An Approach to Tentative Reference Levels Setting for Nanoparticles in the Workroom Air Based on Comparing Their Toxicity with That of Their Micrometric Counterparts: A Case Study of Iron Oxide Fe₃O₄

Table 2

Iron content of rat lung tissue 24 hours after intratracheal instillation of 2 mg of magnetite particles of various sizes or distilled water (x ± s.e.).

Groups of rats that were administered suspensions of particles with diameters
10 nm	50 nm	1 μm	Controls
Iron content (mg/kg raw tissue)
200 ± 9^a	257 ± 8^ab	258 ± 15^ab	141 ± 5^b
Difference between group administered magnetite and controls
59 ± 10	116 ± 9^b	117 ± 16^b	—

^aDesignates values that are statistically significantly different from control value; ^bthe same from the value for the group of rats administered 10 nm particles (𝑃<0.01 by, 𝑡-test allowing for standard error of complex means, whereby data for each rat are considered as a sample consisting of 5 measurements).