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 1

Number of BALF cells 24 hours after intratracheal instillation of suspensions of magnetite particle (2 mg/mL) of various sizes to rats (𝑥±s.e.).

Particle dia.		Number of cells, mln.		NL/AM ratio
	Total	Alveolar macrophages (AMs)	Neutrophil leucocytes (NLs)
—	2.53 ± 0.36	2.06 ± 0.29	0.30 ± 0.05	0.15 ± 0.03
10 nm	18.57 ± 3.20^ac	2.72 ± 0.54	14.99 ± 2.57^ac	6.23 ± 0.62^ac
50 nm	26.37 ± 5.12^ac	5.05 ± 0.93^abc	20.65 ± 4.37^ac	4.42 ± 0.57^abc
1 μm	4.06 ± 0.44^ab	1.81 ± 0.24	1.93 ± 0.28^ab	1.32 ± 0.27^ab

^aDesignates values statistically significant difference from control group; ^bthe same from “10 nm” group; ^cthe same from “1 μm” group (𝑃<0.05 by Student’s 𝑡-test).