Agency for Toxic Substances and Disease Registry (ATSDR):
The principal federal
public health agency involved with hazardous waste issues, responsible for preventing
or reducing the harmful effects of exposure to hazardous substances on human
health and quality of life. ATSDR is part of the U.S. Department of Health and
Human Services.
Aquifer:
An underground formation composed of materials such as sand, soil, or
gravel that can store or supply groundwater to wells and springs.
Contaminant:
A substance that is either present in an environment where it does
not belong or is present at levels that might cause harmful (adverse) health
effects.
Environmental Protection Agency (EPA):
The federal agency that develops and enforces
environmental laws to protect the environment and the public's health.
Exposure:
Contact with a substance by swallowing, breathing, or touching the skin
or eyes. Exposure may be short-term [acute exposure], of intermediate
duration, or long-term [chronic exposure].
Groundwater:
Water beneath the earth's surface in the spaces between soil particles and
between rock surfaces [compare with surface water].
Hazardous substance:
Any material that poses a threat to public health or the
environment. Typical hazardous substances are materials that are toxic, corrosive,
ignitable, explosive, or chemically reactive.
Monitoring wells:
Special wells drilled at locations on or off a hazardous waste
site so water can be sampled at selected depths and studied to determine the
movement of groundwater and the amount, distribution, and type of contaminant.
No apparent public health hazard:
A category used in ATSDR's public health assessments
for sites where human exposure to contaminated media might be occurring, might
have occurred in the past, or might occur in the future, but where the exposure
is not expected to cause any harmful health effects.
Plume:
A volume of a substance that moves from its source to places farther away
from the source. Plumes can be described by the volume of air or water they
occupy and the direction they move. For example, a plume can be a column of
smoke from a chimney or a substance moving with groundwater.
Remedial investigation:
The CERCLA process of determining the type and extent
of hazardous material contamination at a site.
Route of exposure:
The way people come into contact with a hazardous substance. Three routes
of exposure are breathing [inhalation], eating or drinking [ingestion],
or contact with the skin [dermal contact].
Volatile organic compound (VOC):
Organic compounds that evaporate readily into
the air. VOCs include substances such as benzene, toluene, methylene chloride,
and methyl chloroform.
