[Cancer mortality of residents near a steel factory in Udine (Friuli Venezia Giulia Region, Northern Italy)]

Abstract

Objectives: to evaluate the association between distance of residence from a steel factory, a point source of air pollution within an industrial area in Udine (Friuli Venezia Giulia Region, Northern Italy), and cancer mortality.

Design: retrospective study. To evaluate the association between mortality rates and distance from the source, a Stone test analysis for all cases occurred in the entire area was conducted. The significance level was determined using Monte Carlo simulations.

Setting and participants: a GIS mapped residential history of Friuli Venezia Giulia population was completed. Among residents within 5 km from the principal industrial plant of the area from 1989 to 2012, deaths caused by cancer were selected. Furthermore, according to the prevalent wind direction, an analysis was conducted also in a subgroup of residents located into the South-Western quadrant. A set of 8 bands with increasing distance from the point-source was defined. The total population was 37,473 inhabitants.

Main outcome measures: in each band, observed and expected cancer-related deaths (calculated on the basis of mortality rates in the entire area) and standardized mortality ratios (SMRs) were computed to test for decline in risk of mortality at different distances from the main chimney. Stone test, in which a decline in risk of disease with an increase in distance from the source of pollution is tested, was used.

Results: the risk for all cancers and lung cancer was higher than expected. For male residents located within 2 km into the South-Western quarter there were 21 observed deaths from lung cancer vs. 13 expected (SMR: 1.62; p-value=0.02).

Conclusion: despite the fact that in the whole area cancer mortality is not increased, this study seems to support evidence of an excess of cancer deaths, especially lung cancer among males, near a steel factory. However, the study has limitations because of the small number of cases and the lack of individual exposure data and information about confounders (e.g., smoke habits and professional exposure). Therefore, a possible cause-effect interpretation of this association should be considered with caution.