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In vivo and In Vitro Effects of Work Site Fracking Sand Dust (FSD) Inhalation on Rat Lung: Dose‐ and Time‐Response Evaluation
Author(s) -
Fedan Jeffrey S.,
Thompson Janet A.,
Russ Kristen A.,
Newcomer Dean,
McKinney Walter,
Cumpston Amy M.,
Jackson Mark C.,
Reynolds Jeffrey S.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.667.8
Subject(s) - inhalation , methacholine , airway resistance , respiratory system , lung , inhalation exposure , chemistry , in vivo , anesthesia , medicine , biology , respiratory disease , microbiology and biotechnology
A fine dust is generated when sand is manipulated during operations at drilling sites that utilize the hydraulic fracturing, or “fracking,” process, potentially putting workers at risk of inhalation. Previously we investigated the effects of inhalation of 10 and 30 mg/m 3 FSD (mass median aerodynamic diameter,1.75 μm; count median aerodynamic diameter, 227nm) 1, 7 and 27 d after exposure (6 h/d for 4 d) and observed modest changes in airway reactivity (7 d; in terms of lung resistance and dynamic compliance) and inflammation (1 d). In the present investigation, additional animals were exposed to the same inhalation conditions to further study its effects on aspects of lung function. Pulmonary function was examined in anesthetized rats using the Flexivent system (single compartment and constant phase models). There were no changes in respiratory system resistance (Rrs), respiratory elastance (Ers), tissue damping (G), tissue elastance (H), Newtonian resistance (Rn) or hysteresivity (η) after any post‐exposure period in rats exposed to either dose of FSD. To investigate whether reactivity of airway smooth muscle or the modulatory effect of epithelium on airway reactivity was affected by FSD inhalation, methacholine (MCh) was applied to the intraluminalor extraluminal baths of the isolated, perfused trachea preparation (IPT). FSD inhalation had no effect on reactivity(EC50 values) or contractile responses to MCh at any FSD dose or post‐exposure time. The possible effects of FSD inhalation on epithelial ion transport was investigated in vitro using Ussing chambers. Neither dose of FSD affected transepithelial potential difference (V t ) or resistance (R t ), or short‐circuit current ( I sc ) at any time point. Whereas there was no effect of FSD on responses to apical amiloride (Na + channel blocker), apical NPPB(Cl − channel blocker) or basolateral ouabain (Na + ,K + ‐pump inhibitor) at the 10 mg/m 3 dose, responses to amiloride were significantly inhibited at all post‐exposure times in tracheas from rats exposed to 30 mg/m 3 FSD, suggesting that epithelial Na + transport was impaired by FSD. The results indicate that FSD is generally without appreciable biological effects on pulmonary function broadly speaking, either in vivo or in vitro ; however, the dust does interfere with Na + transport at the 30 mg/m 3 dose in a manner that is sustained for at least one month. Such a change could result in hydration of the airway surface liquid. Support or Funding Information NIOSH