![]() (See section 3.1.16 for the range of nano-ZnO covered by this opinion) Therefore, this information is used together with the data from the absorption study provided in the dossier and exposure assumptions from the SCCS Notes of Guidance for the risk assessment of zinc oxide nanoparticles in sun screens as follows:Ĭalculation of the margin of safety for ZnO (nano) The SCCS agrees with the NOAEL indicated in the RAR statement. The MOS between this internal NOAEL and the internal exposure as a result of exposure to sunscreen formulations is 5, which is a factor of 5 larger than the minimal MOS. Given that this study was with women (the most sensitive population in zinc supplementation studies), and that in women clinical signs begin to appear only at a dose three times this NOAEL, a minimal MOS of 1 is considered sufficient when comparing the human NOAEL with the exposure levels for workers/consumers/general population. This NOAEL of 50 mg Zn2+/day results in an internal NOAEL of 10 mg Zn2+/day by correction for oral absorption (20% worst case, because of the homeostasis the relative absorption will be smaller by excess of Zn2+-intake). Assuming a dermal absorption of 2% the uptake is estimated to be 2.14 mg Zn2+/ day.Īn NOAEL of 50 mg Zn2+/day was derived from a 10-week oral study with human volunteers and was used as a starting point for the risk characterization for repeated dose toxicity. Based on the physical appearance, for dust exposure to zinc or zinc compounds a 10-fold lower default value of 0.2% is chosen in the risk assessment.įor sunscreen containing 10% zinc oxide the following exposure assessment was performed:īy an application of 9 g sunscreen/event, 3 events/day during 18 days/year the exposure will be 1,332 mg sunscreen/day, being 107 mg Zn2+/day. By expert judgement, based on the aforementioned considerations, the default for dermal absorption of solutions or suspensions of zinc or zinc compounds is therefore chosen to be 2%. Given the efficient homeostatic mechanisms of mammals to maintain the total body zinc and the physiologically required levels of zinc in the various tissues constant, the anticipated slow release of zinc from the skin is not expected to disturb the homeostatic zinc balance of the body. The total database available indicates that skin-bound zinc may not become systemically available in a way that it results in high peak levels of zinc in serum, but rather in a more gradual way. ![]() Thus, until proven otherwise, it is assumed that any transdermal penetration following application the nano-ZnO containing cosmetic product is that of Zn ions released from the ZnO nanoparticles.Īs internal exposure is likely to be to ionic Zn, the safety considerations as indicated below in the EU Risk Assessment Report on Zinc Oxide (2004) (Reference 44, sub III) are relevant: However, in view of the dissolution rate of ZnO, any translocating ZnO nanoparticles will also be completely solubilized due to the non-static conditions in the biological environment (see section 3.1.6). The maximum solubility is estimated to be around 50 mg/L, depending on the solvent/medium under static equilibrium conditions. This conclusion is based on the weight of evidence from the available studies so far which suggest that only a small fraction of the nano- sized ZnO is likely to be solubilized in a formulation, and possibly when in contact with the skin, and a part of this solubilized fraction may subsequently be absorbed. Although the zinc was determined by methods which do not discriminate between particulate and solubilized forms, considering the dissolution rate of ZnO, it is likely that this was in the form of solubilized zinc ion. ![]() However, some minimal absorption of zinc was demonstrated. The data provided, and as present in the literature, indicate that ZnO nanoparticles do not penetrate through the skin. Safety evaluation (including calculation of the MoS) Are sunscreens using zinc oxide nanoparticles safe?
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