Table 1 Hazard potential of ENM to humans in comparison with conventional materials (microparticles)
From: How to consider engineered nanomaterials in major accident regulations?
ENM | Hazard potentiala | Remarks | ||
|---|---|---|---|---|
Acute toxicity | Chronic effects | Difference (micro/nano) | ||
Nano-TiO2 | Very low | Low | 1:10 | Although TiO2 was placed in class 3 of the carcinogenic materials, its general toxicity is low as shown by many recent studies. There is a difference in the effects of smaller and larger particles, but this, for a release scenario during a major accident, is only of low relevance [34–39] |
Nano-ZnO | Medium | Low | 1:1 | Application of micro- or nanoscale ZnO particles into the lungs of mice or rats causes a strong but intermediate inflammatory reaction. The strength as well as the course of this reaction is practically identical for micro- or nanoscale ZnO [40, 41]. The acute consequence of inhalation of Zn dust is zinc fever; however, for severe effects (deaths), the concentration needs to surpass widely the permissible exposure limit of 5 mg/m3 |
CNT | Low | High | n.a. | Dependent on the type of CNT (physicochemical properties, e.g., single-walled, multi-walled, short/long), long-term effects similar to asbestos need to be considered (mesothelioma) [42] if the conditions like for ‘WHO fibers’ (length >5 μm, diameter <3 μm, and a length/diameter ratio of more than 3:1) are given. So far, most industrially produced CNTs are not considered to be WHO fibers [43–49] |
Nano-Ag | Low | Low | 1:1 | Silver is used since many years in nanoparticulate form (colloidal silver). There is no indication for an acute intoxication of humans with life-threatening degree, unless there is exposure to ultrahigh concentrations. Because Ag particles are added in rather small amounts to products, also the produced and transported amounts are rather small and the risk of a major accident with fatal consequences is therefore limited [50–54] |