William N. Rom

Health implications of natural fibrous zeolites for the intermountain west

INTRODUCTION Fibrous zeolites have recently been implicated in an endemic outbreak of malignant pleural mesothelioma in several villages in Cappadocia in central Tur- key (Baris et al., 1979; Lilis, 1981). The possible association between fibrous zeolites and mesothelioma and the potential biological activity of fibrous erionite from the United States are under active investigation. The zeolite minerals com- prise a group of over forty hydrated aluminum silicates. More than 300 probable deposits of the various natural zeolites are located in 25 states in the United States. Reserves of perhaps 10 trillion tons are present in the western United States; about 120 million tons are deposited near the surface (Sheppard, 1975). Several zeolites, including erionite and mordenite, may occur with a fibrous habit. Fibrous erionite is found in several well-defined deposits in Arizona, Nevada, Oregon, and Utah, where it occurs as thin, pure beds within sedimentary tuff sequences, or as outcrops in desert valleys of the Intermountain region. MINERALOGY Zeolites were first recognized as a new group of minerals by Baron Cronstedt with the discovery of stilbite in 1756 (Papke, 1972). Because of the unique quality of intumescence, zeolites were aptly named from the Greek zein and lithos mean- ing “boiling stones.” Zeolites are a group of crystalline sedimentary minerals’ that contain alkali or alkaline-earth elements in a hydrated aluminum silicate structure. They have an open, three-dimensional framework composed of silicon and aluminum tetrahedra (Flanigan, 1959). The central silicon or aluminum in each tetrahedron is sur- rounded by four oxygen atoms each of which is shared by two tetrahedra in a honeycombed, crystalline lattice with cavities and apertures characteristic of each

Reversible beryllium sensitization in a prospective study of beryllium workers

Chronic beryllium disease is a granulomatous and fibrotic pulmonary disorder with increased numbers and percentage of lymphocytes in bronchoalveolar lavage fluid similar to that found in hypersensitivity pneumonitis. Blastogenic lymphocyte transformation (LT) to beryllium salts has been described in lavage and blood lymphocytes in patients with chronic beryllium disease. We conducted a 3-yr prospective study to evaluate the relationship between LT and beryllium exposure and pulmonary changes consistent with chronic beryllium disease. There were 15.9% (13/82) positive LTs in 1979 and 8.2% (5/61) in 1982. Of 11 positive LTs in 1979, 8 were negative in 1982, concomitant with a significant reduction in exposure. A positive LT was not associated with reduced pulmonary function, and no radiographic changes consistent with beryllium disease were identified. We propose that LT in beryllium workers is related to exposure and is reversible when exposure levels are reduced through diligent industrial hygiene measures.

Lung cancer mortality among residents living near the El Paso smelter.

Occupational exposure to arsenic has been associated with cancer of the lung, but epidemiological studies of cancer of the lung and environmental exposure to arsenic have produced conflicting results. Case-control studies about point sources of pollution have been useful in identifying environmental hazards. This technique was used to evaluate the risk for lung cancer near a smelter in El Paso, Texas, that uses an arsenic-containing ore and has been in continuous operation since 1887. A comparison of 575 cases of lung cancer with 1490 breast and prostate controls collected from 1944 to 1973 found no significant associations with distance using 2-km concentric circles out to 20 km from the smelter.

Characterization of Zeolite Fiber Sizes Using Scanning Electron Microscopy

A synthetic zeolite and four natural zeolites from the western United States were examined for fibers using a scanning electron microscope. The distributions of fiber sizes were compared to distributions of fiber sizes of erionite and fibrous glass to determine if the fiber sizes were similar to those associated with mesothelioma in humans and animals. Fibers were abundant in two samples of natural erionite, rare in two samples of natural mordenite, and not present in the sample of synthetic mordenite. Although the majority of the erionite fibers were short (less than 8 mu long) and thicker than the tumorigenic erionite (greater than 0.25 mu wide), 6% and 11% of the fibers corresponded to fiber size categories of fibrous glass that have correlated with pleural mesothelioma production in rats. Even a single species of zeolite (erionite) is not uniform in its distribution of fiber sizes. On the basis of fiber size, these natural zeolites should be evaluated because of their potential carcinogenic risk.

Arsenic Distribution in Soils Surrounding the Utah Copper Smelter

We investigated the extent of arsenic contamination from a Utah copper smelter as reflected by arsenic residue accumulated in the surface soil. The highest arsenic concentrations occurred within 3 km of the smelter. Arsenic soil contamination was evident up to 10 km from the smelter, with the major transport direction being ESE. Data from the subsurface soil samples indicated that arsenic has also leached through the soil.

Health effects among refrigeration repair workers exposed to fluorocarbons

Refrigeration repair workers may be intermittently exposed to fluorocarbons and their thermal decomposition products. A case of peripheral neuropathy (distal axonopathy) in a commercial refrigeration repairman prompted an epidemiological investigation of the health of refrigeration repair workers. No additional cases of peripheral neuropathy were identified among the 27 refrigeration repair workers studied. A reference group of 14 non-refrigeration repair workers was also studied. No differences were noted between groups for the ulnar (motor and sensory), median (motor and sensory), peroneal, sural, or tibial nerve conduction velocities. Refrigeration repair workers reported palpitations and lightheadedness significantly more often than workers in the reference group. No clinical neurological or electroneurophysiological abnormalities were detected in eight refrigeration repair workers followed up for three years during continuous employment.

An Epidemiologic Study of the Respiratory Effects of Trona Dust

Trona (sodium sesquicarbonate) is mined from an underground deposit in Wyoming and processed for use in glass, paper, detergent, and chemical applications. Trona dust is alkaline (pH 10.5) and can have an irritant effect on respiratory airways, mucous membranes, and the skin. A study population of 142 underground miners and 88 surface workers from one facility volunteered for an epidemiologic study. Their mean age was 37.6 yr and mean duration of employment was 10.0 yr. The percentage with chronic cough and phlegm was 23%; both symptoms were more common among smokers than nonsmokers. Thirty-three percent of the workers complained of dyspnea when hurrying on level ground or walking up a slight hill. Half of the workers complained of upper respiratory tract symptoms and eye irritation. Both smokers and exsmokers had significant declines of forced expiratory volume in 1 sec (FEV1.0) with age; exsmokers also had declines with work-years when compared to a nonsmoking comparison population. Nonsmokers with personal dust measurements had a significant decline of FEV1.0 related to respirable dust exposure. A shift study of 104 workers revealed a significant fall in FEV1.0 among nonsmokers and surface workers. Significance was approached in the high dust exposure group. An increase in the mean percent predicted forced vital capacity and FEV1.0 was shown for the 125 workers who had a 5-yr follow-up of pulmonary function. There was no correlation between the shift study decrements and the longitudinal 5-yr follow-up. Industrial hygiene dust sampling found elevated levels of total dust but lower respirable dust, with no detectable free silica.

Morbidity Survey of U.S. Oil Shale Workers Employed During 1948–1969

The health status of 325 oil shale workers employed at the Anvil Points, Colorado, demonstration facility from 1948 to 1969 was evaluated. As a comparison population, 323 Utah coal miners frequency matched for age were studied. The prevalence of respiratory symptoms among oil shale workers who smoked were similar to the coal miners who smoked, although nonsmoking oil shale workers had fewer symptoms compared to nonsmoking coal workers. Four cases of skin cancers were found on the oil shale workers and eight cases in the controls. Similar numbers of nevi, telangiectasiae, possible pitch warts, pigment changes (solar/senile lentigo), and papillomata (seborrheic keratoses and skin tags) were seen in both groups, while actinic keratoses were more frequent in the oil shale workers. The prevalence of actinic keratoses was significantly associated with oil shale work after allowing for age, sun exposure, and other exposures. The prevalence of pulmonary cytology metaplasia was associated with years of production work in oil shale among both smokers and exsmokers. More of the oil shale workers had atypical cells in the urine, but the excess was mostly found among exsmokers. Although these workers had short-term and limited oil shale exposure work exposure, we recommend that medical surveillance of oil shale workers consider the skin, respiratory, and urinary systems for special observation.