Absence of toxic effects in silver reclamation workers.

Abstract

KINTZ RT, STOCKDALE DK. Absenceof toxic effects in silverreclamation workers. Scand J Work Environ Health 1989;15:210-221. Recent reports have alleged that silver presents a toxic hazard to exposed workers. To define the potential risks of long-term exposure to silver better, a cross-sectional investigation was conducted of 27 Caucasian males occupationally exposed to primarily insoluble silvercompounds and 27 matched referents. Physicalexamination and electron microscopy of skin biopsies revealed no cases of generalized argyria. Measurements of facial discoloration judged from color photographs by panels of laymen and physicians, showed no significant difference between the two groups. Although 29 % of the silver workers and none of the referents exhibited ocular silver deposition, optometric and contrast sensitivitytest results revealed no significant deficits in visual performance. The kidney and respiratory findings were essentially normal in both populations. Despite the increased presence of silver in the blood, feces, and hair of the recovery workers versus the referents, there was no evidence that chronic silver exposure adversely affected the health of these employees.Key terms: argyria, argyrosis, biological monitoring, clinical study, contrast sensitivity, epidemiologic study, insoluble silver compound, occupational silver exposure.From an occupational health standpoint, interest in the dermatologic effects of silver (argyria) has lessened considerably during the past few decades as changes in manufacturing processes and improved industrial hygiene practices have significantly reduced workplace exposures . Toxicologic evidence has generally supported the clinical observation that chronic exposure to metallic silver and its soluble salts (and pre sumably insoluble compounds) does not appear to represent a serious health risk to man. However, health data from clinical studies in the United States (1-3), and case histories reported in the European literature during the past 15 years (4-15) have suggested the need to reevaluate the human toxicologic effects of silver for such target organs as the skin, eyes, lungs, and kidneys. In addition, it is important to define more precisely the potential risks of long-term exposure to insoluble forms of silver, which have been incompletely studied and for which there is no workplace standard in the United States (US). This paper describes air sampling results and clinical and epidemiologic findings for a group of silver reclamation employees and their matched referents at a large photographic manufacturing facility . Specific study objectives included investigations of (i) 210ver deposition), (iii) visual contrast sensitivity, (iv) respiratory symptoms and diseases (pulmonary function and chest radiographs) , and (v) renal function (clinical laboratory studies). To augment the determinations of the airborne silver levels, biological monitoring was also performed. Subjects and methods Silver recovery operations and air sampling dataThe silver recovery department of...

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“…A study that measured levels of several liver enzymes (alanine amino transferase, aspartate amino transferase, gamma glutamyl transferase, and alkaline phosphatase) found no significant differences between workers exposed to silver and insoluble silver compounds and those with no history of silver exposure (Pifer et al 1989).…”

“…Inhalation exposure also led to decreased red blood cell count and an increased mean corpuscular volume (Pifer et al 1989). However, these potential hematologic biomarkers are not specific for silver exposure, and do not indicate or predict significant clinical sequelae.…”

“…Blood counts were reported to be normal in all individuals observed in the occupational study of silver-exposed workers conducted by Rosenman et al (1979) with the exception of one individual with an elevated hemoglobin level. In a study by Pifer et al (1989), silver reclamation workers chronically exposed to insoluble silver compounds (e.g., the silver halides) exhibited a marginal decrease in red blood cell count, as well as an increase in mean corpuscular volume. However, the toxicological significance of these findings is unclear.…”

“…An investigation of silver reclamation workers found that 21% and 25% exhibited conjunctival and cornea1 argyrosis (silver staining or deposition), respectively (Pifer et al 1989). Moreover, 74% of the subjects exhibited some degree of internal nasal-septal pigmentation.…”

“…The granular deposition of silver in the cornea of workers has been loosely associated with complaints of decreas.ed night vision Rosenman et al 1979). However, Pifer et al (1989) studied various ophthalmological end points in workers exposed to silver and silver compounds and could find no significant ocular impairments associated with the metal.…”