Health Risks of Ionizing Radiation: - Clark University

200 Glossary
Cohort study: A study in which a population (i.e., a cohort) is defined according to the presence or
absence of a factor that might influence the probability of occurrence of a given disease or other
outcome. The cohort is then followed to determine if those exposed to the factor are indeed at greater
risk of the outcome.
Committed dose equivalent: The dose equivalent to organs or tissues of reference that will be received
from an intake of radioactive material by an individual during the 50 year period following the intake.
Committed Effective Dose Equivalent: The sum of the products of the weighting factors applicable
to each of the body organs or tissues that are irradiated and the committed dose equivalent to these
organs or tissues.
Confidence Intervals: The computed interval with a given probability (i.e., 95%) that the true value of
the statistic—such as a mean, proportion, or rate—is contained within the interval.
Congenital Malformations: Abnormal shapes or structures present at birth.
Continuous Variable: A variable that can take any value measured on a continuous scale, for example:
height, weight, age.
Cross-Sectional Surveys: Descriptive studies that compare disease status, demographics and distance
from a hazardous facility of a randomly selected group near a facility with a randomly selected group
located not near the facility.
Curie (ci): The curie is a unit used to measure radioactivity. One curie is that quantity of a radioactive
material that will have 37, 000, 000, 000 transformations in one second. Often radioactivity is
expressed in smaller units like thousandths (mCi), millionths (uCi) or even billionths (nCi) of a curie.
A becquerel is a unit that describes one radioactive disintegration per second.
Cytogenetics: The study of chromosomes.
Deep Dose Equivalent: Applies to external whole-body exposure and is the dose equivalent at a tissue
depth of one centimeter (1000 mg/cm 2 ).
Descriptive Studies: Descriptive studies explore associations between exposure and disease incidence
and sometimes precede more expensive and time-consuming analytical studies. Ecologic studies are
descriptive studies that compare disease incidence between populations based on public records and
so do not use case specific data.
Dose: The absorbed dose, given in rads (or in SI units, (Gy) grays), that represents the energy in ergs or
Joules absorbed from the radiation per unit mass of tissue. Furthermore, the biologically effective
dose or dose equivalent, given in rem or sieverts, is a measure of the biological damage to living
tissue from radiation exposure.
Dose Rate Effectiveness Factor (DREF): A factor by which the effect caused by a specific type of
radiation changes at low as compared to high dose rate.
Dose-response: Correlation between a quantified exposure (dose) and the proportion of a population
demonstrating a specific effect (response).