Post-occupational health surveillance of asbestos workers.

BACKGROUND: Italian law requires an extensive health surveillance of workers after cessation of their employment status in the case of occupational exposure to carcinogens, including asbestos. Nonetheless, Italian law does not specify the timeframe of these clinical checks, nor who has financial and organizational responsibility for this surveillance. A literature search confirmed a lack of consensus around the objectives and methods to follow up workers with past occupational exposure to asbestos. OBJECTIVES: To develop an updated evidence-based methodology for an appropriate health surveillance programme. METHODS: We present an overview of the field experience developed by the Veneto Region from 2000 to 2011, and new studies that could contribute to establishing a national policy for the medical surveillance of workers with past asbestos exposure. RESULTS: There were three specific topics: (1) definition of a reliable method to identify asbestos workers (through multiple sources and procedures that meet current confidentiality regulations); (2) detection of asbestos fibres in biological media (to support the etiological diagnosis of asbestos-related diseases); (3) creation of a national protocol of health surveillance (through the assessment of policies developed by other Regions in this field, and recruiting from these regions a cohort of past-exposed workers: the epidemiological study should offer relevant suggestions for specific surveillance approaches, based on either estimated cumulative asbestos exposure or detection of x-ray patterns of pleural plaques and/or asbestosis). CONCLUSIONS: These studies will support the Regions in setting up health care policies directed at workers with past asbestos exposure.

Asbestos exposure and benign asbestos diseases in 772 formerly exposed workers: dose-response relationships.

BACKGROUND: Since previous studies have provided conflicting results, we investigated the relationship between the risk of benign asbestos-related diseases and different aspects of asbestos exposure in previous asbestos workers who underwent low-dose computed tomography (CT). METHODS: CT scans were carried out in 772 subjects. A questionnaire was employed to collect data on smoking habits and duration, peak and cumulative exposure, and time since first exposure to asbestos. Multiple logistic regression models with stepwise selection of variables were used to evaluate the associations. RESULTS: Fourteen (1.8%) cases of asbestosis, 187 (24.2%) of pleural plaques (PP), and 50 (6.5%) of diffuse pleural thickening (DPT) were found. The significant risk factors were: cumulative exposure for asbestosis (P for trend = 0.004); time since first exposure (P for trend <0.001), and peak exposure (P for trend <0.001) for PP; and time since first exposure for DPT (P for trend = 0.024). CONCLUSIONS: Parenchymal asbestosis and PP are associated with different aspects of asbestos exposure. DPT appears to be less specific for asbestos exposure.

[Feasibility of a screening programme for lung cancer among workers previously heavily exposed to asbestos]. / Valutazione di un programma per la diagnosi precoce di cancro polmonare negli ex esposti ad asbesto.

BACKGROUND: We evaluated the feasibility and costs of a screening programme with spiral CT for the early diagnosis of lung cancer among workers previously heavily exposed to asbestos. METHODS: We invited 2000 workers, 1165 (58%) of whom accepted. Women and individuals with incomplete information were excluded; 1119 subjects (mean age, 57 years) entered the main analysis. Subjects with non-calcified lung nodules and/or dubious pleural plagues (No=338) entered a post-screening diagnostic protocol based on radiological follow-up. RESULTS: Twenty-five biopsies were performed (13 pulmonary, 9 pleural, 3 combined) revealed 5 cases of lung cancer (including 1 in stage IA). The positive predictive value of the screening test was low (31%) despite its known high sensitivity (100%) and specificity (99%). Incidence of lung cancer was similar to that registered among male residents of the Veneto Region aged 55 to 59 years. The cost of the programme was Euro 1,000 per screened subject and Euro 245,000 per diagnosis (total cost, Euro 1,181,310). The total radiation dose administered to healthy subjects was about 1,100 mSv (220 mSv per lung cancer diagnosis). CONCLUSIONS: This screening programme was ineffective due to the low participation rate, the small number of diagnoses, low predictive value, and high costs.

Feasibility of a screening programme for lung cancer in former asbestos workers.

BACKGROUND: Low-dose computed tomography (CT) has been found to detect more Stage IA lung cancer than chest x-ray. AIMS: To investigate whether lung cancer screening with CT was effective and acceptable in former asbestos workers. METHODS: CT scanning was carried out following the protocol previously described in the literature. A questionnaire was used to assess cumulative asbestos exposure. An economic analysis was also performed. Informed consent was obtained from all patients. RESULTS: A total of 1119 male asbestos workers (58% of invited) were examined, of whom 65% were smokers or ex-smokers. Mean age was 57.1 years with mean cumulative exposure to asbestos of 123 fibres/ml x years. Pleural plaques were found in 375 workers (32%), while 338 workers (29%) were included in the radiological follow-up, which led to 25 biopsies (13 of lung, 9 of pleura, 3 of both) and five screen-detected lung cancers (0.4%), one in Stage I. Incidence rate was 149 per 10(5), equal to that in the male general population of similar age. The expenses for diagnosis were 1014 and 244962 Euro per screened subject and screen-detected lung cancer case, respectively. CONCLUSIONS: Screening adherence and frequency of detection were low, while costs and radiation dose were high. In spite of a high cumulative asbestos exposure, lung cancer risk was not increased relative to the general population. The screening programme was not felt to be cost-effective from the perspective of the government as a third-party funding agency.