Pulmonary and cardiovascular responses of rats to inhalation of a commercial antimicrobial spray containing titanium dioxide nanoparticles

Abstract

Our laboratory has previously demonstrated that application of an antimicrobial spray product containing titanium dioxide (TiO₂) generates an aerosol of titanium dioxide in the breathing zone of the applicator. The present report describes the design of an automated spray system and the characterization of the aerosol delivered to a whole body inhalation chamber. This system produced stable airborne levels of TiO₂ particles with a median count size diameter of 110 nm. Rats were exposed to 314 mg/m³ min (low dose), 826 mg/m³ min (medium dose), and 3638 mg/m³ min (high dose) of TiO₂ under the following conditions: 2.62 mg/m³ for 2 h, 1.72 mg/m³ 4 h/day for 2 days, and 3.79 mg/m³ 4 h/day for 4 days, respectively. Pulmonary (breathing rate, specific airway resistance, inflammation, and lung damage) and cardiovascular (the responsiveness of the tail artery to constrictor or dilatory agents) endpoints were monitored 24 h post-exposure. No significant pulmonary or cardiovascular changes were noted at low and middle dose levels. However, the high dose caused significant increases in breathing rate, pulmonary inflammation, and lung cell injury. Results suggest that occasional consumer use of this antimicrobial spray product should not be a hazard. However, extended exposure of workers routinely applying this product to surfaces should be avoided. During application, care should be taken to minimize exposure by working under well ventilated conditions and by employing respiratory protection as needed. It would be prudent to avoid exposure to children or those with pre-existing respiratory disease.

Keywords::

• Nano TiO₂
• antimicrobial spray
• inhalation studies
• pulmonary responses
• cardiovascular responses

Acknowledgement

The authors thank the US Consumer Product Safety Commission for partial financial support of this product through an Interagency Agreement.

Declaration of interest

The findings and conclusions in this article are those of the author and do not necessarily represent the views of the National Institute for Occupational Safety and Health (NIOSH) or the US Consumer Product Safety Commission (CPSC). The mention of any company names or products does not imply an endorsement by NIOSH or CPSC, nor does it imply that alternative products are unavailable or unable to be substituted after appropriate evaluation.