[Comparison of data between intratracheal instillation and inhalation studies for estimation of harmful effects of manufactured nanomaterials].

We reviewed the difference in data between the inhalation and intratracheal instillation studies of inhaled materials and how to diminish the difference in data between the two studies in order to examine the usefulness of intratracheal instillation study for the estimation of the harmful effects of manufactured nanomaterials. The differences in the data of the intratracheal instillation study from those of the inhalation study, which is the gold standard, are as follows: 1) artificial effect of the bolus, 2) nonuniformity of lung distribution of materials, 3) no threshold of clearance, 4) low deposition level of materials in the brain and neonates, and 5) the effect of dispersant on the lung. We consider that the approaches to diminishing the difference in data between the two studies are as follows: 1) maintain the dispersion of nanomaterials, 2) avoid the overdosing of nanomaterials, and 3) maintain a low concentration of the dispersant in the intratracheal instillation study.