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]

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.

Benign fibrous histiocytoma of prepuce in the mule

Here we present a case of preputial benign fibrous histiocytoma in a 7-year-old mule. This case was treated surgically. Pathologic analysis and diagnosis of these lesions were based on a combination of light microscopy and immunohistochemistry. Histologically, the tumour was composed primarily of a storiform pattern of fibroblastic and poligonal cells. In immunohistochemistry, except for consistent immunoreactivity for vimentin, nearly all tumour cells were positive for CD68, S-100 protein, pan-cytokeratin, alpha-smooth muscle actin, and desmin. Benign fibrous histiocytoma of the prepuce in mule is rarely reported in veterinary literature.

Mesotheliomas among Italians, returned to the home country, who worked when migrant at a cement-asbestos factory in Switzerland

OBJECTIVES

To report the occurrence of mesotheliomas in Italy among subjects who worked, when migrant, at a cement-asbestos factory in Niederurnen, Switzerland, and had resettled to the home country.

METHODS

Information about the disease and on the working history of subjects was collected by regional mesothelioma registries. Only cases diagnosed by means of histo-pathological examinations have been considered here.

RESULTS

15 mesotheliomas (13 pleural, 2 perithoneal; 12 among males, 3 among females) have been identified among Italians, who had worked at the factory. None of them had other occupational exposure to asbestos. The majority was living in the Veneto Region (North East of Italy), and in Puglia (Southern Italy).

CONCLUSIONS

Exposure to asbestos at this factory has already caused an important number of occupational cancers among the employees, a large fraction being constituted of migrants. In order to avoid under-estimation of risks and to allow compensation, diseases which occur among foreign workers returned to their home country should be evaluated. Migration for work is at the genesis of asbestos-related mesotheliomas now occurring in Italy.

[Pleural mesothelioma in women in the Veneto Region who used to work as rag sorters for textile recycling and paper production]

The paper reports 9 cases of mesothelioma diagnosed by means of histology or cytology that were observed among women resident in the Veneto Region, Northern Italy, whose only activity that could involve exposure to asbestos was as rag sorter. These cases are part of a group of about 260 subjects with mesothelioma whose entire working and residential history has been collected. The women worked as rag sorters between the 1940's and 1960's in textile recycling (8 cases) or (one case) at a paper mill where cotton was used for paper production. The work as rag sorter helps to explain the high proportion of mesotheliomas among women with an occupational exposure to asbestos.

Liver toxicity due to 1,2-dichloropropane in the rat

The effect of 1,2-dichloropropane on rat liver was studied after short (5 days) and long term (4 weeks) i.p. administration. Animals were injected daily with 10-500 mg/kg body wt 1,2-dichloropropane and biochemical and histological changes of liver were investigated. Treatment was monitored by measuring urinary mercapturic acid excretion. A significant increase of mercapturate excretion was observed at all dose levels, with no further increase during the treatment; at lower doses a return to baseline values occurred within 48 h after the end of treatment. Mercapturate excretion at the end of weeks 2, 3 and 4 of treatment was significantly lower than that observed at the end of week 1. The liver reduced glutathione content was different after single or repeated injections. A dose-dependent decrease of liver reduced glutathione was observed after a single injection and a dose-dependent increase after 4 weeks. The liver biochemical pattern after 4 weeks of treatment (characterized by a decrease of cytochrome P-450 and by an increase of reduced glutathione and glutathione S-transferase activity) suggests a hyperplastic evolution of the liver cells, probably a repair mechanism induced by early depletion of reduced glutathione. Light microscopy confirms that the prevalent alterations are regenerative in type (atypical mitosis and hyperplastic nodules). Areas of focal necrosis are isolated, and trend to disappear after long term treatment.