Tag Archives: sunscreens

Adding as little as 0.1% of rosmarinic acid reduced amount of sunscreen needed to protect skin and more

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Since metallic nanoparticles are now pretty much accepted as being relatively safe ingredients, I don’t write about sunscreens very often anymore. Of course metallic nanoparticles had to be rebranded as ‘minerals’ after some civil society groups raised a great fuss. (See my February 9, 2012 posting “Unintended consequences: Australians not using sunscreens to avoid nanoparticles?” for a rundown of the situation.)

This April 5, 2023 news item about a different kind of sunscreen ingredient on phys.org caught my eye,

An article published in the journal Cosmetics reports an investigation of the effects of including rosmarinic acid, an active antioxidant, in a sunscreen along with two conventional ultraviolet light filters, ethylhexyl methoxycinnamate (against UVB) and avobenzone (against UVA).

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They don’t seem to have tested this new ingredient in any ‘mineral’ sunscreens but it seems an intriguing possibility. Here’s more about rosmarinic acid and why it may be a good addition to sunscreens from an April 5, 2023 Fundação de Amparo à Pesquisa do Estado de São Paulo (São Paulo Research Foundation; FAPESP) press release (also on EurekAlert), which originated the news item, Note: Links have been removed)

The research group increased the sunscreen’s photoprotective efficacy by adding rosmarinic acid at 0.1%, a very small proportion compared with those of conventional UV filters. They believe their findings suggest that incorporating natural molecules with antioxidant activities into sunscreens could decrease the proportion of conventional UV filters in the final product, with the advantage of providing other functional properties.

The product’s performance improved without the need to increase active principle levels, reducing both the amount of sunscreen needed to protect the same skin area and the volume of synthetic chemicals discharged into the environment.

In vitro and clinical trials obtained a 41% increase in sun protection factor (SPF). The higher the SPF, the more sunburn protection increases.

Another advantage of including rosmarinic acid was the addition of antioxidant activity to photoprotection so that the product could be used in antiaging cosmetics, for example.

“Our research on photoprotective systems aims primarily to evaluate potential sunscreen enhancement strategies. We’re interested above all in discovering ways to increase sunburn protection while also improving the stability of the product so that it remains safe and effective for longer,” said pharmaceutical scientist and biochemist André Rolim Baby, last author of the article and a professor at the University of São Paulo’s School of Pharmaceutical Sciences (FCF-USP) in Brazil.

“We’re also looking for products or systems with less environmental impact and ways of reducing the concentration of conventional filters by including natural ingredients that enhance the formulation. And we’re very interested in mapping other cosmetic properties of photoprotective molecules, such as anti-free radical action and protection of biomarkers in the outermost skin layers.”

Multifunctional compound

The investigation was part of a project supported by FAPESP to map chemopreventive properties of various UV filters.

In addition to being an antioxidant, rosmarinic acid, a natural polyphenol antioxidant found in rosemary, as well as sage, peppermint and many other herbal plants, has antiviral, anti-inflammatory, immunomodulatory, antibiotic and anticancer properties.

In a review article published in 2022 in the journal Nutrients, the research group highlighted the beneficial effects of rosmarinic acid as a food supplement, such as improvement in skin firmness and wrinkle reduction.

“In another investigation, we found potential benefits of rosmarinic acid for skin surface hydration, reinforcing the need for more research on the substance in the field of cosmetology,” Baby said.

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Here’s a link to and a citation for the research team’s latest paper,

Photoprotective Efficacy of the Association of Rosmarinic Acid 0.1% with Ethylhexyl Methoxycinnamate and Avobenzone by Maíra de Oliveira Bispo, Ana Lucía Morocho-Jácome, Cassiano Carlos Escudeiro, Renata Miliani Martinez, Claudinéia Aparecida Sales de Oliveira Pinto, Catarina Rosado, Maria Valéria Robles Velasco and André Rolim Baby. Cosmetics 2023, 10(1), 11; https://doi.org/10.3390/cosmetics10010011 Published: 5 January 2023 (This article belongs to the Special Issue Feature Papers in Cosmetics in 2022)

This paper is open access.

Methylene Blue-based sunscreen—anti-aging and coral reef safe

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In any event, it’s time to start thinking about sunscreens (for those of us in the Northern Hemisphere.) One other thing, this is informational; it is not an endorsement. A March 1, 2022 Mblue Labs product announcement on EurekAlert (also on EIN Presswire) describes some of the research that went into this new sunscreen,

(Bethesda, MD – March 1, 2022) Mblue Labs releases the first sunscreen based on a recent study that found Methylene Blue, a century old medicine, to be  a highly effective, broad-spectrum UV irradiation protector that absorbs UVA and UVB, repairs ROS (Free Radicals) and UV irradiation induced DNA damages, and is safe for coral reefs. The research paper, “Ultraviolet radiation protection potentials of Methylene Blue for human skin and coral reef health ” was published in Nature’s Scientific Reports (5/28/2021) https://www.nature.com/articles/s41598-021-89970-2 [open access].

80% of today’s sunscreens use Oxybenzone as a chemical UV blocker, despite multiple studies that have shown it expedites the destruction of coral reefs. Several states and countries have now banned the use of Oxybenzone and its derivatives to stop the devastating effects on the world’s marine ecosystem. In addition, consumers focus primarily on the Sun Protection Factor (SPF) to prevent sunburns and potentially dangerous long-term health issues. However, SPF only measures UVB exposure, leaving sunscreen users vulnerable to UVA-triggered oxidative stress and photo-aging.

“Our peer-reviewed study demonstrates that Methylene Blue is an effective UV blocker with a number of highly desired characteristics as a novel ingredient to be included in sunscreens. It shows a broad spectrum absorption of both UVA and UVB rays, promotes DNA damage repair, combats reactive oxygen species (ROS) induced by UVA, and most importantly, poses no harm to coral reefs.” says the study’s senior author Dr. Kan Cao, Founder of Mblue Labs, Bluelene Skincare and a Professor at the University of Maryland Department of Cell Biology and Molecular Genetics.

Mblue Labs and the University of Maryland have a pending patent on the property of Methylene Blue as an effective UV blocking agent that also delays skin aging and promotes DNA damage repair. The company’s first anti-aging sunscreen called “Bluevado SunFix”, contains the FDA approved, safe active ingredients Zinc Oxide and Titanium Dioxide, together with an optimized dosage of Methylene Blue. 

“Our Vision for this novel multifunctionsunscreen is deeply rooted in our concern for coral reefs – the rainforest of the ocean. We look forward to working with the industry and the FDA to get Methylene Blue included in the sunscreen monograph. We are confident that Bluevado SunFix not only delivers broad spectrum UVB/UVA protection and post sun repair, but also provides the full anti-aging benefits of our Bluelene Moisturizer with the same cosmetic elegance.”  says Jasmin EL Kordi, CEO Mblue Labs.

This research was supported by a National Science Foundation (NSF) Small Business Technology Transfer Grant (Grant: 1842745). This press release does not necessarily represent the views of the NSF. This study was conducted jointly by researchers at Mblue Labs and the University of Maryland.

About Mblue Labs + Bluelene: 

MBlue Labs provides revolutionary anti-aging technology to consumers around the world.  The company’s clinical skincare brand Bluelene uses patented ingredient Methylene Blue to repair and protect skin on the mitochondrial level. Mblue Labs’ recent research demonstrates Methylene Blue as the new retinol challenger for anti-aging treatments, in addition to its exciting properties as a new UV sunscreen.

I went looking for the new sunscreen (Bluevado SunFix) and found this,

$58.00

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Bluevado SunFix is the first FDA-approved anti-aging sunscreen with Methylene Blue. Methylene Blue’s unique ability to promote skin cell health, repair/delay skin aging and protect against UVA and UVB radiation, is now captured in the bravado of this revolutionary SPF Day Cream.

Our innovative formulation blends Methylene Blue with proven minerals to outperform Oxybenzone, deliver cosmetic elegance, and protect our precious coral reefs from harmful substances. 

Methylene Blue is a preferred alternative to retinol for sensitive skin sufferers and with SunFix there is no retinol sun sensitivity.

Bluevado SunFix is proudly made in the USA and is formulated for ALL skin types.

Preorder now to reserve your SunFix. First shipments are available in mid-March [2022].

Application:

Use as a daily SPF Moisturizer. For sun protection apply 15mins before sun exposure and reapply after 40 minutes of swimming or sweating.

Benefits:

Broad-spectrum UVA/UVB sun protection 

Prevents pre-mature aging 

Repairs photo-aging DNA damage caused by UVA exposure

Reduces fine lines, crows feet, and wrinkles

Improves skin elasticity & firmness

Provides all-day skin hydration

Protects coral reefs

Free USPS shipping for all domestic orders over $34!

Ingredients:

Active Ingredients: Zinc Oxide 8.2%, Titanium Dioxide 2.8%   

Inactive Ingredients: Water (Aqua), Caprylic/Capric Triglyceride, C13-15 Alkane, Cetearyl Alcohol, Glycerin, Oryza Sativa (Rice) Bran Oil, Heptyl Undecylenate, Cetyl Alcohol, Argania Spinosa (Argan) Kernel Oil, Tocopheryl Acetate, Glyceryl Stearate, PEG-100 Stearate, Capryloyl Glycerin/Sebacic Acid Copolymer, Sorbitan Laurate, Butyrospermum Parkii (Shea) Butter, Cocos Nucifera (Coconut) Oil, Bisabolol, Xanthan Gum, Polyhydroxystearic Acid, Jojoba Esters, Polysorbate 60, Ascorbyl Palmitate, Citrus Aurantium Bergamia (Bergamot) Peel Oil, Pelargonium Graveolens (Geranium) Leaf Oil, Citrus Grandis (Grapefruit) Peel Oil, Lavandula Angustifolia (Lavender) Oil, Phenoxyethanol, Caprylyl Glycol, Methylene Blue. [emphasis mine]

Caution: For external use only. Keep out of reach of children. In case of irritation or allergic reaction, discontinue use and consult your physician.

There’s 3 fl oz or 90 mL of product in the tube and it’s SPF 21. (If memory serves, Methylene Blue’s placement at the end of the list ingredients means that it’s the ingredient that weighs the least.)

Again, I am not endorsing this product. That said, it does look interesting.

Caption: Corals exposed to Methylene Blue remain healthy. Credit: Mblue Labs

BTW, Finding a product announcement on EurekAlert (online science news service sponsored by the American Association for the Advancement of Science [AAAS]) was a little unexpected but only because I was ignorant of their Content Eligibility Guidelines (scroll down to Business Announcements). Duly noted.

Get better protection from a sunscreen with a ‘flamenco dancing’ molecule?

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Caption: illustrative image for the University of Warwick research on ‘Flamenco dancing’ molecule could lead to better-protecting sunscreen created by Dr. Michael Horbury. Credit:: created by Dr Michael Horbury

There are high hopes (more about why later) for a plant-based ‘flamenco dancing molecule’ and its inclusion in sunscreens as described in an October 18, 2019 University of Warwick press release (also on EurekAlert),

A molecule that protects plants from overexposure to harmful sunlight thanks to its flamenco-style twist could form the basis for a new longer-lasting sunscreen, chemists at the University of Warwick have found, in collaboration with colleagues in France and Spain. Research on the green molecule by the scientists has revealed that it absorbs ultraviolet light and then disperses it in a ‘flamenco-style’ dance, making it ideal for use as a UV filter in sunscreens.

The team of scientists report today, Friday 18th October 2019, in the journal Nature Communications that, as well as being plant-inspired, this molecule is also among a small number of suitable substances that are effective in absorbing light in the Ultraviolet A (UVA) region of wavelengths. It opens up the possibility of developing a naturally-derived and eco-friendly sunscreen that protects against the full range of harmful wavelengths of light from the sun.

The UV filters in a sunscreen are the ingredients that predominantly provide the protection from the sun’s rays. In addition to UV filters, sunscreens will typically also include:

Emollients, used for moisturising and lubricating the skin
Thickening agents
Emulsifiers to bind all the ingredients
Water
Other components that improve aesthetics, water resistance, etc.

The researchers tested a molecule called diethyl sinapate, a close mimic to a molecule that is commonly found in the leaves of plants, which is responsible for protecting them from overexposure to UV light while they absorb visible light for photosynthesis.

They first exposed the molecule to a number of different solvents to determine whether that had any impact on its (principally) light absorbing behaviour. They then deposited a sample of the molecule on an industry standard human skin mimic (VITRO-CORNEUM®) where it was irradiated with different wavelengths of UV light. They used the state-of-the-art laser facilities within the Warwick Centre for Ultrafast Spectroscopy to take images of the molecule at extremely high speeds, to observe what happens to the light’s energy when it’s absorbed in the molecule in the very early stages (millionths of millionths of a second). Other techniques were also used to establish longer term (many hours) properties of diethyl sinapate, such as endocrine disruption activity and antioxidant potential.

Professor Vasilios Stavros from the University of Warwick, Department of Chemistry, who was part of the research team, explains: “A really good sunscreen absorbs light and converts it to harmless heat. A bad sunscreen is one that absorbs light and then, for example, breaks down potentially inducing other chemistry that you don’t want. Diethyl sinapate generates lots of heat, and that’s really crucial.”

When irradiated the molecule absorbs light and goes into an excited state but that energy then has to be disposed of somehow. The team of researchers observed that it does a kind of molecular ‘dance’ a mere 10 picoseconds (ten millionths of a millionth of a second) long: a twist in a similar fashion to the filigranas and floreos hand movements of flamenco dancers. That causes it to come back to its original ground state and convert that energy into vibrational energy, or heat.

It is this ‘flamenco dance’ that gives the molecule its long-lasting qualities. When the scientists bombarded the molecule with UVA light they found that it degraded only 3% over two hours, compared to the industry requirement of 30%.

Dr Michael Horbury, who was a Postgraduate Research Fellow at The University Warwick when he undertook this research (and now at the University of Leeds) adds: “We have shown that by studying the molecular dance on such a short time-scale, the information that you gain can have tremendous repercussions on how you design future sunscreens.
Emily Holt, a PhD student in the Department of Chemistry at the University of Warwick who was part of the research team, said: “The next step would be to test it on human skin, then to mix it with other ingredients that you find in a sunscreen to see how those affect its characteristics.”

Professor Florent Allais and Dr Louis Mouterde, URD Agro-Biotechnologies Industrielles at AgroParisTech (Pomacle, France) commented: “What we have developed together is a molecule based upon a UV photoprotective molecule found in the surface of leaves on a plant and refunctionalised it using greener synthetic procedures. Indeed, this molecule has excellent long-term properties while exhibiting low endocrine disruption and valuable antioxidant properties.”

Professor Laurent Blasco, Global Technical Manager (Skin Essentials) at Lubrizol and Honorary Professor at the University of Warwick commented: “In sunscreen formulations at the moment there is a lack of broad-spectrum protection from a single UV filter. Our collaboration has gone some way towards developing a next generation broad-spectrum UV filter inspired by nature. Our collaboration has also highlighted the importance of academia and industry working together towards a common goal.”

Professor Vasilios Stavros added, “Amidst escalating concerns about their impact on human toxicity (e.g. endocrine disruption) and ecotoxicity (e.g. coral bleaching), developing new UV filters is essential. We have demonstrated that a highly attractive avenue is ‘nature-inspired’ UV filters, which provide a front-line defence against skin cancer and premature skin aging.”

Here’s a link to and a citation for the paper,

Towards symmetry driven and nature inspired UV filter design by Michael D. Horbury, Emily L. Holt, Louis M. M. Mouterde, Patrick Balaguer, Juan Cebrián, Laurent Blasco, Florent Allais & Vasilios G. Stavros. Nature Communications volume 10, Article number: 4748 (2019) DOI: https://doi.org/10.1038/s41467-019-12719-z

This paper is open access.

Why the high hopes?

Briefly (the long story stretches over 10 years), the most recommended sunscreens today (2020) are ‘mineral-based’. This is painfully amusing because civil society groups (activists) such as Friends of the Earth (in particular the Australia chapter under Georgia Miller’s leadership) and Canada’s own ETC Group had campaigned against these same sunscreen when they were billed as being based on metal oxide nanoparticles such zinc oxide and/or titanium oxide. The ETC Group under Pat Roy Mooney’s leadership didn’t press the campaign after an initial push. As for Australia and Friend of the Earth, their anti-metallic oxide nanoparticle sunscreen campaign didn’t work out well as I noted in a February 9, 2012 posting and with a follow-up in an October 31, 2012 posting.

The only civil society group to give approval (very reluctantly) was the Environmental Working Group (EWG) as I noted in a July 9, 2009 posting. They had concerns about the fact that these ingredients are metallic but after a thorough of then available research, EWG gave the sunscreens a passing grade and noted, in their report, that they had more concerns about the use of oxybenzone in sunscreens. That latter concern has since been flagged by others (e.g., the state of Hawai’i) as noted in my July 6, 2018 posting.

So, rebranding metallic oxides as minerals has allowed the various civil society groups to support the very same sunscreens many of them were advocating against.

In the meantime, scientists continue work on developing plant-based sunscreens as an improvement to the ‘mineral-based’ sunscreens used now.

Sunscreens: 2018 update

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I don’t usually concern myself with SPF numbers on sunscreens as my primary focus has been on the inclusion of nanoscale metal particles (these are still considered safe). However, a recent conversation with a dental hygienist and coincidentally tripping across a June 19, 2018 posting on the Schrodinger’s Cat blog shortly after the convo. has me reassessing my take on SPF numbers (Note: Links have been removed),

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So, what’s the deal with SPF? A recent interview of Dr Steven Q Wang, M.D., chair of The Skin Cancer Foundation Photobiology Committee, finally will give us some clarity. Apparently, the SPF number, be it 15, 30, or 50, refers to the amount of UVB protection that that sunscreen provides. Rather than comparing the SPFs to each other, like we all do at the store, SPF is a reflection of the length of time it would take for the Sun’s UVB radiation to redden your skin (used exactly as directed), versus if you didn’t apply any sunscreen at all. In ideal situations (in lab settings), if you wore SPF 30, it would take 30 times longer for you to get a sunburn than if you didn’t wear any sunscreen.

What’s more, SPF 30 is not nearly half the strength of SPF 50. Rather, SPF 30 allows 3% of UVB rays to hit your skin, and SPF 50 allows about 2% of UVB rays to hit your skin. Now before you say that that is just one measly percent, it actually is much more. According to Dr Steven Q. Wang, SPF 30 allows around 1.5 times more UV radiation onto your skin than SPF 50. That’s an actual 150% difference [according to Wang’s article “… SPF 30 is allowing 50 percent more UV radiation onto your skin.”] in protection.

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Schrodinger’s Cat (author of the ‘eponymous’ blog) offers a good overview of the topic in a friendly, informative fashion albeit I found the ‘percentage’ to be a bit confusing. (S)he also provides a link to a previous posting about the ingredients in sunscreens (I do have one point of disagreement with Schrodinger’s Cat regarding oxybenzone) as well as links to Dr. Steven Q. Wang’s May 24, 2018 Ask the Expert article about sunscreens and SPF numbers on skincancer.org. You can find the percentage under the ‘What Does the SPF Number Mean?’ subsection, in the second paragraph.

Ingredients: metallic nanoparticles and oxybenzone

The use of metallic nanoparticles  (usually zinc oxide and/or (titanium dioxide) in sunscreens was loathed by civil society groups, in particular Friends of the Earth (FOE) who campaigned relentlessly against their use in sunscreens. The nadir for FOE was in February 2012 when the Australian government published a survey showing that 13% of the respondents were not using any sunscreens due to their fear of nanoparticles. For those who don’t know, Australia has the highest rate of skin cancer in the world. (You can read about the debacle in my Feb. 9, 2012 posting.)

At the time, the only civil society group which supported the use of metallic nanoparticles in sunscreens was the Environmental Working Group (EWG).  After an examination of the research they, to their own surprise, came out in favour (grudgingly) of metallic nanoparticles. (The EWG were more concerned about the use of oxybenzone in sunscreens.)

Over time, the EWG’s perspective has been adopted by other groups to the point where sunscreens with metallic nanoparticles are commonplace in ‘natural’ or ‘organic’ sunscreens.

As for oxybenzones, Schrodinger’s Cat in a May 23, 2018 posting about sunscreen ingredients notes this (Note: Links have been removed),

Oxybenzone – Chemical sunscreen, protects from UV damage. Oxybenzone belongs to the chemical family Benzophenone, which are persistent (difficult to get rid of), bioaccumulative (builds up in your body over time), and toxic, or PBT [or: Persistent, bioaccumulative and toxic substances (PBTs)]. They are a possible carcinogen (cancer-causing agent), endocrine disrupter; however, this is debatable. Also could cause developmental and reproductive toxicity, could cause organ system toxicity, as well as could cause irritation and potentially toxic to the environment.

It seems that the tide is turning against the use of oxybenzones (from a July 3, 2018 article by Adam Bluestein for Fast Company; Note: Links have been removed),

On July 3 [2018], Hawaii’s Governor, David Ig, will sign into law the first statewide ban on the sale of sunscreens containing chemicals that scientists say are damaging the Earth’s coral reefs. Passed by state legislators on May 1 [2018], the bill targets two chemicals, oxybenzone and octinoxate, which are found in thousands of sunscreens and other skincare products. Studies published over the past 10 years have found that these UV-filtering chemicals–called benzophenones–are highly toxic to juvenile corals and other marine life and contribute to the fatal bleaching of coral reefs (along with global warming and runoff pollutants from land). (A 2008 study by European researchers estimated that 4,000 to 6,000 tons of sunblock accumulates in coral reefs every year.) Also, though both substances are FDA-approved for use in sunscreens, the nonprofit Environmental Working Group notes numerous studies linking oxybenzone to hormone disruption and cell damage that may lead to skin cancer. In its 2018 annual sunscreen guide, the EWG found oxybenzone in two-thirds of the 650 products it reviewed.

The Hawaii ban won’t take effect until January 2021, but it’s already causing a wave of disruption that’s affecting sunscreen manufacturers, retailers, and the medical community.

For starters, several other municipalities have already or could soon join Hawaii’s effort. In May [2018], the Caribbean island of Bonaire announced a ban on chemicals sunscreens, and nonprofits such as the Sierra Club and Surfrider Foundation, along with dive industry and certain resort groups, are urging legislation to stop sunscreen pollution in California, Colorado, Florida, and the U.S. Virgin Islands. Marine nature reserves in Mexico already prohibit oxybenzone-containing sunscreens, and the U.S. National Park Service website for South Florida, Hawaii, U.S. Virgin Islands, and American Samoa recommends the use of “reef safe” sunscreens, which use natural mineral ingredients–zinc oxide or titanium oxide–to protect skin.

Makers of “eco,” “organic,” and “natural” sunscreens that already meet the new standards are seizing on the news from Hawaii to boost their visibility among the islands’ tourists–and to expand their footprint on the shelves of mainland retailers. This past spring, for example, Miami-based Raw Elements partnered with Hawaiian Airlines, Honolulu’s Waikiki Aquarium, the Aqua-Aston hotel group (Hawaii’s largest), and the Sheraton Maui Resort & Spa to get samples of its reef-safe zinc-oxide-based sunscreens to their guests. “These partnerships have had a tremendous impact raising awareness about this issue,” says founder and CEO Brian Guadagno, who notes that inquiries and sales have increased this year.

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As Bluestein notes there are some concerns about this and other potential bans,

“Eliminating the use of sunscreen ingredients considered to be safe and effective by the FDA with a long history of use not only restricts consumer choice, but is also at odds with skin cancer prevention efforts […],” says Bayer, owner of the Coppertone brand, in a statement to Fast Company. Bayer disputes the validity of studies used to support the ban, which were published by scientists from U.S. National Oceanic & Atmospheric Administration, the nonprofit Haereticus Environmental Laboratory, Tel Aviv University, the University of Hawaii, and elsewhere. “Oxybenzone in sunscreen has not been scientifically proven to have an effect on the environment. We take this issue seriously and, along with the industry, have supported additional research to confirm that there is no effect.”

Johnson & Johnson, which markets Neutrogena sunscreens, is taking a similar stance, worrying that “the recent efforts in Hawaii to ban sunscreens that contain oxybenzone may actually adversely affect public health,” according to a company spokesperson. “Science shows that sunscreens are a key factor in preventing skin cancer, and our scientific assessment of the lab studies done to date in Hawaii show the methods were questionable and the data insufficient to draw factual conclusions about any impact on coral reefs.”

Terrified (and rightly so) about anything scaring people away from using sunblock, The American Academy of Dermatology, also opposes Hawaii’s ban. Suzanne M. Olbricht, president of the AADA, has issued a statement that the organization “is concerned that the public’s risk of developing skin cancer could increase due to potential new restrictions in Hawaii that impact access to sunscreens with ingredients necessary for broad-spectrum protection, as well as the potential stigma around sunscreen use that could develop as a result of these restrictions.”

The fact is that there are currently a large number of widely available reef-safe products on the market that provide “full spectrum” protection up to SPF50–meaning they protect against both UVB rays that cause sunburns as well as UVA radiation, which causes deeper skin damage. SPFs higher than 50 are largely a marketing gimmick, say advocates of chemical-free products: According to the Environmental Working Group, properly applied SPF 50 sunscreen blocks 98% of UVB rays; SPF 100 blocks 99%. And a sunscreen lotion’s SPF rating has little to do with its ability to shield skin from UVA rays.

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I notice neither Bayer nor Johnson & Johnson nor the American Academy of Dermatology make mention of oxybenzone’s possible role as a hormone disruptor.

Given the importance that coral reefs have to the environment we all share, I’m inclined to support the oxybenzone ban based on that alone. Of course, it’s conceivable that metallic nanoparticles may also have a deleterious effect on coral reefs as their use increases. It’s to be hoped that’s not the case but if it is, then I’ll make my decisions accordingly and hope we have a viable alternative.

As for your sunscreen questions and needs, the Environment Working Group (EWG) has extensive information including a product guide on this page (scroll down to EWG’s Sunscreen Guide) and a discussion of ‘high’ SPF numbers I found useful for my decision-making.

European Commission okays use of nanoscale titanium dioxide in cosmetics and beauty products (sunscreens)

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Lynn L. Bergeson has a July 21, 2016 post on Nanotechnology Now with information about a July 14, 2016 European Commission (EC) regulation allowing nanoscale titanium dioxide to be used as a UV (ultraviolet) filter, i.e., sunscreen in various cosmetic and beauty products. You can find more details about the regulation and where it can be found in Bergeson’s posting. I was most interested in the specifics about the nano titanium dioxide particles,

… Titanium dioxide (nano) is not to be used in applications that may lead to exposure of the end user’s lungs by inhalation. Only nanomaterials having the following characteristics are allowed:
– Purity ¡Ý [sic] 99 percent;
– Rutile form, or rutile with up to 5 percent anatase, with crystalline structure and physical appearance as clusters of spherical, needle, or lanceolate shapes;
– Median particle size based on number size distribution ¡Ý [sic] 30 nanometers (nm);
– Aspect ratio from 1 to 4.5, and volume specific surface area ¡Ü [sic] 460 square meters per cubic meter (m2/cm3);
– Coated with silica, hydrated silica, alumina, aluminum hydroxide, aluminum stearate, stearic acid, trimethoxycaprylylsilane, glycerin, dimethicone, hydrogen dimethicone, or simethicone;
– Photocatalytic activity ¡Ü [sic] 10 percent compared to corresponding non-coated or non-doped reference, and
– Nanoparticles are photostable in the final formulation.

I’m guessing that purity should be greater than 99%, that median particle size should be greater than 30 nm, that aspect ratio should be less than 460 square meters per cubic meter, and that photocatalytic activity should be less than 10%.

If anyone should know better or have access to the data, please do let me know in the comments section.

Animal-based (some of it ‘fishy’) sunscreen from Oregon State University

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In the Northern Hemisphere countries it’s time to consider one’s sunscreen options.While this Oregon State University into animal-based sunscreens is intriguing,  market-ready options likely won’t be available for quite some time. (There is a second piece of related research, more ‘fishy’ in nature [pun], featured later in this post.) From a May 12, 2015 Oregon State University news release,

Researchers have discovered why many animal species can spend their whole lives outdoors with no apparent concern about high levels of solar exposure: they make their own sunscreen.

The findings, published today in the journal eLife by scientists from Oregon State University, found that many fish, amphibians, reptiles, and birds can naturally produce a compound called gadusol, which among other biologic activities provides protection from the ultraviolet, or sun-burning component of sunlight.

The researchers also believe that this ability may have been obtained through some prehistoric, natural genetic engineering.

Here’s an amusing image to illustrate the researchers’ point,

Gadusol is the gene found in some animals which gives natural sun protection. Courtesy: Oregon State University

Gadusol is the gene found in some animals which gives natural sun protection.
Courtesy: Oregon State University

The news release goes on to describe gadusol and its believed evolutionary pathway,

The gene that provides the capability to produce gadusol is remarkably similar to one found in algae, which may have transferred it to vertebrate animals – and because it’s so valuable, it’s been retained and passed along for hundreds of millions of years of animal evolution.

“Humans and mammals don’t have the ability to make this compound, but we’ve found that many other animal species do,” said Taifo Mahmud, a professor in the OSU College of Pharmacy, and lead author on the research.

The genetic pathway that allows gadusol production is found in animals ranging from rainbow trout to the American alligator, green sea turtle and a farmyard chicken.

“The ability to make gadusol, which was first discovered in fish eggs, clearly has some evolutionary value to be found in so many species,” Mahmud said. “We know it provides UV-B protection, it makes a pretty good sunscreen. But there may also be roles it plays as an antioxidant, in stress response, embryonic development and other functions.”

In their study, the OSU researchers also found a way to naturally produce gadusol in high volumes using yeast. With continued research, it may be possible to develop gadusol as an ingredient for different types of sunscreen products, cosmetics or pharmaceutical products for humans.

A conceptual possibility, Mahmud said, is that ingestion of gadusol could provide humans a systemic sunscreen, as opposed to a cream or compound that has to be rubbed onto the skin.

The existence of gadusol had been known of in some bacteria, algae and other life forms, but it was believed that vertebrate animals could only obtain it from their diet. The ability to directly synthesize what is essentially a sunscreen may play an important role in animal evolution, and more work is needed to understand the importance of this compound in animal physiology and ecology, the researchers said.

Here’s a link to and a citation for the paper,

De novo synthesis of a sunscreen compound in vertebrates by Andrew R Osborn, Khaled H Almabruk, Garrett Holzwarth, Shumpei Asamizu, Jane LaDu, Kelsey M Kean, P Andrew Karplus, Robert L Tanguay, Alan T Bakalinsky, and Taifo Mahmud. eLife 2015;4:e05919 DOI: http://dx.doi.org/10.7554/eLife.05919 Published May 12, 2015

This is an open access paper.

The second piece of related research, also published yesterday on May 12, 2015, comes from a pair of scientists at Harvard University. From a May 12, 2015  eLife news release on EurekAlert,

Scientists from Oregon State University [two authors are listed for the ‘zebrafish’ paper and both are from Harvard University] have discovered that fish can produce their own sunscreen. They have copied the method used by fish for potential use in humans.

In the study published in the journal eLife, scientists found that zebrafish are able to produce a chemical called gadusol that protects against UV radiation. They successfully reproduced the method that zebrafish use by expressing the relevant genes in yeast. The findings open the door to large-scale production of gadusol for sunscreen and as an antioxidant in pharmaceuticals.

…

Gadusol was originally identified in cod roe and has since been discovered in the eyes of the mantis shrimp, sea urchin eggs, sponges, and in the dormant eggs and newly hatched larvae of brine shrimps. It was previously thought that fish can only acquire the chemical through their diet or through a symbiotic relationship with bacteria.

Marine organisms in the upper ocean and on reefs are subject to intense and often unrelenting sunlight. Gadusol and related compounds are of great scientific interest for their ability to protect against DNA damage from UV rays. There is evidence that amphibians, reptiles, and birds can also produce gadusol, while the genetic machinery is lacking in humans and other mammals.

The team were investigating compounds similar to gadusol that are used to treat diabetes and fungal infections. It was believed that the biosynthetic enzyme common to all of them, EEVS, was only present in bacteria. The scientists were surprised to discover that fish and other vertebrates contain similar genes to those that code for EEVS.

Curious about their function in animals, they expressed the zebrafish gene in E. coli and analysis suggested that fish combine EEVS with another protein, whose production may be induced by light, to produce gadusol. To check that this combination is really sufficient, the scientists transferred the genes to yeast and set them to work to see what they would create. This confirmed the production of gadusol. Its successful production in yeast provides a viable route to commercialisation.

As well as providing UV protection, gadusol may also play a role in stress responses, in embryonic development, and as an antioxidant.

Here’s a link to and a citation for the second paper from this loosely affiliated team of Oregon State University and Harvard University researchers,

Biochemistry: Shedding light on sunscreen biosynthesis in zebrafish by Carolyn A Brotherton and Emily P Balskus. eLife 2015;4:e07961 DOI: http://dx.doi.org/10.7554/eLife.07961 Published May 12, 2015

This paper, too, is open access.

One final bit and this is about the journal, eLife, from their news release on EurekAlert,

About eLife

eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented, and shared. eLife publishes outstanding works across the life sciences and biomedicine — from basic biological research to applied, translational, and clinical studies. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Learn more at elifesciences.org.

It seems this journal is a joint, US (Howard Hughes Medical Institute), German (Max Planck Society), UK (Wellcome Trust) effort.

Nanotechnology risk perceptions in 2015 from Australia

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I haven’t stumbled across a study on the perceptions of risk and nanotechnology in quite a while.  Before commenting on this latest research from the University of Sydney, here’s a link to and a citation for this new Australian study, which is an open access paper,

Perceptions of risk from nanotechnologies and trust in stakeholders: a cross sectional study of public, academic, government and business attitudes by Adam Capon, James Gillespie, Margaret Rolfe, and Wayne Smith. BMC Public Health 2015, 15:424 Published April 26, 2015  DOI: 10.1186/s12889-015-1795-1

According to the authors, this is the first study that surveyed the general public, academics, government officials, and business people with an eye to distinguishing any differences that might exist in their attitudes,

Our study proposes to extend and develop the knowledge base regarding perceptions of risk from nanotechnology and trust by stakeholders. To do this we use a standardised questionnaire across all the stakeholders surveyed. Secondly we examine stakeholder groups beyond highly published scientists and people attending nano conferences/working in nano laboratories that had previously been surveyed to include academic, government and business stakeholders. These three groups were chosen not just for their expertise, but because they represent the interplay of stakeholders most likely to shape policy in this field. Thirdly we seek and report on views of general risk perception (to health) and for specific products (food, cosmetics and sunscreens, medicines, pesticides, tennis racquets and computers) which broadly represent Australian regulatory arms [22]. Finally we explore several trust actors (health department, scientists, journalists and politicians), all of who have the ability to shape policy.

Our study aims to test six hypotheses. First, very little targeted research has been undertaken on differing stakeholder views of risks from nanotechnology. To explore this we hypothesise that public perceptions of risks from nanotechnology will be greater than those held by ‘experts’. Second, existing studies suggest that food and health applications of nanotechnology are likely to arouse more controversy [23]. We will test the hypothesis that the public, academics, government and business respondents will all perceive a higher level of risk in nanotechnologies that penetrate or have close and prolonged contact with the body. Three, there is inconsistent evidence that increased familiarity with nanotechnology is associated with differing perceptions of nanotechnologies [24]. Our third hypothesis proposes that public self-reported familiarity with nanotechnology will be associated with a reduction in risk perception. This relationship will be found with each of the nano products in the study. Four, the public holds less trust in the government agencies with responsibility for regulating nanotechnology than that expressed by people working in nanotechnology based industries/researching nanotechnology [23]. Our fourth hypothesis tests the evidence for this proposition. We hypothesise that the trust the public vests in scientists, the health department, journalists and politicians will be less than those held by business, academic, and government respondents who have an interest in nanotechnology.

The last two hypotheses expand on hypothesis four, examining the trust of the public in greater detail. Studies have shown that the Australian public are more likely to trust scientists and scientific institutions, followed by government agencies with industry and mass media holding the least amount of trust [25],[26]. In our fifth hypothesis we test the proposition that the public will have greatest trust in scientists, followed by the health department with trust in journalists and politicians below these two. Finally, public trust in business leaders [27], science and consumer protection agencies [28] and government agencies [29] have all been associated with decreased nano risk perception. Examining other stakeholders, the greater trust that people working in nanotechnology based industries or researching nanotechnology had with scientists and government agencies, the less they perceived risk from nanotechnology [23],[30]. Our sixth hypothesis is that significant negative associations exist between the trust the public vest in scientists, health department, journalists and politicians and perceived risk of nanotechnology, both when this risk is considered to health and across all risk applications. Understanding this relationship between trust and risk perception is an important avenue for risk communication and education.

As interesting as I find methodology I’m going to skip most of it and focus on the sample size and demographics,

The surveys consisted of 1355 public, 301 academic, 19 government and 21 business responses. Gender representation of the weighted public survey population was comparable to the June 2012 Australian population estimates of approximately 50% male and female. Gender representationa for academic and business responses was more likely to be male (≈70%) while the gender of government respondents was almost evenly balanced.

Three hundred and ninety eight public respondents (30%) were categorised as having no familiarity with nanotechnology, while 528 (39%) were categorised as having some familiarity and 422 (31%) as having moderate familiarity with nanotechnology.

Amongst the academic responses, the best represented area of research (38%) was in the field of nanomaterials. Nanocharacterisation, nanofabrication, nanobiotechnology/nanomedicine, nanoscale theory/computation, nanophotonics, and nanoelectronics/nanomagnetics represented between 15% to 4% per discipline in descending order. The least represented discipline was translational nanoresearch (2%), of which half were involved in nanotoxicology and the other either in ethical or social research on risk/public attitudes/public impact or did not provide a sub specialisation. Of the business responses the greatest percentage of business involvement was in nanomaterial manufacture, importation or research (33% – 23%). Importation of products containing nanomaterials, waste collection/processing and legal issues had little representation. The highest representation of government respondents was health and safety (37%) followed by communication/social impact (26%), business development (16%) and environment (11%).

The analysis of the results is well worth reading,

The Australian public perceives greater risks from manufactured nanomaterials and shows less trust in scientists and the health department to provide protection from possible health effects than academic, business and government stakeholders in the nanotechnology sector. Food applications and cosmetics/sunscreens loom high on the list of public concerns, although medicines and pesticides are also causes of public concern. Policy makers should be aware of these risk and trust disparities and address public sentiment by treating nanotechnology applications in the higher risk areas with greater caution. Risk communication is best placed in the hands of trusted scientists.

I am a little surprised that no mention was made of the nanosunscreen situation of 2012 where a research study found that 13% (originally reported as 17%) of Australians surveyed said they didn’t use any sunscreens due to fear of nanoparticles. I have the story in my Feb. 9, 2012 posting. Be sure to read through to the end as there were a couple of updates.

Bioprospecting yields sunscreen ingredient fromTrondheim Fjord microorganism

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Norwegian business, Promar, has taken out patents based on research showing that a bacterium living in the Trondheim Flord has a trait much prized by makers of sunscreens, from an Aug. 6, 2013 news item on ScienceDaily,

Norwegian researchers have recently discovered a microorganism with very special properties — a bacteria living in Trondheim Fjord with the Latin name Micrococcus luteus. It possesses a trait which is rare and highly sought-after by medical science and the cosmetics industry — a pigment which can absorb long-wavelength UV radiation (in the range 350-475 nanometres).

The researchers are from SINTEF (Norwegian: Stiftelsen for industriell og teknisk forskning), which bills itself as the largest independent research organization in Scandinavia. Their July 25, 2013 news release by Christina Benjaminsen, which originated the news item, explains why this discovery is causing some excitement,

Long-wavelength UV radiation is linked to many forms of skin cancer and malignant melanomas. Currently, there are no sunscreens on the market able to filter out this type of radiation.

However, the Norwegian company Promar AS has taken out patents for both the manufacture and use in future sunscreens of a light-filtering substance extracted from this bacterium. This has been achieved with the help of researchers at SINTEF.

Researchers at SINTEF have what amounts to a library of microorganisms after years of bioprospecting (exploring for organisms with traits useful in industrial applications), from the SINTEF nrews release,

The backdrop to this project involved activities taking place at SINTEF and NTNU [Norwegian University of Science and Technology] by which we collected a variety of different microorganisms from the water surface in Trondheim Fjord. These organisms had one thing in common. They possessed a variety of naturally-occurring light-absorbing pigments. “This is why they are very colourful”, says Trygve Brautaset, Project and Research Manager at SINTEF. The end result was an entire “library” of such microorganisms.

At about the same time, the Norwegian company Promar AS had been working on the idea of manufacturing a substance with a property lacking in sunscreen products currently on the market – the ability to filter out long-wavelength UV radiation.

This is why SINTEF and NTNU were contracted to look for a pigment with this trait. After investigating hundreds of different bacteria, the researchers found Mirococcus luteus in “the library”. It ticked all the boxes. The microscopic organism, no bigger than 1-2 micrometres across, was found to contain a particular carotenoid, known to organic chemists as sarcinaxanthin. This pigment absorbs sunlight at just the wavelength which Promar wanted to provide protection against. By adding sarcinaxanthin to sunscreen, harmful solar radiation is absorbed by the cream before it reaches the skin. However, commercial production of the carotenoid required some tricky genetic engineering.

The process of isolating the particular pigment took two years, from the SINTEF news release,

Firstly, the pigments produced by the bacteria had to be characterized using a variety of chemical techniques designed to identify the desired sarcinaxanthin carotenoid. Subsequently, the genes used by the bacterium to synthesise sarcinaxanthin had to be isolated. Finally, the research team had to transfer all the genes into a host bacterium. The aim was to create an artificial bacterium able to produce sarcinaxanthin sufficiently effectively to be of commercial interest.

“After about two years’ intensive work SINTEF had the first examples of this bacterium ready”, says Brautaset. “We have now synthesised a sarcinaxanthin-producing bacterium which can be cultivated.

We will now be carrying out tests to see if we can produce it in so-called fermenters (cultivation tanks) in the laboratory. This represents an excellent method for the effective production of sarcinaxanthin in volumes large enough to make industrial applications possible”, he says.

UVAblue is the commercial name that’s been given to this new synthetically derived version of sarcinaxanthi. This new substance has aroused much interest,

… “We have been in France talking to many of the world’s largest cosmetics manufacturers”, he says. “Everyone we talked to was very interested in making use of this type of sunscreen factor in their products”, says Goksøyr [Managing Director Audun Goksøyr at Promar AS].

Among the reasons for this is that the cells which generate malignant melanomas are located deep in the skin. It is primarily long-wavelength UV radiation which penetrates to these cells when we sunbathe. By preventing this radiation from penetrating the skin will be an excellent way of averting the development of this highly lethal form of cancer. It will also act as an anti-wrinkle agent.

You can find out more about UVAblue at its eponymous website. ETA Aug. 13, 2013 1230 pm PDT: I’ve removed a citation for and a link to a paper that was incorrectly placed here.

Sunscreen from coral

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It’s a fascinating project they’re working on at King’s College London (KCL), converting an amino acid found in coral into a sunscreen for humans. The researchers have just signed an agreement to work with skincare company, Aethic but the  research was first discussed when it was still at the laboratory stage in an Aug. 2011 video produced by KCL,

The Sept. 12, 2012 news item on physorg.com makes the latest announcement about the project,

King’s College London has entered into an agreement with skincare company Aethic to develop the first sunscreen based on MAA’s (mycosporine-like amino acids), produced by coral.

It was last year that a team led by Dr Paul Long at King’s discovered how the naturally-occurring MAA’s were produced. Algae living within coral make a compound that is transported to the coral, which then modifies it into a sunscreen for the benefit of both the coral and the algae. Not only does this protect them both from UV damage, but fish that feed on the coral also benefit from this sunscreen protection.

The KCL Sept. 11, 2012 news release (which originated the new item) notes,

The next phase of development is for the researchers to work with Professor Antony Young and colleagues at the St John’s Institute of Dermatology at King’s, to test the efficacy of the compounds using human skin models.

Aethic’s Sôvée sunscreen was selected as the best ‘host’ product for the compound because of its existing broad-spectrum UVA/UVB and photo-stability characteristics and scientifically proven ecocompatibility credentials.

Dr Paul Long, Reader in Pharmacognosy at King’s Institute of Pharmaceutical Science, said: “While MAA’s have a number of other potential applications, human sunscreen is certainly a good place to begin proving the compound’s features. If our further studies confirm the results we are expecting, we hope that we will be able to develop a sunscreen with the broadest spectrum of protection.  Aethic has the best product and philosophy with which to proceed this exciting project.” [emphasis mine]

I went to the Aethic website and found this on the Be Aethic page,

Being Aethic means you are one with nature through our products. It means your skin lives better, feels better and looks better.

It means you do too.

…

Your skin is your largest organ. It’s worth looking after from within, with a good diet, and from the outside by protecting it from daily life and the sun’s harmful rays, by keeping it nourished.

Aethic Sôvée has the most photostable sun filters – anywhere. It has organic moisturisers. It contains a skin anti-oxidant. We developed this formula to treat your skin like royalty. And nature will love you for it as well.

People have been telling us that doing less damage to your skin and the ocean are amazing things to do together

Be loved by nature even more – share this with your friends. The more people you tell, the bigger the difference you make. Here’s why.

Deep down, most people probably suspected that the many ingredients they put on their skin from other sunscreens, must do some harm somewhere. Sure enough, in 2008 it was proven by Prof Roberto Danovaro, from Marche Polytechnic University in Italy, that these products can seriously damage coral. He has since discovered they do damage to clams too.

When you use Aethic Sôvée, you know that you’re leaving nothing behind to harm the ocean. In fact, with your contribution to The Going Blue Foundation’s coral nursery fund, you are going positive. Marine Positive – the certification Aethic Sôvée has received.

Unfortunately this copy is a bit of heavy on the sanctimonious side but the possibility of minimizing one’s negative impact on the  world’s oceans while preventing damage to skin can’t be ignored.

In any event, I found the information about the sunscreen making its way up the food chain and benefitting predators amused me when I considered the possibility of a bear or cougar benefitting should they happen to eat me while I’m using this new sunscreen. Given that this solution is not based on metal oxides perhaps it will find more favour with the ‘anti-nanosunscreen’ crowd.

Sunscreen and nano time, again (part 1)

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Before launching into another discussion about the safety of sunscreens with titanium dioxide and/or zinc oxide nanoparticles, I’m going to mention uncertainty and risk. First, the notion of uncertainty that I”m using is proposed in a theory coined Knightian Uncertainty and comes from the field of economics. Here’s a definition from an article by Peter Dizikes at the Massachusetts Institute of Technology News Office,

Frank Knight was an idiosyncratic economist who formalized a distinction between risk and uncertainty in his 1921 book, Risk, Uncertainty, and Profit. As Knight saw it, an ever-changing world brings new opportunities for businesses to make profits, but also means we have imperfect knowledge of future events. Therefore, according to Knight, risk applies to situations where we do not know the outcome of a given situation, but can accurately measure the odds. Uncertainty, on the other hand, applies to situations where we cannot know all the information we need in order to set accurate odds in the first place.

Making a distinction between uncertainty and risk is very helpful in trying to understand some of the less pleasant possibilities of nanotechnology-enabled products. As more research about titanium dioxide and zinc oxide nanoparticles in sunscreens is published, there’s more information that can be used to assess risk.

With regard to health, two categories of risk are commonly discussed, absolute risk and relative risk. Here is a definition excerpted  from the Patient UK website,

Absolute risk of a disease is your risk of developing the disease over a time-period. We all have absolute risks of developing various diseases such as heart disease, cancer, stroke, etc. The same absolute risk can be expressed in different ways. For example, say you have a 1 in 10 risk of developing a certain disease in your life. This can also be said a 10% risk, or a 0.1 risk – depending if you use percentages or decimals.

Relative risk is used to compare the risk in two different groups of people. For example, the groups could be ‘smokers’ and ‘non-smokers’. All sorts of groups are compared to others in medical research to see if belonging to a group increases or decreases your risk of developing certain diseases. For example, research has shown that smokers have a higher risk of developing heart disease compared to (relative to) non-smokers.

In these scenarios (heart diseases and smoking vs. non-smoking) there’s enough information to make an informed guess even though a degree of uncertainty still exists. By contrast, the situation with nanosunscreens doesn’t lend itself to an analysis of absolute or relative risk as basic information is still being gathered.

Meanwhile the civil society/activist group, Friends of the Earth (FOE) has renewed their call to remove sunscreens with titanium dioxide and/or zinc oxide nanoparticles from the market. Andrew Maynard at 2020 Science has very carefully analysed the six studies that FOE has published on their nanosunscreen page. From Andrew’s posting,

As these are evidence-based statements, I thought it would be worth while going through them, and taking a look at the evidence they are based on:

FoE: “Manufactured nanomaterials used in sunscreens (such as zinc oxide and titanium oxide) can Damage human colon cells: A study from the University of Utah showed that nano zinc oxide is toxic to colon cells even in small amounts. The scientists called for more research and warned that the evidence is especially concerning for children who are more likely to accidently ingest sunscreen. The colon is vital because it eliminates food waste and absorbs important nutrients.”

This was a study that looked at interactions between zinc oxide (ZnO) particles and cells derived from the human colon, and was carried out in vitro (i.e. in a cell culture rather than in animals or people). It did indeed indicate that nanometer scale ZnO particles were around twice as potent as larger ZnO particles in their ability to kill these cells under idealized conditions. But the research also emphasized that direct contact with the cells was needed for a nanoscale particle-related effect. In fact, the title of the paper was “ZnO Particulate Matter Requires Cell Contact for Toxicity in Human Colon Cancer Cells,” emphasizing this point above the higher potency of the more finely structured particles.

The research was interesting, but did not resolve whether zinc oxide particles could survive long enough in the gut to come into contact with cells lining the colon, whether interactions like those observed in the laboratory are plausible under real-world conditions, and what levels of exposure would be needed to cause significant harm. The research also indicated that larger particles of zinc oxide – similar to particles that have been used in sunscreens and other topical creams for decades – were toxic to cells under the conditions of the study.

So regular and nanosized particles of zinc oxide are both toxic to colon cells with the nanosized particles being 2 x more toxic. That’s not great but we’ve been using regular sized zinc oxide particles  for quite some time and, as far as I know, no one claims that it causes colon cancer.  Also, these tests were conducted with cultures (i. e. not inside the human or any other type of body) so there’s no proof that zinc oxide of any size survives long enough to enter the colon. If there were an absolute risk associated with using regular sized zinc oxide particles, theoretically we could infer an absolute risk for nanosized zinc oxide particles.

More later today.