Central nervous system dysfunction due to lead exposure.

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.

Interaction of asbestos, age, and cigarette smoking in producing radiographic evidence of diffuse pulmonary fibrosis.

The study of 3,472 chest x-rays from four populations with different levels of exposure to asbestos and with different cigarette smoking histories shows that smoking in the general population does not produce pulmonary fibrosis recognizable on chest radiography. In the general population of Michigan, the prevalence of a radiographic pattern of fibrosis was 0.5 percent in men and 0.0 percent in women. In a Long Beach, California census tract population, the prevalences were 3.7 percent for men and 0.6 percent for women. Similarly, cigarette smoking does not enhance fibrosis when the exposure to asbestos has been as light as that in households of shipyard workers. Asbestosis was recognized in 6.6 percent of 137 shipyard workers' wives who have never smoked and 7.6 percent of 132 who had ever smoked. Cigarette smoking and asbestos appear to be synergistic in those occupationally exposed to asbestos (as insulators), since 7.2 percent of 97 nonsmokers and 20.5 percent of 316 ever-smokers showed fibrosis. This apparent synergy was also found in shipyard workers up to age 70 with 31 percent of nonsmokers and 43.3 percent of ever-smokers having fibrosis. There were increases of approximately 10 percent in the prevalence of fibrosis in cigarette smokers and nonsmokers for each decade after age 40.

Review of pulmonary effects of poly(vinyl chloride) and vinyl chloride exposure.

The contributions of several recent reports to the definition of pulmonary effects of PVC dust inhalation are reviewed. Granulomatous reaction, with inclusion of PVC particles in macrophages and histocytes, and associated interstitial pulmonary fibrosis have been found to lead to exertional dyspnoea, diffuse micronodular chest radiographic opacities and restrictive pulmonary dysfunction. The effects of vinyl chloride (VC) monomer (gas) on proteins and the immunologic mechanisms triggered by the altered protein are possible mechanisms for the development in some cases of interstitial pulmonary fibrosis secondary to VC exposure. Vinyl chloride, a confirmed carcinogen, has been associated with, among other malignant tumors, a significant increase in the incidence of lung cancer. The magnitude of this effect has not yet been completely evaluated.

Hemoglobin, serum iron, and zinc protoporphyrin in lead-exposed workers.

In a previous study of secondary lead smelter workers (males), a significant prevalence of low hemoglobin levels (less than 14 g/100 ml) was found; a statistically significant negative correlation between hemoglobin and zinc protoporphyrin was also detected. In the present study serum iron (Fe) levels and total iron binding capacity (TIBC) were included in the investigation of 111 secondary lead smelter workers and 37 nonexposed controls. The distribution and mean values of serum iron and TIBC were found to be in the normal range in the lead exposed workers; there was no significant difference when compared to the control population. There was no significant correlation between blood lead or zinc protoporphyrin and serum iron, TIBC and Fe/TIBC. A statistically significant negative correlation between hemoglobin and blood lead levels was found; the correlation between hemoglobin and zinc protoporphyrin reached a much higher level of significance. The results support the view that anemia (low hemoglobin levels) in lead exposed male workers is related to the heme synthesis inhibiting effects of lead, as reflected by elevated zinc protoporphyrin levels, and is not due to iron deficiency.

Comparative neurobehavioral study of a polybrominated biphenyl-exposed population in Michigan and a nonexposed group in Wisconsin.

An analysis of findings regarding the prevalence and time course of symptoms and the results of neurobehavioral testing among Michigan and Wisconsin dairy farmers, is reported. Reviewed are: (1) differences in the prevalence of neurological symptoms at the time of examination; (2) differences in the incidence and time course of symptoms for the period 1972--1976; (3) differences among populations and subgroups (sex and age) regarding performance test scores; (4) correlations between performance test scores and neurological symptoms; and (5) correlations between serum PBB levels as indicators of exposure and performance tests and neurological symptoms.

Comparison of findings among residents on Michigan dairy farms and consumers of produce purchased from these farms.

Consumers who had purchased farm products from both quarantined and nonquarantined farms were examined during the cross-sectional clinical survey of 1,029 Michigan residents. Since PBB had inadvertently contaminated cattle and other farm animals, ingestion of meat, milk, eggs and other farm products was thought to have possibly resulted in significant PBB body burdens in some consumers. Findings were considered in comparison with those made among farm residents. Prevalence of symptoms in consumers of farm products from quarantined farms (CQ) was similar to that found in farmers on quarantined farms (FQ); the prevalence was lower in consumers of products from nonquarantined farms (CNQ). Liver function abnormalities were found with similar prevalence in dairy farmers and consumers. Distribution, mean and median values of PBB serum levels in consumers were found to be similar to those of dairy farmers. These results indicate that significant body burdens of PBB had been accumulated by some consumers of farm products in Michigan and that prevalence of symptoms and liver function abnormalities resembled those found among dairy farm residents.

Unanticipated prevalence of symptoms among dairy farmers in Michigan and Wisconsin.

Adverse human health effects resulting from exposure to polychlorinated biphenyls (PBBs) were unknown until the accidental contamination of Michigan dairy farm animal feed in 1973-1974. Human exposure resulted from the consumption of contaminated meat, milk, dairy products, and eggs. In November 1976, the Environmental Sciences Laboratory conducted comprehensive examinations of 933 farmers and residents in Mighigan who were likely to have consumed farm products contaminated with PBB. A comparison group of 229 Wisconsin dairy farmers were examined in March 1977 and the same scientific and medical staffs that conducted the Michigan survey were responsible and the same procedures used. A complete history of symptomatology by organ system, including year of first onset, duration, frequency, and severity of each symptom was obtained by a physician on all adults examined. Statistical analysis of the prevalence of symptoms at the time of examination or during the preceding year in the Michigan and Wisconsin populations studied found the Michigan group to have a significantly higher prevalence of skin, neurological and musculoskeletal symptoms. The increase was seen among the younger age groups 16-35 and 36-55. Michigan females had a higher prevalence of neurological symptoms than the Michigan males. The existing differences could not be explained without considering an etiologic role for exposure to PBB.

Epidemiologic study of renal function in copper smelter workers.

A medical cross-sectional examination of a copper smelter work force was undertaken after environmental contamination with lead, cadmium and arsenic had been documented. A total of 920 subjects was examined, including active smelter employees, retired workers and copper mine employees who had never worked in the smelter. Slight to moderate absorption of lead and cadmium was definitely present in the active copper smelter employees, who had significantly higher levels of Pb-B, ZPP and Cd-B than retired employees and miners. Cd-U levels were higher in retired workers, who were also older and had, as a group, longer duration of exposure in the smelter. Cd-U did not exceed 10 micrograms/g creatinine, the level considered critical for nephrotoxicity, in any of the subjects. Median Cd-B level for active workers was 2.75 micrograms/L. Lead absorption was characterized by a relatively small proportion (16.7%) of active employees with Pb-B levels 40 micrograms/dL or higher. We were particularly interested in exploring the possibility that simultaneous exposure to lead and cadmium, although at levels not associated with nephrotoxicity for each metal separately, could result in renal function impairment. Distribution patterns of BUN and serum creatinine levels were unremarkable. Urinary beta 2-microglobulin levels were less than 200 micrograms/g creatinine in 95% of copper smelter employees. There were no significant correlations between urinary beta 2-microglobulin levels and Cd-U, Cd-B, Pb-B and ZPP or between urinary beta 2-microglobulin excretion and serum creatinine or BUN levels. Urinary beta 2-microglobulin levels were significantly correlated with age in the copper smelter workers, but not in the miners. Nevertheless, in the absence of any significant correlations between urinary beta 2-microglobulin and Cd-U, Cd-B, a causal relationship with cadmium absorption cannot be affirmed. That kidney function could be impaired by long-term exposure in the smelter was only indirectly suggested. Effects on renal function at the low levels of cadmium and lead absorption that were observed in this smelter population are minimal.

Clinical studies of styrene workers: initial findings.

Styrene monomer is a high volume chemical used chiefly in production of polystyrene. A clinical survey of 493 production workers was undertaken at the oldest and largest monomer production, polymerization, and extrusion facility in the U.S. Relative exposure durations and levels were obtained from occupational histories. Significant differences between the high and low exposure groups were found with regard to history of acute prenarcotic symptoms, acute lower respiratory symptoms, prevalence of FEV 1/FV less than 75 per cent, and elevated GCTP. Other liver function tests, chest x-ray, FVC less than 80 per cent, and hematological parameters showed no distinct pattern. A concomitant mortality study has been mounted and is in progress.

Chemical pneumonitis due to exposure to bromine compounds.

A 60-year-old laboratory technician developed pulmonary infiltrates consistent with chemical pneumonitis following accidental exposure to a mixture of hydrogen bromide and phosphorus tribromide. A protracted clinical course ensued consistent with bronchiolitis obliterans. These problems may have been avoided if the potential for subsequent damage had been realized at the time of the initial exposure. Health personnel must be aware of the potentially delayed effects of accidental exposures to respiratory irritants.

Acute mercury poisoning with severe chronic pulmonary manifestations.

This report describes a patient who developed acute chemical pneumonitis following overexposure to metal mercury vapor. The exposure occurred in a gold extraction facility where a gold-mercury amalgam was heated in a confined area. Prompt treatment with penicillamine and corticosteroids was instituted; radiologic pulmonary infiltrates disappeared within a week, but there was little change in the pulmonary function abnormalities (restriction and diffusion impairment) over the period of 11 months of follow-up. This raises the possibility of persistent pulmonary function impairment after metal mercury vapor-induced chemical pneumonitis.

Spirometric impairments in long-term insulators. Relationships to duration of exposure, smoking, and radiographic abnormalities.

A study of 2,611 long-term asbestos insulators was well suited to provide information on (1) the prevalence of spirometric impairments in a large, well-defined population and (2) the effects of cigarette smoking, radiographic abnormalities, and duration from onset of exposure on pulmonary function. Prevalences are reported by a mutually exclusive classification of impairments (normal, restrictive, obstructive, small airways, and combined) as well as by abnormality of specific spirometric tests (FVC, FEV1/FVC, and midexpiratory time). Only 3 percent of nonsmokers (NS) had obstruction and 6 percent a decreased FEV1/FVC. Frequency of restriction did not vary by smoking history; it was 31 percent in NS and current smokers (CS) and 34 percent in ex-smokers (XS). Obstruction (present in 17 percent) and combined impairment (in 18 percent) were most common in CS. The FEV1/FVC was decreased in 35 percent of CS and 18 percent of XS. The FVC was decreased in 49 percent of CS, 44 percent of XS, and 33 percent of NS. Normal spirometry was most common when the radiograph was normal (almost half the workers with normal radiographs had normal spirometry). Nevertheless, FVC was reduced in 27 percent of those with normal radiographs and a normal radiograph was seen in 11 percent of workers with restriction. Restrictive and combined impairments were most frequent when both parenchyma and pleura were abnormal. Restriction was more frequent in isolated pleural disease (seen in 34 percent such subjects) than in isolated parenchymal disease (22 percent). The contribution of pleural fibrosis to reduced FVC and of asbestos exposure and smoking both to reduced FVC and to reduced FEV1/FVC was confirmed by regression analysis. That reduced FVC and reduced FEV1/FVC are both more frequent in insulators who have smoked (compared with NS insulators or smokers in the general population) suggests an interaction between asbestos and smoking in producing both these physiologic abnormalities.

Long-term mortality experience of chrysotile miners and millers in Thetford Mines, Quebec.

Among a cohort of 544 men with at least 20 years of employment in chrysotile mining and milling at Thetford Mines, Canada, 16% of the deaths were from lung cancer and 15% from asbestosis. The excess over expected deaths from these causes account for 43 of 178 deaths in the group. The risk of death of asbestosis, at equal times fron onset of exposure, is very similar in miners and millers, factory workmen and insulators. The ratio of observed to expected deaths from lung cancer is similar in the miners and millers and factory workers, but higher in insulators. The risk of death of mesothelioma in miners and millers is decidedly less than the other two groups. The exact causes of the reduced risk in this category are not yet completely clarified.

Asbestos disease in maintenance workers of the chemical industry.

In several large groups of workers employed in chemical plants, chest x-ray abnormalities (small irregular opacities and/or pleural changes) of the type known to be induced by asbestos were found in a proportion of those examined. A cross-sectional study of maintenance workers in a large chemical plant was undertaken to evaluate the prevalence of asbestosis; 185 workers were examined. Radiologic evidence of parenchymal interstitial fibrosis was found in 24% of those examined; in 10% of workers, parenchymal fibrosis was the only abnormality. Pleural fibrosis and/or calcification was found in the absence of parenchymal fibrosis in 14% of cases; in another 14% of workers, both parenchymal and pleural abnormalities were detected. The prevalence was significantly higher in those employed 20 or more years. Pleural abnormalities were more prevalent than were parenchymal changes. The increased risk of lung cancer and mesothelioma remains to be studied.

The neurotoxicity of polybrominated biphenyls: results of a medical field survey.

Neurologic symptoms were the earliest and most prominent symptoms recorded in Michigan farm residents exposed to PBB as compared to a non-PBB exposed control farm population in Wisconsin. In Michigan (particularly among males) those who exhibited the most marked symptoms tended to show diminished performance as assessed by special tests, although population differences in performance were not as marked. Low indices of performance were also significantly correlated with intake of home-produced foodstuffs, particularly during the years 1972--1974 and store-bought products during the years 1975--1976. Between 1972 and 1976 the Michigan farm residents studied made significant changes in their consumption patterns of products suspected to be contaminated with PBB, as compared to those of Wisconsin farm residents. Serum PBB levels were not found to be significantly higher in Michigan males and females exhibiting the most prominent neurologic symptoms. Serum PBB levels were negatively correlated with performance test scores, particularly in males in older age groups.

Lead exposure and nerve conduction velocity: the differential time course of sensory and motor nerve effects.

Nerve conduction velocities (NCV) of the median motor, median sensory, peroneal motor, and sural nerves were measured on 40 lead-exposed automobile production workers as part of a comprehensive health survey. Blood lead (Pb-B) and blood zinc protoporphyrin (ZPP) were measured. The control group (N = 31) consisted of workers without lead exposure. All subjects were screened for the following conditions: Limb, neck or back injury, diabetes, neurological disease, and alcohol consumption of more than 28 alcoholic beverages per week. Limb temperature was assessed at three sites for each NCV measurement. The lead-exposed workers had slower median sensory NCV (42.9 vs. 46.8 m/sec, p less than 0.006) and slower sural NCV (37.8 vs. 42.8 m/sec, p less than 0.0004). All NCV estimates were then statistically adjusted for age and temperature, and transformed to Z values for further analyses. The mean standardized NCVs were slower in the lead-exposed group for the median sensory (-1.03 vs. -0.04, p less than 0.0003) and the sural nerves (-2.52 vs. -0.52, p less than 0.001). The study group was divided into two groups, with less than ten years and more than ten years of lead exposure. The subsample exposed less than ten years showed slowing of the median sensory (-0.94 vs. -0.04, p less than 0.005) and the sural nerves (-2.42 vs. -0.52, p less than 0.0001). Pb-B and ZPP levels were correlated with sural velocity (r = -0.54, p less than 0.04, and 4 = -49, p less than 0.06, respectively. Mean Pb-B was 59.7 micrograms/dl and mean ZPP was 175.8 micrograms/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Biological indicators of exposure in styrene polymerization workers. Styrene in blood and adipose tissue and mandelic and phenylglyoxylic acids in urine.

The concentrations of mandelic and phenylglyoxylic acids, urinary metabolites of styrene, and styrene in blood were determined for 491 styrene polymerization workers. Styrene in subcutaneous fat was determined for 25 workers. The levels of styrene exposure were estimated to be less than 10 ppm, and urinary metabolite and blood styrene concentrations indicated that significant recent exposure (within 4 h) had occurred among workers in areas of styrene polymerization and styrene monomer production. Styrene analysis of subcutaneous fat suggested that the monomer may have been present for as long as 3 d after exposure, a time when urinary metabolites and blood styrene were almost invariably undetectable. All three biological parameters were correlated with recency of exposure and estimated intensity of exposure within job categories.

Health status of styrene-polystyrene polymerization workers.

Styrene monomer is a greatly used chemical, chiefly in the production of polystyrene. A cross-sectional health survey of 493 production workers was undertaken at the oldest and largest monomer production, polymerization, and extrusion facility in the United States. Relative exposure durations and levels were obtained from occupational histories and corroborated by spot air sampling, blood and fat styrene concentrations and levels of urinary mandelic and phenylglyoxylic acids. Statistically significant differences between the prevalence of abnormalities in high and low exposure groups were found for the following: history of acute prenarcotic symptoms, history of acute lower respiratory symptoms, peroneal nerve conduction velocities, relative lymphocytosis, and elevated gamma glutamyl transpetsidase. The following showed no distinct pattern in prevalence when analyzed by exposure group: chest radiographic changes; indices or restrictive, obstructive and small airway dysfunction; other hepatic and hematological parameters; carcinoembryonic antigen level; sputum cytopathology; radial nerve conduction velocities; and ophthalmological findings. Clinically significant abnormalities were rare.

Acute arsenic intoxication from environmental arsenic exposure.

Reports of acute arsenic poisoning arising from environmental exposure are rare. Two cases of acute arsenic intoxication resulting from ingestion of contaminated well water are described. These patients experienced a variety of problems: acute gastrointestinal symptoms, central and peripheral neurotoxicity, bone marrow suppression, hepatic toxicity, and mild mucous membrane and cutaneous changes. Although located adjacent to an abandoned mine, the well water had been tested for microorganisms only and was found to be "safe." Regulations for testing of water from private wells for fitness to drink are frequently nonexistent, or only mandate biologic tests for microorganisms. Well water, particularly in areas near mining activity, should be tested for metals.

Radiological abnormalities among sheet-metal workers in the construction industry in the United States and Canada: relationship to asbestos exposure.

We investigated the possible adverse health effects to sheet-metal workers who had past exposure to asbestos. A cross-sectional medical examination of 1,330 workers was conducted during 1986 and 1987 in seven cities in the United States and Canada. A total of 1,016 workers had been employed for at least 35 y in the industry, and the mean duration from onset of asbestos exposure was 39.5 y (SD = 7.41 y). Chest x-ray abnormalities were found in more than half of the group. Pleural fibrosis, the most frequently found abnormality, was present in 47.0% of the cases and was the only abnormality found in 27.8% of cases; parenchymal interstitial fibrosis, found in 33.1% of cases, was the only abnormality found in 16.2% of cases. Radiologic abnormalities increased as duration of exposure increased. A positive smoking history was associated with a higher prevalence of radiologically detectable parenchymal abnormalities, a finding confirmed by us and others. Dyspnea on exertion was graded by a Medical Research Council questionnaire, the examinee's self-assessment, and a more detailed 12-point scale questionnaire. Few persons had marked shortness of breath, and approximately one-third had slight dyspnea. Individuals who had radiologic abnormalities experienced more shortness of breath than did those who had no radiologic abnormalities. Cigarette smoking also resulted in a higher prevalence of dyspnea. The results indicate that during the past, construction sheet-metal workers have been significantly exposed to asbestos on the job. Every effort should be made to minimize the anticipated serious health consequences, and further asbestos exposure for those who continue in this trade should be avoided.