Glossary of Environmental Health Terms

This glossary is intended to help people become familiar with the terms they are likely to see in government reports, engineering studies and health literature. It is divided into four sections:

Terms
Agencies
Units of Measure
Conversion Tables

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Terms

Absorption
The process of taking in, as when a sponge takes up water. Chemicals can be absorbed into the bloodstream after breathing or swallowing. Chemicals can also be absorbed through the skin into the bloodstream and then transported to other organs. Not all of the chemical breathed, swallowed, or touched is always absorbed.
Acute
Occurring over a short time, usually a few minutes or hours. An acute exposure can result in short term or long term health effects. An acute effect happens within a short time after exposure.
Ambient
Surrounding. Ambient air usually means outdoor air (as opposed to indoor air).
Analyte
A chemical for which a sample (such as water, air, blood, urine or other substance) is tested. For example, if the analyte is mercury, the laboratory test will determine the amount of mercury in the sample.
Aquifer
An underground source of water. This water may be contained in a layer of rock, sand or gravel.
Background level
A typical level of a chemical in the environment. Background often refers to naturally occurring or uncontaminated levels. Background levels in one region of the state may be different than those in other areas.
Bedrock
The solid rock underneath surface soils.
Biological monitoring
Analyzing chemicals, hormone levels or other substances in biological materials (blood, urine, breath, etc.) as a measure of chemical exposure, health status, etc. in humans or animals. A blood test for lead is an example of biological monitoring.
Body burden
The total amount of a chemical in the body. Some chemicals build up in the body because they are stored in body organs like fat or bone or are eliminated very slowly.
Case control study
A study in which people with a disease (cases) are compared to people without the disease (controls) to see if their past exposures to chemicals or other risk factors were different.
Central nervous system (CNS)
The part of the nervous system that includes the brain and the spinal cord.
CERCLA
Comprehensive Environmental Response, Compensation and Liability Act. See "Superfund."
Chronic
Occurring over a long period of time, several weeks, months or years.
Cohort study
A study in which a group of people with a past exposure to chemicals or other risk factors are followed over time and their disease experience compared to that of a group of people without the exposure.
Composite sample
A sample which is made by combining samples from two or more locations. The sample can be of water, soil or another medium.
Concentration
The amount of one substance dissolved or contained in a given amount of another substance or medium. For example, sea water has a higher concentration of salt than fresh water does.
Contaminant
Any substance that enters a system (the environment, human body, food, etc.) where it is not normally found. Contaminants are usually referred to in a "negative" sense and include substances that spoil food, pollute the environment or cause other adverse effects.
Dermal
Referring to the skin. For example, dermal absorption means absorption through the skin.
Detection limit
The smallest amount of substance that a laboratory test can reliably measure in a sample of air, water, soil or other medium.
Dose
The amount of substance to which a person is exposed.
Epidemiology
The study of the occurrence and causes of health effects in human populations. An epidemiological study often compares two groups of people who are alike except for one factor such as exposure to a chemical or the presence of a health effect. The investigators try to determine if the factor is associated with the health effect.
Exposure
Contact with a chemical by swallowing, by breathing or by direct contact (such as through the skin or eyes). Exposure may be either short term (acute) or long term (chronic).
Exposure assessment
A process that estimates the amount of a chemical that enters or comes into contact with people or animals. An exposure assessment also describes how often and for how long an exposure occurred, and the nature and size of a population exposed to a chemical.
Feasibility Study (FS)
A study that compares different ways to clean up a contaminated site. The feasibility study recommends one or more actions to remediate the site. See "Remedial investigation".
Gradient
The change in a property over a certain distance. For example, lead can accumulate in surface soil near a road due to automobile exhaust. As you move away from the road, the amount of lead in the surface soil decreases. This change in the lead concentration with distance from the road is called a gradient.
Health assessment for contaminated sites
Determination of actual or possible health effects due to environmental contamination or exposure. It includes a health-based interpretation of all the information known about the situation. The information may come from site investigations (environmental sampling and studies), exposure assessments, risk assessments, biological monitoring or health effects studies. The health assessment is used to advise people how to prevent or reduce their exposures, to determine remedial actions or the need for additional studies.
Health effects studies related to contaminants
Studies of the health of people who may have been exposed to contaminants. They include, but are not limited to, epidemiological studies, reviews of health status of people in exposure or disease registries, and doing medical tests.
Health registry
A record of people exposed to a specific substance (such as a heavy metal), or having a specific health condition (such as cancer or a communicable disease). New York State maintains several health registries.
Ingestion
Swallowing (such as eating or drinking). Chemicals in or on food, drink, utensils, cigarettes, hands, etc. can be ingested. After ingestion, chemicals may be absorbed into the blood and distributed throughout the body.
Inhalation
Breathing. People can take in chemicals by breathing contaminated air.
Interim Remedial Measure (IRM)
An action taken at a contaminated site to reduce the chances of human or environmental exposure to site contaminants. Interim remedial measures are planned and carried out before comprehensive remedial studies. They can prevent additional damage during the study phase, but don’t interfere in any way with the need to develop a complete remedial program. An example of an interim remedial measure is removing drums of chemicals to a storage facility from a site that has drums sitting in an empty field.
Latency period
The period of time between exposure to something that causes a disease and the onset of the health effect. Cancer caused by chemical exposure may have a latency period of 5 to 40 years.
Leaching
As water moves through soils or landfills, chemicals in the soil may dissolve in the water thereby contaminating the groundwater. This is called leaching.
Maximum Contaminant Level (MCL)
The highest (maximum) level of a contaminant allowed to go uncorrected by a public water system under federal or state regulations. Depending on the contaminant, allowable levels might be calculated as an average over time, or might be based on individual test results. Corrective steps are implemented if the MCL is exceeded.
Media
Elements of a surrounding environment that can be sampled for contamination; usually soil, water, or air. Plants, as well as humans (when sampling blood, urine, etc) and animals (such as sampling fish to update fish consumption advisories) can also be considered media. The singular of "media" is "medium".
Metabolism
All the chemical reactions that enable the body to work. For example, food is metabolized (chemically changed) to supply the body with energy. Chemicals can be metabolized by the body and made either more or less harmful.
Morbidity
Illness or disease. A morbidity rate for a certain illness is the number of people with that illness divided by the number of people in the population from which the illnesses were counted.
National Priority List (NPL)
A list maintained by the U.S. Environmental Protection Agency (EPA) of certain inactive hazardous waste sites. The list is produced and updated periodically by the EPA. See "Superfund".
Odor threshold
The lowest concentration of a chemical that can be smelled. Different chemicals have different odor thresholds. Also, some people can smell a chemical at lower concentrations than others can.
Organic
Generally considered as originating from plants or animals, and made primarily of carbon and hydrogen. Scientists use the term organic to mean those chemical compounds which are based on carbon.
Permeability
The property of permitting liquids or gases to pass through. A highly permeable soil, such as sand, allows a liquid to pass through quickly. Clay has a low permeability.
Persistence
The quality of remaining for a long period of time (such as in the environment or the body). Persistent chemicals (such as DDT and PCBs) are not easily broken down.
Preliminary Site Assessment (PSA)
A process followed by the NYS Department of Environmental Conservation (DEC) to determine if a site contains hazardous waste and its potential for harming the public health or environment. This process includes inspecting the site, sampling if needed, and taking physical or hydrological measurements as appropriate.
Plume
An area of chemicals moving away from its source in a long band or column. A plume, for example, can be a column of smoke from a chimney or chemicals moving with groundwater.
Protocol
The detailed plan for conducting a scientific procedure. A protocol for measuring a chemical in soil, water or air describes the way in which samples should be collected and analyzed.
Quality assurance and quality control (QA/QC)
A system of procedures, checks and audits to judge and control the quality of measurements and reduce the uncertainty of data. Some quality control procedures include having more than one person review the findings and analyzing a sample at different times or laboratories to see if the findings are similar.
Registry of Inactive Hazardous Waste Disposal Sites
The New York State Department of Environmental Conservation (DEC) maintains a list of inactive hazardous waste disposal sites in New York State. When DEC finds that a site may contain hazardous waste, the site is listed in the registry and a preliminary site assessment is planned. The status of the site is updated in the registry as investigations and remediation occur.
Remedial Investigation (RI)
An in-depth study (including sampling of air, soil, water and waste) of a contaminated site needing remediation to determine the nature and extent of contamination. The remedial investigation (RI) is usually combined with a feasibility study (FS).
Remediation
Correction or improvement of a problem, such as work that is done to clean up or stop the release of chemicals from a contaminated site. After investigation of a site, remedial work may include removing soil and/or drums, capping the site or collecting and treating the contaminated fluids.
Risk
Risk is the possibility of injury, disease or death. For example, for a person who has measles, the risk of death is one in one million.
Risk assessment
A process which estimates the likelihood that exposed people may have health effects. The four steps of a risk assessment are: hazard identification (Can this substance damage health?); dose-response assessment (What dose causes what effect?); exposure assessment (How and how much do people contact it?); and risk characterization (combining the other three steps to characterize risk and describe the limitations and uncertainties).
Risk management
The process of deciding how and to what extent to reduce or eliminate risk factors by considering the risk assessment, engineering factors (Can procedures or equipment do the job, for how long and how well?), social, economic and political concerns.
Route of exposure
The way in which a person may contact a chemical substance. For example, drinking (ingestion) and bathing (skin contact) are two different routes of exposure to contaminants that may be found in water. See "Exposure".
Safe
Strictly, free from harm or risk. Exposure to a chemical usually has some risk associated with it, although the risk may be very small. However, many people use the word safe to mean something that has a very low risk or one that is acceptable to them.
Site inspection
A Department of Health visit to a site to evaluate the likelihood of human exposure to toxic chemicals, and to do an exposure assessment. See "Exposure assessment."
Solubility
The largest amount of a substance that can be dissolved in a given amount of a liquid, usually water. For a highly water-soluble compound, such as table salt, a lot can dissolve in water. Motor oil is only slightly soluble in water.
Superfund (federal and state)
The federal and state programs to investigate and clean up inactive hazardous waste sites.
Target organ
An organ (such as the liver or kidney) that is specifically affected by a toxic chemical.
Volatile
Evaporating readily at normal temperatures and pressures. The air concentration of a highly volatile chemical can increase quickly in a closed room.
Volatile organic compound (VOC)
An organic chemical that evaporates readily. Petroleum products such as kerosene, gasoline and mineral spirits contain VOCs. Chlorinated solvents such as those used by dry cleaners or contained in paint strippers are also VOCs. See "organic" and "volatile".

Agencies

ACGIH
See "American Conference of Governmental Industrial Hygienists"
Ag & Mkts
See "New York State Department of Agriculture and Markets"
AG's Office
Attorney General's Office. See "New York State Department of Law"
American Conference of Governmental Industrial Hygienists (ACGIH)
ACGIH is a professional society of government workers and educators who work to promote occupational safety and health. The organization publishes recommendations on ventilation, air sampling and air concentration guidelines (threshold limit values or TLVS) designed to control exposure of workers to chemicals, noise and radiation in the workplace.
Agency for Toxic Substances and Disease Registry (ATSDR)
ATSDR is part of the U.S. Department of Health and Human Services. As mandated by the federal superfund law, the agency assesses health risks from hazardous waste sites on the National Priority 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.
Attorney General's Office
See "New York State Department of Law."
ATSDR
See "Agency for Toxic Substances and Disease Registry."
CDC
See "Centers for Disease Control."
Centers for Disease Control and Prevention (CDC or CDCP)
The CDC, part of the U.S. Department of Health and Human Services, provides federal leadership in the prevention and control of diseases. The CDC includes many programs that conduct research and provide information on public health issues such as occupational health, AIDS, cancer, infectious diseases and other diseases.
Consumer Product Safety Commission (CPSC)
The CPSC, a federal commission, protects the public from injury caused by consumer products. The CPSC evaluates products, investigates the causes of product-related injuries and issues and enforces safety standards. For example, the CPSC has banned certain products containing asbestos. The CPSC also regulates the lead content of paints.
CPSC
See "Consumer Product Safety Commission."
DEC
See "New York State Department of Environmental Conservation."
DHHS
See "U.S. Department of Health and Human Services."
DOE
See "U.S. Department of Energy."
DOH
See "New York State Department of Health."
DOL
See "New York State Department of Labor" or "New York State Department of Law"
ENCON
See "New York State Department of Environmental Conservation."
EPA
See "U.S. Environmental Protection Agency".
FDA
See "U.S. Food and Drug Administration".
IARC
See "International Agency for Research on Cancer."
IRIS
Short for "Integrated Risk Information System"; see "U.S. Environmental Protection Agency".
International Agency for Research on Cancer (IARC)
IARC, part of the World Health Organization, is an international organization that evaluates the human cancer risk from chemical exposure. IARC evaluates scientific studies on chemicals and publishes critical reviews on the cancer risks of these substances. IARC also identifies further research that is needed to evaluate the cancer- causing ability of some chemicals.
NAS
See "National Academy of Sciences."
National Academy of Sciences (NAS)
NAS is a private, nonprofit corporation established by Congress to investigate and report on science and technology at the request of the federal government. The National Research Council (NRC) is a part of the NAS and has reported on public health problems such as chemical contamination of drinking water.
National Institute of Environmental Health Sciences
The NIEHS tries to reduce human illness from environmental causes by understanding environmental factors, individual susceptibility and age. The NIEHS conducts biomedical research programs, prevention and intervention efforts, and education.
National Institute for Occupational Safety and Health (NIOSH)
NIOSH, part of the Centers for Disease Control, conducts research on worker safety and health and recommends standards for worker protection to OSHA. For example, NIOSH recommends guidelines for workplace exposure to hazardous substances and has published criteria documents on many chemicals.
National Institutes of Health (NIH)
NIH, part of the U.S. Department of Health and Human Services, conducts scientific research into the causes, prevention and cure of diseases. For example, the National Cancer Institute (part of NIH) studies how some environmental chemicals cause cancer. Many other diseases, some related to chemical exposure, are also under study at NIH.
National Research Council
See "National Academy of Sciences."
National Toxicology Program (NTP)
NTP, part of the U.S. Department of Health and Human Services (DHHS), coordinates the toxicology research being conducted within DHHS. The NTP selects priority chemicals for study, develops necessary testing procedures and coordinates the research done by programs in three DHHS agencies: NIH, FDA and CDC.
New York State Department of Agriculture and Markets (NYS Ag & Mkts or A&M)
The Department of Agriculture and Markets is the state agency that carries out programs on food supplies for consumers. For example, the department licenses and inspects grocery and other food stores, regulates the state's dairy industry and monitors and enforces standards for pesticide residues in agricultural produce.
New York State Department of Environmental Conservation (NYSDEC, DEC or ENCON)
DEC is the state agency that carries out and enforces laws to protect the environment in New York State. DEC administers programs that regulate discharges into air and water, the disposal of solid and hazardous waste, protection of natural resources and wildlife management.
New York State Department of Health (NYSDOH or DOH)
DOH is the state agency responsible for protecting public health in New York State. DOH records the occurrence of birth defects, cancer, AIDS and other diseases, and conducts research into the causes and prevention of these diseases. DOH also carries out programs to prevent or reduce disease or harmful health effects. Some of these programs provide services such as nutritional programs for mothers and infants; other programs regulate hospitals, home health care and public water supplies. Many programs provide information on topics such as chemical exposures and radiation.
New York State Department of Labor (NYSDOL or DOL)
DOL is the state agency that carries out and enforces laws to protect the safety and health of workers in New York State. DOL enforces public employee safety and health regulations, carries out inspections and provides consultation to employers to help them comply with health and safety laws. For example, DOL licenses asbestos contractors and inspects and enforces asbestos abatement projects.
New York State Department of Law (DOL or AG's Office)
The Department of Law, headed by the Attorney General (AG), takes legal action on behalf of New York State citizens and state agencies. The AG's office investigates and prosecutes those who violate consumer protection, public health or environmental laws. It also conducts environmental crime investigations, sues for clean up of toxic sites and works to improve state and federal environmental laws.
New York State Energy Research and Development Authority (NYSERDA)
The New York State Energy Research and Development Authority coordinates energy matters and monitors low-level radioactive waste generation and management for the State. It also finances energy-related projects, makes energy more affordable for residential and low-income households, and conducts energy and environmental research.
NIEHS
National Institute of Environmental Health Sciences
NIH
See "National Institutes of Health."
NIOSH
See "National Institute for Occupational Safety and Health."
NRC
See "National Academy of Sciences."
NYS Ag & Mkts
See "New York State Department of Agriculture and Markets."
NYS A&M
See "New York State Department of Agriculture and Markets."
NYS DEC
See "New York State Department of Environmental Conservation."
NYS DOH
See "New York State Department of Health."
NYS DOL
See "New York State Department of Labor" or "New York State Department of Law"
Occupational Safety and Health Administration (OSHA)
OSHA, part of the U.S. Department of Labor, enforces federal laws that protect worker safety and health, such as maintaining standards for occupational exposure to chemicals, training employees and keeping records of chemical exposures.
OSHA
See "Occupational Safety and Health Administration."
U.S. Department of Energy (DOE)
The DOE administers federal energy research, development, regulation and policy. DOE is in charge of federal research on the storage and disposal of radioactive waste and can provide information to the public on radioactive waste disposal and management.
U.S. Department of Health and Human Services (DHHS)
DHHS carries out federal health and social programs such as social security, human development, family support, health care financing and public health. The Public Health Service, a part of DHHS, includes agencies such as the Centers for Disease Control, the Agency for Toxic Substances and Disease Registry, the Food and Drug Administration and the National Institutes of Health.
U.S. Environmental Protection Agency (EPA)
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. EPA’s Integrated Risk Information System (IRIS) is an electronic database containing information on health effects that may result from exposure to chemicals. IRIS is intended for those without extensive training in toxicology, but with some knowledge of health sciences.
U.S. Food and Drug Administration (FDA)
The FDA, part of the U.S. Department of Health and Human Services, carries out and enforces laws that protect the quality and safety of foods, food additives, cosmetics and medical drugs and devices. For example, the FDA monitors the quality of foods and drugs through product testing, and reviews food and drug ingredients, including pesticide residues, to determine if they pose health hazards.
USGS
See "US Geological Survey"
U.S. Geological Survey (USGS)
The USGS, part of the U.S. Department of the Interior, identifies the nation's land, water, mineral and energy resources. USGS conducts research, prepares topographic maps and collects and interprets data on mineral and water resources.
WHO
See "World Health Organization."
World Health Organization (WHO)
WHO, an agency of the United Nations, carries out public and environmental health programs throughout the world. For example, WHO trains health personnel and assists countries to provide primary health care, prevent communicable diseases and combat malnutrition. WHO has developed international guidelines for pesticide residues in foods and chemicals in drinking water.

Units of Measure

Length — Units of length in the metric system are based on the meter. For measuring things much smaller or larger than a meter, scientists use units that convert easily — units that are 100, 1000, or 1,000,000 times smaller or larger than the meter. Commonly used ones are included below.

meter (m)
A softball bat is about a meter long. One meter is about 39 inches -- slightly longer than a yard.
centimeter (cm)
A centimeter is one one-hundredth (1/100) of a meter. One inch is about 2.5 cm; a penny is about 2 cm wide.
kilometer (km)
A kilometer is equal to 1,000 meters. There are about one and a half kilometers in a mile.
millimeter (mm)
One millimeter is equal to one one-thousandth (1/1,000) of a meter. A dime is slightly thicker than one mm. About 25 mm equal one inch.

Weight — Units of weight in the metric system are based on the gram. For measuring things much smaller or larger than a gram, scientists use units that convert easily from grams — units that are 100, 1000, or 1,000,000 times smaller or larger than the gram. Commonly used ones are included below.

gram (g or gm)
A paper clip weighs about 1 gram. An eighth of a teaspoon of sugar weighs about a gram. A penny is about 3 grams. There are about 28 grams in one ounce; 454 grams is about one pound.
kilogram (k or kg)
A unit of mass (weight) in the metric system equal to 1,000 grams. A kilogram is about 2.2 pounds, which is about the same weight as 9 sticks of butter.
microgram (ug or mcg)
A microgram is one one-millionth (1/1,000,000) of a gram, or about one half billionth (1/500,000,000) of a pound.
milligram (mg)
A milligram is one one-thousandth (1/1,000) of a gram, or about one half million times smaller than a pound. A regular aspirin tablet weighs about 400 milligrams.
nanogram (ng)
A nanogram is one one-billionth (1/1,000,000,000) of a gram. It is 1,000 times smaller than a microgram.
picogram (pg)
A picogram is one one-trillionth of a gram. One picogram is 1,000 times smaller than a nanogram.

Volume — Units of volume in the metric system are primarily based on the liter for liquids, and the cubic meter for gases and solids.

liter (l or L)
This term is generally used when measuring a volume of liquid. A liter is slightly larger than a quart; about 3.8 liters are in a gallon.
milliliter (ml)
A milliliter is one one-thousandth (1/1,000) of a liter. One teaspoon holds about 5 ml of water.
cubic meter (m3 or cu. m.)
This term is commonly used when measuring a volume of air. A cubic meter is the space inside of a box that is one meter wide, one meter high, and one meter deep. A softball bat is about a meter long (39 inches, or just over a yard). The cabinet under a kitchen sink has about one cubic meter of volume.

Concentration is measured using two units, because it is a measure of how much of one substance is contained in another. Typical units of concentration are described below.

micrograms per cubic meter (ug/m3 or mcg/cu.m.)
A unit that expresses the concentration of a substance in air. A microgram per cubic meter is one one-millionth of a gram of substance per cubic meter of air.
micrograms per liter (ug/L or mcg/L)
A unit that expresses the concentration of a substance in a solution. A microgram per liter is one one-millionth of a gram of substance per liter of solution. A ug/L of sugar in water is about the same as a teaspoon of sugar in 2,100,000 gallons of water. For low concentrations in water, a microgram per liter is about the same as a part per billion (ppb).
milligrams per cubic meter (mg/m3 or mg/cu.m.)
A unit that expresses the concentration of a substance in air. A milligram per cubic meter is one one-thousandth of a gram per cubic meter of air. The milligram (1,000 micrograms) is used with higher concentrations.
milligrams per kilogram (mg/kg)
This unit expresses concentration by measuring the weight of a substance by the weight of the substance with the medium containing it. A milligram per kilogram is the same as one part per million. Mg/kg is also used when measuring a person or animal’s exposure to a substance. For example, a 70 kg person (about 154 lbs) given one aspirin which has 325 mg of active ingredient would get a dose of 325 mg/70 kg, or 4.6 mg/kg.
milligrams per liter (mg/L)
A unit that expresses the concentration of a substance in a solution. A millligram per liter is one one-thousandth of a gram of substance per liter of solution. One mg/L of sugar in water is about the same as a teaspoon of sugar in 2,100 gallons of water. For low concentrations in water, milligrams per liter (mg/L) is about the same as parts per million (ppm).
parts per billion (ppb)
A way of expressing the concentration of a substance in air, water, soil or food. A microgram per kilogram is the same as one part per billion. One ppb means that there is one part of a substance for every billion parts of substance and the medium containing it. One ppb is about one drop of dye in 18,000 gallons of water or about 1 second in 32 years. One ppb is 1,000 times less than one ppm.
parts per million (ppm)
The concentration of a substance in air, water or soil. A milligram per kilogram is the same as one part per million. One ppm means that there is one part of a substance for every million parts of substance and water or soil containing it. One ppm is about one drop of dye in 18 gallons of water, about one inch in 16 miles, or one penny in $10,000.
parts per trillion (ppt)
The concentration of a substance in air, water or soil. A nanogram per kilogram is the same as one part per trillion. One ppt means that there is one part of a substance for every trillion parts of substance and air, water or soil containing it. One ppt is about one drop of dye in 18 million gallons of water or about 1 second in 32,000 years. One ppt is 1,000 times less than 1 ppb.
picocuries per liter (PCi/l)
Unit of measure used to express the results of radioactivity tests in air and water. For radon gas, one picocurie per liter is the amount of radon in the air so that 2.2 atoms of radon decay during one minute in one liter of air.

Conversion Tables

Length

English   Metric
1 mile = 1.61 kilometers
1 foot = 30.5 centimeters
1 inch = 2.54 centimeters
0.621 mile = 1 kilometer
39.4 inches = 1 meter

Metric Conversions (length)

Unit   Number of meters
Kilometers = 1,000
Meter = 1
Centimeter = 0.01
Millimeter = 0.001
Micrometer (also micron) = 0.000001

Mass and Weight

English   Metric
1 pound = 0.454 kilograms
1 ounce = 28.3 grams
2.20 pounds = 1 kilogram
0.0353 ounce = 1 gram

Metric Conversions (mass)

Unit   Number of grams
Kilogram (kg) also called metric tonne = 1,000
Hectogram = 100
Dekagram = 10
Gram (g) = 1
Milligram (mg) = 0.001
Microgram (mcg) = 0.000001
Nanogram = 0.000000001
Picogram (pg) = 0.000000000001

Expressing Concentrations (weight/weight)

1 part per million = 1 milligram per kilogram
  = 1 microgram per gram
1 part per billion = 1 microgram per kilogram
1 part per trillion = 1 nanogram per kilogram

Volume (Liquids)

English   Metric
1 gallon = 3.79 liters
1 quart = 0.946 liters
1.06 quarts = 1 liter
0.264 gallons = 1 liter

Metric Conversions (volume)

Unit   Number of liters
Kiloliter = 1,000
Hectoliter = 100
Dekaliter = 10
Liter = 1
Deciliter = 0.1
Centiliter = 0.01
Milliliter = 0.001
Cubic Centimeter = 0.001
Microliter = 0.000001

Expressing concentrations (weight/volume)*

1 part per million = 1 milligram per liter*
  = 1 microgram per milliliter*
1 part per billion = 1 microgram per liter*
1 part per trillion = 1 nanogram per liter*

*indicates approximate values

Volume (Gases)

English   Metric
1 cubic foot = 0.0283 cubic meter
35.3 cubic feet = 1 cubic meter

Metric Conversions (volume)

Unit   Number of cubic meter
1 cubic meter = 1
1 liter = 0.001
1 cubic centimeter = 0.000001

Comments on Glossary

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