Use of Stone's method in studies of disease risk around point sources of environmental pollution.

The Small Area Health Statistics Unit is a national facility funded by the U.K. government for the analysis of disease risk around sources of environmental pollution. It holds cancer incidence (from 1974) and mortality data (from 1981) for Great Britain. Data retrieval is based on the postcode of residence, relating on average to 14 households. Population data for the calculation of disease rates and small area measures of socioeconomic deprivation are from census small area statistics for 1981 and 1991. Isotonic regression methods first described by Stone are used to test for declines in disease risk with distance from point sources of environmental pollution. This paper describes modifications of the method to include adjustments for socioeconomic confounding, a conditional approach to allow for generally elevated risks near the source, and methods to deal with pooling of data around a number of point sources. Examples from recent studies are given.