Periportal fibrosis and other liver ultrasonography findings in vinyl chloride workers

Abstract

Aims: To investigate the presence of liver lesions and their relation with vinyl chloride monomer (VCM) exposure or other personal risk factors, in workers involved in the production of VCM and polyvinyl chloride (PVC). Methods: A liver ultrasonography examination was conducted in 757 workers, some of whom had long standing service in the production of VCM and PVC. The study involved: assessment of individual past and present VCM exposure of each worker; collection of past personal health history, lifestyle and personal data; routine liver function tests; and liver ultrasonography. Results: No cases of liver malignancies were detected. Angiomas and liver cysts were found with a frequency of occurrence within the expected range of the general population. The main findings consisted of hepatomegaly (34.7%), steatosis (31.8%), and periportal fibrosis (16.0%). A logistic regression analysis indicated that hepatomegaly and steatosis were associated with obesity and lipid metabolism disturbances and not with VCM exposure. Periportal fibrosis, in addition to constitutional or dietary factors, was shown to be associated with VCM exposure, but only when maximum exposure in the subject's history had been at least 200 ppm as a yearly average; no effects were observed at 50 ppm or below. Conclusions: Workers exposed to 200 ppm VCM for at least one year have a fourfold increased risk of developing periportal liver fibrosis. Liver ultrasonography is a suitable and important diagnostic test for the medical surveillance of vinyl chloride workers.T he production of vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) started in Italy in the 1950s and 1960s in six chemical plants, four of which were still in operation in the year 2000. Mortality studies conducted on workers employed in these plants, indicated an increased incidence of liver angiosarcoma, while the presence of other liver lesions and other types of cancer was unclear. [1][2][3][4] After the recognition of the carcinogenicity of VCM in the early 1970s, measures were adopted in the plants to decrease VCM exposure and monitor the occupational exposure levels of the workers. From levels of air concentrations of hundreds of ppm, common in the 1960s and 1970s, the VCM concentrations in the manufacturing plants were reduced to a few ppm in the 1980s and, more recently, to values below 1 ppm.The workforce currently employed in VCM/PVC production includes workers with a long standing service in these plants; some of these workers worked in the plants when high levels of VCM exposure were common. Although all VCM and PVC production workers in Italy are medically examined with a battery of liver tests twice a year, this medical surveillance has a limited diagnostic power for the identification of focal or diffuse lesions of the liver. Thus a liver ultrasonography examination was carried out to detect the presence of hidden liver lesions and to investigate their relation with VCM exposure or other personal risk factors.This paper describes and analyses the results of thi...

Hepatocellular carcinoma and the risk of occupational exposure

“…Maroni et al [105] reported the hepatotoxicity of VCM and other studies have shown the capacity of VCM to Group 1 [76] TCE 79-01-6 Dry cleaning; paint stripping; metal degreasing; production of chlorinated chemical compounds; shoe manufacturing; aircraft/aerospace, electronics and printing industry [125,127] Group 1 [129] PCE 127-18-4 Dry cleaning; textile processing; metal degreasing [138] Group 2A [129] DDT 50-29-3 Farming industry [141,145] Group 2B [148] N-nitrosamines 35576-91-1 Plastic, rubber and pharmacological manufacturing; farming industry; metalworking; electrical component production and use; gasoline and lubricant additives, production and use [159][160][161][162][163][164][165] Group [160,161] TCDD 1746-01-6 Waste management; paper mill; timber manufacturing; iron and steel manufacturing; electric power industry [175,179] Group 1 [76] PeCDF 57117-31-4 Cement and metalworking industry; chemical manufacturing [171,172,175] Group 1 [76] PCB 1336-36-3 Electrical industry, plastic and chemical industry; maintenance/repair technicians of PCB devices [175,[186][187][188][189][190] 1 Group [76,207] PBB Electronics recycling industry; maintenance/repair technicians of PBB devices [209][210][211][212] Group 2A [207] Chloral 75-87-6 Insecticides and herbicide production; p...…”

“…induce specific gene mutations in the liver [105][106][107][108][109][110][111][112][113][114][115][116][117] . Various European and Italian studies have reported the apparent association between the amount and timing of exposure to VCM and development of HCC in those exposed [118][119][120] .…”

Liver function assessment in workers exposed to vinyl chloride

“…The data presented in this paper have already been partly described in a former study (Maroni et al 2003).…”

“…Cumulative VCM exposures (ppm · years) were also computed and the workers grouped into five classes (0, 1-10, 11-100, 101-1000, > 1000 ppm · years). For more details on exposure assessment see Maroni et al 2003.…”

“…Although the use of liver ultrasonography in VCM exposed workers was first proposed in 1975 (Taylor et al 1975) to improve the efficacy of the medical surveillance of the workers employed in the production of polyvinylchloride (VCM/PVC), this examination has been seldom carried out in a systematic way among large groups of VCM exposed workers until recently (Maroni et al 2003;Hsiao et al 2004). This fact has probably limited a complete and correct interpretation of the liver function findings in most of the studies above mentioned.…”