Background Occupational exposure to vinyl chloride monomer (VCM) has been established as a cause of hepatocellular carcinoma (HCC) and liver angiosarcoma (ASL). However, some controversy remains due to conflicting results on liver cirrhosis, and to evidence on HCC based on few confirmed cases. The aim of the study is to clarify the association between VCM exposure and mortality from liver diseases. Methods In a cohort of 1658 workers involved in VCM production and polymerization, Poisson regression was adopted to estimate rate ratios (RR) across categories of VCM exposure for mortality due to ASL (n = 9), HCC (n = 31) confirmed by histological/clinical records, and the combination of deaths from liver cirrhosis and from liver cancer with clinical/histological evidence of cirrhosis (n = 63). Results Cumulative VCM exposure was associated with study outcomes; RRs in the highest compared to the lowest exposure category were: ASL 91.1 (95%Confidence Interval 16.8‐497), HCC 5.52 (2.03‐15.0), liver cirrhosis 2.60 (1.19‐5.67). Conclusions The risk of death from liver cirrhosis, as well as from HCC in the largest available series of confirmed cases, increased with VCM exposure.

Certain esterase inhibitors protect from organophosphate-induced delayed polyneuropathy (OPIDP) when given before a neuropathic organophosphate by inhibiting neuropathy target esterase (NTE). In contrast, they can exaggerate OPIDP when given afterwards and this effect (promotion) is associated with inhibition of another esterase (M200). In vitro sensitivities of hen, rat, and human NTE and M200 to the active metabolites of molinate, sulfone, and sulfoxide, were similar. NTE and M200 were irreversibly inhibited (> 78%) in brain and peripheral nerve of hens and rats given molinate (100-180 mg/kg, sc). No clinical or morphological signs of neuropathy developed in these animals. Hens and rats were protected from di-n-butyl dichlorovinyl phosphate neuropathy (DBDCVP, 1 and 5 mg/kg, sc, respectively) by molinate (180 or 100 mg/kg, sc, 24 h earlier, respectively) whereas 45 mg/kg, sc molinate causing about 34% NTE inhibition offered partial protection to hens. Hens treated with DBDCVP (0.4 mg/kg, sc) developed a mild OPIDP; molinate (180 mg/kg, 24 h later) increased the severity of clinical effects and of histopathology in spinal cord and in peripheral nerves. Lower doses of molinate (45 mg/kg, sc), causing about 47% M200 inhibition, did not promote OPIDP whereas the effect of 90 mg/kg, sc (corresponding to about 50-60% inhibition) was mild and not statistically significant. OPIDP induced by DBDCVP (5 mg/kg, sc) in rats was promoted by molinate (100 mg/kg, sc). In conclusion, protection from DBDCVP neuropathy by molinate is correlated with inhibition of NTE whereas promotion of DBDCVP neuropathy is associated with > 50% M200 inhibition.