The study area consisted of four Fr

The study area consisted of four French administrative departments, comprising a total of 2270
block groups. NHL cases that had been diagnosed during the period 1990–1999, and were aged 15 years
and over, were considered. Each case was assigned a block group by residential address geocoding.
Atmospheric Dispersion Model System software was used to estimate immissions in the surroundings of
13 incinerators which operated in the study area. Then, cumulative ground-level dioxin concentrations
were calculated for each block group. Poisson multiple regression models, incorporating penalized
regression splines to control for covariates and dealing with Poisson overdispersion, were used. Five
confounding factors were considered: population density, urbanisation, socio-economic level, airborne
traffic pollution, and industrial pollution.