Concentration The amount of one substance dissolved or contained in a given amount of another substance or medium. For example, sea water has a higher concentration of salt than fresh water does. 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. Dermal Referring to the skin. For example, dermal absorption means absorption through the skin. Detection limit The smallest amount of substance that a laboratory test can reliably measure in a sample of air, water, soil or other medium. Dose The amount of substance to which a person is exposed. 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). Exposure assessment A process that estimates the amount of a chemical that enters or comes into contact with people or animals. An exposure assessment also describes how often and for how long an exposure occurred, and the nature and size of a population exposed to a chemical. Feasibility Study (FS) A study that compares different ways to clean up a contaminated site. The feasibility study recommends one or more actions to remediate the site. See "Remedial investigation". Gradient The change in a property over a certain distance. For example, lead can accumulate in surface soil near a road due to automobile exhaust. As you move away from the road, the amount of lead in the surface soil decreases. This change in the lead concentration with distance from the road is called a gradient.
Posted on: Mon, 16 Sep 2013 13:18:30 +0000
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