Suchergebnisse

The purpose of the present paper is to review the origin and development of the epidemiology of mesothelioma in Italy, starting with the detection and investigation of the major outbreak of the disease observed in Casale Monferrato, Piedmont Region. Over the last four decades, mortality among the cohort of ex-Eternit workers has been measured at three points in time. More recently, population based case-control studies in the area of Casale Monferrato have provided new light on the dose-response curve of the relationship between asbestos exposure and mesotheliomas. The publication of the first Casale Monferrato study had a major impact in the country and contributed to the decision of the Italian Parliament to ban the use of asbestos. The experience of Casale Monferrato represents a lesson in several terms, from the epidemiological surveillance to the health care of the victims and the relationship between epidemiologists, victims, their relatives and residents in contaminated areas.

Abstract
The largest chrysotile mine in Western Europe was active in Balangero (Italy) from 1917 to 1990. We quantitatively assessed exposure to asbestos in the framework of a cohort study on mortality of Balangero miners and millers. Using documents filed at the Italian State Archive we reconstructed the job-histories of cohort members. The concentration of asbestos fibres by work-area was derived from industrial hygiene surveys since 1968 and monitoring programs since 1975. Earlier exposures had been estimated based on the experimental reconstruction of past working conditions. In the mine concentrations of about 20 fibres per millilitre (f/ml) were initially present, decreasing to 5 in the mid-1950s and to <1 in late 1970s. In milling areas higher levels were present and did not fall below 1 f/ml until the mid-1980s. Cumulative exposure of cohort members, as the sum over their job-history of their year- and area-specific exposures, were <10 fibre/millilitre years (f/ml-y) in 18% of workers, 10–100 in 32%, 100–1000 in 37%, and >1000 in 13%. Compared with recently published estimates for the Russian chrysotile mine in Asbest, fibre concentrations in Balangero were higher during the 1950s and 1960s. Such difference may be partly accounted for by difficulties in converting dust measurements to fibre concentrations in the Russian study and the need to rely on the experimental reconstruction of exposures before 1968 in our study.

Abstract

Objectives
This study was performed with the aim of investigating the temporal patterns and determinants associated with mortality from asbestosis among 21 cohorts of Asbestos-Cement (AC) workers who were heavily exposed to asbestos fibres.


Methods
Mortality for asbestosis was analysed for a cohort of 13 076 Italian AC workers (18.1% women). Individual cumulative asbestos exposure index was calculated by factory and period of work weighting by the different composition of asbestos used (crocidolite, amosite, and chrysotile). Two different approaches to analysis, based on Standardized Mortality Ratios (SMRs) and Age-Period-Cohort (APC) models were applied.


Results
Among the considered AC facilities, asbestos exposure was extremely high until the end of the 1970s and, due to the long latency, a peak of asbestosis mortality was observed after the 1990s. Mortality for asbestosis reached extremely high SMR values [SMR: males 508, 95% confidence interval (CI): 446–563; females 1027, 95% CI: 771–1336]. SMR increased steeply with the increasing values of cumulative asbestos exposure and with Time Since the First Exposure. APC analysis reported a clear age effect with a mortality peak at 75–80 years; the mortality for asbestosis increased in the last three quintiles of the cumulative exposure; calendar period did not have a significant temporal component while the cohort effect disappeared if we included in the model the cumulative exposure to asbestos.


Conclusions
Among heaviest exposed workers, mortality risk for asbestosis began to increase before 50 years of age. Mortality for asbestosis was mainly determined by cumulative exposure to asbestos.