemicals or their metabolites. The reaction products in tissue or fluids such as blood and urine may also be observed to assess exposure.

Inductively coupled plasma mass spectrometry

A complex laboratory method used to analyze metals and many inorganic chemicals at very low concentrations. These concentrations can be as low as one part per billion or one part per trillion.


One or more items, characteristics, or markers to be assessed. Indicators provide information about a population's health, environment, and other factors. This helps in efforts to monitor trends, compare situations, and understand the link between environment and health.

Limit of detection

The smallest amount of a substance that can be measured consistently by laboratory analysis.


Average of a list of numbers. Mean is calculated by adding all the numbers and then dividing by the total number of items in the list.


The middle value in a set of values that are arranged in ascending or descending order.


The conversion or breaking down of a substance from one form to another by a living organism. Also refers to the conversion of chemicals into other products in the body.


A substance produced when the body breaks down a chemical or compound.

National Health and Nutrition Examination Survey

Ongoing survey of studies to assess the health and nutritional status of adults and children in the United States.


Chemical in tobacco that causes and maintains the powerful addicting effects of tobacco products.


An atom (tiny elements that make up everything, including humans) characterized by the number of protons and neutrons in the nucleus. The atom is also characterized by the amount of energy it contains.

Nutritional indicator

Vitamins, trace elements, body iron stores, or other dietary measures that determine a person's or population's health status.



Term that describes a chemical that remains in the environment or the body for a long time (typically months to years).


Any substance released into the environment that adversely affects the health of humans, animals, or the environment.

Proficiency testing

Assessing a laboratory's ability to accurately measure a substance sample against a known standard sample.


Energy moving in the form of particles or waves. Familiar radiations are heat, light, radio, and microwaves.


An unstable nuclide with excessive energy that is given off to form radiation.

Random sample

A process where members or items are chosen from a group (population) in no order or pattern.

Simple random sample

A sample (smaller group) of items or members chosen from a larger group. This allows all members within the larger group to have an equal chance of being chosen.

Reference range

The highest and lowest values that will be used to measure or compare with other values.

For example, CDC's National Exposure Report provides reference ranges of environmental chemicals for the US population. This enables researchers, physicians, and health authorities to identify unusual exposure levels.

Reference values

Values used to compare other results of the same test. For example, total cholesterol of 200 might be the reference value. Above this value, a result is considered elevated or high and likely to need intervention.

Rapid toxic screen

A series of tests used at CDC's Division of Laboratory Sciences to identify and measure a number of high-priority chemicals.


A portion of blood, urine, or other body fluid or tissue taken for scientific and laboratory testing.


A portion of a population or whatever is being studied. For example, CDC's National Exposure Report uses human blood and urine samples for analysis.


The liquid part of blood that remains after clotting proteins and blood cells are removed.

Special populations

People who are more sensitive to the effects of hazardous substances because of age, occupation, sex, or behaviors (for instance, cigarette smoking). Special populations can be children, pregnant women, and older adults.

Standardized reagents

A reagent is a substance or chemical used to prepare a solution used in chemical analysis. Standardized reagents are usually a solution with a known amount of the chemical. They are used to measure unknown quantities of the same chemical.

Public health surveillance

Collection, analyzing, interpreting, and distributing health data continuously and logically.

Quality assurance/Quality control

A program designed to produce results that are valid, scientifically provable, precise, accurate, and fair.


The extent to which a substance is harmful.


Harmful or poisonous substance produced by an organism such as a bacteria, plant, or animal.

Volatile organic compounds (VOCs)

Contaminants that contain carbon atoms and easily become vapors or gases at room temperature. Some VOCs are released from burning fuel such as gasoline and coal.


95% confidence interval

A range that is calculated based on the standard error of a measurement and conveys how precise a measurement is. 95% confidence interval means the likelihood of the true mean falling within the interval is 95%.

95th percentile

A value in a set of data where 95% of the other values are estimated to be smaller. Also can be a value in a data set where only 5% of the other values are estimated to be larger. For example, in the National Exposure Report, the 95th percentile of a measurement indicates that 95% of the population is estimated to have lower concentration values and 5% of the population is estimated to have higher concentration values.