Risk Analysis Glossary: D - F

Damage

1. Damage is the severity of injury or the physical, functional, or monetary loss that could result if control of a hazard is lost.

Danger

1. Expresses a relative exposure to a hazard. A hazard may be present, but there may be little danger because of the precautions taken.

Daughter products

1. The nuclides formed by the radioactive disintegration of a first nuclide (parent).

Death from accident

1. A death which occurs within one year of the accident.

Decay

1. The spontaneous radioactive transformation of one nuclide into a different nuclide or into a different energy state of the same nuclide. Every decay process has a definite half-life.

Degradation

1. Physical, metabolic, or chemical change to a less complex form.

De minimis risk

1. From the legal maxim "de minimis non curat lex" or "the law is not concerned with trifles."

Deposition

1. The laying down or precipitation of mineral matter that may eventually form rocks or that creates secondary land forms such as deltas and sand dunes.
2. The transfer of substances in air to surfaces, including soil, vegetation, surface water, or indoor surfaces, by dry or wet processes. [S. L. Brown]

Disabling injury

1. An injury causing death, permanent disability, or any degree of temporary total disability beyond the day of the accident.

Disease

1. A general term describing a morbid condition which can be defined by objective, physical signs (e.g. hypertension), subjective symptoms or mental phobias, disorder of function (e.g. biochemical abnormality), or disorders of structure (anatomic or pathological change) . Existence of disease may be questioned in disorder of structure without associated disorder of function.

Dispersion

1. A suspension of particles in a medium; the opposite of flocculation; a scattering process.

Diversity

1. Pertaining to the variety of species within a given association of organisms. Areas with low diversity are characterized by a few species; often relatively large numbers of individuals represent each species.

Dose

1. The amount or concentration of undesired matter or energy deposited at the site of effect.
2. See also absorbed dose.

Dose-effect

1. The relationship between dose (usually an estimate of dose) and the gradation of the effect in a population, that is a biological change measured on a graded scale of severity, although at other times one may only be able to describe a qualitative effect that occurs within some range of exposure levels.

Dose equivalent

1. The product of the absorbed dose from ionizing radiation and such factors as account for differences in biological effectiveness due to the type of radiation and its distribution in the body as specified by the International Commission on Radiological Units and Measurements (ICRU).

Dose-response

1. A correlation between a quantified exposure (dose) and the proportion of a population that demonstrates a specific effect (response).

Dose-response assessment

1. The process of characterizing the relation between the dose of an agent administered or received and the incidence of an adverse health effect in exposed populations and estimating the incidence of the effect as a function of human exposure to the agent.

Dust

1. Fine grain particles light enough to be suspended in air.

 

Ecological fallacy

1. The inference that a correlation between variables derived from data grouped in social or other aggregates (ecological units) will hold between persons (individual units).

Ecological impact

1. The total effect of an environmental change, natural or man-made, on the community of living things.

Ecology

1. The science dealing with the relationship of all living things with each other and with their environment.

Ecosystem

1. The interacting system of a biological community and its nonliving surroundings.

Effect

1. A biological change caused by an exposure.

Efficacy

1. A measure of the probability and intensity of beneficial effects.

Effluent

1. Waste material discharged into the environment, treated or untreated. Generally refers to water pollution.

Emission

1. Like effluent but used in regard to air pollution.

Emission rate

1. The amount of pollutant emitted per unit of time.

Environment

1. Water, air, land, and all plants and man and other animals living therein, and the interrelationships which exist among them.

Environmental impact appraisal

1. An environmental review supporting a negative declaration, i.e., the action is not a major Federal action significantly affecting the environment. It describes a proposed EPA action, its expected environmental impact, and the basis for the conclusion that no significant impact is anticipated.

Environmental impact statement

1. A document required of Federal agencies by the National Environmental Policy Act for major projects or legislative proposals. They provide information for decision makers on the positive and negative effects of the undertaking, and list alternatives to the proposed action, including taking no action. For example, an environmental impact assessment report, prepared by an applicant for an NPDES permit to discharge as a new source, identifies and evaluates the environmental impacts of the applicant's proposed source and feasible alternatives.

Environmental pathway

1. All routes of transport by which a toxicant can travel from its release site to human populations including air, food chain, and water.
2. The connected set of environmental media through which a potentially harmful substance travels from source to receptor. [S. L. Brown]

Epidemiology

1. The study of the distribution and dynamics of diseases and injuries in human populations.
2. Specifically, the investigation of the possible causes of a disease and its transmission. [S. L. Brown]

Excess deaths

1. The excess over statistically expected deaths in a population within a given time interval. Attempts are made to relate excess deaths to specific causes. Note that since every person can (and must) die only once, there can be no excess deaths over all time.

Expected deaths

1. The number of deaths statistically expected in a population in a given time interval obtained by summing the product of age-, sex-, and race-specific mortality rates from a standard population and person-years in each age, sex, and race category in the study population.

Expected loss

1. The quantity obtained by multiplying the magnitude of health or environmental effect loss by the probability (or risk) of that loss and adding the products. The expected loss is the average loss over a large number of trials; one must reflect on the appropriateness of its use in cases for which there will be only one, or a few, trials.

Exposure

1. The time integral of the concentration of a toxicant which is in the immediate vicinity of various ports of entry (such as lung, GI tract and skin).
2. Qualitatively, contact between a potentially harmful agent and a receptor (e.g., a human or other organism) that could be affected. [S. L. Brown]

Exposure assessment

1. The process of measuring or estimating the intensity, frequency, and duration of human exposures to an agent currently present in the environment or of estimating hypothetical exposures that might arise from the release of new chemicals into the environment.

Extrapolation

1. In risk assessment, this process entails postulating a biologic reality based on observable responses and developing a mathematical model to describe this reality. The model may then be used to extrapolate to response levels which cannot be directly observed.

Failure modes and effects analysis

1. A tool to systematically analyze all contributing component failure modes and identify the resulting effects on the system.

False negative results

1. Results which show no effect when one is there.

False positive results

1. Results which show an effect when one is not there.

Fatal accident

1. An accident which results in one or more deaths within one year.

Fault tree analysis

1. A technique by which many events that interact to produce other events can be related using simple logical relationships permitting a methodical building of a structure that represents the system.

Fly-ash

1. Small solid ash particles from the noncombustible portion of fuel that are small enough to escape with the exhaust gases.

Fine suspended particulate matter (FSP)

1. Airborne particles in the range of a diameter smaller than approximately 1 or 2 micrometers.

Food chain

1. Dependence of a series of organisms, one upon the other, for food. The chain begins with plants and ends with the largest carnivores.

Fossil fuel

1. Natural gas, petroleum, coal, and any form of solid, liquid, or gaseous fuel derived from such materials for the purpose of creating useful heat.

Fuel cycle

1. The complete series of steps involved in supplying a fuel.
2. Most often refers to the fissionable fuel for a nuclear reactor and includes management of spent fuel. [S. L. Brown]