EPA's Benchmark Dose Software (BMDS) fits mathematical models to dose-responseresponseThe biological result of an exposure or dose. Biological responses can be quantified in several ways. Some examples of the type of response data that can be used in a BMD dose-response analysis are dichotomous data (quantal data), nested data, continuous data, and categorical data. or exposure-response data. This software can help EPA risk assessors estimate the doseDoseThe amount of a substance available for interactions with metabolic processes or biologically significant receptors after crossing the outer boundary of an organism. The POTENTIAL DOSE is the amount ingested, inhaled, or applied to the skin. The APPLIED DOSE is the amount presented to an absorption barrier and available for absorption (although not necessarily having yet crossed the outer boundary of the organism). The ABSORBED DOSE is the amount crossing a specific absorption barrier (e.g. the exchange boundaries of the skin, lung, and digestive tract) through uptake processes. INTERNAL DOSE is a more general term denoting the amount absorbed without respect to specific absorption barriers or exchange boundaries. The amount of the chemical available for interaction by any particular organ or cell is termed the DELIVERED or BIOLOGICALLY EFFECTIVE DOSE for that organ or cell. or exposureexposureContact made between a chemical, physical, or biological agent and the outer boundary of an organism. Exposure is quantified as the amount of an agent available at the exchange boundaries of the organism (e.g., skin, lungs, gut). of a chemical or chemical mixture, with confidence limitconfidence limitAn estimated value below (or above) which the true value of an estimated parameter is expected to lie for a specified percentage of such estimated limits.s, that is associated with a given response level. This dose or exposure estimate can be used as a benchmark for establishing guidelines that help protect against the adverse health effects associated with the chemical or chemical mixture.

This site's purpose is to help EPA risk assessors learn how to use BMDS to evaluate data from a variety of bioassaybioassayAn assay for determining the potency (or concentration) of a substance that causes a biological change in experimental animals. study designs in a manner consistent with EPA benchmark dose (BMDBMDAn exposure due to a dose of a substance associated with a specified low incidence of risk, generally in the range of 1% to 10%, of a health effect; or the dose associated with a specified measure or change of a biological effect.) methods. The EPA BMD methods are described in the EPA Benchmark Dose Technical Guidance Document. Methods for using the results of a BMD analysis in a health assessment are available from other relevant risk assessment documents on the Integrated Risk Information System (IRIS) site.