Pulmonary and Cardiovascular Responses of Rats to Inhalation of Silver Nanoparticles

Abstract

Exposure to wet aerosols generated during use of spray products containing silver (Ag) has not been evaluated. The goal was to assess the potential for cardiopulmonary toxicity following an acute inhalation of wet silver colloid. Rats were exposed by inhalation to a low concentration (100 μg/m³ ) using an undiluted commercial antimicrobial product (20 mg/L total silver; approximately 33 nm mean aerodynamic diameter [MAD]) or to a higher concentration (1000 μg/m³) using a suspension (200 mg/L total silver; approximately 39 nm MAD) synthesized to possess a similar size distribution of Ag nanoparticles for 5 h. Estimated lung burdens from deposition models were 0, 1.4, or 14 μg Ag/rat after exposure to control aerosol, low, and high doses, respectively. At 1 and 7 d postexposure, the following parameters were monitored: pulmonary inflammation, lung cell toxicity, alveolar air/blood barrier damage, alveolar macrophage activity, blood cell differentials, responsiveness of tail artery to vasoconstrictor or vasodilatory agents, and heart rate and blood pressure in response to isoproterenol or norepinephrine, respectively. Changes in pulmonary or cardiovascular parameters were absent or nonsignificant at 1 or 7 d postexposure with the exceptions of increased blood monocytes 1 d after high-dose Ag exposure and decreased dilation of tail artery after stimulation, as well as elevated heart rate in response to isoproterenol 1 d after low-dose Ag exposure, possibly due to bioavailable ionic Ag in the commercial product. In summary, short-term inhalation of nano-Ag did not produce apparent marked acute toxicity in this animal model.

Acknowledgments

This project was supported in part by an Interagency Agreement (CPSC-I-11-005) from the U.S. Consumer Product Safety Commission to the National Institute for Occupational Safety and Health. The findings and conclusions in this article are those of the authors and do not necessarily represent the view of the National Institute for Occupational Safety and Health or the U.S. Consumer Product Safety Commission.

Notes

¹Certain trade names and company products are mentioned in order to adequately specify the experimental procedures and equipment used. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology (NIST), nor does it imply that the products are necessarily the best available for the purpose.