Ante was upped in the nanotechnology debate when a trio of organisations released a report detailing safety and efficacy concerns, and urged consumers to avoid sunscreens containing nano particles.
The groups — Friends of the Earth, Consumers Union and the International Center for Technology Assessment — assert that the nano process has created chemicals that act differently and have not been studied.
"Nano-sunscreens are being promoted as safe sun protection, but the evidence of potential risk we've collected shows otherwise," said Friends of the Earth's health and environment campaigner Ian Illuminato. "Consumers must be aware that nanomaterials are being put into sunscreens with very little evidence about their safety and relative efficacy."
The particles in question are titanium dioxide and zinc oxide. Standard sunscreens block UV-B rays, which cause sunburns, but do nothing about UV-A rays, which are deeper-penetrating, lower-energy rays that can cause skin cancer long term. Zinc oxide mostly blocks UV-A rays while titanium dioxide blocks both.
In 2007, Consumer Reports tested sunscreens containing nanomaterials and found no correlation between their presence and sun protection. Consumer Reports testing found neither nanoscale zinc nor titanium oxides provide a clear and consistent performance advantage over other active ingredients.
"Adding nanoparticles to sunscreens means adding an unnecessary potential risk to our health and to the environment, with no significant gain. Why take the chance?" asked Michael Hansen, PhD, co-author of the report and senior scientist at Consumers Union.
The consumer conundrum has been that non-nano ingredients would traditionally apply as an unsightly, heavy white layer. Nanotech particles, on the other hand, are delivered as a clear lotion, even as convenient sprays.
Even industry players acknowledge the uncertainties surrounding nanotech particles. "There is some concern — there's no evidence nano particles cause any problems but there's no evidence they're safe," said Guy Langer, president of Qumulus Group, which specialises in cosmetic and nutritional technologies, ingredients, product development and marketing. "No one's really studied whether these particles penetrate. The nano particles of these inorganic sunscreen materials usually re-agglomerate to a few hundred nanometers and don't penetrate as much as the smaller primary particles. They've been on the market a long time. Alternative chemical sunscreens have problems, too, with irritation and estrogenicity. Nanotech generally has unbelievable promise. The risks are not understood and uncertainty causes concern, but the benefits are very promising."
The group also cited studies they say demonstrate environmental impacts that may stem from the release of nanomaterials into broader ecosystems. A 2006 study showed that some forms of titanium dioxide nanoparticles are toxic to algae and water fleas, especially after exposure to UV light. Algae and water fleas are a vital part of marine ecosystems.