Exposure-Related Health Effects of Silver and Silver Compounds: A Review

Abstract

A critical review of studies examining exposures to the various forms of silver was conducted to determine if some silver species are more toxic than others. The impetus behind conducting this review is that several occupational exposure limits and guidelines exist for silver, but the values for each depend on the form of silver as well as the individual agency making the recommendations. For instance, the American Conference of Governmental Industrial Hygienists has established separate threshold limit values for metallic silver (0.1 mg/m3) and soluble compounds of silver (0.01 mg/m3). On the other hand, the permissible exposure limit (PEL) recommended by the Occupational Safety and Health Administration and the Mine Safety and Health Administration and the recommended exposure limit set by the National Institute for Occupational Safety and Health is 0.01 mg/m3 for all forms of silver. The adverse effects of chronic exposure to silver are a permanent bluish-gray discoloration of the skin (argyria) or eyes (argyrosis). Most studies discuss cases of argyria and argyrosis that have resulted primarily from exposure to the soluble forms of silver. Besides argyria and argyrosis, exposure to soluble silver compounds may produce other toxic effects, including liver and kidney damage, irritation of the eyes, skin, respiratory, and intestinal tract, and changes in blood cells. Metallic silver appears to pose minimal risk to health. The current occupational exposure limits do not reflect the apparent difference in toxicities between soluble and metallic silver; thus, many researchers have recommended that separate PELs be established.

Inactivation of bacteria from contaminated streams in Limpopo, South Africa by silver- or copper-nanoparticle paper filters

“…Measured porosities are similar to typical paper grades (70%), though filter papers typically have higher porosities, as high as 87%. 24 Porosity measured in this manner varied by only ∼3% (absolute) between samples, significantly less than the ∼10% error of the method. The permeabilities of the filter papers ranged from 7.4x10 -14 – 9.7x10 -13 m 2 , which falls in the range of fibrous filter media with similar solid volume fractions, 0.27–0.35, (1-porosity) 25 .…”

“…29 The average copper content in the permeate water from the rural surface water was 562 (± 100) ppb, which meets the US-EPA guideline for drinking water of less than 1000 ppb. 24 Problematically, the average copper in the permeate from the urban surface water was over the limit with an average of 1,497 (± 242) ppb. However all of the excessive copper release occurred over the initial 0.5 L of stream water filtered, after which copper levels were consistently less than the 1000 ppb limit (Figure 5b).…”

Effects of particle size and coating on toxicologic parameters, fecal elimination kinetics and tissue distribution of acutely ingested silver nanoparticles in a mouse model

“…Silver nanoparticle (AgNP) utilization in consumer products has increased regulatory concern over exposure via ingestion (Bergin & Witzmann, 2013; Drake & Hazelwood, 2005; Hadrup & Lam, 2014; Nowack et al, 2011; O’Brien & Cummins, 2010; Varner et al, 2010; Wijnhoven et al, 2009). These potential exposures include AgNP dietary supplements, AgNP-coated food containers, water contamination or accumulation in food fish and other aquatic organisms (Sharma et al, 2014; Shaw & Handy, 2011; Volker et al, 2013; Walters et al, 2014).…”

Impact of pulmonary exposure to gold core silver nanoparticles of different size and capping agents on cardiovascular injury

“…Two hundred microliters of AgNP suspension containing 200 μg of AgNP or vehicle was dispensed into the glottal opening and the rat was stimulated to inhale while securing the tongue with forceps, ensuring pulmonary aspiration. The dose selected was set as a proof of concept dose agreed upon by the NCNHIR consortium members for AgNP in vivo toxicity and at this dosing could induce potential toxicological effects but not mortality or morbidity to the animal, and represents approximately 720 times the permissible exposure limit to all forms of silver at 0.01 mg/m 3 for an 8 h work day as established by NIOSH and OSHA [31] based on rat minute ventilation rate and alveolar surface area [32]. Following instillation the rats were returned to their home cage and monitored until they resumed normal grooming behavior.…”