Background — Pollution by particulates has been consistently associated with increased cardiovascular morbidity and mortality. However, the mechanisms responsible for these effects are not well-elucidated. Methods and Results — To assess to what extent and how rapidly inhaled pollutant particles pass into the systemic circulation, we measured, in 5 healthy volunteers, the distribution of radioactivity after the inhalation of “Technegas,” an aerosol consisting mainly of ultrafine ^99m Technetium-labeled carbon particles (<100 nm). Radioactivity was detected in blood already at 1 minute, reached a maximum between 10 and 20 minutes, and remained at this level up to 60 minutes. Thin layer chromatography of blood showed that in addition to a species corresponding to oxidized ^99m Tc, ie, pertechnetate, there was also a species corresponding to particle-bound ^99m Tc. Gamma camera images showed substantial radioactivity over the liver and other areas of the body. Conclusions — We conclude that inhaled ^99m Tc-labeled ultrafine carbon particles pass rapidly into the systemic circulation, and this process could account for the well-established, but poorly understood, extrapulmonary effects of air pollution.

Policy coordination is needed for global supply chains

The mechanisms of particulate pollution-related cardiovascular morbidity and mortality are not well understood. We studied the passage of radioactively labeled ultrafine particles after their intratracheal instillation. Hamsters received a single intratracheal instillation of 100 μ g albumin nanocolloid particles (nominal diameter ⩽ 80 nm) labeled with 100 μ Ci technetium-99m and were killed after 5, 15, 30, and 60 min. In blood, radioactivity, expressed as percentage of total body radioactivity per gram blood, amounted to 2.88 ± 0.80%, 1.30 ± 0.17%, 1.52 ± 0.46%, and 0.21 ± 0.06% at 5, 15, 30, and 60 min, respectively. Thin-layer chromatography showed only one peak of radioactivity corresponding to unaltered 99mTc-albumin nanocolloid. In the liver, radioactivity, expressed as percentage of total radioactivity per organ, amounted to 0.10 ± 0.07%, 0.23 ± 0.06%, 1.24 ± 0.27%, and 0.06 ± 0.02% at 5, 15, 30, and 60 min, respectively. Lower values were observed in the heart, spleen, kidneys, and brain. Dose dependence was assessed at 30 min following instillation of 10 μ g and 1 μ g 99mTc-albumin per animal (n = 3 at each dose), and values of the same relative magnitudes as after instillation of 100 μ g were obtained. We conclude that a significant fraction of 99mTc-albumin, taken as a model of ultrafine particles, rapidly diffuses from the lungs into the systemic circulation.