Tag Archives: nano titanium dioxide

Dunkin’ Donuts and nano titanium dioxide

It’s been a busy few days for titanium dioxide, nano and otherwise, as the news about its removal from powdered sugar in Dunkin’ Donuts products ripples through the nano blogosphere. A March 6, 2015 news item on Azonano kicks off the discussion with an announcement,

Dunkin’ Brands, the parent company of the Dunkin’ Donuts chain, has agreed to remove titanium dioxide, a whitening agent that is commonly a source of nanomaterials, from all powdered sugar used to make the company’s donuts. As a result of this progress, the advocacy group As You Sow has withdrawn a shareholder proposal asking Dunkin’ to assess and reduce the risks of using nanomaterials in its food products.

Here’s a brief recent history of Dunkin’ Donuts and nano titanium dioxide from my Aug. 21, 2014 posting titled, FOE, nano, and food: part two of three (the problem with research),

Returning to the ‘debate’, a July 11, 2014 article by Sarah Shemkus for a sponsored section in the UK’s Guardian newspaper highlights an initiative taken by an environmental organization, As You Sow, concerning titanium dioxide in Dunkin’ Donuts’ products (Note: A link has been removed),

The activists at environmental nonprofit As You Sow want you to take another look at your breakfast doughnut. The organization recently filed a shareholder resolution asking Dunkin’ Brands, the parent company of Dunkin’ Donuts, to identify products that may contain nanomaterials and to prepare a report assessing the risks of using these substances in foods.

Their resolution received a fair amount of support: at the company’s annual general meeting in May, 18.7% of shareholders, representing $547m in investment, voted for it. Danielle Fugere, As You Sow’s president, claims that it was the first such resolution to ever receive a vote. Though it did not pass, she says that she is encouraged by the support it received.

“That’s a substantial number of votes in favor, especially for a first-time resolution,” she says.

The measure was driven by recent testing sponsored by As You Sow, which found nanoparticles of titanium dioxide in the powdered sugar that coats some of the donut chain’s products. [emphasis mine] An additive widely used to boost whiteness in products from toothpaste to plastic, microscopic titanium dioxide has not been conclusively proven unsafe for human consumption. Then again, As You Sow contends, there also isn’t proof that it is harmless.

“Until a company can demonstrate the use of nanomaterials is safe, we’re asking companies either to not use them or to provide labels,” says Fugere. “It would make more sense to understand these materials before putting them in our food.”

As I understand it, Dunkin’ Donuts will be removing all titanium dioxide, nano-sized or other, from powdered sugar used in its products. It seems As You Sow’s promise to withdraw its July 2104 shareholder resolution is the main reason for Dunkin’ Donuts’ decision. While I was and am critical of Dunkin’ Donuts’ handling of the situation with As You Sow, I am somewhat distressed that the company seems to have acquiesced on the basis of research which is, at best, inconclusive.

Dr. Andrew Maynard, director of the University of Michigan Risk Science Centre, has written a substantive analysis of the current situation regarding nano titanium dioxide in a March 12, 2015 post on his 2020 Science blog (Note: Links have been removed),

Titanium dioxide (which isn’t the same thing as the metal titanium) is an inert, insoluble material that’s used as a whitener in everything from paper and paint to plastics. It’s the active ingredient in many mineral-based sunscreens. And as a pigment, is also used to make food products look more appealing.

Part of the appeal to food producers is that titanium dioxide is a pretty dull chemical. It doesn’t dissolve in water. It isn’t particularly reactive. It isn’t easily absorbed into the body from food. And it doesn’t seem to cause adverse health problems. It just seems to do what manufacturers want it to do – make food look better. It’s what makes the powdered sugar coating on donuts appear so dense and snow white. Titanium dioxide gives it a boost.

And you’ve probably been consuming it for years without knowing. In the US, the Food and Drug Administration allows food products to contain up to 1% food-grade titanium dioxide without the need to include it on the ingredient label. Help yourself to a slice of bread, a bar of chocolate, a spoonful of mayonnaise or a donut, and chances are you’ll be eating a small amount of the substance.

Andrew goes on to describe the concerns that groups such as You As Sow have (Note: Links have been removed),

For some years now, researchers have recognized that some powders become more toxic the smaller the individual particles are, and titanium dioxide is no exception. Pigment grade titanium dioxide – the stuff typically used in consumer products and food – contains particles around 200 nanometers in diameter, or around one five hundredth the width of a human hair. Inhale large quantities of these titanium dioxide particles (I’m thinking “can’t see your hand in front of your face” quantities), and your lungs would begin to feel it.

If the particles are smaller though, it takes much less material to cause the same effect.

But you’d still need to inhale very large quantities of the material for it to be harmful. And while eating a powdered donut can certainly be messy, it’s highly unlikely that you’re going to end up stuck in a cloud of titanium dioxide-tinted powdered sugar coating!

… Depending on what they are made of and what shape they are, research has shown that some nanoparticles are capable of getting to parts of the body that are inaccessible to larger particles. And some particles are more chemically reactive because of their small size. Some may cause unexpected harm simply because they are small enough to throw a nano-wrench into the nano-workings of your cells.

This body of research is why organizations like As You Sow have been advocating caution in using nanoparticles in products without appropriate testing – especially in food. But the science about nanoparticles isn’t as straightforward as it seems.

As Andrew notes,

First of all, particles of the same size but made of different materials can behave in radically different ways. Assuming one type of nanoparticle is potentially harmful because of what another type does is the equivalent of avoiding apples because you’re allergic to oysters.

He describes some of the research on nano titanium dioxide (Note: Links have been removed),

… In 2004 the European Food Safety Agency carried out a comprehensive safety review of the material. After considering the available evidence on the same materials that are currently being used in products like Dunkin’ Donuts, the review panel concluded that there no evidence for safety concerns.

Most research on titanium dioxide nanoparticles has been carried out on ones that are inhaled, not ones we eat. Yet nanoparticles in the gut are a very different proposition to those that are breathed in.

Studies into the impacts of ingested nanoparticles are still in their infancy, and more research is definitely needed. Early indications are that the gastrointestinal tract is pretty good at handling small quantities of these fine particles. This stands to reason given the naturally occurring nanoparticles we inadvertently eat every day, from charred foods and soil residue on veggies and salad, to more esoteric products such as clay-baked potatoes. There’s even evidence that nanoparticles occur naturally inside the gastrointestinal tract.

He also probes the issue’s, nanoparticles, be they titanium dioxide or otherwise, and toxicity, complexity (Note: Links have been removed),

There’s a small possibility that we haven’t been looking in the right places when it comes to possible health issues. Maybe – just maybe – there could be long term health problems from this seemingly ubiquitous diet of small, insoluble particles that we just haven’t spotted yet. It’s the sort of question that scientists love to ask, because it opens up new avenues of research. It doesn’t mean that there is an issue, just that there is sufficient wiggle room in what we don’t know to ask interesting questions.

… While there is no evidence of a causal association between titanium dioxide in food and ill health, some studies – but not all by any means – suggest that large quantities of titanium dioxide nanoparticles can cause harm if they get to specific parts of the body.

For instance, there are a growing number of published studies that indicate nanometer sized titanium dioxide particles may cause DNA damage at high concentrations if it can get into cells. But while these studies demonstrate the potential for harm to occur, they lack information on how much material is needed, and under what conditions, for significant harm. And they tend to be associated with much larger quantities of material than anyone is likely to be ingesting on a regular basis.

They are also counterbalanced by studies that show no effects, indicating that there is still considerable uncertainty over the toxicity or otherwise of the material. It’s as if we’ve just discovered that paper can cause cuts, but we’re not sure yet whether this is a minor inconvenience or potentially life threatening. In the case of nanoscale titanium dioxide, it’s the classic case of “more research is needed.”

I strongly suggest reading Andrew’s post in its entirety either here on the University of Michigan website or here on The Conversation website.

Dexter Johnson in a March 11, 2015 post on his Nanoclast blog also weighs in on the discussion. He provides a very neat summary of the issues along with these observations (Note Links have been removed),

With decades of TiO2 being in our food supply and no reports of toxic reactions, it would seem that the threshold for proof is extremely high, especially when you combine the term “nano” with “asbestos”.

As You Sow makes sure to point out that asbestos is a nanoparticle. While the average diameter of an asbestos fiber is around 20 to 90 nm, their lengths varied between 200 nm and 200 micrometers.

The toxic aspect of asbestos was not its diameter, but its length. …

In addition to his summary Dexter highlights As You Sows attempt to link titanium dioxide nanoparticles to asbestos. I suggest reading his post for an informed description of what made asbestos so toxic (here) and why the linkage seems specious at this time.

For anyone interested in how As You Sow managed to introduce asbestos toxicity issues into a discussion about nano titanium dioxide and food products, there’s this from As You Sow’s FAQs (frequently asked questions) about nanomaterials in food page,

Why are nanomaterials in food important to investors?

When technology is used before ensuring that it is safe for humans and the environment, and before regulatory standards exist, companies can be exposed to significant financial, legal, and reputational risk. The limited studies that exist on nanomaterials, including nanoscale titanium dioxide*, have indicated that ingestion of these particles may pose health hazards.

The inaction of regulators does not protect companies, especially when the regulators themselves warn of the dangers of nanoparticles’ largely unknown risks. Draft guidance issued by the U.S. Food and Drug Administration raises questions about the safety of nanoparticles and demonstrates the general lack of knowledge about the technology and its effects. (1)

Asbestos litigation is a good example of the risks that can arise from using an emerging technology before it is proven safe. Use of asbestos (a nanomaterial) has created the longest, most expensive mass tort in national history with total U.S. costs now standing at over $250 billion. (2) If companies been asked to investigate and minimize or avoid risks prior to adopting asbestos technology, a sad and expensive chapter in worker harm could have been avoided.

* Titanium dioxide is a common pigment and FDA-approved food additive. It is used as a whitener, a dispersant, and a thickener.

While I don’t particularly appreciate fear-mongering as a tactic, the strategy of targeting investors and their concerns, seems to have helped As You Sow win its way.

Removing titanium dioxide nanoparticles from water may not be that easy

A March 10, 2015 news item on Nanowerk highlights some research into the removal of nanoscale titanium dioxide particles from water supplies (Note: A link has been removed),

The increased use of engineered nanoparticles (ENMs) in commercial and industrial applications is raising concern over the environmental and health effects of nanoparticles released into the water supply. A timely study that analyzes the ability of typical water pretreatment methods to remove titanium dioxide, the most commonly used ENM, is published in Environmental Engineering Science (“Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry”). The article is available free on the Environmental Engineering Science website until April 10, 2015.

A March 10, 2015 Mary Ann Liebert, Inc., publishers news release (also on EurekAlert), which originated the news item, provides more details about the work (Note: A link has been removed),

Nichola Kinsinger, Ryan Honda, Valerie Keene, and Sharon Walker, University of California, Riverside, suggest that current methods of water prefiltration treatment cannot adequately remove titanium dioxide ENMs. They describe the results of scaled-down tests to evaluate the effectiveness of three traditional methods—coagulation, flocculation, and sedimentation—in the article “Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry.”

“As nanoscience and engineering allow us to develop new exciting products, we must be ever mindful of associated consequences of these advances,” says Domenico Grasso, PhD, PE, DEE, Editor-in-Chief of Environmental Engineering Science and Provost, University of Delaware. “Professor Walker and her team have presented an excellent report raising concerns that some engineered nanomaterials may find their ways into our water supplies.”

“While further optimization of such treatment processes may allow for improved removal efficiencies, this study illustrates the challenges that we must be prepared to face with the emergence of new engineered nanomaterials,” says Sharon Walker, PhD, Professor of Chemical and Environmental Engineering, University of California, Riverside.

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

Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry by Nichola Kinsinger, Ryan Honda, Valerie Keene, and Sharon L. Walker. Environmental Engineering Science. doi:10.1089/ees.2014.0288.

This paper is freely available until April 10, 2015.

Interestingly Sharon Walker and Nichola Kinsinger recently co-authored a paper (mentioned in my March 9, 2015 post) about copper nanoparticles and water treatment which concluded this about copper nanoparticles in water supplies,

The researchers found that the copper nanoparticles, when studied outside the septic tank, impacted zebrafish embryo hatching rates at concentrations as low as 0.5 parts per million. However, when the copper nanoparticles were released into the replica septic tank, which included liquids that simulated human digested food and household wastewater, they were not bioavailable and didn’t impact hatching rates.

Taking these these two paper into account (and the many others I’ve read), there is no simple or universal answer to the question of whether or not ENPs or ENMs are going to pose environmental problems.

Laundry detergents that clean clothes and pollution from the air

Tony Ryan, as an individual (and with Helen Storey), knows how to provoke interest in a topic many of us find tired, air pollution. This time, Ryan and Storey have developed a laundry detergent additive through their Catalytic Clothing venture (mentioned previously in a Feb. 24, 2012 posting and in a July 8, 2011 posting). From Adele Peters’ July 22, 2014 article for Fast Company (Note: A link has been removed),

Here’s another reason cities need more pedestrians: If someone is wearing clothes that happened to be washed in the right detergent, just their walking down the street can suck smog out of the surrounding air.

For the last few years, researchers at the Catalytic Clothing project have been testing a pollution-fighting laundry detergent that coats clothing in nano-sized particles of titanium dioxide. The additive traps smog and converts it into a harmless byproduct. It’s the same principle that has been used smog-eating buildings and roads, but clothing has the advantage of actually taking up more space.

Kasey Lum in a June 25, 2014 article for Ecouterre describes the product as a “laundry additive [which] could turn clothing in mobile air purifiers,”

CatClo piggybacks the regular laundering process to deposit nanoparticles of titanium dioxide onto the fibers of the clothing. Exposure to light excites electrons on the particles’ surface, creating free radicals that react with water to make hydrogen peroxide. This, in turn, “bleaches out” volatile organic compounds and nitrogen oxides in the atmosphere, according to Storey, rendering them harmless.

Lum referenced a May 23, 2014 article written by Helen Storey and Tony Ryan for the UK’s Guardian, newspaper which gives a history of their venture, Catalytic Clothing, and an update on their laundry additive (Note: Links have been removed),

It was through a weird and wonderful coincidence on BBC [British Broadcasting Corporation] Radio 4 that we met to discuss quantum mechanics and plastic packaging, resulting in the Wonderland Project, where we created disappearing gowns and bottles as a metaphor for a planet that is going the same way.

Spurred by this collaborative way of working, Wonderland led to Catalytic Clothing, a liquid laundry additive. The idea came out of conversations about how we could harness the surface of our clothing and the power of fashion to communicate complex scientific ideas – and so began the campaign for clean air.

(When I first wrote about Catalytic Clothing I was under the impression that it was an art/science venture focused on clothing as a means of cleaning the air. I was unaware they were working on a laundry additive.)

Getting back to Storey’s and Ryan’s article (Note: A link has been removed),

Catalytic Clothing (CatClo) uses existing technology in a radical new way. Photocatalytic surface treatments that break down airborne pollutants are widely applied to urban spaces, in concrete, on buildings and self-cleaning glass. The efficacy is greatly increased when applied to clothing – not only is there a large surface area, but there is also a temperature gradient creating a constant flux of air, and movement through walking creates our own micro-wind, so catalysing ourselves makes us the most effective air purifiers of them all.

CatClo contains nanoparticles of titania (TiO2) a thousand times finer than a human hair. [generally nanoscale is described as between 1/60,000 to 1/100,000 of a hair’s width] When clothes are laundered through the washing process, particles are deposited onto the fibres of the fabric. When the catalysed clothes are worn, light shines on the titanium particles and it excites the electrons on the particle surface. These electrons cause oxygen molecules to split creating free-radicals that then react with water to make hydrogen peroxide. This then bleaches out the volatile organic compounds and nitrogen oxides (NOx) that are polluting the atmosphere.

The whole process is sped up when people, wearing the clothes, are walking down the street. The collective power of everyone wearing clothes treated with CatClo is extraordinary. If the whole population of a city such as Sheffield was to launder their clothes at home with a product containing CatClo technology they would have the power to remove three tonnes per day of harmful NOx pollution.

So, if the technology exists to clear the air, why isn’t it available? From Storey’s and Ryan’s article,

Altruism, is a hard concept to sell to big business. We have approached and worked with some of the world’s largest producers of laundry products but even though the technology exists and could be relatively cheap to add to existing products, it’s proved to be a tough sell. The fact that by catalysing your clothes the clean air you create will be breathed in by the person behind you is not seen as marketable.

A more serious issue is that photocatalysts can’t tell the difference between a bad pollutant and a “good” one; for example, it treats perfume as just another volatile organic compound like pollution. This is an untenable threat to an entire industry and existing products owned by those best able to take CatClo to market.

We’ve recently travelled to China to see whether CatClo could work there. China is a place where perfume isn’t culturally valued, but the common good is, so a country with one of the biggest pollution problems on the planet, and a government that isn’t hidebound by business as usual, might be the best place to start.

In the midst of developing their laundry additive, Storey and Ryan produced a pop-up exhibition, A Field of Jeans (first mentioned here in an Oct. 13, 2011 posting which lists events for the 2011 London Science Festival), to raise public awareness and support (from the article),

During the research period, we realised that there were more jeans on the planet than people. Knowing this, we launched a pop-up exhibition, A Field of Jeans. The jeans we catalysed are all recycled and as it turns out, because of the special nature of cotton denim, are the most efficacious fabric of all to support the catalysts.

The public have been overwhelmingly supportive; once fears about the “chemicals”, “nanotech” or becoming dirt magnets were dispelled, we captured people’s imagination and proved that CatClo could eventually be as normal as fluoride in toothpaste with enormous potential to increase wellbeing and clean up our polluted cities.

The pop-up exhibition is now at Thomas Tallis School in London (from the Catalytic Clothing homepage),

New 2013/2014
Field of Jeans is at Thomas Tallis school from December 2nd 2013 until further notice. Jeans can be viewed from Kidbrooke Park Road, London SE3 outside the main school entrance. This will inspire a piece of work across the school called Catalytic Learning. More will be posted here soon.
Click here for images

http://www.thomastallis.co.uk/

Here’s an image from the Field of Jeans,

Image can be found here at: https://www.flickr.com/photos/helenstoreyfoundation/sets/72157638346745735/

Image can be found here at: https://www.flickr.com/photos/helenstoreyfoundation/sets/72157638346745735/

I last featured Tony Ryan’s work here in a May 15, 2014 posting about a poem and a catalytic billboard at the University of Sheffield where Ryan is the Pro-Vice-Chancellor for Science.

Sandia National Laboratories looking for commercial partners to bring titanium dioxide nanoparticles (5 nm in diameter) to market

Sandia National Laboratories (Sandia Labs) doesn’t  ask directly but I think the call for partners is more than heavily implied. Let’s start with a June 17, 2014 news item on ScienceDaily,

Sandia National Laboratories has come up with an inexpensive way to synthesize titanium-dioxide nanoparticles and is seeking partners who can demonstrate the process at industrial scale for everything from solar cells to light-emitting diodes (LEDs).

Titanium-dioxide (TiO2) nanoparticles show great promise as fillers to tune the refractive index of anti-reflective coatings on signs and optical encapsulants for LEDs, solar cells and other optical devices. Optical encapsulants are coverings or coatings, usually made of silicone, that protect a device.

Industry has largely shunned TiO2 nanoparticles because they’ve been difficult and expensive to make, and current methods produce particles that are too large.

Sandia became interested in TiO2 for optical encapsulants because of its work on LED materials for solid-state lighting.

Current production methods for TiO2 often require high-temperature processing or costly surfactants — molecules that bind to something to make it soluble in another material, like dish soap does with fat.
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Those methods produce less-than-ideal nanoparticles that are very expensive, can vary widely in size and show significant particle clumping, called agglomeration.

Sandia’s technique, on the other hand, uses readily available, low-cost materials and results in nanoparticles that are small, roughly uniform in size and don’t clump.

“We wanted something that was low cost and scalable, and that made particles that were very small,” said researcher Todd Monson, who along with principal investigator Dale Huber patented the process in mid-2011 as “High-yield synthesis of brookite TiO2 nanoparticles.” [emphases mine]

A June 17, 2014 Sandia Labs news release, which originated the news item, goes on to describe the technology (Note: Links have been removed),

Their (Monson and Huber) method produces nanoparticles roughly 5 nanometers in diameter, approximately 100 times smaller than the wavelength of visible light, so there’s little light scattering, Monson said.

“That’s the advantage of nanoparticles — not just nanoparticles, but small nanoparticles,” he said.

Scattering decreases the amount of light transmission. Less scattering also can help extract more light, in the case of an LED, or capture more light, in the case of a solar cell.

TiO2 can increase the refractive index of materials, such as silicone in lenses or optical encapsulants. Refractive index is the ability of material to bend light. Eyeglass lenses, for example, have a high refractive index.

Practical nanoparticles must be able to handle different surfactants so they’re soluble in a wide range of solvents. Different applications require different solvents for processing.

“If someone wants to use TiO2 nanoparticles in a range of different polymers and applications, it’s convenient to have your particles be suspension-stable in a wide range of solvents as well,” Monson said. “Some biological applications may require stability in aqueous-based solvents, so it could be very useful to have surfactants available that can make the particles stable in water.”

The researchers came up with their synthesis technique by pooling their backgrounds — Huber’s expertise in nanoparticle synthesis and polymer chemistry and Monson’s knowledge of materials physics. The work was done under a Laboratory Directed Research and Development project Huber began in 2005.

“The original project goals were to investigate the basic science of nanoparticle dispersions, but when this synthesis was developed near the end of the project, the commercial applications were obvious,” Huber said. The researchers subsequently refined the process to make particles easier to manufacture.

Existing synthesis methods for TiO2 particles were too costly and difficult to scale up production. In addition, chemical suppliers ship titanium-dioxide nanoparticles dried and without surfactants, so particles clump together and are impossible to break up. “Then you no longer have the properties you want,” Monson said.

The researchers tried various types of alcohol as an inexpensive solvent to see if they could get a common titanium source, titanium isopropoxide, to react with water and alcohol.

The biggest challenge, Monson said, was figuring out how to control the reaction, since adding water to titanium isopropoxide most often results in a fast reaction that produces large chunks of TiO2, rather than nanoparticles. “So the trick was to control the reaction by controlling the addition of water to that reaction,” he said.

Some textbooks dismissed the titanium isopropoxide-water-alcohol method as a way of making TiO2 nanoparticles. Huber and Monson, however, persisted until they discovered how to add water very slowly by putting it into a dilute solution of alcohol. “As we tweaked the synthesis conditions, we were able to synthesize nanoparticles,” Monson said.

Whoever wrote the news release now makes the plea which isn’t quite a plea (Note: A link has been removed),

The next step is to demonstrate synthesis at an industrial scale, which will require a commercial partner. Monson, who presented the work at Sandia’s fall Science and Technology Showcase, said Sandia has received inquiries from companies interested in commercializing the technology.

“Here at Sandia we’re not set up to produce the particles on a commercial scale,” he said. “We want them to pick it up and run with it and start producing these on a wide enough scale to sell to the end user.”

Sandia would synthesize a small number of particles, then work with a partner company to form composites and evaluate them to see if they can be used as better encapsulants for LEDs, flexible high-index refraction composites for lenses or solar concentrators. “I think it can meet quite a few needs,” Monson said.

I wish them good luck.

Anatase and rutile titanium dioxide and nanosunscreens

The American Chemical Society (ACS) features some research into nanoscreens and the anatase form of titanium dioxide in a Sept. 25, 2013 news release,,

Using a particular type of titanium dioxide — a common ingredient in cosmetics, food products, toothpaste and sunscreen — could reduce the potential health risks associated with the widely used compound. The report on the substance, produced by the millions of tons every year for the global market, appears in the ACS journal Chemical Research in Toxicology.
Francesco Turci and colleagues explain that titanium dioxide (TiO2) is generally considered a safe ingredient in commercially available skin products because it doesn’t penetrate healthy skin. But there’s a catch. Research has shown that TiO2 can cause potentially toxic effects when exposed to ultraviolet light, which is in the sun’s rays and is the same kind of light that the compound is supposed to offer protection against. To design a safer TiO2 for human use, the researchers set out to test different forms of the compound, each with its own architecture.

They tested titanium dioxide powders on pig skin (which often substitutes for human skin in these kinds of tests) with indoor lighting, which has very little ultraviolet light in it. They discovered that one of the two most commonly used crystalline forms of TiO2, called rutile, easily washes off and has little effect on skin. Anatase, the other commonly used form, however, was difficult to wash off and damaged the outermost layer of skin — even in low ultraviolet light. It appears to do so via “free radicals,” which are associated with skin aging. “The present findings strongly encourage the use of the less reactive, negatively charged rutile to produce safer TiO2-based cosmetic and pharmaceutical products,” the researchers conclude.

It should be noted that the researchers used pig skin, i.e., the skin was not on a pig and, therefore, not part of a living organism with its various biological systems coming into play. As well, the testing was done indoors not under direct sunlight which is the condition under which most of us use sunscreen. This research points to problems  with using anatase nanoscale titanium dioxide in sunscreens but it doesn’t provide unequivocal proof.

The Danish Environmental Protection Agency report (this Oct. 3, 2013 posting of mine) on the state of the art of research into nanomateial dermal absorption does refer to research in this area, although it does not include Turci’s work (Note: The numbers n the excerpted text are reference numbers for the bibliography)),

When looking at bulk composition and the level of dermal penetration noted in studies using a specific material type, there appears to be very little pattern between bulk composition and penetration depth. Taking for example TiO2 as one of the most widely studied nanoparticles, we see reports of penetration no further than the SC [subcutaneous skin layer] 78, 86, 91 but also several studies suggesting deeper penetration (basal cell layer) and even penetration into the dermis 63, 84 although this is often reported as being a very small fraction/infrequent. Another compositional issue in relation to nanoparticles and in particular TiO2 is the crystalline structure. TiO2 is often used in either its anatase or rutile form or as mixture of both. Within the literature, there are studies using both the anatase form 86, 94, the rutile form 91, 114 or a mixture 84, 114 although we were unable to find any studies which appear to systematically evaluate the role of crystal form in TiO2 absorption into the skin. [emphasis mine] (p. 44 of this report: Dermal Absorption of Nanomaterials Part of the ”Better control of nano” initiative 2012 – 2015 Environmental Project No. 1504, 2013).

For those who would like to read Turci’s research for themselves,

Crystalline Phase Modulates the Potency of Nanometric TiO2 to Adhere to and Perturb the Stratum Corneum of Porcine Skin under Indoor Light by Francesco Turci, Elena Peira, Ingrid Corazzari, Ivana Fenoglio, Michele Trotta, and Bice Fubini. Chem. Res. Toxicol., Article ASAP DOI: 10.1021/tx400285j Publication Date (Web): September 12, 2013
Copyright © 2013 American Chemical Society

This research is behind a paywall.

Czech nanotechnology efforts in China

There’s a Sept. 27, 2013 news item about the Czech Republic’s latest technology mission to China on the Nanowerk website,

This week [Sept.  23 – 27, 2013], the representatives of Czech nanotechnology firms, two famous technical universities and CzechInvest took part in a technology mission to China, where they met Chinese counterparts and discussed the further strengthening of cooperation in the field of nanotechnology. This technology mission to China, together with activities of some Czech nanotechnology companies, which have also been extensively supported by the Czech embassy in Beijing in recent months, has brought new opportunities for investment and the further collaboration of highly innovative technologies originated in the Czech Republic.

The Sept. 25, 2013 Czechinvest news release, which originated the news item,  offers more details about the mission,

“The Czech Republic is a world leader in the field of nanotechnology, which has an impact on numerous industrial sectors and places major demands on research. Czech nanotechnology firms are highly respected on the Chinese market,” says Marian Piecha, CEO of CzechInvest.

Representatives of CzechInvest, the Technical University of Liberec, Brno University of Technology and the Czech nanotechnology firms NAFIGATE Corporation, Elmarco, ACT Nami and Noen are taking part in CHINanoForum 2013, which is being held from 24 to 27 September in Jiangsu province. Within the forum’s accompanying programme, CzechInvest and NAFIGATE Corporation conducted a seminar title Nanosolutions for Green Economy – Investment Opportunity in China on 24 September. On 27 September the Czech delegates and their Chinese counterparts will be at the Czech embassy in Beijing to discuss the topic of using nanotechnologies in water treatment, among other things.

“China offers tremendous space for introducing new high-tech products to the market,” says Ladislav Mareš, chairman of the board of directors of NAFIGATE Corporation. “This technology mission therefore has major significance for supporting Czech exports to the Chinese market. Presentation of the potential of Czech nanotechnologies is also a signal for Chinese investors.”

According to the news release, a memorandum of understanding will be signed,

Technological cooperation between the two countries will also be supported by the signing of a Memorandum of Understanding between the Technology Agency of the Czech Republic and the Suzhou Industrial Park Administrative Committee. The signing of the memorandum, which will facilitate cooperation between Czech and Chinese firms with a high technological profile, will be attended by representatives of CzechInvest and His Excellency Libor Sečka, the Czech ambassador in China.

Earlier this years,  in June 2013, Nafigate signed a letter of intent with its Chinese partner, Guodian Technology & Environment Group Corporation Limited, regarding the development of a green nanotechnology centre. From a June 21, 2013 news release on PR newswire,

In the last few days, Czech nanotechnology pioneers have been presenting possible ways of utilizing Czech nanotechnology with specific examples taken from the Clean Air Nanosolution and Clean Water Nanosolution projects to representatives of the most significant Chinese companies at the Embassy of the Czech Republic in Beijing. “There is a lot of interest in the new technology because it solves fundamental problems in air and water cleaning. At the same time the Czech Republic is the world leader in the field of nanofibers and has much to offer China, from cooperation in research and development to putting specific innovative approaches into practice. Cooperation in this field could become an important new branch of mutual trade and scientific and technological exchanges and bring qualitative changes in the life of Chinese society,” said H. E. Mr. Libor Secka, Ambassador of the Czech Republic to the People’s Republic of China.

The signing of the Letter of Intent between NAFIGATE China (a subsidiary of the Czech company NAFIGATE Corporation JSC) and their Chinese partner Guodian Technology & Environment Group Corporation Limited (a subsidiary of one of the most prominent Chinese energy companies) is a significant milestone in Czech-Chinese cooperation in nanotechnology sector. Since January 2013 both companies have been preparing the foundation of the NANODEC (Nanofiber Development Center) project for the development of final applications for water and air cleaning.

The establishment of the center will be a major breakthrough with a global impact in the field of nanofiber applications. The aim of this initiative is to build a center of excellence which will utilize the best available worldwide know-how, the technological and infrastructural potential of one of the most significant Chinese companies and the potential of the market for new low carbon and green technologies. The Letter of Intent specifies the steps required to open the center according to the schedule in the last quarter of 2013.

For those interested in the overall nanotechnology scene in the Czech Republic, I found a 2012 article in the New York Times and a paper (2009?)  written for the National Information Centre For European Research (NICER) and located on the Organization of Economic Cooperation and Development.

Here’s some of what Jacy Meyer wrote for the New York Times in a May 22, 2012 article,

Industries based on nanotechnology are a rapidly growing niche in the economy of the Czech Republic, which, although small, is widely respected for its technical prowess. In February, the country had its own pavilion at the International Nanotechnology Trade Fair, Nanotech 2012, in Tokyo. Ten Czech companies took part.

One was Advanced Materials-JTJ, which produces photocatalytic coating materials incorporating titanium dioxide nanoparticles, known as FN coatings. The semi-transparent, odorless coatings have the unusual property of purifying the air around them — removing viruses, bacteria, toxins, cigarette smoke and more through a light-activated catalytic process.

Over the course of a year, “one square meter of FN-painted facade will clean and decontaminate over three million cubic meters of air,” or 106 million cubic feet, removing several kilograms of pollution, Mr. Prochazka [Jan Prochazka, Advanced Materials-JTJ’s chief executive] said.

As well as cleaning the air, the coating protects the painted surfaces from mold, fungus and the slow accumulation of dirt deposits that cause erosion and discoloring, he said.

The process, activated by ultraviolet light — that is, sunshine — is both environmentally friendly and cost-effective.

“For many people nano is a question mark, but really, everything is nano, except for gravel, sand and a few other materials,” Mr. Prochazka said in an interview in Prague. “Take a cup of water; you can’t imagine how many nanoparticles are inside.”

The National Information Centre For European Research (NICER) report titled, Czech Experience in the International Nanotechnology Cooperation, by Jitka Kubatova on the OECD website offers an overview of the public funding of R&D and much more,

the total (public + private) expenditure on R&D:

in 2005
42,2 billion CZK(€1,58 billion)
1,41% GDP (gross domestic product)

in 2006
49,9 billion CZK (€1,87 billion)
1,55% GDP

in 2007
54,3 billion CZK, (€2,03 billion)
1,53% GDP (p. 3 of the PDF)

Combining bacteriorhodopsin with semiconducting nanoparticles to generate hydrogen

Scientists at the US Argonne National Laboratory have created a hybrid bio-assisted photocatalyst according to a July 19, 2013 news item on ScienceDaily,

A protein found in the membranes of ancient microorganisms that live in desert salt flats could offer a new way of using sunlight to generate environmentally friendly hydrogen fuel, according to a new study by researchers at the U.S. Department of Energy’s Argonne National Laboratory.

Argonne nanoscientist Elena Rozhkova and her colleagues combined a pigment called bacteriorhodopsin with semiconducting nanoparticles to create a system that uses light to spark a catalytic process that creates hydrogen fuel.

Before getting to the new hybrid the story starts with nano titanium dioxide (from the July 16, 2013 Argonne National Laboratory press release, which originated the news item),

Scientists have been aware of the potential of titanium dioxide nanoparticles for light-based reactions since the early 1970s, when Japanese researchers discovered that a titanium dioxide electrode exposed to bright ultraviolet light could split water molecules in a phenomenon that came to be known as the Honda-Fujishima effect. Since then, scientists have made continuous efforts to extend the light reactivity of titanium dioxide photocatalysts into the visible part of the spectrum. The promise of these photocatalysts prompted scientists to experiment with different modifications to their basic chemistry in hope of making the reaction more efficient, Rozhkova said.

“Titanium dioxide alone reacts with ultraviolet light, but not with visible light, so we used biological photoreactive molecules as a building block to create a hybrid system that could use visible light efficiently,” Rozhkova said.

Rozhkova and her colleagues turned to bacteriorhodopsin – which is responsible for the unusual purple color of a number of salt flats in California and Nevada – because it uses sunlight as an energy source that allows it to act as a “proton pump.”  Proton pumps are proteins that typically straddle a cellular membrane and transfer protons from inside the cell to the extracellular space.

Here’s an image of the purple membrane caused by bacteriorhodopsin (from University of Bari [Italy] Professor Angela Correlli’s webpage of Photorecptors and Olfactory Receptors,

Bacteriorhodopsin is the only protein of purple membranes, which contains few different lipids. [downloaded from the University of Bari: http://www.biologia.uniba.it/fisiologia/corcelli/en/ric2.html]

Bacteriorhodopsin is the only protein of purple membranes, which contains few different lipids. [downloaded from the University of Bari: http://www.biologia.uniba.it/fisiologia/corcelli/en/ric2.html]

The press release goes on to describe the hybrid system,

In the Argonne system, the protons provided by the bacteriorhodopsin are combined with free electrons at small platinum sites interspersed in the titanium dioxide matrix. “The platinum nanoparticles are essential for creating a distinct spot for the production of the hydrogen molecule,” said Peng Wang, an Argonne postdoctoral researcher in Rozhkova’s group at Argonne’s Center for Nanoscale Materials.

“It is interesting that in biology, bacteriorhodopsin does not naturally participate in these kind of reactions,” Rozhkova said. “Its natural function really doesn’t have much to do at all with creating hydrogen. But as part of this hybrid, it helps make hydrogen under white light and at environmentally friendly conditions.”

This bio-assisted hybrid photocatalyst outperforms many other similar systems in hydrogen generation and could be a good candidate for fabrication of green energy devices that consume virtually infinite sources — salt water and sunlight.

You can find the published paper with the link below,

High-Performance Bioassisted Nanophotocatalyst for Hydrogen Production by Shankar Balasubramanian, Peng Wang, Richard D. Schaller, Tijana Rajh, and Elena A. Rozhkova. Nano Lett., 2013, 13 (7), pp 3365–3371 DOI: 10.1021/nl4016655 Publication Date (Web): June 19, 2013
Copyright © 2013 American Chemical Society

The paper is behind a paywall.

*The head for this posting was corrected from Combining bacteriorhodopsin with semiconduction nanopartcles to generate hydrogen to Combining bacteriorhodopsin with semiconductor nanoparticles to generate hydrogen on July 22, 2013 at 3:03 pm PDT.

** I changed the head for this posting again from ‘semiconductor’ to ‘semiconducting’ on July 23, 2013 at 6:50 am PDT.

Gloves, Québec’s (Canada) Institut de recherche Robert-Sauvé en santé et en sécurité du travail, and a workplace nanotoxicity methodology report

A new report on a workplace health and safety issue in regard to nanoparticles (Development of a Method of Measuring Nanoparticle Penetration through Protective Glove Materials under Conditions Simulating Workplace Use)  was released in June 2013 by Québec’s Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). Little research has been done on exposure through skin (cutaneous exposure), most research has focused on exposure by inhalation according to the report (en français version here),

In the workplace, the main pathway to NP exposure is inhalation (Ostiguy et al., 2008a). Exposure by the cutaneous route has not been studied much, partly because of the widely held belief that skin offers an impermeable barrier to NPs (Truchon et al., 2008). Yet a growing number of studies have pointed to the possible percutaneous absorption of NPs, such as in the case of skin damaged by abrasion (Zhang et al., 2008), repeated flexion (Rouse et al., 2007) or even through intact skin (Ryman-Rasmussen et al., 2006). Pores, hair follicles and sweat glands may also play a role in facilitating absorption of NPs through the skin (Hervé-Bazin, 2007). The nanoparticles are then carried throughout the body by the lymphatic circulatory system (Papp et al., 2008). Induced direct toxic effects have also been reported for epidermal keratinocyte cells exposed to carbon nanotubes and other types of NPs (Shvedova, 2003). [p. 17 PDF version; p. 1 print version; Note: See report bibliography for citations]

The researchers examined gloves made of four different types of material: nitrile, latex, neoprene, and butyl rubber under a number of different conditions. One type of nanoparticle was used for the study, titanium dioxide in powder and liquid forms. The report summary provides a bit more detail about the decision to develop a methodology and the testing methods,

With the exponential growth in industrial applications of nanotechnologies and the increased risk of occupational exposure to nanomaterials, the precautionary principle has been recommended. To apply this principle, and even though personal protective equipment against nanoparticles must be considered only as a last resort in the risk control strategy, this equipment must be available. To respond to the current lack of tools and knowledge in this area, a method was developed for measuring the penetration of nanoparticles through protective glove materials under conditions simulating workplace use.

This method consists of an experimental device for exposing glove samples to nanoparticles in powder form or in colloidal solution, while at the same time subjecting them to static or dynamic mechanical stresses and conditions simulating the microclimate in the gloves. This device is connected to a data control and acquisition system. To complete the method, a sampling protocol was developed and a series of nanoparticle detection techniques was selected.

Preliminary tests were performed using this method to measure the resistance of four models of protective gloves of different thicknesses made of nitrile, latex, neoprene and butyl to the passage of commercial TiO2 nanoparticles in powder form or colloidal solution. The results seem to indicate possible penetration of the nanoparticles in some types of gloves, particularly when subjected to repeated mechanical deformation and when the nanoparticles are in the form of colloidal solutions. Additional work is necessary to confirm these results, and consideration should be given to the selection of the configurations and values of the parameters that best simulate the different possible workplace situations. Nevertheless, a recommendation can already be issued regarding the need for regular replacement of gloves that have been worn, particularly with the thinnest gloves and when there has been exposure to nanoparticles in colloidal solution.

For interested parties, here’s a citation for and a link to the report (PDF),

Development of a Method of Measuring Nanoparticle Penetration through Protective Glove Materials under Conditions Simulating Workplace Use by Dolez, Patricia; Vinches, Ludwig; Perron, Gérald; Vu-Khanh, Toan; Plamondon, Philippe; L’Espérance, Gilles; Wilkinson, Kevin; Cloutier, Yves; Dion, Chantal; Truchon, Ginette
Studies and Research Projects / Report  R-785, Montréal, IRSST, 2013, 124 pages.

I last wrote about gloves and toxicity in a June 11, 2013 posting about gloves with sensors (they turned blue when exposed to toxic levels of chemicals). It would be interesting if they could find a way to create gloves with sensors that warn you when you are reaching dangerous levels of exposure through your gloves. Of course, first they’d have to determine what constitute a dangerous level of exposure. The US National Institute of Occupational Health and Safety (NIOSH) recently released its recommendations for exposure to carbon nanofibers and carbon nanotubes (my April 26, 2013 posting). In layperson’s terms, the recommended exposure is close to zero exposure. Presumably, the decision was based on the principle of being ‘safe rather than sorry’.

One final comment about exposure to engineered nanoparticles through skin, to date there has been no proof that there has been any significant exposure via skin. In fact, the first significant breach of the skin barrier was achieved for medical research, Chad Mirkin and his team at Northwestern University trumpeted their research breakthrough (pun intended) last year, from my July 4, 2012 posting,

Researchers at Northwestern University (Illinois, US) have found a way to deliver gene regulation technology using skin moisturizers. From the July 3, 2012 news item on Science Blog,

A team led by a physician-scientist and a chemist — from the fields of dermatology and nanotechnology — is the first to demonstrate the use of commercial moisturizers to deliver gene regulation technology that has great potential for life-saving therapies for skin cancers.

The topical delivery of gene regulation technology to cells deep in the skin is extremely difficult because of the formidable defenses skin provides for the body. The Northwestern approach takes advantage of drugs consisting of novel spherical arrangements of nucleic acids. These structures, each about 1,000 times smaller than the diameter of a human hair, have the unique ability to recruit and bind to natural proteins that allow them to traverse the skin and enter cells.

This goes a long way to explaining why primary occupational health and safety research has focused on exposure via inhalation rather than skin.  That said, I think ensuring safety means minimizing exposure by all routes until more is known about the hazards.

Self-cleaning products dangerous?

For anyone else out there who hates housecleaning, this is heartbreaking research. Personally, I’m not sure I can ever forgive Professor Jonathan Raff at Indian University for this (from a June 12, 2103 Indiana University news release; also on EurekAlert),

Research by Indiana University [IU] environmental scientists shows that air-pollution-removal technology used in “self-cleaning” paints and building surfaces may actually cause more problems than they solve.

The study finds that titanium dioxide coatings, seen as promising for their role in breaking down airborne pollutants on contact, are likely in real-world conditions to convert abundant ammonia to nitrogen oxide, the key precursor of harmful ozone pollution.

“As air quality standards become more stringent, people are going to be thinking about other technologies that can reduce pollution,” said Jonathan D. Raff, assistant professor in the School of Public and Environmental Affairs at IU Bloomington and an author of the study. “Our research suggests that this may not be one of them.”

Here’s a link to and a citation for this published study,

Photooxidation of Ammonia on TiO2 as a Source of NO and NO2 under Atmospheric Conditions by Mulu A. Kebede, Mychel E. Varner ‡, Nicole K. Scharko, R. Benny Gerber, and Jonathan D. Raff. J. Am. Chem. Soc., 2013, 135 (23), pp 8606–8615 DOI: 10.1021/ja401846x Publication Date (Web): May 30, 2013

Copyright © 2013 American Chemical Society

This research is behind a paywall.

The news release goes on to explain what makes this latest discovery about titanium dioxide particularly relevant,

The findings are timely because the Environmental Protection Agency is developing stricter regulations for ground-level ozone, a primary component in photochemical smog. The pollution is linked to serious health problems, including breathing difficulties and heart and lung disease.

Ozone is produced by reactions involving nitrogen oxides (NOx), which come primarily from motor vehicle emissions, and volatile organic compounds resulting from industrial processes. Equipping cars with catalytic converters has been effective at reducing ozone in urban areas. But different technologies may be needed to meet tighter air-quality standards of the future.

The need has sparked interest in titanium dioxide, a common mineral that is used as a whitening agent in paints and surface coatings. The compound acts as a photocatalyst, breaking down nitrogen oxides, ammonia and other pollutants in the presence of sunlight. “Self-cleaning” surfaces coated with titanium dioxide can break down chemical grime that will otherwise adhere to urban buildings. News stories have celebrated “smog-eating” tiles and concrete surfaces coated with the compound.

But Raff and his colleagues show that, in normal environmental conditions, titanium dioxide also catalyzes the incomplete breakdown of ammonia into nitrogen oxides. Ammonia is an abundant constituent in motor vehicle emissions, and its conversion to nitrogen oxides could result in increases in harmful ozone concentrations.

“We show that uptake of atmospheric NH3 (ammonia) onto surfaces containing TiO2 (titanium dioxide) is not a permanent removal process, as previously thought, but rather a photochemical route for generating reactive oxides of nitrogen that play a role in air pollution and are associated with significant health effects,” the authors write.

Raff, who is also an adjunct professor of chemistry in the IU College of Arts and Sciences, said other studies missed the effect on ammonia because they investigated reactions that occur with high levels of emissions under industrial conditions, not the low levels and actual humidity levels typically present in urban environments.

The findings also call into question other suggestions for using titanium dioxide for environmental remediation — for example, to remove odor-causing organic compounds from emissions produced by confined livestock feeding operations. Titanium dioxide has also been suggested as a geo-engineering substance that could be injected into the upper atmosphere to reflect sunlight away from the Earth and combat global warming.

Further studies in Raff’s lab are aimed at producing better understanding of the molecular processes involved when titanium dioxide catalyzes the breakdown of ammonia. The results could suggest approaches for developing more effective pollution-control equipment as well as improvements in industrial processes involving ammonia.

It’ll be interesting to see how that resolves itself. I imagine some of the civil society groups are going to get very excited about this research.