Acute Acute means sudden or brief. Acute can be used to describe either an exposure or a health effect. Symptoms or signs that begin and worsen quickly; not chronic. An acute exposure can result in short term or long term health effects. Acquired Deafness - loss of hearing that occurs or develops some time during the lifespan but is not present at birth.

Anosmia - absence of the sense of smell.

Aphasia - total or partial loss of the ability to use or understand language; usually caused by stroke, brain disease, or injury.

Aphonia - complete loss of voice.

Apraxia - inability to execute a voluntary movement despite being able to demonstrate normal muscle function.

Aquifer
An underground source of water. This water may be contained in a layer of rock, sand or gravel.

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.

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

Cognition - thinking skills that include perception, memory, awareness, reasoning, judgment, intellect, and imagination.

Conductive Hearing Impairment - hearing loss caused by dysfunction of the outer or middle ear.

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.

Decibel - unit that measures the intensity or loudness of sound.

Dermal
Referring to the skin. For example, dermal absorption means absorption through the skin.

Dizziness - physical unsteadiness, imbalance, and lightheadedness associated with balance disorders.

Dose
The amount of substance to which a person is exposed.
Dysarthria - group of speech disorders caused by disturbances in the strength or coordination of the muscles of the speech mechanism as a result of damage to the brain or nerves.

Dysequilibrium - any disturbance of balance.

Dysfluency - disruption in the smooth flow or expression of speech.

Dysgeusia - distortion or absence of the sense of taste.

Dyslexia - learning disability characterized by reading difficulties. Some individuals may also have difficulty writing, spelling, or working with numbers.

Dysosmia - distortion or absence of the sense of smell.

Dysphagia - difficulty swallowing.

Dysphonia - any impairment of the voice or speaking ability.

Dyspraxia of Speech - in individuals with normal muscle tone and speech muscle coordination, partial loss of the ability to consistently pronounce words.

Dystonia - abnormal muscle tone of one or more muscles.

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).

Gustation - act or sensation of tasting.
Haptic Sense - sense of physical contact or touch.

Hoarseness - abnormally rough or harsh-sounding voice caused by vocal abuse and other disorders such as gastroesophageal reflux, thyroid problems, or trauma to the larynx (voice box).

Hypogeusia - diminished sensitivity to taste.

Hyposmia - diminished sensitivity to smell.

Kallmann's Syndrome - disorder that can include several characteristics such as absence of the sense of smell and decreased functional activity of the gonads (organs that produce sex cells), affecting growth and sexual development.

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.

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.

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.

Meningitis - inflammation of the meninges, the membranes that envelop the brain and the spinal cord; may cause hearing loss or deafness.

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.

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.

Otologist - physician/surgeon who specializes in diseases of the ear.

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.
Perception (Hearing) - process of knowing or being aware of information through the ear.

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.

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.

Stroke - also known as a cerebrovascular accident (CVA); caused by a lack of blood to the brain, resulting in the sudden loss of speech, language, or the ability to move a body part, and, if severe enough, death.

Sudden Deafness - loss of hearing that occurs quickly due to such causes as explosion, a viral infection, or the use of some drugs.

Tactile - related to touch or the sense of touch.

Tactile Devices - mechanical instruments that make use of touch to help individuals who have certain disabilities, such as deaf-blindness, to communicate.

Taste - sensation produced by a stimulus applied to the gustatory nerve endings in the tongue. The four tastes are salt, sour, sweet, and bitter. Some scientists indicate the existence of a fifth taste, described as savory.

Taste Buds - groups of cells located on the tongue that enable one to recognize different tastes.

Volatile
Evaporating readily at normal temperatures and pressures. The air concentration of a highly volatile chemical can increase quickly in a closed room.

Waardenburg Syndrome - hereditary disorder that is characterized by hearing impairment, a white shock of hair and/or distinctive blue color to one or both eyes, and wide-set inner corners of the eyes. Balance problems are also associated with some types of Waardenburg syndrome.
Vertigo - illusion of movement; a sensation as if the external world were revolving around an individual (objective vertigo) or as if the individual were revolving in space (subjective vertigo).

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