VANCOUVER, CLARK COUNTY, WASHINGTON
January 29, 2002
Washington State Department of Health
Under a Cooperative Agreement with the
Agency for Toxic Substances and Disease Registry
TABLE OF CONTENTS
- Occurring over a short period of time. An acute exposure is one which lasts for less than 2 weeks.
- 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.
- An underground formation composed of materials such as sand, soil, or gravel that can store and/or supply groundwater to wells and springs.
- Cancer Risk Evaluation Guide (CREG):
- The concentration of a chemical in air, soil, or water that is expected to cause no more than one excess cancer in 1 million persons exposed over a lifetime. The CREG is a comparison value used to select contaminants of potential health concern and is based on the cancer slope factor (CSF).
- Cancer Slope Factor :
- A number assigned to a cancer-causing chemical that is used to estimate its ability to cause cancer in humans.
- Any substance that can cause or contribute to the production of cancer.
- Chronic :
- A long period of time. A chronic exposure is one which lasts for a year or longer.
- Comparison value :
- A concentration of a chemical in soil, air, or water that, if exceeded, requires further evaluation as a contaminant of potential health concern. The terms comparison value and screening level are often used synonymously.
- Contaminant :
- Any chemical that exists in the environment or living organisms that is not normally found there.
- Dose :
- A dose is the amount of a substance that gets into the body through ingestion, skin absorption, or inhalation. It is calculated per kilogram of body weight per day.
- Environmental Media Evaluation Guide (EMEG) :
- A concentration in air, soil, or water below which adverse noncancer health effects are not expected to occur. The EMEG is a comparison value used to select contaminants of potential health concern and is based on ATSDR's minimal risk level (MRL).
- Exposure :
- Contact with a chemical by swallowing, by breathing, or by direct contact (such as through the skin or eyes). Exposure might be short-term (acute) or long-term (chronic).
- Groundwater :
- Water found underground that fills pores between materials such as sand, soil, or gravel. In aquifers, groundwater often occurs in quantities where it can be used for drinking water, irrigation, and other purposes.
- Hazardous substance :
- Any material that poses a threat to public health and/or the environment. Typical hazardous substances are materials that are toxic, corrosive, ignitable, explosive, or chemically reactive.
- Indeterminate public health hazard :
- Sites for which no conclusions about public health hazard can be made because data are lacking.
- Ingestion rate :
- The amount of an environmental medium which could be ingested typically on a daily basis. Units for IR are usually liter/day for water, and mg/day for soil.
- Lowest Observed Adverse Effect Level (LOAEL) :
- LOAELs have been classified into "less serious" or "serious" effects. In dose-response experiments, the lowest exposure level at which there are statistically or biologically significant increases in the frequency or severity of adverse effects between the exposed population and its appropriate control.
- Maximum Contaminant Level (MCL) :
- A drinking water regulation established by the federal Safe Drinking Water Act. It is the maximum permissible concentration of a contaminant in water that is delivered to the free-flowing outlet of the ultimate user of a public water system. MCLs are enforceable standards.
- Soil, water, air, plants, animals, or any other part of the environment that can contain contaminants.
- Minimal Risk Level (MRL) :
- An amount of chemical that gets into the body (i.e., dose) below which health effects are not expected. MRLs are derived by ATSDR for acute, intermediate, and chronic duration exposures by the inhalation and oral routes.
- Monitoring wells :
- Resource protection wells installed at locations on or off a hazardous waste site so groundwater 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 :
- Sites where human exposure to contaminated media is occurring or has occurred in the past, but the exposure is below a level of health hazard.
- Oral Reference Dose (RfD) :
- An amount of chemical ingested into the body (i.e., dose) below which health effects are not expected. RfDs are published by the U.S. Environmental Protection Agency (EPA).
- Parts per billion (ppb)/Parts per million (ppm) :
- Units commonly used to express low concentrations of contaminants. For example, 1 ounce of trichloroethylene (TCE) in 1 million ounces of water is 1 ppm. 1 ounce of TCE in 1 billion ounces of water is 1 ppb. If one drop of TCE is mixed in a competition-size swimming pool, the water will contain about 1 ppb of TCE.
- Plume :
- An area of contaminants in a specific media such as groundwater.
- U.S. Environmental Protection Agency (EPA) :
- Established in 1970 to bring together parts of various government agencies involved with the control of pollution.
- Volatile organic compound (VOC) :
- An organic (carbon-containing) compound that evaporates (volatilizes) easily at room temperature. A significant number of the VOCs are commonly used as solvents.