Letter Concerning Nanoparticles
Dear Concerned Customer,
Over the last few weeks we have received several requests for information regarding an article published by Consumers Union, publishers of Consumer Reports. The article is on the use of nanoparticles in sunscreens.
To be very clear, we are supporters of Consumers Union and in general respect and understand the value of their place as a voice of consumer protection in the marketplace. We do find however, that in this article, they are under-researched, misleading in their assumptions, and are quite frankly providing a disservice to their readers.
We do understand that sometimes it is not sexy to report the facts especially if they bear out issues that do not rattle in the headlines. This is the case with micronized titanium dioxide and zinc oxide.
Let's look at the facts as they exist today, especially with respect to the following questions:
1) What is a nano? What is a nanoparticle?
Preface: Before we examine the facts, is important to know that over the last 5 years or so these ingredients have been under great scrutiny. Theoretical safety issues surfaced from very well meaning organizations such as the Environmental Working Group (EWG), Friends of the Earth, and others. Their hard work helped to step up the much needed research on these ingredients, and for that we are all thankful. That being said, let's jump into the issues.
2) What types of micronized ingredients are used in sunscreens?
3) Are zinc oxide and/or titanium dioxide safe when applied on the skin? Is there any research to back up the findings?
4) What does Aubrey use as a physical block and why? What is the size of the particles used in Aubrey sun products? Are they considered nanoparticles?
1) What is a nano? Simply stated, a nano is a unit of measure. It is a billionth of something. In the same way as a centimeter (cm) is 1/100 of a meter, a nanometer (nm) is 1 billionth of a meter. Here is a link to help to understand the size issue. (9)
The illustration below will also help. It is taken directly from the FDA.gov website found here: http://www.fda.gov/consumer/updates/nanotech072507.html (10)
What is a nanoparticle? A nanoparticle as defined in the USA, and for that matter worldwide, is a particle that has at least one dimension in the 0 to 100 nm in length. (14) Nanoparticles are found all around us in nature every day. Here is some information from the National Nanotechnology Initiative (NNI). The NNI is the program established in fiscal year 2001 to coordinate Federal nanotechnology research and development. Found here http://www.nano.gov/html/facts/whatIsNano.html (12)
"Where are nanoscale materials found? ... Nanoscale materials and effects are found in nature all around us. Nature's secrets for building from the nanoscale create processes and machinery that scientists hope to imitate. Researchers already have copied the nanostructure of lotus leaves to create water repellent surfaces used today to make stain-proof clothing, other fabrics, and materials. Others are trying to imitate the strength and flexibility of spider silk, which is naturally reinforced by nanoscale crystals.
Many important functions of living organisms take place at the nanoscale. Our bodies and those of all animals use natural nanoscale materials, such as proteins and other molecules, to control our bodies' many systems and processes. A typical protein such as hemoglobin, which carries oxygen through the bloodstream, is 5 nanometers, or 5 billionths of a meter, in diameter.
Nanoscale materials are all around us, in smoke from fire, volcanic ash, sea spray, as well as products resulting from burning or combustion processes. Some have been put to use for centuries. One material, nanoscale gold, was used in stained glass and ceramics as far back as the 10th Century. But it took 10 more centuries before high-powered microscopes and precision equipment were developed to allow nanoscale materials to be imaged and moved around."
2) What types of micronized ingredients are used in sunscreens? The two primary micronized ingredients found today in sunscreens are titanium dioxide and zinc oxide. For our discussion, we will focus on titanium dioxide. Titanium dioxide is a naturally occurring mineral derived from oxide of titanium. The oxides are typically mined and then further processed and purified for use in consumer products. Titanium dioxide also absorbs, reflects, or scatters light. Titanium dioxide is an important ingredient used in sunscreen products. Sunscreens are regulated by the Food and Drug Administration (FDA) as Over-The-Counter (OTC) drug products. As such, they must be demonstrated to be safe and effective in protecting the user from the harmful effects of ultraviolet radiation that is part of sunlight. (7)
"Skin absorption. EWG carefully studied all scientific publications and government safety assessments on the risk of nanoparticle penetration from zinc and titanium in sunscreen. The current weight of evidence suggests that these nanoparticles do not penetrate the skin, diminishing concerns for their adverse effects for sunscreen users.
3) Are micronized titanium dioxide and/or zinc oxide safe when applied onto the skin in sunscreens? Is there any research to support the findings? The simple answer to both questions is yes. There are a number of studies supporting the safety claims of micronized titanium dioxide and zinc oxide. The scientific research and literature to date overwhelmingly supports the safety of micronized and nano-sized particles of titanium dioxide and zinc oxide in sunscreens. Below is the summary information from the EWG (Environmental Working Group) as well as a sampling of the research to date. More detail can be found here. (2)
The concerns of skin penetration were raised a decade ago by a pilot study of 13 Australian patients scheduled for skin surgery. Patients applied an 8% nano-titanium sunscreen for 2 to 6 weeks before surgery. Researchers found higher titanium levels in the epidermis of these patients than a comparison group, but only after removing one elevated value in the comparison group (Tan 1996). The studies performed subsequently have failed to detect similar evidence of penetration.
The European Union-funded NanoDerm project conducted a series of experimental studies over three years and found no evidence of dermal penetration in intact human and pig skin using a variety of analytical techniques, titanium types, and test conditions. NanoDerm focused on titanium penetration since zinc is not used in European sunscreens. They observed that nano-scale titanium particles often aggregated into larger masses on skin, and penetrated deepest in hair shafts. The project also performed absorption studies on skin samples from several patients with psoriasis, which has been a particular concern because skin affected by this condition lacks a protective barrier. Titanium particles penetrated nearly to the level of living skin cells (keratinocytes), but researchers found no evidence that the particles reached the bloodstream. None of their 11 publications found evidence that nano-scale titanium reached "vital tissues" (NanoDerm 2007; Kiss 2008).
EWG separately reviewed results from academic experiments representing a variety of skin types (mouse, pig or human skin) and including nano-scale titanium and zinc. At least 16 laboratory studies have tested nano-metal penetration through intact skin, each finding that very few particles, if any, reach living skin cells (Baroli 2007; Cross 2007; Dussert 1997; Gamer 2006; Gontier 2004; Gottbrath 2003; Kiss 2007; Lademann 1999; Landsdown 1997; Mavon 2007; Menzel 2004; NanoDerm 2008; Pflücker 2001; SCCNFP 2004; Schulz 2002; Tan 1996). The most recent study offered by industry found no titanium particle penetration and 1.5 to 2.3% penetration by nano zinc, though the study is difficult to interpret because of evidence that the experiment was affected by background levels of zinc contamination (Gamer 2006). Hair follicles make up 0.1% of the skin surface and can be potential openings for deeper movement of nanoparticles into skin. However penetration studies for nano zinc and titanium note follicular accumulation, but not penetration, from the hair shaft into deeper tissues (Lademann 2005, 2006, 2007; NanoDerm 2007).
|TITANIUM DIOXIDE (TiO2)
||pig skin, human skin
||TiO2 was generally detected on top of the stratum corneum and topmost layers of the stratum corneum disjunctum for healthy skin. Penetration via mechanical action and no diffusive transport takes place.
||20 nm by 100 nm
||3 forms of TiO2 from sunscreen
||Penetration to upper layers of stratum corneum. No TiO2 in follicles, viable epidermis or dermis.
||No penetration, recoveries <1.5% in receptor fluid.
||silica or methicone
||pig skin, in vitro
||Particles in/on stratum corneum; minimal penetration into stratum granulosum. No penetration into living skin.
||45-150 nm needles
||No penetration of particles beyond upper layers of stratum corneum
||TiO2 from sunscreen
||pig, human, in vitro tests
||No penetration beyond stratum corneum. No TiO2 was detected in the follicle, viable epidermis or dermis
||coated and uncoated TiO2
||human, in vitro
||Penetration limited to upper layers of stratum corneum
||50 - 100 nm
||Human volunteers applied sunscreen for 2 to 6 weeks. Inconclusive results for TiO2 in epidermis.
||human skin, in vitro
||No particles in epidermis or dermis
||1.5 to 2.3% of particles penetration
||80 nm, with 90% <160 nm
||human healthy and psoriatic skin, in-vitro pig skin
||No increase in zinc plasma levels. In-vitro penetration <1% of dose.
||not necessarily nano
||human skin, in vitro
||Penetration limited to upper layers of stratum corneum
4) What does Aubrey use as a physical block and why? Aubrey uses micronized titanium dioxide with an average particle size of 202nm. This size is safely above the sizes used in clinical tests (see above) and twice the size by definition of nanoparticles. Some of the particles might very well fall below the 100nm threshold and be classified as nanoparticles, but that is not the rule and they usually do not exist in isolation. We are very comfortable with this ingredient in terms of safety and are convinced it is one of the safest active ingredients accepted (required) by the FDA in sunscreens. To make an SPF claim in the USA today at least one of the below-listed ingredients MUST be contained in the sun product. We find the advantages of using titanium dioxide or zinc oxide as physical blocks far outweigh the safety issues surrounding the many petroleum based chemical blocks on the list. Here is the list provided by the FDA:
The active ingredient of the product consists of any of the following, within the concentration specified for each ingredient, and the finished product provides a minimum SPF value of not less than 2 as measured by the testing procedures established in subpart D of this part.
(a)Aminobenzoic acid (PABA) up to 15 percent.
(b) Avobenzone up to 3 percent.
(c) Cinoxate up to 3 percent.
(e) Dioxybenzone up to 3 percent.
(f) Homosalate up to 15 percent.
(h) Menthyl anthranilate up to 5 percent.
(i) Octocrylene up to 10 percent.
(j) Octyl methoxycinnamate up to 7.5 percent.
(k) Octyl salicylate up to 5 percent.
(l) Oxybenzone up to 6 percent.
(m) Padimate O up to 8 percent.
(n) Phenylbenzimidazole sulfonic acid up to 4 percent.
(o) Sulisobenzone up to 10 percent.
(p) Titanium dioxide up to 25 percent.
(q) Trolamine salicylate up to 12 percent.
(r) Zinc oxide up to 25 percent.
5) Comments and Conclusions: The bottom line is that we must all protect the consumer at hand. We feel that although Consumers Union had only the best of intentions at the time the article was published, the article was not balanced and may indeed have a reverse effect in terms of protecting consumer safety. It may indeed scare the consumer away from some of the most effective, safest, and thoroughly tested sun products on the planet.
Finally, we'd like to ask you to review the closing comments from the Environmental Working Group and then from the NIA respectively. Both are cut and pasted below for your reference.
All research tells us that micronized physical blocks (titanium dioxide, zinc oxide) provide the most effective protection from both UVA and UVB sun rays… and protection from both is of great importance. The article fails to mention that the majority of chemical blocks do not provide adequate broad spectrum protection from both UVA and UVB rays. Exposure to UVA is a real cancer risk. The use of a limited spectrum sunscreen can in fact put the user at risk. This is not always the case with properly formulated physical blocks.
The current review of the scientific and regulatory studies clearly shows evidence that nano-sized particles of both titanium dioxide and zinc oxide remain on the skin and do not penetrate the skin. (2)(13) The FDA, the Australian government, and the German government have all concluded that these ingredients reside on the surface and do not penetrate the outer layer of skin and regard them safe for topical use in sunscreens. (4) (5)
Unfortunately, there is no magic bullet to completely prevent damage or to protect one from harmful rays of the sun. The only alternative option is to avoid the sun completely and to cover up the skin as much as possible. One has to always measure the cost/benefit of any product or ingredient.
Comments from EWG (2)
"When we began our sunscreen investigation at the Environmental Working Group, our researchers thought we would ultimately recommend against micronized and nano-sized zinc oxide and titanium dioxide sunscreens. After all, no one has taken a more expansive and critical look than EWG at the use of nanoparticles in cosmetics and sunscreens, including the lack of definitive safety data and consumer information on these common new ingredients, and few substances more dramatically highlight gaps in our system of public health protections than the raw materials used in the bizarre and burgeoning field of nanotechnology. But many months and nearly 400 peer-reviewed studies later, we find ourselves drawing a different conclusion, and recommending some sunscreens that may contain nano-sized ingredients.
Our study shows that consumers who use sunscreens without zinc and titanium are likely exposed to more UV radiation and greater numbers of hazardous ingredients than consumers relying on zinc and titanium products for sun protection. We found that consumers using sunscreens without ZnO and TiO2 would be exposed to an average of 20% more UVA radiation with increased risks for UVA-induced skin damage, premature aging, wrinkling, and UV-induced immune system damage than consumers using zinc- and titanium-based products. Sunscreens without zinc or titanium contain an average of 4 times as many high hazard ingredients known or strongly suspected to cause cancer or birth defects, to disrupt human reproduction or damage the growing brain of a child. They also contain more toxins on average in every major category of health harm considered: cancer (10% more), birth defects and reproductive harm (40% more), neurotoxins (20% more), endocrine system disruptors (70% more), and chemicals that can damage the immune system (70% more) (EWG 2007).
Comments from NIA (8)
We also reviewed 16 peer-reviewed studies on skin absorption, nearly all showing no absorption of small-scale zinc and titanium sunscreen ingredients through healthy skin. In the past year a new European Union assessment of nano-scale titanium penetration has been completed with no evidence of absorption of particles through pig and human skin, including patients with skin disorders (NanoDerm 2007).
On balance when it comes to sunscreen, EWG researchers found that zinc and titanium-based formulations are among the safest, most effective sunscreens on the market based on available evidence. The easy way out of the nano debate would be to steer people clear of zinc and titanium sunscreens with a call for more data. In the process such a position would implicitly recommend sunscreen ingredients that don't work, that break down soon after they are applied, that offer only marginal UVA protection, or that have fewer studies demonstrating lack of skin penetration."
"We would furthermore like to provide some additional comments and reference to
scientific evidence, which we consider necessary to fully evaluate the use of nanomaterials in cosmetic products:
1. Many studies show that the use of sunscreens reduces the occurrence and the
development of skin and lips cancers, and herpes labial (Pogoda 1996; Rooney
1991; Nohynek 2001)
2. Sunscreens protect DNA from deteriorations induced by ultra-violet radiations,
reduce the appearance of modified squamous cells and the development of certain
indices of the melanoma (Young 2000; Gallagher 2005; Mahroos 2002; Lee 2005).
3. Today, one cancer in three is skin cancer. Each year 2 to 3 million skin cancers
(carcinoma type) and over 130,000 melanomas are diagnosed. One American in
five will develop a skin cancer in his life.
4. The incidence of skin cancer has increased considerably over the last decade. The
popularity of outdoor activities, including "sun bathing" is the leading cause of this
increase. The reduction of the level of protection from the ozone layer, if continued,
will worsen this tendency: it is estimated that a decrease of 10% of stratospheric
ozone would be responsible for 300,000 carcinoma and 4,500 additional
melanomas each year (WHO 2007).
5. In many countries dermatologists' associations (such as The Cancer Council
Australia) and national sanitary authorities regularly launch information campaigns
inviting people to apply sun products before exposing themselves to the sun. For
example, in 2006 this public health strategy was re-confirmed by The American
Academy of Dermatology (AAD 2007).
6. According to the IARC (International Agency for Research on Cancer), the regular
use of sun creams is essential in the prevention of the skin cancers and those that
contain nano titanium dioxide or zinc oxide are the most effective (IAR 2001).
7. A large number of studies have demonstrated the titanium dioxide nanopigments
do not cross the skin barrier after topical application. Studies carried out within the
framework of the European research program NANODERM showed that
nanopigments do not cross the skin barrier in the case of both healthy skin or
compromised skin (acne, psoriasis) (Lademann 1999; Dussert 1997; Pflucker 1999;
Gamer 2006; Roberts 2006; Nohynek 2007; Mavon 2007; Butz 2005).
8. Indeed, M. Kraeling and R. Bronaugh of the FDA recently reported that even
quantum dots nanoparticles not used in cosmetics, but used as cell markers and
designed to penetrate into cells do not cross the skin barrier when applied
topically (Kraeling 2007).
9. Other studies by the FDA showed that, in mice, subcutaneously injected TiO2
nanoparticles were not systemically available, but remained at the injection site;
intravenously injected TiO2 nanoparticles were rapidly cleared from the circulation
and were found inside macrophages in the liver, spleen and the lungs, suggesting
normal clearance by the phagocytic barrier (Umbreit 2007; Wiebert 2006).
10. It is worth mentioning that the IARC classification of TiO2 as possibly carcinogenic
to humans was made on the basis of animal inhalation studies that were conducted
with micro-sized and not with nano-sized particles. It has recently been suggested
that all respirable, inert and non-toxic particles may produce carcinogenic effects
identical to those of TiO2. Therefore, the inhalation carcinogenicity of (micro-sized)
TiO2 is not due a specific carcinogenic activity of the material, but represents a
general biological activity of all investigated bio-durable particles without significant
specific toxicity, such as carbon black, aluminium oxide, aluminium silicate, kaolin,
titanium dioxide, zirconium dioxide or amorphous silica all of which produce lung
overload at high concentrations and all of which were shown to be similarly
carcinogenic in rats (Mohr 2006).
11. It is suggested by the SCCP that cosmetics may produce human systemic exposure
via inhalation. Hairsprays are listed as cosmetic products producing human systemic
exposure to nanoparticles. However, to our knowledge, current hairsprays do not
contain nanoparticles and therefore do not produce human systemic exposure to
12. In conclusion, the non-penetration of TiO2 or ZnO nanoparticles used in sunscreens
into or through human skin as well as absence of a health risk has been
acknowledged by the German and Australian health authorities, and the recent
international expert group assembled by ECETOC. This is hardly surprising given
that sunscreen pigments must be present on the surface of the skin in order to
protect from UV light (BfR 2006; TGA 2006; Borm 2006).
13. The guidelines set out recently by the US federal government within the context of
the TSCA (TSCA Inventory Status of Nanoscale Substances -- General Approach) do
"not consider particle size to distinguish for Inventory purposes two substances that
are known to have the same molecular identity. Under principles of traditional
chemistry different forms of such substances would not be considered different
chemicals". This interesting approach is also being discussed within the FDA Task
force on Nanotechnology."
To say the least this is a very complex yet important issue. People's health is at risk. The issue and discussion goes far beyond asking a customer service rep ... "Do you use nanoparticles in your products?"
Just some food for thought.
(1) Environmental Working Group - Special report on Skin Safety
(2) Environmental Working Group - Nanotechnology Summary - special report
(3) US Food and Drug Admin. (FDA) - Sunscreen Drug Products - 21CFR352
(4) Australian Government - Department of Health and Ageing - A revive of the safety of nanoparticle titanium dioxide and zinc oxide in sunscreen
(5) Germany's Federal Institute for Risk Assessment (English Website)
(6) Cosmetics Info.org - Info, links, research - titanium dioxide
(7) Cosmetics Info.org - Info, links, research - nanotechnology
(8) NIA - SCCP Preliminary on Safety of Nanomaterials in Cosmetics Products 0907
(9) Nanooze - How Big is a Nanometer - English Website
(10) US Food and Drug Admin. (FDA) - FDA readies for nanotechnology information
(11) Environmental Working Group - Nanotechnology Summary - special report
(12) NNI.gov - What is nano - Fact sheet
(13) Cosmetic, Toiletry and Fragrance Assn. - comments to FDA
(14) US Food and Drug Admin. (FDA) - FAQs on nanotechnology
(15) National Geographic Green Guide - Screen Test: Reading the Micro-Fine Print 6/07