Roberts Stephen M, Rohr Annette C, Mikheev Vladimir B, Munson John, Sabo-Attwood Tara
a Center for Environmental & Human Toxicology , University of Florida , Gainesville , FL , USA.
b Electric Power Research Institute , Palo Alto , CA , USA.
Inhal Toxicol. 2018 Jan;30(1):19-28. doi: 10.1080/08958378.2018.1438539. Epub 2018 Feb 21.
Most studies report that inhaled volatile and semivolatile organic compounds (VOCs/SVOCs) tend to deposit in the upper respiratory tract, while ultrafine (or near ultrafine) particulate matter (PM) (∼100 nm) reaches the lower airways. The objective of this study was to determine whether carbon particle co-exposure carries VOCs/SVOCs deeper into the lungs where they are deposited.
Male Sprague-Dawley rats were exposed by inhalation (nose-only) to radiolabeled toluene (20 ppm) or naphthalene (20 ppm) on a single occasion for 1 h, with or without concurrent carbon particle exposure (∼5 mg/m). The distribution of radiolabel deposited within the respiratory tract of each animal was determined after sacrifice. The extent of adsorption of toluene and naphthalene to airborne carbon particles under the exposure conditions of the study was also assessed.
We found that in the absence of particles, the highest deposition of both naphthalene and toluene was observed in the upper respiratory tract. Co-exposure with carbon particles tended to increase naphthalene deposition slightly throughout the respiratory tract, whereas slight decreases in toluene deposition were observed. Few differences were statistically significant. Naphthalene showed greater adsorption to the particles compared to toluene, but overall the particle-adsorbed concentration of each of these compounds was a small fraction of the total inspired concentration.
These studies imply that at the concentrations used for the exposures in this study, inhaled carbon particles do not substantially alter the deposition of naphthalene and toluene within the respiratory tract.
大多数研究报告称，吸入的挥发性和半挥发性有机化合物（VOCs/SVOCs）往往沉积在上呼吸道，而超细（或接近超细）颗粒物（PM）（约100纳米）则会到达下呼吸道。本研究的目的是确定碳颗粒共同暴露是否会将VOCs/SVOCs携带至肺部更深处并在那里沉积。
雄性Sprague-Dawley大鼠通过仅经鼻吸入的方式，单次暴露于放射性标记的甲苯（20 ppm）或萘（20 ppm）1小时，同时有或没有碳颗粒共同暴露（约5毫克/立方米）。处死每只动物后，确定呼吸道内放射性标记物的沉积分布。还评估了在本研究暴露条件下甲苯和萘在空气中碳颗粒上的吸附程度。
我们发现，在没有颗粒的情况下，萘和甲苯在上呼吸道的沉积量最高。与碳颗粒共同暴露往往会使萘在整个呼吸道的沉积量略有增加，而甲苯的沉积量则略有下降。几乎没有差异具有统计学意义。与甲苯相比，萘对颗粒的吸附性更强，但总体而言，这些化合物中每种化合物在颗粒上吸附的浓度仅占总吸入浓度的一小部分。
这些研究表明，在本研究中用于暴露的浓度下，吸入的碳颗粒不会显著改变萘和甲苯在呼吸道内的沉积。
