A number of industry commentators have pointed to the European Commission’s (EC) Scientific Committee on Consumer Safety (SCCS)’s recent Opinion on nano zinc oxide (ZnO) as evidence of its safety. However, the SCCS Opinion clearly describes how nano-zinc oxide has been shown to be more toxic and have greater potential for skin penetration than larger particles of zinc oxide.
Despite this, the SCCS concludes that the specific zinc oxide nanoparticles it looked at “can be considered not to pose a risk of adverse effects in humans after dermal application.”
The SCCS notes that this conclusion does not apply to other applications such as sunscreen spray products, which might be inhaled. The Opinion states that “in view of the lung inflammation induced by ZnO particles after inhalation exposure, the use of ZnO in cosmetic products which may result in inhalation is of concern.” The SCCS also notes that “any cosmetic products containing ZnO particles (nano or non-nano) with coatings that can promote dermal penetration will also be of concern.” This is important, since many cosmetic sunscreens contain penetration enhancers.
Friends of the Earth share the SCCS’s conclusion that clear positive toxic responses in much of the data reviewed clearly show the potential for human health risk. We also share the SCCS’s concerns regarding the use of ZnO in cosmetic products, which may result in inhalation.
However, Friends of the Earth does not agree with the SCCS’s conclusion that the forms of nano-zinc oxide outlined in the document are safe for use in sunscreens. This conclusion is based on the assumption that any zinc that penetrates the skin is likely to be ions (and therefore safe) not nanoparticles.
We believe that there is insufficient evidence to make such an assumption and are concerned about:
1) The SCCS’s reliance on unrealistic ZnO skin penetration research data provided by industry groups with a vested interest in negating such concerns
The majority of the skin penetration studies evaluated by the SCCS are short term, in vitro and don’t consider the role of flexing, skin condition and the widespread use of penetration enhancers in cosmetics.
2) The high degree of uncertainty regarding the extent of skin penetration by nano ZnO
There are still no long-term human in vivo studies looking at the extent of penetration into the basal skin layer. In formulating its opinion we believe the SCCS failed to adequately consider evidence of skin penetration by other nanomaterials. The SCCS also appears to have failed to consider the strong affinity nanoparticles have with proteins and how this might impact the extent of ionisation and skin penetration.
3. The numerous data gaps regarding the toxicity and fate of nano ZnO
The SCCS noted numerous data gaps regarding the toxicity and fate of nano ZnO, including information regarding long term toxicity, solubility, phototoxicity and carcinogenicity.
We believe that, given the clear evidence of toxicity and the data gaps regarding the fate of nano zinc oxide, a precautionary approach is warranted.