- Affected area
- Any real property affected, suspected of being affected, or modeled to be likely
affected by a release occurring at a site
- Background standard
- A standard which represents a concentration of a contaminant which is
naturally occurring or are generally present and not related to a readily identifiable
- Cancer Risk
- The incremental risk of a person developing cancer over a lifetime (70 years)
as a result of exposure to a hazardous substance, expressed as a probability such as
five in a million (5 x 10-6). The contaminant level for the probability value is
derived from application of exposure assumptions and a slope factor. Cumulative cancer
risk is the sum of cancer risks to the same individual from exposure to multiple
contaminants and multiple media.
- Chemical Abstracts Service Registry Number which is a unique number assigned to a
substance or mixture by the American Chemical Society Abstracts Service.
- Construction worker
- An adult who is assumed to be involved in construction work involving
excavation at the site for 200 days during 1 year. The construction worker is
assumed not to drink contaminated groundwater from the site, but is exposed to
soil greater than 2 feet deep via both ingestion and dermal contact and may be
exposed to contaminants in air.
- Cumulative risk
- A summation of cancer and noncancer risks, determined separately, based on
exposure to multiple contaminants from the same medium plus exposure of the same
individual to contaminants in multiple media.
- The "cumulative risk calculator"
- A tool for determining compliance with the cumulative risk criteria in the
Iowa Land Recycling Program (LRP) per subrule 567 IAC 137.10(7). The cumulative
risk calculator can assess risk to potentially exposed parties, based on
three standard exposure scenarios, from multiple contaminants and multiple
media (i.e., groundwater, soil, and air). The cumulative risk calculator
enables the user to select the potentially exposed party and enter site-specific
contaminant concentrations for each medium that the exposed party may come in
- Exposure Point Concentration
- The concentration of a contaminant in groundwater, soil, or air at a
location where exposure is possible or typifying the average exposure from the site.
- Group A, B, C, D and E chemicals
- Hazardous substances which have been classified based on the weight of
evidence of human carcinogenicity. Group A substances are carcinogenic to humans.
Group B substances are likely to be carcinogenic to humans. Group C substances
have suggestive evidence of human carcinogenicity, but not sufficient evidence to
assess human carcinogenic potential. Data are inadequate to assess human carcinogenic
potential for Group D substances. Group E substances are not likely to be
carcinogenic to humans.
- Hazard quotient
- The ratio of the level of exposure of a single hazardous substance in a
single medium over a specified time period to a reference dose, which represents a safe level,
derived for a similar time period.
- Lifetime health advisory (HAL)
- An advisory level established by USEPA which represents the concentration
of a single contaminant in drinking water which is not expected to cause adverse
health effects over lifetime exposure.
- Maximum contaminant level (MCL)
- A standard for drinking water established by USEPA under the Safe Drinking
Water Act which is the maximum permissible level of a contaminant in water which
is delivered to any user of a public water supply.
- Noncancer risk
- The potential for adverse systemic or toxic effects other than cancer
caused by exposure to hazardous substances expressed as the hazard quotient for
a hazardous substance. Cumulative noncancer risk is assessed using the sum of
hazardous quotients per target organ.
- Nonprotected groundwater source
- A saturated bed, formation, or group of formations which is not a
protected groundwater source. (See definition of "protected groundwater source".)
- Nonresidential land-use area
- Any area that is not a residential land-use area.
(See definition of residential land-use area.)
- Protected groundwater source
- A saturated bed, formation, or group of formations which has a
hydraulic conductivity of at least 0.44 meters per day (m/d) and a total dissolved
solids concentration of less than 2,500 milligrams per liter (mg/l).
- Reference dose
- The amount of contaminant that an individual can ingest on a daily basis
for their lifetime that is not likely to result in adverse noncancer health effects.
A reference dose is protective of the entire human population, including sensitive
subpopulations. A reference dose is expressed in units of milligrams per day
exposure to the contaminant per kilogram of body weight of the exposed individual.
- Residential land-use area
- An area zoned for residential use or an area where residential use currently
exist, is planned, or is not otherwise precluded. In addition, a residential
land-use area includes other areas where frequent, long-term, close contact with
soils is likely to occur (e.g. playgrounds, sport fields, gardens, child-care facilities).
- Site resident
- An individual who is assumed to live at a site for 30 years
starting at birth. The site resident may be exposed to contaminants from ingestion of
groundwater from an on-site drinking-water well, ingestion and dermal contact with soil,
and inhalation. The site resident generally represents the worst-case exposure scenario.
- Site-specific standard
- A concentration of a contaminant in a specific media of an affected area at
which exposure through a specific exposure pathway is considered unlikely to pose a
threat to human health based on site-specific exposure potential.
- Site worker
- An adult who is assumed to work at the site for 25 years. The site-worker
scenario may include drinking water from an on-site well, exposure to soil less than
2 feet deep by both ingestion and dermal contact, and exposure to contaminants in air.
- Slope factor
- An upper bound estimate, approximating a 95% confidence limit, of the
increased cancer risk from a lifetime exposure to a contaminant. This estimate
is expressed in units of proportion of a population affected per milligram
per day exposure to the contaminant per kilogram of body weight of the exposed individual.
- Statewide standard
- A standard which represents a concentration of a contaminant in a
specific medium of an affected area at which normal, unrestricted exposure
through a specific exposure pathway is considered unlikely to pose a threat
to human health.
- Target organ
- An organ(s) (e.g., liver) or system(s) (e.g., respiratory system) of
the human body determined to be susceptible to a noncancer health effect
from exposure to a contaminant of concern. A reference dose used to calculate
noncancer health risk is normally established based on adverse impact to a
target organ or organs from exposure to the contaminant of concern.
- Universal background level
- The concentration of a contaminant determined by the DNR from generally
available information on background levels of contaminants that may be reasonably
expected to exist anywhere in the state due to naturally occurring conditions
or widespread impact from human activities that cannot be attributed to a
single, readily identifiable source.
- The U.S. Environmental Protection Agency.