Lead exposure reduction in workers using stabilizers in PVC manufacture: effects of a new encapsulated stabilizer.
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Biomedical subjects
Publications and source records attributed to A Fischbein.
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Mesothelioma is a rare neoplasm in the general population, but it is strongly associated with previous asbestos exposure. The endemic occurrence of this disease in two villages in central Turkey has raised the question of whether the inhalation of naturally occurring zeolite dust may also be a factor in the development of mesothelioma. During the past few years a large portion of the inhabitants of one of the two villages of concern has immigrated to Sweden. This report presents three cases of malignant pleural mesothelioma and the results of a chest radiographic survey among these immigrants. Mineralogical analysis of lung tissue specimens from two of the cases revealed the presence of both zeolite and asbestos minerals and therefore suggested a synergistic effect involving both types of minerals. The importance of close medical surveillance of this high-risk population is emphasized, as is the possibility that similar cases appear in other countries because of increased migration.
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The results of cross-sectional clinical field surveys of 45 cable manufacturing workers and 90 telephone cable splicers are presented. Despite the rare occurrence of clinically overt lead poisoning among these occupational groups, high prevalence of lead-associated central nervous system symptoms and gastrointestinal symptoms was found. Hierarchical log-linear models for multidimensional contingency tables were fitted to those data and indicate that there is a partial correlation between reported symptoms and zinc protoporphyrin: individuals with high zinc protoporphyrin levels were more likely to report symptoms than those with low levels. No significant partial association was found between symptoms and blood lead. Because of the intermittent lead exposure encountered in one of the populations, individuals were identified with "normal" blood lead levels associated with "elevated" zinc protoporphyrin concentrations, thus indicating the difference in the biological significance between indicators of lead absorption (blood lead) and of biological response tests (ZPP). Suggestion is made that both types of diagnostic tests be utilized in the medical surveillance of lead-exposed workers.
Potential kidney function decrement with long term lead exposure is important in the overall assessment of adverse health effects of lead in industrial workers or other exposed groups. Two clinical field studies of secondary lead smelter workers have shown that a significant proportion of workers had slightly to moderately elevated blood urea nitrogen (BUN) and creatinine levels; the prevalence was higher in those with longer lead exposure. Since a decrement of kidney function with age has been documented, and since duration of lead exposure may also be strongly related to age, it was necessary to assess the age dependent renal function decrement in control (non-lead-exposed) populations. BUN and creatinine levels in the lead exposed workers showed a much more significant correlation with age than that which was found in the non-exposed populations; the correlation remained statistically significant after correcting for the age-dependent decrement derived from the control populations. Moreover, highly significant correlations between BUN and creatinine and the biological indicator of lead absorption, zinc protoporphyrin, were found. The results indicate a sizeable and significant decrement in kidney function in the secondary lead smelter workers studied; by removing its age-dependency, this effect was found to be lead-induced. In other occupational groups, with lesser and/or shorter lead exposure, a significant effect on renal function as reflected in BUN and creatinine levels could not be detected.
The association between lead absorption and objective psychological performance tests in five groups with different levels of lead absorption was studied in the following groups: (1) a control, non-lead-exposed group; (2) cable splicers, (3) cable manufactures, and (4) secondary lead smelter workers. The following performance tests were used: Block Design, Digit Symbol, and Embedded Figures. Age-corrected performance test scores and the average of three test scores (INDEX) were used throughout. A significant association between performance tests scores and increased lead absorption was found. Zinc protoporphyrin level was a more "powerful" (in the statistical sense) indicator of lead-induced CNS effects than blood lead levels. This study provides additional evidence that neurotoxic effects associated with occupational exposure to lead can be demonstrated by means of performance tests. It has been known and widely accepted that increased lead absorption is associated with "non-specific" subjective symptoms: tiredness, sleep disturbance, irritability, etc. Psychometric techniques (including an appropriate statistical analysis strategy) are highly sensitive for the early detection of CNS neurotoxicity, such as metal toxicity. Moreover, even in lead-exposed but asymptomatic individuals, a significant correlation (negative) between test scores and levels of lead absorption could be detected. It is concluded that workers exposed to lead at levels considered "safe" might be at risk of developing brain dysfunction with long term exposure.
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.
The results of a cross-sectional clinical field survey of 90 telephone cable splicers are presented. Despite the rare occurrence of clinically overt lead poisoning among cable splicers, the observed prevalence of symptoms was 29% for lead-associated central nervous system symptoms and 21% for gastrointestinal symptoms. These two groups of symptoms were directly related to zinc protoporphyrin (ZPP) levels but no relationship was found between them and blood lead concentrations. Only 5% of the workers had significantly elevated blood lead levels (greater than 40 microgram/100ml). Because of the intermittent lead exposure encountered in this trade, individuals were identified with "normal" blood lead levels associated with "elevated" zinc protoporphyrin concentrations, indicating the difference in biological significance between exposure-(blood lead) and biological-response tests (ZPP). Suggestion is made that both types of diagnostic tests be utilized in the medical surveillance of lead-exposured workers.
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Although the intrafamilial transmission of infectious diseases has long been recognized, the induction of environmental disease in household contacts is being increasingly documented and requires a higher index of suspicion. An incidental radiographic finding, such as pleural thickening or calcification, or even interstitial pulmonary fibrosis in a young person without obvious occupational exposure to asbestos, should prompt the physician to clarify the parental occupational history. Likewise, unexpected evidence of lead induced abnormalities, such as elevated blood lead and/or erythrocyte protoporphyrin levels, should focus the examiner's attention on possible intrafamilial transmission, treatment, and prevention.
Pulmonary function was evaluated in 243 workers exposed to PCB in the manufacture of capacitors. Mean employment was greater than 15 years. Thirty-four of the workers (14%) were found to have a reduced Forced Vital Capacity (FVC less than 80% of Morris' predicted). Of the 34 with reduced FVC, 27 (80%) demonstrated a restrictive pattern of impairment (FEV1/FVC greater than 0.7). Only one of these 27 workers had an abnormal chest roentgenogram (greater than or equal to 1/0 by ILO UC Classification of Radiographs of Pneumoconioses). These findings are of interest in view of recent experimental data indicating the accumulation of PCBs and PCB metabolites in lung tissue (Brandt and Jansson). Restrictive spirometric impairment with no radiographic change is unusual in occupational exposure.
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In 1973 inadvertent contamination occurred in a special farm feed supplement for lactating cows. Polybrominated biphenyls (PBBs) were used in place of magnesium oxide resulting in serious harm to farm animals, including cattle, chickens, geese, ducks. Farm families, accustomed to eating their own products, were most heavily exposed. To further study the impact of PBBs, 45 adult Michigan farm residents who were originally examined in a clinical field survey were further studied with respect to their immunologic status. For comparison, 46 dairy farm residents in Wisconsin, who had not eaten PBB-contaminated food, were examined, as were 79 healthy subjects in New York City. Abnormalities in the Michigan group included significant decrease in absolute numbers and percentages of T and B-lymphocytes and increased number of lymphocytes with no detectable surface markers ("null cells"). Significant reduction of in vitro immune function was noted in 35--40% of the Michigan farm residents who had eaten food containing PBB. Despite the absence of any apparent numerical reduction, both T and B lymphocyte subpopulations of peripheral blood lymphocytes showed evidence of functional defect. Ten of the 45 Michigan farmers studied showed impaired PHA-induced blastogeneic response, due to the decreased number and percent of T-cells in the PBLs. The decreased immune function detected among the PBB-exposed farm residents tended to affect families as a unit and was independent of exposed individuals' age or sex, speaking against the possibility of genetic predisposition.
Members of law enforcement agencies were examined for adverse health effects caused by their activities in firing ranges and exposure to lead. Central nervous system and gastrointestinal symptoms were prominent and correlated with blood lead and zinc protoporphyrin levels. Half the group had blood lead levels exceeding 40 microgram/dL, and four (5%) exceeded 60 microgram/dL. Environmental surveys of three firing ranges indicate that indoor facilities with insufficient ventilation may have considerable air lead concentrations with levels up to 900 microgram/cu m or 4.5 times the current Occupational Safety and Health Administration standard for an eight-hour shift. Evaluation of lead effects should be taken into account in medical surveillance programs of firearms instructors. Zinc protoporphyrin determination has proved a suitable and practical way to assess biological effects among exposed persons and should be available at medical facilities responsible for the health of indoor firing range employees.
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.
Central nervous system dysfunction was investigated in workers at a secondary lead smelter by means of performance tests. Correlations between test scores and zinc protoporphyrin levels, a biological indicator of lead toxicity, are statistically significant. This correlation should prove to be useful in current efforts to evaluate effects of lead exposure.
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