Mortality and cancer morbidity in workers exposed to low levels of vinyl chloride monomer at a polyvinyl chloride processing plant

To study whether exposure to low levels of vinyl chloride monomer (VCM) causes increased risk for cancer morbidity and death from ischemic heart disease, a cohort study was performed among 2,031 male workers at a polyvinyl chloride (PVC) processing plant who had been employed for at least 3 months during the period 1945-1980. An almost significantly increased total mortality (SMR = 116, 95% CI 99-136) was found. Deaths caused by violence or intoxication were significantly increased (SMR = 153, 95% CI 109-213), but not deaths from ischemic heart disease (SMR = 100, 95% CI 73-135). A significant increase in total cancer morbidity was observed (SMR = 128, 95% CI 101-161). Respiratory cancers were significantly increased (SMR = 213, 95% CI 127-346). Furthermore, six brain tumors (vs. 2.6 expected) were observed. This increase, however, was not significant (SMR = 229, 95% CI 84-498). No liver hemangiosarcoma was observed. Applying a latency period of greater than or equal to 10 years from start of employment did not change the risk patterns. There were no significant exposure-response associations between exposure estimates for VCM, asbestos, and plasticizers and cancer morbidity.

[Occupational angioneurotic disorders provoked by vinyl monochloride and vibration]

Microcirculatory disorders of the extremities may have an occupational origin, which it is desirable to specify. Exposure to vinyl monochloride results in a chemical nuisance which also proved to be carcinogenic in man. Strict preventive measures are therefore enforced in the industry and angioneurotic disorders should no longer be observed. Use of vibrating tools results in a microvascular response to a physical nuisance which is difficult to prevent completely. In both cases the physiopathology is not well-known, but compensation is possible as occupational diseases. Repeated trauma of the ulnar artery, and/or its superficial palmar branch are, on the contrary, the main explanation for hypothenar hammer syndrome, which is easily prevented by mere adjustment of the work position and occupational movements: the conditions for medico-legal compensation for this particular syndrome, which is still not listed among occupational diseases, will be in effect in the very near future.

Genetic susceptibility to scleroderma-like syndrome in symptomatic and asymptomatic workers exposed to vinyl chloride

We have previously reported a genetic susceptibility to a scleroderma-like disorder in a group of workers exposed to polyvinyl chloride and this susceptibility could be mapped to the major histocompatibility complex area of the 6th chromosome. To date no genetic studies have been reported comparing affected with unaffected workers. We report such data and discuss it in the light of our previous findings in vinyl chloride exposed patients and in patients with classical scleroderma. Our results suggest that susceptibility to this disorder is increased in the presence of HLA-DR5 or of a gene in linkage disequilibrium with it and an antigen associated with the haplotype A1 B8, while DR3 favours progression of the disease.

Use of serum bile acids in the identification of vinyl chloride hepatotoxicity

Most previous studies proposing serum bile acids as indicators of hepatic function have been performed in hospitalized patients in whom overt symptomatic liver disease was present. The ability of fasting levels of serum bile acids to identify mild, clinically inapparent chemical liver injury in an occupational setting was compared with that of indocyanine green clearance and routine biochemical liver tests in 67 asymptomatic chemical workers in whom liver biopsies had been performed for medical indications. Histologically, 15 were found to have chemical liver injury, 27 had nonchemical liver disease, and 25 were normal. Two serum bile acids, cholylglycine and conjugates of cholic acid, were determined by radioimmunoassay, using 466 "normal" males from the same worker cohort as a reference range. The geometric mean concentrations of cholylglycine in patients with chemical liver injury, patients with nonchemical liver disease, and normal subjects were 47.9, 19.1, and 20.0 micrograms/dl, respectively (p = 0.036 by analysis of variance). Conjugates of cholic acid showed similar differences (p = 0.027), as did indocyanine green clearance with mean half-life of 4.2, 3.2, and 3.3 minutes in the three biopsy subgroups, respectively (p = 0.043). Such differences were not observed for biochemical liver tests. The fasting level of serum bile acids provided high specificity but lower sensitivity in the detection of all types of liver disease. However, serum bile acids and indocyanine green clearance provided a higher specificity and sensitivity for chemical liver injury than for nonchemical liver disease. An index of average exposure to vinyl chloride was significantly greater in the subgroup with chemical liver injury than in the other two groups, further supporting the association of chemical type injury with impaired anion uptake. These data identify the fasting level of serum bile acids as a clinically usable indicator of early chemical injury in chemically exposed asymptomatic worker populations with liver dysfunction. Further investigation is needed in other occupational hepatotoxic environments to determine if this association is limited to vinyl monomer type injury.

Early hepatic histologic alterations among chemical (vinyl monomer) workers

Focal hepatocellular hyperplasia and focal mixed (hepatocytes and sinusoidal cells) hyperplasia are early histological alterations indicative of vinyl monomer exposure. To evaluate their uses in screening chemical workers, 93 liver biopsy specimens from 78 persons were examined in double-blind duplicative fashion. Forty-eight specimens were from exposed chemical workers, 35 of them having liver biopsy(ies) for hepatic test abnormalities and 13 for nonliver -related reasons. A comparison group consisted of 30 nonchemical workers who had undergone liver biopsy for nonliver related reasons. Twenty-three of the exposed workers (48%) had hepatic lesions consistent with exposure: 17 (35%) of these had focal hepatocytic hyperplasia, while 6 (13%) had focal mixed hyperplasia or more advanced lesions. Only five of the comparison group had like findings: four (13%) had focal hepatocytic hyperplasia; one had focal mixed hyperplasia and sinusoidal dilatation. This individual had persistent hepatic test abnormalities with the focal mixed hyperplasia and a sinusoidal dilatation, and on subsequent biopsy, angiosarcoma (and a history of using hair spray containing vinyl chloride propellant ). Ten individuals had 25 multiple biopsies also read double-blindly; 10 had two or more readings of the same biopsy. Duplicate 21 of 23 (91%) and multiple 27 of 28 (96%) biopsy interpretations in the same individual were identical. Only 6% of either duplicate and/or multiple readings disagreed. Both focal hepatocellular and mixed hyperplasia were always associated with abnormalities in hepatic test results of which indocyanine green clearance was the most sensitive and gamma-glutamyl transpeptidase the least specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of some leukocyte cytoenzymochemical investigations in detecting the noxious effects of the vinyl chloride monomer or polymer

A group of 100 workers exposed to vinyl chloride (VC) (mean duration of exposure-13.2 years) were subjected to a complex medical examination for the detection of eventual alterations of the biologic parameters, induced by occupational exposure. Leukocyte cytoenzymochemical determinations (lymphocytic RNA--Plenert's method modified by Micu and glycogen--Hotchkiss McManus method), which might give some information on two important metabolic processes--of proteins and of carbohydrates--were performed in peripheral blood smears. Lymphocytic nucleologram and the relative and absolute nucleolar area showed an increase of endolymphocytic RNA, due to the high percentage of binucleolated cells and of spherical macronucleoli. The increase of the endolymphocytic glycogen score in parallel with the duration exposure was in correlation with high titers of serum gamma GT.

Power considerations in epidemiologic studies of vinyl chloride workers

Nine retrospective mortality studies of workers exposed to vinyl chloride were reviewed to determine whether differences in their hypothesis testing results might be due to differences in statistical power. Where possible, the power of each study was calculated for cancer of the lung, brain and liver. When power was taken into consideration, the results for liver and brain cancer were found to be consistent with an etiologic role for vinyl chloride. For lung cancer, the data were not consistent with an etiologic role in that two studies with very high power yielded negative results.

Evidence for endothelial cell origin of vinyl chloride-induced hepatic angiosarcoma

Previous reports of hepatic angiosarcoma have not clearly defined the cellular type from which this tumor arises, as evidenced by the terminology of endothelioma, Kupffer cell sarcoma, endothelial cell sarcoma, and hemangioendothelial sarcoma, etc., which have been used interchangeably. In addition, there has been no consensus on the separate entity of Kupffer and sinusoidal endothelial cells. In the work presented here, evidence for the endothelial cell origin of this tumor is provided by the demonstration of factor VIII, a known endothelial cell marker, in the tumor cells. Fluorescence due to the presence of factor VIII appeared intense in the tumor sinusoidal cells of all four vinyl chloride-associated angiosarcomas studied, whereas normal liver sinusoidal lining cells showed negligible fluorescence.

Acetylcholinesterase activity in several rat liver cell fractions after repeated poisoning with some organophosphates

The reported investigations were carried out on female Wistar rats aged about 6 weeks, weighing 150 g. During 28 days the fats were given daily organophosphates (DFP, DDVP, Chlorfenvinphos, IPO-62, IPO-63, Phospholine) in a dose of 1/10 LD50 subcutaneously. The observations were conducted on groups of 8 rats. The body weight of the animals was noted on the 10th, 20th and 28th day of the experiment. On the 28th day the rats were killed and the activity of acetylcholinesterase (AChE) was determined by the biochemical method of Hestrin in liver homogenate and in the microsomal, mitochondrial and soluble fractions of liver cells. After 28 days of the experiment the body weight of the rats poisoned with these substances amounted to from 80.8% (DFP) to 90.7% (IPO-63) of that in control animals. The AChE activity was also reduced in relation to the control group ranging in the liver homogenate from 49.7% (DFP) to 75.6% (IPO-63), in the microsomal fraction from 33.0% (DFP) to 63.8% (IPO-63), in the mitochondrial fraction from 45.5% (DFP) to 72.9% (IPO-63), and in the soluble fraction from 52.8% (DFP) to 80.5% (DDVP).

Scleroderma simulating vinyl chloride disease

Progressive systemic sclerosis, especially prior to distinctive internal organ involvement can be difficult to distinguish from vinyl chloride disease. A 50-year-old male developed classic scleroderma while working with polyvinyl chloride. Early in his disease he displayed a number of features common to both disorders, including acroosteolysis, sclerodactyly, polygammopathy and circulating immune complexes. Characteristic visceral involvement was the cardinal feature which distringuished his disease from the pseudoscleroderma of vinyl chloride disease.

Occupational acroosteolysis in vinyl chloride workers in Israel

Exposure to vinyl chloride monomer (VCM) may result in a bizarre syndrome, which is characterized by lytic changes in the distal phalanges, cutaneous stigmata of scleroderma, and Raynaud's phenomenon. Detailed case histories of two such patients are presented. Epidemiologic, pathogenetic and radiological aspects of occupational acroosteolysis are briefly reviewed. The possibility is emphasized that the condition may result not only from industrial (i.e., occupational) exposure to VCM but also from exposure in the home or neighborhood (i.e., nonoccupational).

Angiosarcoma of the liver: an epidemiologic survey

Diagnosed from 1970 through 1975, the annual incidence rate for angiosarcoma of the liver among residents of New York State (excluding New York City) was 0.25 per million. A case-control study indicated that direct exposure to arsenic, vinyl chloride (VC), and thorium dioxide was a significantly important factor in the etiology of this disorder (P less than 0.02). Direct exposure to these chemicals could not be demonstrated for 19 (73%) of the 26 study patients. The fact that 5 of these patients lived nearer to VC fabrication or polymerization plants than did their matched controls lent some support to the hypothesis that indirect modes of exposure, not specifically related to occupation, might be important in the etiology of this disorder.

[Enzyme histochemical, histometrical and ultrastructural studies of spleens in vinylchloride-disease (author's transl)]

By means of histometric, enzyme histochemical, and electron microscopic investigations it was demonstrated that the pathological changes in the spleen in vinylchloride-disease are primary. Fibroblastic cells are the only specific splenic cells involved. Fibre-associated reticulum cells of the red pulp and fibroblastic reticulum cells in white pulp are stimulated to produce excessive amounts of the extracellular elements of connective tissue, especially collagen fibrils. The newly formed connective tissue causes obliteration of extracellular blood channels in the red pulp and thus a reduction in the number of pulp-cord macrophages, and scarring of the periaterial lymphatic sheaths. The results of this fibrosing process are characteristic quantitative changes in the splenic histologic structures. These changes are different from those structural alterations occurring in spleens following extrasplenic hemodynamic changes, such as thrombosis of the splenic veins or cirrhosis of the liver.

Vinyl chloride: its impact on occupational medicine practice in Iran

Upon the establishment of a positive relationship between occupational exposure to VCM and angiosarcoma of the liver, strict precautionary measures for the protection of VCM exposed employees in the Abadan Petrochemical Company have been instituted. All such workers have been required to have pre-employment and annual medical examinations with emphasis on liver functions. Among 43 such employees who have undergone regular medical evaluation in the past three years, no instance of liver dysfunction of angiosarcoma has been discovered. The Iranian Standards Institute reviewing occupational health data and local conditions provisionally set in 1976 a TLV of VCM of 25 ppm TWA for 8 hours with revision foreseen for 1977. It is believed that such precautionary measures should be revised and improved according to available data and knowledge and that variations in other environmental and local factors which may well play an important role in the potential pathogenicity of the exposure should be carefully considered in determining the extent of the precautionary measures and standards in each locality.

[Aetiology of the thrombocytopenia in vinylchloride disease (author's transl)]

Thrombocytopenia is often one of the first signs of vinylchloride disease. Morphological investigations showed that it is caused by splenic alterations. Besides splenomegaly, there are significant structural changes in the red pulp cords affecting the microcirculation. These quantitative and qualitative alterations cause increased platelet pooling and and increased destruction of platelets, which result in a decrease in thrombocytes in the peripheral blood.

Vinyl chloride cytogenetics

This report presents cytogenetic findings from a group of 209 workers employed for up to 28 years in the manufacture of vinyl chloride monomer at the Texas Division of Dow Chemical U.S.A. Cytogenetic evaluation results from this group were compared to results found in examination of individuals being considered for employment. Statistical analyses were performed on a group basis for chromatid aberrations, chromosome aberrations and proportion of abnormal cells; no statistical difference of significance was found between the two groups. Comparison of these results with reported studies suggests that the level of cytogenetic aberrations in vinyl chloride workers is probably related to the length and level of exposure, and that risk of adverse genetic effect can be avoided in controlled, minimal-exposure environments.

[Ultrastructure of liver damage in chronic vinyl chloride intoxication (author's transl)]

Liver biopsies taken from 15 workers at a PVC-producing factory were examined by electron microscopy. The hepatocytes showed focal hydropic swelling, disseminated toxic steatosis, peculiar para-crystalline inclusions in enlarged mitochondria, focal cytoplasmic degradations, and occasional single cell necroses. These regressive changes were more prominent in cases with a shorter interval of non-exposure prior to the biopsy. Further, a focal compensatory hyperplasia of the smooth endoplasmatic reticulum was found. With increase of the non-exposure time interval, a regression of the degree of steatosis as well as an age-independent excessive lipofuscin deposition was seen in the hepatocytes. Apparently, these are sequelae of increased autophagia of lipids and increased lipid oxidation by the vinylchloride. In the sinusoids, activation, enlargement and proliferation of Kupffer cells was noted. The tendency of these cells to proliferate is apparently caused by the cancerogenic stimulation by vinylchloride. The prominent hyperplasia of lipocytes is probably connected with the deposition of collagen and the peculiar perisinusoidal fibrosis.

Hemangiosarcoma and hepatocellular carcinoma of the liver following vinyl chloride exposure. A report of two cases

A report is given of the clinical and autopsy findings of two men who died from malignant liver neoplasm following occupational exposure to vinyl chloride. The first patient was a 44-year-old man with an hemangiosarcoma of the liver, the second patient a 67-year-old man with an hepatocellular carcinoma. So far an hepatocellular carcinoma due to vinyl chloride has not yet been observed in man. Its occurrence, however, has been suggested from the results of animal experiments. The connection of hepatocellular carcinoma with exposure to vinyl chloride is discussed.

Low mortality rates in industrial cohort studies due to selection for work and survival in the industry

Occupational groups are often described as being relatively healthy because their mortality rates are lower than those of the national average. Although correct this confuses the issue for those who are interested in assessing the effects of exposure to a particular chemical. In a further analysis of data collected in a study of all men ever exposed to vinyl chloride monomer in the manufacture of polyvinyl chloride in Great Britain, three factors have been shown to contribute to the low mortality rates that were observed. The three factors: the selection of a healthy population for employment, the survival in the industry of the healthier men, and the length of time that this population has been pursued, have been quantified. The mortality experience within five years of entering this industry was shown to be as low as 37% of that expected; for circulatory disease and respiratory disease it was as low as 21%. There was a progressive increase in standardized mortality ratio with the length of time since entry so that the effect had almost disappeared 15 years after entry. To avoid confounding the selection effect with the survival effect the latter was measured by separating men who survived 15 years after entering the industry according to whether or not they were still in the industry after this period. Those who had left experienced an overall standardized mortality ratio some 50% higher than those still in the industry. This effect, although consistent in the age groups between 25 and 74 years and for all cause groups studied, was greatest in those aged between 25 and 44 years and for lung cancer and respiratory disease.

[The so-called vinyl chloride disease in the Federal Republic of Germany]

A short outline is given of the historical development of the so-called vinyl chloride disease in the Federal Republic of Germany. It is a report on the measures taken--including the research work. Latest statistics about the cases of occupational disease are shown.

[Clinical picture and pathology of the so-called vinyl chloride disease]

About 26 years ago symptoms of liver and spleen were described for the first time by Tribukh et al. in laborers exposed to vinyl chloride. Besides these symptoms sclerodermia, acroosteolysis and Raynaud's phaenomenon are known to be typical for the VC disease. Rather high concentrations of VC seem to be necessary to cause this disease. After cessation of exposure the symptoms may improve partly. Haemangiosarcoma of the liver may occur as the most serious effect of prolonged exposure to vinyl chloride. Presently 48 cases induced by VC exposure are observed all over the world. Diagnosis is difficult, the prognosis of this cancer is practically always fatal. The improvement of working places by the chemical industries should further reduce the risk of acquiring VC disease as well as haemangioma of the liver due to VC exposure.

Special communication. Polyvinyl chloride - vinyl chloride disease: an occupational health hazard

Poly Vinly Chloride (PVC) is a very durable, practical and economical plastic, which is so wide spread in its use that it may become difficult to replace it. The annual amount of world production has been constantly increasing and has reached the figure of 8.5m tons. While PVC is so useful, the health hazards which accompany this plastic are causing alarm in the industrially developed countries. The hazards are severe and include defects such as Haemangioendothelial sarcoma (Angiosarcoma) of the liver, Acro-Osteolysis of the fingers and Sclerodermic type skin lesions. This paper illustrates the recent developments, the clinical findings and the measures necessary to control the disease. Moreover, this paper should help alerting the health authorities in the developing countries about the health hazards involved in the manufacture and utilization of PVC. Due to the restrictions imposed on PVC producing plants, there is a real eventuality that these plants may be transferred to the developing countries, where this disease is still unknown.