Australia has the highest rate of skin cancer in the world. Along with wearing a broad brimmed hat, protective clothing and sunglasses, and seeking shade, using sunscreen is one important action to reduce the risk of developing skin cancer. Friends of the Earth Australia is committed to sunscreen safety, and to helping you and your family make an informed, safe sunscreen choice.
Some nanoparticles produce free radicals that can damage DNA and skin cells, especially with exposure to UV light
If nanoparticles are absorbed into living skin cells, they could make sun damage to our skin worse, in a worst case scenario increasing the risk of skin cancer
We do not yet know whether or not nanoparticles in sunscreens penetrate intact, healthy skin, although it seems possible they will be taken up through damaged skin. Many chemicals used in sunscreens act as ‘penetration enhancers’, which could also make skin penetration by nanoparticles more likely
Nanoparticles are not subject to safety testing before being allowed in sunscreen
Nanoparticles in sunscreens are not subject to mandatory labelling. This is especially a problem for people with skin conditions such as eczema, who may be more vulnerable to skin penetration, who cannot choose to avoid using nano
‘Nanoparticles’ are tiny particles, typically measuring 100 nanometres (nm) or less in one or more dimensions, or larger particles that have an internal structure at this scale (eg when they are composed of ‘clumps’ of particles <100nm in size)i
. To put 100nm in context: a strand of DNA is 2.5nm wide, a red blood cell is 7,000 nm and a human hair is 80,000 nm wide. 20-30nm particles are now used in many sunscreens– these nanoparticles are more than 200 times smaller than a red blood cell.
Tiny nanoparticles are used for their novel properties. For example, titanium dioxide and zinc oxide are commonly used in sunscreens and cosmetics to block UV light and give sun protection. As larger particles, these minerals are usually white and opaque (although some companies have found a way to make 1,000nm particles of zinc oxide transparent). When these particles are ground down to nano size, they become transparent. In 2006 Australia’s sunscreen regulator the Therapeutic Goods Administration (TGA) said that 70% of titanium dioxide sunscreens and 30% of zinc sunscreens sold in Australia contain ‘manufactured’ nanoparticles (particles that have intentionally been produced in nano form)ii
If nanoparticles are accidentally inhaled (eg from spray on sunscreen), eaten (eg when wearing sunscreen and handling sandwiches) or absorbed through our skin, they could pose health problems.
Scientific studies have shown that nanoparticles of titanium dioxide and zinc oxide commonly used in sunscreens can produce free radicalsiii
, damage DNAiv
and cause cell toxicity in test tube studiesv
, especially when exposed to UV lightvi
. The concern is that rather than offering us sun protection, if they are absorbed into our skin, nanoparticles used in sunscreens could actually result in serious skin damage or other health harm. Last year, the director of CSIRO’s Nanosafety research program told The 7.30 Report
that: “the worst case scenario, I suspect, could be development of cancer. But we don't know. That's what we're trying to find out”vii
. Dr McCall cautioned that it will take up to another two years before the CSIRO can reach a conclusion on nano-sunscreens.
Animal studies have shown that after inhalationviii
into the blood stream of pregnant mice, titanium dioxide nanoparticles can cross the placenta and enter developing embryos. This has altered gene expression associated with brain function in the mice offspringx
, affected their behaviourxi
and damaged the brains and reproductive systems of baby micexii
. Mice studies have also found that inhalation of nanoparticles of titanium dioxide caused inflammation to the lungs of test animalsxiii
. Furthermore, inhaled titanium dioxide nanoparticles can be transported to the brainxiv
, raising concerns of potential neurotoxicity.
Whether or not nanoparticles used in sunscreens will penetrate the dead outer layers of our skin, and pose risks to living cells, remains unknown. CSIRO and other researchers are conducting ongoing studies into skin penetration. The Australian Therapeutic Goods Administration, Australia’s sunscreens regulator, claims that despite their potential toxicity, nanoparticles do not pose health risks because they remain in the outer layers of dead skinxv
. The problem is that not enough research has been done to know if this claim is true. Several studies have shown that nanoparticles used in sunscreens do not penetrate intact, healthy adult skinxvi
. However Friends of the Earth is concerned that many factors that are relevant to real life conditions have not been included in these studies. We agree with a recent scientific review of the potential risks associated with nano-sunscreens that skin penetration research is required that takes into account real life variables including sunburn, skin damage and UV exposurexvii
Scientific studies have shown that nanoparticles not used in sunscreen can penetrate skinxviii
, especially if skin is flexedxix
(as during exercise). Incredibly, one study found that even particles up to 1,000nm in size can be taken up through intact skin to reach living cells, when skin is flexedxx
. The same study found that particles 1,000nm clustered in the living layers of the skin underneath a tear in the skin. But we are not aware of any studies that have looked at the influence of flexing on skin penetration of 20-30nm nanoparticles from sunscreens. Similarly, many chemicals found in sunscreens and cosmetics act as penetration enhancersxxi
, increasing the absorption of other substances through skin. Although one study has found that penetration enhancers “greatly enhance” the uptake of nanoparticles through skinxxii
, to our knowledge the influence of penetration enhancers hasn’t been explored in relation to nano-sunscreens.
Finally, nanoparticle uptake may be much greater in people with damaged or compromised skin, but skin condition hasn’t been adequately investigated in relation to nano-sunscreens. A recent study has shown that skin penetration by nanoparticles is also more likely in sunburnt skinxxiv
. Nanoparticle penetration may also be greater through thinner skin – eg in elderly people or babies. A pilot study using elderly human volunteers that suggested that skin absorption of titanium dioxide nanoparticles took placexxv
highlights the need for further research into skin condition and penetration by nanoparticles in sunscreens.
It is important to note that not all chemicals used in sunscreens as UV absorbers pose health risks, but there are growing numbers of people who prefer to use non-nano sunscreens that are free of chemical UV absorbers. Some UV-absorbing chemicals cause skin sensitivityxxvi
. When exposed to UV light, other UV-absorbing chemicals produce free radicals that can interfere with cellular signalling, damage DNA, cause mutations and even lead to cell deathxxvii
. Some chemicals act as endocrine disruptors and can cause developmental toxicityxxviii
. Finally, UV-absorbing chemicals including oxybenzone, octyl-methoxycinnamate (OMC), padimate-O, homosalate and octyl salicylate (octisalate) are not only rapidly absorbed by skin themselves, but also act as penetration enhancers, promoting the skin absorption of other chemicalsxxix
. This can be a concern where such chemicals are used in products that also contain nanoparticles of zinc oxide or titanium dioxide.
The Australian government is not doing enough to keep sunscreens safe, or to give Australians the ability to make informed sunscreen choices. The United Kingdom’s Royal Society, the world’s oldest scientific institution, recommended in 2004 that given the evidence of serious nanotoxicity risks, nanoparticles should be treated as new chemicalsxxx
and subject to new safety assessments before being allowed in consumer productsxxxi
. It also recommended that nano-ingredients in products should be labelled, to give people the chance to make an informed choice.
The European Parliament has passed new laws that will require most nanoparticles in sunscreens and cosmetics to go through nano-specific safety testing before they can be sold, and to be listed on product labels. But the Australian Therapeutic Goods Administration (TGA) does not treat nanoparticles as new chemicals, require sunscreen or cosmetics manufacturers to conduct new safety testing of nano-ingredients nor require nano-ingredients to be labelled.
The TGA has also refused to release publicly the names of sunscreens that contain manufactured nanoparticles, despite previous requests from journalistsxxxii
and a Freedom of Information request from NSW Greens MLC Lee Rhiannonxxxiii
. The TGA’s approach has been questioned by legal and medical academics at the Australian National University and Monash University who suggest that the potential for health harm warrants a precautionary approach to regulation of nanoparticles in sunscreensxxxiv
i See European Parliament’s definition of nanoparticles at: http://www.europarl.europa.eu/oeil/file.jsp?id=5598862
ii Australian TGA. (2006). Safety of sunscreens containing nanoparticles of zinc oxide or titanium dioxide. Available at: http://www.tga.gov.au/npmeds/sunscreen-zotd.htm
iii Nel A, Xia T, Li N. (2006). “Toxic potential of materials at the nanolevel”. Science Vol 311:622-627
iv Donaldson K, Beswick P, Gilmour P. (1996). Free radical activity associated with the surface of particles: a unifying factor in determining biological activity? Toxicol Lett 88:293-298.
v For example Brunner T, Piusmanser P, Spohn P, Grass R, Limbach L, Bruinink A, Stark W (2006). In Vitro Cytotoxicity of Oxide Nanoparticles: Comparison to Asbestos, Silica, and the Effect of Particle Solubility. Environ Sci Technol 40:4374-4381; Long T, Saleh N, Tilton R, Lowry G, Veronesi B. (2006). Titanium dioxide (P25) produces reactive oxygen species in immortalized brain microglia (BV2): Implications for nanoparticle neurotoxicity. Environ Sci Technol 40(14):4346-4352; Sayes C, Wahi R, Kurian P, Liu Y, West J, Ausman K, Warheit D, Colvin V. (2006). Correlating nanoscale titania structure with toxicity: A cytotoxicity and inflammatory response study with human dermal fibroblasts and human lung epithelial cells. Toxicol Sci 92(1):174–185.
vi Dunford R, Salinaro A, Cai L, Serpone N, Horikoshi S, Hidaka H, Knowland J. (1997). Chemical oxidation and DNA damage catalysed by inorganic sunscreen ingredients. FEBS Lett 418:87-90
viii Hougaard K, Jackson P, Jensen K, Vogel U, Wallin H (2009). Nano-sized titanium dioxide: Effects of gestational exposure. Reproductive Toxicology 28, p122
ix Shimizu M, Tainaka H, Oba T, Mizuo K, Umezawa M, Takeda K. (2009). Maternal exposure to nanoparticulate titanium dioxide during the prenatal period alters gene expression related to brain development in the mouse. Particle and Fibre Toxicology 2009, 6:20; Takeda K, Suzuki K, Ishihara A, Kubo-Irie M, Fujimoto R, Tabata M, Oshio S, Nihei Y, Ihara T, Sugamata M. (2009). Nanoparticles transferred from pregnant mice to their offspring can damage the genital and cranial nerve systems. J Health Sci 55(1):95-102
x Shimizu M, Tainaka H, Oba T, Mizuo K, Umezawa M, Takeda K. (2009). Maternal exposure to nanoparticulate titanium dioxide during the prenatal period alters gene expression related to brain development in the mouse. Particle and Fibre Toxicology 2009, 6:20
xi Hougaard K, Jackson P, Jensen K, Vogel U, Wallin H (2009). Nano-sized titanium dioxide: Effects of gestational exposure. Reproductive Toxicology 28, p122
xii Takeda K, Suzuki K, Ishihara A, Kubo-Irie M, Fujimoto R, Tabata M, Oshio S, Nihei Y, Ihara T, Sugamata M. (2009). Nanoparticles transferred from pregnant mice to their offspring can damage the genital and cranial nerve systems. J Health Sci 55(1):95-102
xiii Grassian V, Adamcakova-Dodd A, Pettibone J, O’Shaughnessy P, Thorne P. (2007). Inflammatory response of mice to manufactured titanium dioxide nanoparticles: Comparison of size effects through different exposure routes. Nanotoxicology, 1(3): 211-226
xiv Wang J, Chen C, Yu H, Sun J, Li B, Li Y, Gao Y, He W, Huang Y, Chai Z, Zhao Y, Deng X, Sun H. (2007). Distribution of TiO2 particles in the olfactory bulb of mice after nasal inhalation using microbeam SRXRF mapping techniques. Journal of Radioanalytical and Nuclear Chemistry, 272 (3): 527–531
xv Australian TGA. (2006). Safety of sunscreens containing nanoparticles of zinc oxide or titanium dioxide. Available at: http://www.tga.gov.au/npmeds/sunscreen-zotd.htm
xvi Lademann J, Weigmann H, Rickmeyer C, Bathelmes H, Schaefer H, Mueller G and Sterry W (1999). “Penetration of titanium dioxide microparticles in a sunscreen formulation into the horny layer and the follicular orifice”. Skin Pharamacol Appl Skin Physiol 12:247-256; Pflücker P, Wendel V, Hohenberg H, Gärtner E, Will T, Pfeiffer S, Wepf and R and Gers-Barslag H (2001). “The Human Stratum corneum Layer: An Effective Barrier against Dermal Uptake of Topically Applied Titanium Dioxide”. Skin Pharmacology and Applied Skin Physiology 14 (Suppl 1): 92-97; Shulz J, Hohenberg H, Pflucker F, Gartner E, Will, T, Pfeiffer S, Wepf R, Wendel V, Gers-Barlag H, Wittern K-P (2002). “Distribution of sunscreens on skin”. Advanced Drug Delivery Reviews 54 Supplement 1:S157-S163; Zvyagin A, Zhao X, Gierden A, Sanchez W, Ross J, Roberts M. (2008). Imaging of zinc oxide nanoparticle penetration in human skin in vitro and in vivo. Journal of Biomedical Optics 13(6).
xvii Newman M, Stotland M, Ellis J. (2009). The safety of nanosized particles in titanium dioxide and zinc oxide based sunscreens. Journal American Academy of Dermatology 61(4):685-692.
xviii Ryman-Rasmussen J, Riviere J, Monteiro-Riviere N. (2006). Penetration of intact skin by quantum dots with diverse physicochemical properties. Toxicol Sci 91(1):159-165.
xix Rouse J, Yang J, Ryman-Rasmussen J, Barron A, Monteiro-Riviere N. (2007). Effects of mechanical flexion on the penetration of fullerene amino acid derivatized peptide nanoparticles through skin. Nano Lett 7(1):155-160.
xx Tinkle S, Antonini J, Roberts J, Salmen R, DePree K, Adkins E. (2003). Skin as a route of exposure and sensitisation in chronic beryllium disease, Environ Health Perspect 111:1202-1208.
xxi Eg Pont AR, Charron AR, Brand RM. (2004). Active ingredients in sunscreens act as topical penetration enhancers for the herbicide 2,4-dichlorophenoxyacetic acid. Toxicol Appl Pharmacol 195(3): 348-354.
xxii Monteiro-Riviere N, Yang J, Inman A, Ryman-Rasmussen J, Barron A, Riviere J. (2006). Skin penetration of fullerene substituted amino acids and their interactions with human epidermal keratinocytes. Toxicol 168 (#827).
xxiii Oberdörster G, Oberdörster E, Oberdörster J. (2005). Nanotoxicology: an emerging discipline from studies of ultrafine particles. Environ Health Perspect 113(7):823-839.
xxiv Mortensen L, Oberdörster G, Pentland A, DeLouise L. (2008). In Vivo Skin Penetration of Quantum Dot Nanoparticles in the Murine Model: The Effect of UVR. Nano Lett 8(9):2779-2787
xxv Tan M, Commens C, Burnett L and Snitch P (1996). “A pilot study on the percutaneous absorption of microfine titanium dioxide from sunscreens”. Australasian Journal of Dermatology 37(4):185-187
xxvi Shaw DW. (2006). Allergic contact dermatitis from octisalate and cis-3-hexenyl salicylate. Dermatitis 17(3): 152-155; Singh M, Beck MH. (2007). Octyl salicylate: a new contact sensitivity. Contact Dermatitis 56(1): 48.
xxvii Allen J, Gossett C, Allen S (1996). Photochemical formation of singlet molecular oxygen (1O2) in illuminated aqueous solutions of p-aminobenzoic acid (PABA). Journal of Photochemistry and Photobiology B: Biology 32(1-2):33-37; Hanson KM, Gratton E, Bardeen CJ. 2006. Sunscreen enhancement of UV-induced reactive oxygen species in the skin. Free Radic Biol Med 41(8): 1205-1212; Knowland, John; McKenzie, Edward A.; McHugh, Peter J.; Cridland, Nigel A. (1993). "Sunlight-induced mutagenicity of a common sunscreen ingredient." FEBS Letters 324(3): 309–313; Melanie Gulston, John Knowland; S. H. Moss, D. J. Davies (1999). "Illumination of human keratinocytes in the presence of sunscreen ingredient padimate-O and through an SPF-15 sunscreen reduces direct photodamage to DNA but increases strand breaks." Mutation Research 1999 (444): 49–60.
xxviii Schlumpf M, Durrer S, Faass O, Ehnes C, Fuetsch M, Gaille C, Henseler M, Hofkamp L, Maerkel K, Reolon S, Timms B, Tresguerres JA, Lichtensteiger W. (2008). Developmental toxicity of UV filters and environmental exposure: a review. Int J Androl. 31 (2):144-51; Schlumpf M, Schmid P, Durrer S, Conscience M, Maerkel K, Henseler M, Gruetter M, Herzog I, Reolon S, Ceccatelli R, Faass O, Stutz E, Jarry H, Wuttke W, Lichtensteiger W. (2004). Endocrine activity and developmental toxicity of cosmetic UV filters--an update. Toxicology 205(1-2): 113-122.
xxix Pont AR, Charron AR, Brand RM. (2004). Active ingredients in sunscreens act as topical penetration enhancers for the herbicide 2,4-dichlorophenoxyacetic acid. Toxicol Appl Pharmacol 195(3): 348-354.
xxx P85 Recommendation 10, The Royal Society and The Royal Academy of Engineering, UK (2004). Nanoscience and nanotechnologies. Available at http://www.royalsoc.ac.uk/
xxxi P86 Recommendation 12 (i), The Royal Society and The Royal Academy of Engineering, UK (2004). Nanoscience and nanotechnologies. Available at http://www.royalsoc.ac.uk/
xxxiv Faunce T, Murray K, Nasu H, Bowman D. (2008). Sunscreen safety: The precautionary principle, the Australian Therapeutic Goods Administration and nanoparticles in sunscreens. Nanoethics. DOI 10.1007/s11569-008-0041-z