Shipbuilding and mesothelioma in Monfalcone, Italy.

The Monfalcone area, northeastern Italy, a small industrial district with large shipyards, shows a high incidence of asbestos-related mesothelioma. In order to reconstruct some features of the Monfalcone shipbuilding activity during World War II and its health effects, the shipyard roll were examined, and people hired in 1942 were identified. The list of 2,776 persons hired in 1942 was coupled with the Pathological Anatomy Units archives of the Monfalcone and the Trieste Hospitals. Eighteen of the above persons had been diagnosed with pleural mesothelioma in the period 1981-2005. Eight patients had their first exposure in 1942, and the others had histories of previous exposures. Of 557 persons aged 14-15 years in 1942, six had a diagnosis of pleural mesothelioma. Necropsy findings were available in 14 cases. The burdens of lung asbestos bodies, isolated in 11 cases, showed wide variation (from 150 to 600,000 bodies per gram of dried tissue). While probably underestimated, the present data indicate a high incidence of mesothelioma among the shipyard workers of Monfalcone.

INTRODUCTION

Mortality from malignant mesothelioma has considerably increased in numerous countries. A recent study based on death certificates collected in 83 countries showed the highest rates in the UK (age-adjusted mortality rate 17.8 per million), Australia (AAMR 16.5), and Italy (AAMR 10.3).[1]

The Monfalcone district, northeastern Italy, represents a hot area.[23] Shipyard opened in Monfalcone in 1908. In the subsequent decades, the Monfalcone shipyard became the largest shipbuilding installation in the Mediterranean region. During late 1930s and early 1940s, the workforce of the shipyard was about 5,000 people. Four to five thousand workers were also employed in electro-mechanic shops and in aeronautic works, which were located at the Monfalcone shipyard. In the subsequent decades, the total number of shipyard workers decreased to about 6,000 workers in the 1950s and then ranged between 3,500 and 5,000 in the 1960s and 1970s.

Various studies have explored the features of mesothelioma in Monfalcone.[45] A series of investigations conducted at the Monfalcone Hospital have indicated asbestos exposure occurred at the Monfalcone shipyards as the principal cause of mesothelioma epidemic in the area.[6]

The present study is aimed to delineate some features of the activity in Monfalcone shipyards during the World War II, and to evaluate the effects of such an activity on mesothelioma occurrence in Monfalcone area.

MATERIALS AND METHODS

The Monfalcone shipyard roll was surveyed in order to identify the persons hired in the shipyards in 1942. Available data were registered including: name and family name of the worker, birth year, employment date, trade at the time of employment, Province of origin (available only in a part of the cases). Then, the Pathological Anatomy Units archives of the Monfalcone and Trieste Hospitals were examined. Mesothelioma cases registered in such archives and diagnosed in the workers hired in 1942 were selected and re-examined. The parameters investigated comprised: pathological diagnosis (type and date), occupational history, latency period (defined as time interval elapsed between first exposure to asbestos and diagnosis), markers of asbestos exposure (pleural plaques, presence/burden of asbestos bodies in lung tissue). In several cases isolation and counting of asbestos bodies had been performed following Smith-Naylor method.[7]

RESULTS

In 1942, 2,776 people (2,653 men and 123 women) were hired at the Monfalcone shipyards. Figure 1shows the age distribution of these persons. The tasks of the workers at the time of employment are reported in Figure 2. Among subjects hired in 1942, 16 men and two women had been diagnosed with pleural mesothelioma at the Hospitals of Trieste and Monfalcone. Mesotheliomas were concentrated in some age groups. People aged 14-15 years in 1942 comprised 557 persons with six mesothelioma cases. People aged 20-29 years in 1942 comprised 672 persons and 11 mesotheliomas. People aged 30-39 years in 1942 comprised 580 persons with one mesothelioma. In Table 1 the principal features of the above mesothelioma cases are listed. Fourteen patients had been examined at necropsy. Ten people had histories of asbestos exposure before the 1942 employment. Various workers had changed tasks along their career. In particular, two patients (cases 4 and 10) had also worked as insulators.

Figure 1

Age distribution in the people hired at the monfalcone shipards in 1942

Figure 2

Labour force in the monfalcone shipyards. Tasks of the workers hired in 1942

Table 1

Malignant mesotheliomas of the pleura diagnosed among people hired at the monfalcone shipyard in 1942

DISCUSSION

The relationship between asbestos exposure occurred in shipyards and development of mesothelioma is known since more than 50 years. In 1953 Weiss described in Germany a case of pleural malignancy associated to pulmonary asbestosis in a patient who had worked as insulator in the construction of warships.[8] Some years later a group of pleural mesotheliomas among shipyard workers were reported from Belfast area, Northern Ireland.[910] Successively, mesothelioma clustering in the shipyard areas became one of the most typical features in mesothelioma geography.[11] Some cohort studies have revealed high mortality from pleural cancer among shipyard workers.[12-15]

In the present study data on the Monfalcone shipyard activity hitherto not available were collected. In 1942, the Monfalcone shipyards increased substantially their labour force by employing further 2,776 persons. Women represented only a small fraction of the new employees. At the time of employment, large numbers of the hired persons were very young (14-15 years of age), a fact of critical relevance for the genesis of a tumor that generally requires decades for its development. The tasks were various. A remarkable portion of the workers was assigned to the aeronautic department, at that time an important sector of activity in the Monfalcone shipyards. Asbestos risk in aircraft industry has long time been a neglected issue.[16-18] The topic is not easy to investigate in Monfalcone, since here employees have mostly worked both in shipbuilding and in aircraft construction. Moreover, the latter stopped at the end of World War II.

The impact of asbestos exposure on people hired in 1942 may only partially be evaluated for several reasons. Firstly, investigations on mesothelioma started in Trieste only in 1971 and in Monfalcone in 1980. Secondly, a systematic cancer registration began in northeastern Italy (Friuli Venezia Giulia Region) only in 1995. Thirdly, in the past a not good familiarity with mesothelioma diagnosis led probably to misdiagnose this rare variety of cancer.

In the present study, the identification of mesothelioma cases among people hired in Monfalcone shipyards in 1942 was based on the data of hospital archives. While such archives do not cover the totality of the cases, they include a large majority of them.

All mesothelioma patients in the present series regarded people aged between 14 and 30 years at the time of their first employment. The latency periods ranged between 46 and 63 years with a majority having latency periods over 50 years or more. Possibly, earlier effects of asbestos exposure may be remained not detected, given a lack of attention devoted to mesothelioma in the past decades.

Pleural plaques were observed in all cases seen at necropsy and in some surgical cases. Lung asbestos bodies isolated and counted in 10 cases, showed major variations in their burdens. In evaluating the results of asbestos bodies counting, one should remember that asbestos fiber clearance from the lung represents a phenomenon far more relevant than retained in the past.[19] In many of the present cases exposure to asbestos had been stopped a lot of years before the time of death. This means the asbestos body amounts found at necropsy only partially reflect the exposure actually occurred. On the other hand, the results of investigations, conducted in large necropsy series at the Monfalcone Hospital,[6] indicate that, although involving all people working in the shipyards, asbestos exposure showed marked variations in intensity, depending on a lot of factors (trade, duration of employment, calendar period).

The data obtained in the present study indicate a high incidence of pleural mesotheliomas among people firstly employed in the Monfalcone shipyards in 1942. The wide variability of latency periods in these cases plausibly reflects markedly different occupational settings as well as differences in individual susceptibility.