Health Impacts : hei
Health impact models are used to estimate the health impacts from exposure to the pollutant of concern. Models are defined for noncarcinogenic chemicals, carcinogenic chemicals, and radionuclides and radiation dose. When populations are exposed to carcinogenic pollutants, including radiation, estimates of health impacts to an exposed population may also be made by multiplication of the effect to an average member of the population by the number of people in the exposed population.
Human health impacts are estimated from the average daily dose provided by the exposure pathway models. Impacts from radiation exposure (radionuclides and measured direct radiation), carcinogenic chemicals, and noncarcinogenic chemicals are estimated. Health impact assessments for exposure of an individual or an average member of the population are estimated.
Health impacts from exposure to radiation and radionuclides are expressed as the risk of developing cancer. This risk may be reported as the lifetime risk of total cancer incidence or as cancer fatalities. Two methods are available to estimate the risk of cancer fatalities: use of health- effects conversion factors and use of USEPA slope factors.
The lifetime risk of total cancer incidence is estimated using USEPA slope factors for chemical carcinogens for inhalation and ingestion exposure pathways. Dermal exposures are evaluated as equivalent ingestion intakes as described in the sections on dermal absorption pathways. The USEPA slope factors give the lifetime cancer incidence risk per average daily dose.
The health impacts for exposure to noncarcinogenic chemicals are expressed as a hazard quotient. The hazard quotient is the ratio of the average daily dose to the reference dose. The reference dose is defined by the USEPA for many chemicals for ingestion and inhalation intakes (USEPA 1993). The reference dose represents a level that is believed to be safe for members of the general population. Exposure at this level will result in a hazard quotient of 1.0.
Health impacts from exposure to carcinogenic chemicals and radionuclides can be estimated for the entire exposed population. For these pollutants, the population health impacts are assumed to be proportional to the exposure level. This allows a population health impact to be evaluated as the product of the lifetime risk to the average member of the population times the number of people in the population.
TYPICALLY CONSUMES . . .
TYPICALLY PRODUCES . . .