Glossary
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Adduct
An abnormal chemical structure on DNA.
Assay
Examination and determination of the characteristics and/or the components of a sample.
Biomarker
A biological indicator that signals certain stresses or diseases in the body and gives a measure of exposure, effect, or susceptibility.
Carcinogen
A chemical, physical, or biological substance that is capable of causing cancer.
Chromosome
A physical structure in the cell nucleus containing a molecule of DNA and various proteins that stores and transmits genetic information. Each organism of a species normally has a characteristic number of chromosomes in its cells. The normal number for humans is 46.
Controls (experimental)
A group that comprises those who do not have the disease, intervention, procedure or whatever is being studied, but in all other respects is as nearly identical to the test group as possible. The control group is compared to the test group to help identify the effects of the disease, intervention, procedure, etc.
Deoxyribonucleic acid (DNA)
A nucleic acid in chromosomes, shaped in a double helix, which constitutes the genetic material of all cellular organisms and is the molecular basis of heredity. DNA is composed of four bases (nucleotides), whose order in the DNA strand tell the cell how to make proteins. DNA determines all the physical and functional activities of the cell and consequently of the whole organism.
Detoxification
The process or processes of chemical modification that make a toxic molecule less toxic.
Disinfection by-products (DBPs)
The results of unintended chemical reactions occurring when chlorine is added to water that contains natural organic matter. DBPs are found in low doses in drinking water, but some experts believe that long-term exposure to certain DBPs, such as chloroform and bromoform, may cause health risks.
Dose
The total amount of a substance to which an organism is exposed, contacts, or absorbs. Some use this term to describe a molecular dose, which is the amount of a substance that is in the form of a biologically active product that can interact with cell structures, such as DNA.
Embryogenesis
Formation and development of an embryo, which is the stage in the developing mammal at which organs and organ systems are being formed. In humans, this is usually considered to cover the period from the end of the second week of gestation until the end of the eighth week.
Enzyme
A protein that speeds up chemical reactions in the body. Any group of chemical substances which are produced by living cells and which cause particular chemical reactions to happen while not being changed themselves. E.g., an enzyme in the saliva of the mouth starts the process of breaking down the food.
Epidemiology
Study of the distribution and determinants of health-related states events in populations and the application of this study to control health problems.
Gene
Section of DNA that acts as a template to form an enzyme.
Genetic markers
Segments of DNA with an identifiable physical location on a chromosome and whose inheritance can be followed. Markers are used to discover associations between genetic mutations and diseases.
Genetic polymorphism
A difference in DNA sequence among individuals, groups, or populations, which may be the result of chance processes or may have been induced by external agents.
Genotype
An organism's entire genetic compostion; the complete set of genes, both dominant and recessive.
Immunologic
Relating to immunology, the science that deals with the phenomena and causes of immunity (the ability to resist a particular disease) and immune responses.
Induction
Increase in the rate of synthesis of an enzyme in response to the action of a stimulus or environmental condition.
In utero
In the uterus; before birth.
Mechanistic
Related to the fundamental chemical or physical processes involved in or responsible for an action or reaction.
Metabolism
The sum of the processes by which a particular substance is handled by the body.
Mutagen
A substance or agent that causes an increase in the rate of change in genes. These genetic changes, called mutations, can be passed along as the cell reproduces, sometimes leading to defective cells or cancer.
Oxidative damage
The result of free radicals (highly reactive, electrically-charged molecules) harming cells in the body by damaging nucleic acids, proteins, lipids, and enzymes. This always occurs at low levels, but is balanced by the body's detoxification mechanisms, which can be overwhelmed by exposure to toxic chemicals.
Perinatal
Relating to the period shortly before and after birth; often considered the period from the 20th to the 29th week of pregnancy to one to four weeks after birth.
Risk assessment
Application of methods that measure and/or predict risk to specific situations. The result is quantification of risk for particular substances (chemical or physical agents) in particular situations.
Stochastic
Involving chance and related to the laws of probability.
Susceptibility
Lack of ability to resist some extraneous agent, such as a pathogen, disease, or drug. In susceptible people, normal expected results occur with lower dosages of the agent than in the rest of the population.
Synergistic effect
Biological effect following simultaneous exposure to two or more substances that is greater than the sum of effects that would occur following exposure to the substances individually.
Teratogenesis
Introduction of an agent (chemical substance, virus, or ionizing radiation) that when administered prenatally to the mother can cause malformations of an embryo or fetus (birth defects).
Toxicology
A science that deals with the adverse effects of chemicals on living organisms and ecosystems; also includes the relationship of these effects to exposure and the mechanisms of action, diagnosis, prevention, and treatment.
Toxicodynamics
Process of interaction of potentially toxic substances with target sites (particular cells, organs, or tissues that are targets for the effect), and the subsequent biochemical and physiological reactions leading to adverse effects.
