The glossary includes some of the vocabulary used in the study of how the environment and environmental agents affect human health. This includes preventing, intervening in, and treating human disease associated with the environment. Other glossaries are below.

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.

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.

Allele: An alternative form of a gene or any other segment of a chromosome.

Ambient: Surrounding. Ambient air usually means outdoor air (as opposed to indoor air).

Bioinformatics: The analysis of biological information using computers and statistical techniques; the science of developing and utilizing computer databases and algorithms to accelerate and enhance biological research.

Biomarker: A molecular indicator of a specific biological property; a biochemical feature or facet that can be used to measure the progress of disease or the effects of treatment.

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.

Central nervous system (CNS): The part of the nervous system that includes the brain and the spinal cord.

Chronic: Occurring over a long period of time, several weeks, months or years.

Complementary DNA (cDNA): DNA made from a messenger RNA (mRNA) template. The single-stranded form of cDNA is often used as a probe in physical mapping.

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.

DNA (deoxyribonucleic acid): One of two types of molecules that encode genetic information. (The other is RNA. In humans DNA is the genetic material; RNA is transcribed from it. In some other organisms, RNA is the genetic material and, in reverse fashion, the DNA is transcribed from it.)

Dose: The amount of substance to which a person is exposed.

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).

Expressed sequence tag: A unique stretch of DNA within a coding region of a gene that is useful for identifying full-length genes and serves as a landmark for mapping.

Gene: The basic biological unit of heredity; a segment of deoxyribonucleic acid (DNA) needed to contribute to a function.

Genome: All of the genetic information or hereditary material possessed by an organism; the entire genetic complement of an organism.

Genomics: The study of genes.

Genotype: The genetic composition of an organism or a group of organisms; a group or class of organisms having the same genetic constitution.

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.

In vitro: Literally, “in glass,” i.e., in a test tube or in the laboratory; the opposite of in vivo (in a living organism).

In vivo: In a living organism, as opposed to in vitro (in the laboratory).

Knockout: Inactivation of specific genes. Knockouts are often created in laboratory organisms such as yeast or mice so that scientists can study the knockout organism as a model for a particular disease.

Mapping: Charting the location of genes on chromosomes.

Mass spectrometry: A method used to determine the masses of atoms or molecules in which an electrical charge is placed on the molecule and the resulting ions are separated by their mass to charge ratio.

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.

Messenger RNA (mRNA): A type of RNA that reflects the exact nucleoside sequence of the genetically active DNA. mRNA carries the "message" of the DNA to the cytoplasm of cells where protein is made in amino acid sequences specified by the mRNA.

Microarray: A tool used to sift through and analyze the information contained within a genome. A microarray consists of different nucleic acid probes that are chemically attached to a substrate, which can be a microchip, a glass slide or a microsphere-sized bead.

Northern blot: A technique used to separate and identify pieces of RNA.

Nucleotide: A subunit of DNA or RNA. To form a DNA or RNA molecule, thousands of nucleotides are joined in a long chain.

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.

Phenotype: The observable physical or biochemical traits of an organism, as determined by genetics and the environment; the expression of a given trait based on phenotype; an individual or group of organisms with a particular phenotype.

Polymorphism: The quality or character of occurring in several different forms.

Proteome: All of the proteins produced by a given species, just as the genome is the totality of the genetic information possessed by that species.

Proteomics: The study of the proteome.

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).

RNA (ribonucleic acid): A nucleic acid molecule similar to DNA but containing ribose rather than deoxyribose.

Signal transduction pathway: The course by which a signal from outside a cell is converted to a functional change within the cell.

Single nucleotide polymorphism (SNP): A change in which a single base in the DNA differs from the usual base at that position.

Toxicology: The study of the nature, effects and detection of poisons and the treatment of poisoning.

Toxicogenomics: The collection, interpretation, and storage of information about gene and protein activity in order to identify toxic substances in the environment, and to help treat people at the greatest risk of diseases caused by environmental pollutants or toxicants.

Transgenic: Having genetic material (DNA) from another species. This term can be applied to an organism that has genes from another organism.

Specific glossaries from EHSC Outreach

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