Chronic disease and early exposure to air-borne mixtures: 1. The Environmental Quality Database.

This is the first in a continuing study examining the impact of early exposure to air-borne mixtures of chemicals from industrial sources on the etiology of cancer. The Environmental Quality Database (EQDB) contains lifetime residential histories for approximately 20,000 cases in 18 rare or poorly understood sites and approximately 5000 controls. The EQDB contains all known industrial point sources in approximately 50 U.S.-SIC code operating in Canada, all geolocated, from 1993 to about 1950. Cases and controls were collected in 1993-1995. Both source-centric and case-centric searching is possible. It is possible to search all instances of a source-type or only one. Three features of the design are the management of mobility and latency as epidemiological confounders and a considerable simplification of Retrospective Exposure Assessment by using the RASH relative potency methodology.