Environmental Health Perspectives 105, Supplement 5, September 1997

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Augmentation of Pulmonary Reactions to Quartz Inhalation by Trace Amounts of Iron-containing Particles

Vincent Castranova, 1 Val Vallyathan, 1 Dawn M. Ramsey, 2 Jeffrey L. McLaurin, 2 Donna Pack, 1 Steven Leonard, 1 Mark W. Barger, 1 Jane Y.C. Ma, 1 Nar S. Dalal, 3 and Alex Teass 2

1 Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, West Virginia
2 Division of Biomedical and Behavioral Science, National Institute for Occupational Safety and Health, Cincinnati, Ohio
3 Department of Chemistry, Florida State University, Tallahassee, Florida

Abstract
Fracturing quartz produces silica-based radicals on the fracture planes and generates hydroxyl radicals ( · OH) in aqueous media. · OH production has been shown to be directly associated with quartz-induced cell damage and phagocyte activation in vitro . This · OH production in vitro is inhibited by desferrioxamine mesylate, an Fe chelator, indicating involvement of a Fenton-like reaction. Our objective was to determine if Fe contamination increased the ability of inhaled quartz to cause inflammation and lung injury. Male Fischer 344 rats were exposed 5 hr/day for 10 days to filtered air, 20 mg/m 3 freshly milled quartz (57 ppm Fe), or 20 mg/m 3 freshly milled quartz contaminated with Fe (430 ppm Fe). High Fe contamination of quartz produced approximately 57% more reactive species in water than quartz with low Fe contamination. Compared to inhalation of quartz with low Fe contamination, high Fe contamination of quartz resulted in increases in the following responses: leukocyte recruitment (537%), lavageable red blood cells (157%), macrophage production of oxygen radicals measured by electron spin resonance or chemiluminescence (32 or 90%, respectively), nitric oxide production by macrophages (71%), and lipid peroxidation of lung tissue (38%). These results suggest that inhalation of freshly fractured quartz contaminated with trace levels of Fe may be more pathogenic than inhalation of quartz alone. -- Environ Health Perspect 105(Suppl 5):1319-1324 (1997)

Key words : Fenton reaction, silicosis, reactive oxygen species, inhalation, iron, nitric oxide, pulmonary inflammation, silica

This paper is based on a presentation at The Sixth International Meeting on the Toxicology of Natural and Man-Made Fibrous and Non-Fibrous Particles held 15-18 September 1996 in Lake Placid, New York. Manuscript received at EHP 26 March 1997; accepted 23 April 1997.

Address correspondence to Dr. V. Castranova, PPRB/HELD/NIOSH, 1095 Willowdale Road (M/S 2015), Morgantown, WV 26505. Telephone: (304) 285-6056. Fax: (304) 285-5938. E-mail: vic1@cdc.gov

Abbreviations used: AM, alveolar macrophage(s); CL, chemiluminescence; ESR, electron spin resonance; · OH, hydroxyl radical(s); O 2 - , superoxide anion; PBN, N-tert -butyl-phenylnitrone; PHPA, 4-hydroxyphenylacetic acid; RBC, red blood cell(s); · Si, silicon radical; Si-O · , silicon oxyl radical.

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Last Update: November 21, 1997