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Environmental Health Glossary

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  • Synopsis: Glossary of terms and definitions used in government reports engineering studies and health literature online and off - Published: 2009-02-17 (Rev. 2009-02-21). For further information pertaining to this article contact: Barry White.

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This glossary is intended to help people become familiar with the terms they may see in various government reports, engineering studies and health literature online and off.

This glossary is intended to help people become familiar with the terms they may see in various government reports, engineering studies and health literature online and off.

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.

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.

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 re-mediate 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".


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