Alf Fischbein

HOUSEHOLD‐CONTACT ASBESTOS NEOPLASTIC RISK*

The occupational risk associated with asbestos exposure has been well documented. Asbestosis-parenchymal fibrosis (described in the ILO/UC Pneumoconiosis Classification as irregular opacities), pleural fibrosis, and pleural calcification-has afflicted many occupational groups exposed to these mineral fibers. Although optimistic forecasts had predicted a decline in the incidence of asbestos-induced disease, recent experience proves that the risk is still present, involving large numbers of workers in various trades. Epidemiologic studies have shown that such asbestos-exposed individuals have a significantly increased risk of death due to malignant (mesothelioma, lung, and gastrointestinal cancers) and nonmalignant (asbestosis) diseases. Asbestos pollution from industrial sources was not anticipated to pose any significant health hazard to the general public. However, Wagner’s work in South Africa and Newhouse’s studies in the United Kingdom suggested that the risk had already spread beyond the factory, mine, or mill gate. In 1960, Wagner et a1.l reported mesothelioma in nonoccupationally asbestos-exposed individuals. In 1964, Newhouse et al.’ reported nine cases of mesothelioma in family contacts of asbestos workers and eleven cases among individuals whose only identified asbestos exposure was associated with living within one-half mile of an asbestos factory. These initial case reports were not isolated occurrences, peculiar to only one or two regions (TABLE 1) . Additional reports from nine countries have brought the total number of reported cases of household mesothelioma to 37.1-lG Thus, household asbestos contact has been established as being potentially hazardous. Such case reports did not assess the actual incidence or extent of risk to household members or the general public. nor did they give any suggestion of the prevalence of asbestos-associated radiologic changes in such populations. We have investigated the problem in order to determine whether the potential for such disease hazard is common or rare, since such evaluation would assist in assessing measures needed for clinical surveillance and for preventive control measures.

Prevalence of lead disease among secondary lead smelter workers and biological indicators of lead exposure

The report concerns itself primarily with the assessment of medical and biochemical effects of chronic lead exposure and comparing the usefulness of various biological screening parameters. In addition it appraises the effects of chelation therapy to control blood lead levels in lead workers, which have recently attracted critical attention. It is of considerable importance to ascertain whether such a therapeutic approach may, under some circumstances, in fact contribute to the deleterious effects of undue lead exposure.

Behavioral indicators of lead neurotoxicity: Results of a clinical field survey

SummaryCentral nervous system dysfunction in workers occupationally exposed to lead was investigated by means of performance tests. The test scores of lead-exposed workers were compared with those of control groups (steel workers, papermill workers and farmers). It was found that secondary lead smelter workers showed significantly poorer performance scores than the nonexposed, control groups. The group differences between steel workers and lead workers in test scores were not attributable to differences in age or education. In the lead-exposed workers correlations between test scores and indicators of lead absorption (particularly blood lead and zinc protophyrin levels) were analyzed. Increases in zinc protoporphyrin levels were found to be highly correlated with decreases in test scores. Lower performance test scores were consistent with a sizeable prevalence of central nervous system symptoms among secondary lead smelter workers. Moreover, lead workers without central nervous system symptoms also showed decrements in performance test scores which were also correlated with elevated zinc protoporphyrin levels. The data indicate that certain behavioral tests might be important tools for studying subclinical central nervous system dysfunction due to lead toxicity; significant correlations between zinc protoporphyrin levels and behavioral test scores are considered to be consistent with an etiologic relationship between decrement in performance scores and lead effects on the central nervous system.

Drywall construction and asbestos exposure

The rapid development of the drywall construction trade in the United States is described. It is estimated that some 75,000 U.S. construction workers are currently employed in this trade. The use of a variety of spackle and taping compounds is shown to be associated with significant asbestos exposure; air samples taken in the breathing zone by drywall tapers during sanding of taping compounds show fiber concentrations exceeding, by several times, the maximum level permitted by United States Government regulations. These findings are given together with the result of a clinical field survey of drywall construction workers demonstrating that asbestos disease may be an important health hazard in this trade.

Lead intoxication among demolition workers: The effect of lead on the hepatic cytochrome P‐450 system in humans

Overt clinical disease from undue lead exposure has become a relatively rare phenomenon in adult populations. However, exposure situations that may result in subclinical disease are not uncommon in various occupational settings. Five demolition workers, dismantling an old iron structure covered with lead-content paint, were studied. The use of cutting torches resulted in lead fumes, with significant exposure, albeit without gross lead poisoning. All five workers showed biochemical manifestations of chronic lead intoxication-that is, elevated blood lead level, inhibition of delta-aminolevulinic acid dehydratase (ALA-D), and elevated erythrocytic protoporphyrin concentration (PROTO). The effect of lead on the biosynthesis of heme was assessed by investigating the functional capacity of the cytochrome P-45O system of the liver, through drug metabolism studies. The plasma elimination rates (half-lives) of antipyrine and phenylbutazone-drugs primarily metabolized by the hemeprotein P-450 dependent hepatic microsomal enzyme system-were measured before and after chelation therapy. Prior to chelation therapy all half-lives were within the normal range. A slight decrease in the half-life of antipyrine was found after treatment. These studies show that chronic exposure to lead has only a minimal effect on hepatic cytochrome p-450 dependent enzymatic activities in adult males.

Distribution of blood lead, blood cadmium, urinary cadmium, and urinary arsenic levels in employees of a copper smelter

A cross-sectional medical examination of a copper smelter work force included determination of blood lead (Pb-B), zinc protoporphyrin (ZPP), blood cadmium (Cd-B), urinary cadmium (Cd-U), and urinary arsenic (As-U), since it was known that such metal impurities were present in the copper concentrate. A total of 776 copper smelter employees (680 active and 96 retirees and ex-employees) were examined. Another 144 men, never employed in the smelter, but who had worked in copper mines (and sometimes in gold mines) were also examined. Mean Pb-B, ZPP, Cd-B, and As-U were significantly higher in active copper smelter employees than in retirees or miners, indicating exposure and absorption in the copper smelter. Significant correlations between Pb-B and Cd-B, and Cd-U and As-U were present, confirming the common source of absorption. Although there was evidence for an increased lead absorption, this was very moderate, with practically no Pb-B levels in excess of 60 micrograms/dl. A marked effect of smoking on blood cadmium levels was present; nevertheless, for all smoking categories Cd-B levels were significantly higher in active employees, indicating the independent contribution of exposure to cadmium in the smelter. Cd-U did not exceed 10 micrograms/g creatinine, the generally accepted critical level for the kidney, but was higher than 2 micrograms/g creatinine, a level very rarely exceeded in the general population, in a sizable proportion of those examined. The highest Cd-U levels were found in retired copper smelter employees; age might have been a contributing factor, besides a longer duration of exposure in the smelter.

Comparative lead emissions from conventional and jacketed ammunition

Because of the adverse health effects associated with excessive exposure to lead in firing ranges, attempts have been made to develop ammunition which could prevent such undesirable exposure. This study provides evidence that it is possible to reduce lead exposure significantly at the source of emission with the use of copper and nylon jacketed bullets.

Conjugal exposure to polychlorinated biphenyls (PCBs).

Polychlorinated biphenyls (PCBs) are a group of chlorinated aromatic hydrocarbons that have attrac ted much public health attention. Having been used in industry since the 1930s, PCBs were found to be almost ubiquitous in the environment by 1966.1 Owing to their excellent dielectric and insulating properties, PCBs have been used in transformers and capacitors, hydraulic systems, paints and other sur face coatings, and as a constituent in carbonless copy ing paper. Manufacture of PCBs was discontinued in the United States in 1977 because of concern over potential adverse health effects. Their use, storage, and disposal have subsequently been strictly regulated.2 Adverse health effects from accidental exposure to PCBs and their toxic contaminants, notably poly chlorinated dibenzofurans (PCDFs), have been reported from Japan and Taiwan in connection with two episodes involving ingestion of contaminated rice cooking oil. The clinical syndromes, known as yusho (Japanese: oil disease) and yu-cneng (Chi nese: oil disease) included chloracne, abnormalities in liver function in severely affected subjects, and raised concentrations of serum triglyc?rides.3 More recent studies of occupationally exposed populations have reported less severe clinical manifestations despite the presence of high serum concentrations of PCBs.4 In 1935 chloracne was reported in family members of a worker employed in a factory in which chlo rinated biphenyls and chlorinated naphthalenes were manufactured and it was suggested that household exposure had occurred through chemical laden clothes.5 In the present two cases there is analytical chemical evidence of transmission of PCBs from transformer maintenance workers to their wives.

Carcinoma of the lung in a drywall taping worker report of a case

Abstract Squamous cell carcinoma, together with pulmonary asbestosis is reported in a drywall taping worker. In this trade vigorous sanding of dried taping compounds produces a dust which is known to contain chrysotile asbestos. Fibrils of chrysotile asbestos were seen on transmission electron microscopy of ashed lung tissue. The authors emphasize the need to institute adequate preventive measures in this trade.

Chapter 10 Modified Nucleosides as Biochemical Markers of Asbestos Exposure and Aids

Publisher Summary Cancer patients and tumor-bearing animals excrete in their urine increased amounts of modified purines and pyrimidines. These modified nucleosides, synthesized at the macro-molecular level are primarily constituents of tRNA and to a lesser extent of other RNAs. Slight elevations in urinary modified nucleoside excretion from subjects with bacterial pneumonia and significant elevations from some subjects with urinary tract infections have been noticed. Elevated levels of modified urinary nucleosides and bases in animals precede the appearance of tumor. Modified nucleosides of 24 hours urine samples were determined from the initiation of the experiment until demise of the animals. By the seventh week, when the tumor was not diagnosable, excretion of the nucleosides was elevated. The protracted period of latency poses a difficult problem for early detection, and especially, for successful therapy. The information obtained in retrospective prospective epidemiological investigations of asbestos insulation workers provides evidence for the serious consequences that may occur when there has been a delay in establishing a cause-effect relationship, and when the biological and biochemical events during the latency period remain poorly understood.