Tag Archives: titanium dioxide nanoparticles

Nanosunscreen in swimming pools

Thanks to Lynn L. Bergeson’s Sept. 21, 2016 posting for information about the US Environmental Protection Agency’s (EPA) research into what happens to the nanoparticles when your nanosunscreen washes off into a swimming pool. Bergeson’s post points to an Aug. 15, 2016 EPA blog posting by Susanna Blair,

… It’s not surprising that sunscreens are detected in pool water (after all, some is bound to wash off when we take a dip), but certain sunscreens have also been widely detected in our ecosystems and in our wastewater. So how is our sunscreen ending up in our environment and what are the impacts?

Well, EPA researchers are working to better understand this issue, specifically investigating sunscreens that contain engineered nanomaterials and how they might change when exposed to the chemicals in pool water [open access paper but you need to register for free] … But before I delve into that, let’s talk a bit about sunscreen chemistry and nanomaterials….

Blair goes on to provide a good brief description of  nanosunscreens before moving onto her main topic,

Many sunscreens contain titanium dioxide (TiO2) because it absorbs UV radiation, preventing it from damaging our skin. But titanium dioxide decomposes into other molecules when in the presence of water and UV radiation. This is important because one of the new molecules produced is called a singlet oxygen reactive oxygen species. These reactive oxygen species have been shown to cause extensive cell damage and even cell death in plants and animals. To shield skin from reactive oxygen species, titanium dioxide engineered nanomaterials are often coated with other materials such as aluminum hydroxide (Al(OH)3).

EPA researchers are testing to see whether swimming pool water degrades the aluminum hydroxide coating, and if the extent of this degradation is enough to allow the production of potentially harmful reactive oxygen species. In this study, the coated titanium dioxide engineered nanomaterials were exposed to pool water for time intervals ranging from 45 minutes to 14 days, followed by imaging using an electron microscope.  Results show that after 3 days, pool water caused the aluminum hydroxide coating to degrade, which can reduce the coating’s protective properties and increase the potential toxicity.  To be clear, even with degraded coating, the toxicity measured from the coated titanium dioxide, was significantly less [emphasis mine] than the uncoated material. So in the short-term – in the amount of time one might wear sunscreen before bathing and washing it off — these sunscreens still provide life-saving protection against UV radiation. However, the sunscreen chemicals will remain in the environment considerably longer, and continue to degrade as they are exposed to other things.

Blair finishes by explaining that research is continuing as the EPA researches the whole life cycle of engineered nanomaterials.

Nanotechnology in the house; a guide to what you already have

A July 4, 2016 essay by Cameron Shearer of Flinders University (Australia) on The Conversation website describes how nanotechnology can be found in our homes (Note: Links have been removed),

All kitchens have a sink, most of which are fitted with a water filter. This filter removes microbes and compounds that can give water a bad taste.

Common filter materials are activated carbon and silver nanoparticles.

Activated carbon is a special kind of carbon that’s made to have a very high surface area. This is achieved by milling it down to a very small size. Its high surface area gives more room for unwanted compounds to stick to it, removing them from water.

The antimicrobial properties of silver makes it one of the most common nanomaterials today. Silver nanoparticles kill algae and bacteria by releasing silver ions (single silver atoms) that enter into the cell wall of the organisms and become toxic.

It is so effective and fashionable that silver nanoparticles are now used to coat cutlery, surfaces, fridges, door handles, pet bowls and almost anywhere else microorganisms are unwanted.

Other nanoparticles are used to prepare heat-resistant and self-cleaning surfaces, such as floors and benchtops. By applying a thin coating containing silicon dioxide or titanium dioxide nanoparticles, a surface can become water repelling, which prevents stains (similar to how scotch guard protects fabrics).

Nanoparticle films can be so thin that they can’t be seen. The materials also have very poor heat conductivity, which means they are heat resistant.

The kitchen sink (or dishwasher) is used for washing dishes with the aid of detergents. Detergents form nanoparticles called micelles.

A micelle is formed when detergent molecules self-assemble into a sphere. The centre of this sphere is chemically similar to grease, oils and fats, which are what you want to wash off. The detergent traps oils and fats within the cavity of the sphere to separate them from water and aid dish washing.

Your medicine cabinet may include nanotechnology similar to micelles, with many pharmaceuticals using liposomes.

A liposome is an extended micelle where there is an extra interior cavity within the sphere. Making liposomes from tailored molecules allows them to carry therapeutics inside; the outside of the nanoparticle can be made to target a specific area of the body.

Shearer’s essay goes on to cover the laundry, bathroom, closets, and garage. (h/t July 5, 2016 news item on phys.org)

June 2016: time for a post on nanosunscreens—risks and perceptions

In the years since this blog began (2006), there’ve been pretty regular postings about nanosunscreens. While there are always concerns about nanoparticles and health, there has been no evidence to support a ban (personal or governmental) on nanosunscreens. A June 2016 report  by Paul FA Wright (full reference information to follow) in an Australian medical journal provides the latest insights on safety and nanosunscreens. Wright first offers a general introduction to risks and nanomaterials (Note: Links have been removed),

In reality, a one-size-fits-all approach to evaluating the potential risks and benefits of nanotechnology for human health is not possible because it is both impractical and would be misguided. There are many types of engineered nanomaterials, and not all are alike or potential hazards. Many factors should be considered when evaluating the potential risks associated with an engineered nanomaterial: the likelihood of being exposed to nanoparticles (ranging in size from 1 to 100 nanometres, about one-thousandth of the width of a human hair) that may be shed by the nanomaterial; whether there are any hotspots of potential exposure to shed nanoparticles over the whole of the nanomaterial’s life cycle; identifying who or what may be exposed; the eventual fate of the shed nanoparticles; and whether there is a likelihood of adverse biological effects arising from these exposure scenarios.1

The intrinsic toxic properties of compounds contained in the nanoparticle are also important, as well as particle size, shape, surface charge and physico-chemical characteristics, as these greatly influence their uptake by cells and the potential for subsequent biological effects. In summary, nanoparticles are more likely to have higher toxicity than bulk material if they are insoluble, penetrate biological membranes, persist in the body, or (where exposure is by inhalation) are long and fibre-like.1 Ideally, nanomaterial development should incorporate a safety-by-design approach, as there is a marketing edge for nano-enabled products with a reduced potential impact on health and the environment.1

Wright also covers some of nanotechnology’s hoped for benefits but it’s the nanosunscreen which is the main focus of this paper (Note: Links have been removed),

Public perception of the potential risks posed by nanotechnology is very different in certain regions. In Asia, where there is a very positive perception of nanotechnology, some products have been marketed as being nano-enabled to justify charging a premium price. This has resulted in at least four Asian economies adopting state-operated, user-financed product testing schemes to verify nano-related marketing claims, such as the original “nanoMark” certification system in Taiwan.4

In contrast, the negative perception of nanotechnology in some other regions may result in questionable marketing decisions; for example, reducing the levels of zinc oxide nanoparticles included as the active ingredient in sunscreens. This is despite their use in sunscreens having been extensively and repeatedly assessed for safety by regulatory authorities around the world, leading to their being widely accepted as safe to use in sunscreens and lip products.5

Wright goes on to describe the situation in Australia (Note: Links have been removed),

Weighing the potential risks and benefits of using sunscreens with UV-filtering nanoparticles is an important issue for public health in Australia, which has the highest rate of skin cancer in the world as the result of excessive UV exposure. Some consumers are concerned about using these nano-sunscreens,6 despite their many advantages over conventional organic chemical UV filters, which can cause skin irritation and allergies, need to be re-applied more frequently, and are absorbed by the skin to a much greater extent (including some with potentially endocrine-disrupting activity). Zinc oxide nanoparticles are highly suitable for use in sunscreens as a physical broad spectrum UV filter because of their UV stability, non-irritating nature, hypo-allergenicity and visible transparency, while also having a greater UV-attenuating capacity than bulk material (particles larger than 100 nm in diameter) on a per weight basis.7

Concerns about nano-sunscreens began in 2008 with a report that nanoparticles in some could bleach the painted surfaces of coated steel.8 This is a completely different exposure situation to the actual use of nano-sunscreen by people; here they are formulated to remain on the skin’s surface, which is constantly shedding its outer layer of dead cells (the stratum corneum). Many studies have shown that metal oxide nanoparticles do not readily penetrate the stratum corneum of human skin, including a hallmark Australian investigation by Gulson and co-workers of sunscreens containing only a less abundant stable isotope of zinc that allowed precise tracking of the fate of sunscreen zinc.9 The researchers found that there was little difference between nanoparticle and bulk zinc oxide sunscreens in the amount of zinc absorbed into the body after repeated skin application during beach trials. The amount absorbed was also extremely small when compared with the normal levels of zinc required as an essential mineral for human nutrition, and the rate of skin absorption was much lower than that of the more commonly used chemical UV filters.9 Animal studies generally find much higher skin absorption of zinc from dermal application of zinc oxide sunscreens than do human studies, including the meticulous studies in hairless mice conducted by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) using both nanoparticle and bulk zinc oxide sunscreens that contained the less abundant stable zinc isotope.10 These researchers reported that the zinc absorbed from sunscreen was distributed throughout several major organs, but it did not alter their total zinc concentrations, and that overall zinc homeostasis was maintained.10

He then discusses titanium dioxide nanoparticles (also used in nanosunscreens, Note: Links have been removed),

The other metal oxide UV filter is titanium dioxide. Two distinct crystalline forms have been used: the photo-active anatase form and the much less photo-active rutile form,7 which is preferable for sunscreen formulations. While these insoluble nanoparticles may penetrate deeper into the stratum corneum than zinc oxide, they are also widely accepted as being safe to use in non-sprayable sunscreens.11

Investigation of their direct effects on human skin and immune cells have shown that sunscreen nanoparticles of zinc oxide and rutile titanium dioxide are as well tolerated as zinc ions and conventional organic chemical UV filters in human cell test systems.12 Synchrotron X-ray fluorescence imaging has also shown that human immune cells break down zinc oxide nanoparticles similar to those in nano-sunscreens, indicating that immune cells can handle such particles.13 Cytotoxicity occurred only at very high concentrations of zinc oxide nanoparticles, after cellular uptake and intracellular dissolution,14 and further modification of the nanoparticle surface can be used to reduce both uptake by cells and consequent cytotoxicity.15

The ongoing debate about the safety of nanoparticles in sunscreens raised concerns that they may potentially increase free radical levels in human skin during co-exposure to UV light.6 On the contrary, we have seen that zinc oxide and rutile titanium dioxide nanoparticles directly reduce the quantity of damaging free radicals in human immune cells in vitro when they are co-exposed to the more penetrating UV-A wavelengths of sunlight.16 We also identified zinc-containing nanoparticles that form immediately when dissolved zinc ions are added to cell culture media and pure serum, which suggests that they may even play a role in natural zinc transport.17

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

Potential risks and benefits of nanotechnology: perceptions of risk in sunscreens by Paul FA Wright. Med J Aust 2016; 204 (10): 369-370. doi:10.5694/mja15.01128 Published June 6, 2016

This paper appears to be open access.

The situation regarding perceptions of nanosunscreens in Australia was rather unfortunate as I noted in my Feb. 9, 2012 posting about a then recent government study which showed that some Australians were avoiding all sunscreens due to fears about nanoparticles. Since then Friends of the Earth seems to have moderated its stance on nanosunscreens but there is a July 20, 2010 posting (includes links to a back-and-forth exchange between Dr. Andrew Maynard and Friends of the Earth representatives) which provides insight into the ‘debate’ prior to the 2012 ‘debacle’. For a briefer overview of the situation you could check out my Oct. 4, 2012 posting.

New model to track flow of nanomaterials through our air, earth, and water

Just how many tons of nanoparticles are making their way through the environment? Scientists at the Swiss Federal Laboratories for Materials Science and Technology (Empa) have devised a new model which could help answer that question. From a May 12, 2016 news item on phys.org,

Carbon nanotubes remain attached to materials for years while titanium dioxide and nanozinc are rapidly washed out of cosmetics and accumulate in the ground. Within the National Research Program “Opportunities and Risks of Nanomaterials” (NRP 64) a team led by Empa scientist Bernd Nowack has developed a new model to track the flow of the most important nanomaterials in the environment.

A May 12, 2016 Empa press release by Michael Hagmann, which also originated the news item, provides more detail such as an estimated tonnage for titanium dioxide nanoparticles produced annually in Europe,

How many man-made nanoparticles make their way into the air, earth or water? In order to assess these amounts, a group of researchers led by Bernd Nowack from Empa, the Swiss Federal Laboratories for Materials Science and Technology, has developed a computer model as part of the National Research Program “Opportunities and Risks of Nanomaterials” (NRP 64). “Our estimates offer the best available data at present about the environmental accumulation of nanosilver, nanozinc, nano-tinanium dioxide and carbon nanotubes”, says Nowack.

In contrast to the static calculations hitherto in use, their new, dynamic model does not just take into account the significant growth in the production and use of nanomaterials, but also makes provision for the fact that different nanomaterials are used in different applications. For example, nanozinc and nano-titanium dioxide are found primarily in cosmetics. Roughly half of these nanoparticles find their way into our waste water within the space of a year, and from there they enter into sewage sludge. Carbon nanotubes, however, are integrated into composite materials and are bound in products such as which are immobilized and are thus found for example in tennis racquets and bicycle frames. It can take over ten years before they are released, when these products end up in waste incineration or are recycled.

39,000 metric tons of nanoparticles

The researchers involved in this study come from Empa, ETH Zurich and the University of Zurich. They use an estimated annual production of nano-titanium dioxide across Europe of 39,000 metric tons – considerably more than the total for all other nanomaterials. Their model calculates how much of this enters the atmosphere, surface waters, sediments and the earth, and accumulates there. In the EU, the use of sewage sludge as fertilizer (a practice forbidden in Switzerland) means that nano-titanium dioxide today reaches an average concentration of 61 micrograms per kilo in affected soils.

Knowing the degree of accumulation in the environment is only the first step in the risk assessment of nanomaterials, however. Now this data has to be compared with results of eco-toxicological tests and the statutory thresholds, says Nowack. A risk assessment has not been carried out with his new model so far. Earlier work with data from a static model showed, however, that the concentrations determined for all four nanomaterials investigated are not expected to have any impact on the environment.

But in the case of nanozinc at least, its concentration in the environment is approaching the critical level. This is why this particular nanomaterial has to be given priority in future eco-toxicological studies – even though nanozinc is produced in smaller quantities than nano-titanium dioxide. Furthermore, eco-toxicological tests have until now been carried out primarily with freshwater organisms. The researchers conclude that additional investigations using soil-dwelling organisms are a priority.

Here are links to and citations for papers featuring the work,

Dynamic Probabilistic Modeling of Environmental Emissions of Engineered Nanomaterials by Tian Yin Sun†, Nikolaus A. Bornhöft, Konrad Hungerbühler, and Bernd Nowack. Environ. Sci. Technol., 2016, 50 (9), pp 4701–4711 DOI: 10.1021/acs.est.5b05828 Publication Date (Web): April 04, 2016

Copyright © 2016 American Chemical Society

Probabilistic environmental risk assessment of five nanomaterials (nano-TiO2, nano-Ag, nano-ZnO, CNT, and fullerenes) by Claudia Coll, Dominic Notter, Fadri Gottschalk, Tianyin Sun, Claudia Som, & Bernd Nowack. Nanotoxicology Volume 10, Issue 4, 2016 pages 436-444 DOI: 10.3109/17435390.2015.1073812 Published online: 10 Nov 2015

The first paper, which is listed in Environmental Science & Technology, appears to be open access while the second paper is behind a paywall.

Open access to nanoparticles and nanocomposites

One of the major issues for developing nanotechnology-enabled products is access to nanoparticles and nanocomposites. For example, I’ve had a number of requests from entrepreneurs for suggestions as to how to access cellulose nanocrystals (CNC) so they can develop a product idea. (It’s been a few years since the last request and I hope that means it’s easier to get access to CNC.)

Regardless, access remains a problem and the European Union has devised a solution which allows open access to nanoparticles and nanocomposites through project Co-Pilot. The announcement was made in a May 10, 2016 news item on Nanowerk (Note: A link has been removed),

“What opportunities does the nanotechnology provide in general, provide nanoparticles for my products and processes?” So far, this question cannot be answered easily. Preparation and modification of nanoparticles and the further processing require special technical infrastructure and complex knowledge. For small and medium businesses the construction of this infrastructure “just on luck” is often not worth it. Even large companies shy away from the risks. As a result many good ideas just stay in the drawer.

A simple and open access to high-class infrastructure for the reliable production of small batches of functionalized nanoparticles and nanocomposites for testing could ease the way towards new nano-based products for chemical and pharmaceutical companies. The European Union has allocated funds for the construction of a number of pilot lines and open-access infrastructure within the framework of the EU project CoPilot.

A May 9, 2016 Fraunhofer-Institut für Silicatforschung press release, which originated the news item, offers greater description,

A simple and open access to high-class infrastructure for the reliable production of small batches of functionalized nanoparticles and nanocomposites for testing could ease the way towards new nano-based products for chemical and pharmaceutical companies. The European Union has allocated funds for the construction of a number of pilot lines and open-access infrastructure within the framework of the EU project CoPilot. A consortium of 13 partners from research and industry, including nanotechnology specialist TNO from the Netherlands and the Fraunhofer Institute for Silicate Research ISC from Wuerzburg, Germany as well as seven nanomaterial manufacturers, is currently setting up the pilot line in Wuerzburg. First, they establish the particle production, modification and compounding on pilot scale based on four different model systems. The approach enables maximum variability and flexibility for the pilot production of various particle systems and composites. Two further open access lines will be established at TNO in Eindhoven and at the Sueddeutsche Kunststoffzentrum SKZ in Selb.

The “nanoparticle kitchen”

Essential elements of the pilot line in Wuerzburg are the particle synthesis in batches up to 100 liters, modification and separation methods such as semi-continuous operating centrifuge and in-line analysis and techniques for the uniform and agglomeration free incorporation of nanoparticles into composites. Dr. Karl Mandel, head of Particle Technology of Fraunhofer ISC, compares the pilot line with a high-tech kitchen: “We provide the top-notch equipment and the star chefs to synthesize a nano menu à la carte as well as nanoparticles according to individual requests. Thus, companies can test their own receipts – or our existing receipts – before they practice their own cooking or set up their nano kitchen.”

In the future, the EU project offers companies a contact point if they want to try their nano idea and require enough material for sampling and estimation of future production costs. This can, on the one hand, minimize the development risk, on the other hand, it maximizes the flexibility and production safety. To give lots of companies the opportunity to influence direction and structure/formation/setup of the nanoparticle kitchen, the project partners will offer open meetings on a regular basis.

I gather Co-Pilot has been offering workshops. The next is in July 2016 according to the press release,

The next workshop in this context takes place at Fraunhofer ISC in Wuerzburg, 7h July 2016. The partners present the pilot line and the first results of the four model systems – double layered hydroxide nanoparticle polymer composites for flame inhibiting fillers, titanium dioxide nanoparticles for high refractive index composites, magnetic particles for innovative catalysts and hollow silica composites for anti-glare coatings. Interested companies can find more information about the upcoming workshop on the website of the project www.h2020copilot.eu and on the website of Fraunhofer ISC www.isc.fraunhofer.de that hosts the event.

I tracked down a tiny bit more information about the July 2016 workshop in a May 2, 2016 Co-Pilot press release,

On July 7 2016, the CoPilot project partners give an insight view of the many new functionalization and applications of tailored nanoparticles in the workshop “The Nanoparticle Kitchen – particles und functions à la carte”, taking place in Wuerzburg, Germany. Join the Fraunhofer ISC’s lab tour of the “Nanoparticle Kitchen”, listen to the presentations of research institutes and industry and discuss your ideas with experts. Nanoparticles offer many options for today’s and tomorrow’s products.

More about program and registration soon on this [CoPilot] website!

I wonder if they’re considering this open access to nanoparticles and nanocomposites approach elsewhere?

Synthesizing titanium dioxide nanoparticles with herbal extracts

It was somewhat unexpected to see a science collaboration between an Iranian researcher and an Iraqi researcher given the two countries engaged in a hard-fought war for almost eight years (1980 – 88). However, since almost 30 years have passed, it seems at least two people feel it’s time to approach things differently. A Jan. 28, 2016 news item on Nanotechnology Now announces the research,

Environmental preservation is today one of the greatest concerns of scientists in all scientific aspects.

Given the direct effect of chemical industry on environment, chemists try to present new methods for the synthesis of materials with less chemical pollution but more biocompatibility.

Iranian and Iraqi researchers studied the possibility of the application of herbal extracts to synthesize titanium dioxide nanoparticles. Results prove that the herbal extract enables production of nanoparticles at a higher rate and efficiency but less environmental pollution.

A Jan. 28, 2016 Fars Agency news release, which originated the news item, expands on the theme,

The aim of the research was to synthesize titanium dioxide nanoparticles in a simple, fast and cost effective manner with high efficiency in the presence of Euphorbia heteradena Jaub extract. This plant is found commonly in the western and central parts of Iran.

The nanoparticles also have application in the degradation of organic materials and water and wastewater purification due to their appropriate stability, non-toxicity and photocatalytic activity.

The method presented in this research is in agreement with global standards of green chemistry unlike other chemical methods. In fact, no toxic solvent or reactant (such as chemical reducers and stabilizers) has been used in this method. Elimination of by-products during the synthesis of nanoparticles and ease of production scaling up from laboratorial scale to industrial one are among the other advantages of the new method.

According to the researchers, instability of the synthetic nanoparticles is one of the challenges in previous studies. However, experiments suggest that no structural change is observed in the synthetized nanoparticles even after two months.

Here’s a link to and a citation for the researchers’ 2015 paper,

Synthesis and characterization of titanium dioxide nanoparticles using Euphorbia heteradena Jaub root extract and evaluation of their stability by Mahmoud Nasrollahzadeh, S. Mohammad Sajad. Ceramics International Volume 41, Issue 10, Part B, December 2015, Pages 14435–14439 doi:10.1016/j.ceramint.2015.07.079 Available online 21 July 2015

This paper is behind a paywall.

Titanium dioxide nanoparticles and the brain

This research into titanium dioxide nanoparticles and possible effects on your brain should they pass the blood-brain barrier comes from the University of Nebraska-Lincoln (US) according to a Dec. 15, 2015 news item on Nanowerk (Note: A link has been removed),

Even moderate concentrations of a nanoparticle used to whiten certain foods, milk and toothpaste could potentially compromise the brain’s most numerous cells, according to a new study from the University of Nebraska-Lincoln (Nanoscale, “Mitochondrial dysfunction and loss of glutamate uptake in primary astrocytes exposed to titanium dioxide nanoparticles”).

A Dec. 14, 2015 University of Nebraska-Lincoln news release, which originated the news item, provides more detail (Note: Links have been removed),

The researchers examined how three types of titanium dioxide nanoparticles [rutile, anatase, and commercially available P25 TiO2 nanoparticles], the world’s second-most abundant nanomaterial, affected the functioning of astrocyte cells. Astrocytes help regulate the exchange of signal-carrying neurotransmitters in the brain while also supplying energy to the neurons that process those signals, among many other functions.

The team exposed rat-derived astrocyte cells to nanoparticle concentrations well below the extreme levels that have been shown to kill brain cells but are rarely encountered by humans. At the study’s highest concentration of 100 parts per million, or PPM, two of the nanoparticle types still killed nearly two-thirds of the astrocytes within a day. That mortality rate fell to between half and one-third of cells at 50 PPM, settling to about one-quarter at 25 PPM.

Yet the researchers found evidence that even surviving cells are severely impaired by exposure to titanium dioxide nanoparticles. Astrocytes normally take in and process a neurotransmitter called glutamate that plays wide-ranging roles in cognition, memory and learning, along with the formation, migration and maintenance of other cells.

When allowed to accumulate outside cells, however, glutamate becomes a potent toxin that kills neurons and may increase the risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s. The study reported that one of the nanoparticle types reduced the astrocytes’ uptake of glutamate by 31 percent at concentrations of just 25 PPM. Another type decreased that uptake by 45 percent at 50 PPM.

The team further discovered that the nanoparticles upset the intricate balance of protein dynamics occurring within astrocytes’ mitochondria, the cellular organelles that help regulate energy production and contribute to signaling among cells. Titanium dioxide exposure also led to other signs of mitochondrial distress, breaking apart a significant proportion of the mitochondrial network at 100 PPM.

“These events are oftentimes predecessors of cell death,” said Oleh Khalimonchuk, a UNL assistant professor of biochemistry who co-authored the study. “Usually, people are looking at those ultimate consequences, but what happens before matters just as much. Those little damages add up over time. Ultimately, they’re going to cause a major problem.”

Khalimonchuk and fellow author Srivatsan Kidambi, assistant professor of chemical and biomolecular engineering, cautioned that more research is needed to determine whether titanium dioxide nanoparticles can avoid digestion and cross the blood-brain barrier that blocks the passage of many substances. [emphasis mine]

However, the researchers cited previous studies that have discovered these nanoparticles in the brain tissue of animals with similar blood-brain barriers. [emphasis mine] The concentrations of nanoparticles found in those specimens served as a reference point for the levels examined in the new study.

“There’s evidence building up now that some of these particles can actually cross the (blood-brain) barrier,” Khalimonchuk said. “Few molecules seem to be able to do so, but it turns out that there are certain sites in the brain where you can get this exposure.”

Kidambi said the team hopes the study will help facilitate further research on the presence of nanoparticles in consumer and industrial products.

“We’re hoping that this study will get some discussion going, because these nanoparticles have not been regulated,” said Kidambi, who also holds a courtesy appointment with the University of Nebraska Medical Center. “If you think about anything white – milk, chewing gum, toothpaste, powdered sugar – all these have nanoparticles in them.

“We’ve found that some nanoparticles are safe and some are not, so we are not saying that all of them are bad. Our reasoning is that … we need to have a classification of ‘safe’ versus ‘not safe,’ along with concentration thresholds (for each type). It’s about figuring out how the different forms affect the biology of cells.

I notice the researchers are being careful about alarming anyone unduly while emphasizing the importance of this research. For anyone curious enough to read the paper, here’s a link to and a citation for it,

Mitochondrial dysfunction and loss of glutamate uptake in primary astrocytes exposed to titanium dioxide nanoparticles by Christina L. Wilson, Vaishaali Natarajan, Stephen L. Hayward, Oleh Khalimonchuk and   Srivatsan Kidambi. Nanoscale, 2015,7, 18477-18488 DOI: 10.1039/C5NR03646A First published online 31 Jul 2015

This is paper is open access although you may need to register on the site.

Final comment, I note this was published online way back in July 2015. Either the paper version of the journal was just published and that’s what’s being promoted or the media people thought they’d try to get some attention for this work by reissuing the publicity. Good on them! It’s hard work getting people to notice things when there is so much information floating around.

Tomatoes and some nano-sized nutrients

While zinc is a metal, it’s also a nutrient vital to plants as a Nov. 5, 2015 news item on ScienceDaily notes,

With the world population expected to reach 9 billion by 2050, engineers and scientists are looking for ways to meet the increasing demand for food without also increasing the strain on natural resources, such as water and energy — an initiative known as the food-water-energy nexus.

Ramesh Raliya, PhD, a postdoctoral researcher, and Pratim Biswas, PhD, the Lucy & Stanley Lopata Professor and chair of the Department of Energy, Environmental & Chemical Engineering, both at the School of Engineering & Applied Science at Washington University in St. Louis, are addressing this issue by using nanoparticles to boost the nutrient content and growth of tomato plants. Taking a clue from their work with solar cells, the team found that by using zinc oxide and titanium dioxide nanoparticles, the tomato plants better absorbed light and minerals, and the fruit had higher antioxidant content.

A Nov. 5, 2015 Washington University in St. Louis news release by Beth Miller (also on EurekAlert but dated Nov. 6, 2015), which originated the news item, describes the work in more detail,

“When a plant grows, it signals the soil that it needs nutrients,” Biswas says. “The nutrient it needs is not in a form that the plant can take right away, so it secretes enzymes, which react with the soil and trigger bacterial microbes to turn the nutrients into a form that the plant can use. We’re trying to aid this pathway by adding nanoparticles.”

Zinc is an essential nutrient for plants, helps other enzymes function properly and is an ingredient in conventional fertilizer. Titanium is not an essential nutrient for plants, Raliya says, but boosts light absorption by increasing chlorophyll content in the leaves and promotes photosynthesis, properties Biswas’ lab discovered while creating solar cells.

The team used a very fine spray using novel aerosolization techniques to directly deposit the nanoparticles on the leaves of the plants for maximum uptake.

“We found that our aerosol technique resulted in much greater uptake of nutrients by the plant in comparison to application of the nanoparticles to soil,” Raliya says. “A plant can only uptake about 20 percent of the nutrients applied through soil, with the remainder either forming stable complexes with soil constituents or being washed away with water, causing runoff. In both of the latter cases, the nutrients are unavailable to plants.”

Overall, plants treated with the nanoparticles via aerosol routes produced nearly 82 percent (by weight) more fruit than untreated plants. In addition, the tomatoes from treated plant showed an increase in lycopene, an antioxidant linked to reduced risk of cancer, heart disease and age-related eye disorders, of between 80 percent and 113 percent.

Previous studies by other researchers have shown that increasing the use of nanotechnology in agriculture in densely populated countries such as India and China has made an impact on reducing malnutrition and child mortality. These tomatoes will help address malnutrition, Raliya says, because they allow people to get more nutrients from tomatoes than those conventionally grown.

In the study, published online last month in the journal Metallomics, the team found that the nanoparticles in the plants and the tomatoes were well below the USDA limit and considerably lower than what is used in conventional fertilizer. However, they still have to be cautious and select the best concentration of nanoparticles to use for maximum benefit, Biswas says.

Raliya and the rest of the team are now working to develop a new formulation of nanonutrients that includes all 17 elements required by plants.

“In 100 years, there will be more cities and less farmland, but we will need more food,” Raliya says. “At the same time, water will be limited because of climate change. We need an efficient methodology and a controlled environment in which plants can grow.”

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

Mechanistic evaluation of translocation and physiological impact of titanium dioxide and zinc oxide nanoparticles on the tomato (Solanum lycopersicum L.) plant by Ramesh Raliya, Remya Nair, Sanmathi Chavalmane, Wei-Ning Wang and Pratim Biswas. Metallomics, 2015, Advance Article DOI: 10.1039/C5MT00168D First published online 08 Oct 2015

I believe this article is behind a paywall.

Metal nanoparticles and gut microbiomes

What happens when you eat or drink nanoparticles, metallic or otherwise? No one really knows. Part of the problem with doing research now is there are no benchmarks for the quantity we’ve been ingesting over the centuries. Nanoparticles do occur naturally, as well, people who’ve eaten with utensils made of or coated with silver or gold have ingested silver or gold nanoparticles that were shed by those very utensils. In short, we’ve been ingesting any number of nanoparticles through our food, drink, and utensils in addition to the engineered nanoparticles that are found in consumer products. So, part of what researchers need to determine is the point at which we need to be concerned about nanoparticles. That’s trickier than it might seem since we ingest our nanoparticles and recycle them into the environment (air, water, soil) to reingest (inhale, drink, eat, etc.) them at a later date. The endeavour to understand what impact engineered nanoparticles in particular will have on us as more are used in our products is akin to assembling a puzzle.

There’s a May 5, 2015 news item on Azonano which describes research into the effects that metallic nanoparticles have on the micriobiome (bacteria) in our guts,

Exposure of a model human colon to metal oxide nanoparticles, at levels that could be present in foods, consumer goods, or treated drinking water, led to multiple, measurable differences in the normal microbial community that inhabits the human gut. The changes observed in microbial metabolism and the gut microenvironment with exposure to nanoparticles could have implications for overall human health, as discussed in an article published in Environmental Engineering Science, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. The article is available free on the Environmental Engineering Science website until June 1, 2015.

A May 4, 2015 Mary Ann Liebert publisher news release on EurekAlert, which originated the news item, describes the research in more detail (Note: A link has been removed),

Alicia Taylor, Ian Marcus, Risa Guysi, and Sharon Walker, University of California, Riverside, individually introduced three different nanoparticles–zinc oxide, cerium dioxide, and titanium dioxide–commonly used in products such as toothpastes, cosmetics, sunscreens, coatings, and paints, into a model of the human colon. The model colon mimics the normal gut environment and contains the microorganisms typically present in the human microbiome.

In the article “Metal Oxide Nanoparticles Induce Minimal Phenotypic Changes in a Model Colon Gut Microbiota” the researchers described changes in both specific characteristics of the microbial community and of the gut microenvironment after exposure to the nanoparticles.

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

Metal Oxide Nanoparticles Induce Minimal Phenotypic Changes in a Model Colon Gut Microbiota by Alicia A. Taylor, Ian M. Marcus Ian, Risa L., Guysi, and Sharon L. Walker. Environmental Engineering Science. DOI:10.1089/ees.2014.0518 Online Ahead of Print: April 24, 2015

I’ve taken a quick look at the research while it’s still open access (till June 1, 2015) to highlight the bits I consider interesting. There’s this about the nanoparticle (NP) quantities used in the study (Note: Links have been removed),

Environmentally relevant NP concentrations were chosen to emulate human exposures to NPs through ingestion of both food and drinking water at 0.01 μg/L ZnO NP, 0.01 μg/L CeO2 NP, and 3 mg/L TiO2 NP (Gottschalk et al., 2009; Kiser et al., 2009, 2013; Weir et al., 2012; Keller and Lazareva, 2013). Recent work has also indicated that adults in the USA ingest 5 mg TiO2 per day, half of which is in the nano-size range (Lomer et al., 2000; Powell et al., 2010). Exposure routes and reliable dosing information of NPs that are embedded in solid matrices are difficult to predict, and this is often a limitation of analytical techniques (Nowack et al., 2012; Yang and Westerhoff, 2014). The exposure levels used in this study were predominately selected from literature values that give predictions on amount of NPs in water and food sources (Gottschalk et al., 2009; Kiser et al., 2009; Weir et al., 2012; Keller and Lazareva, 2013; Keller et al., 2013).

For anyone unfamiliar with chemical notations, ZnO NP is zinc oxide nanoparticle, 0.01 μg/L is one/one hundredth of a microgram per litre,  CeO2 is cesisum dioxide NP, and TiO2 is titanium dioxide NP while 3 mg/L, is 3 milligrams per litre.

After assuring the quantities used in the study are the same as they expect humans to be ingesting on a regular basis, the researchers describe some of the factors which may affect the interaction between the tested nanoparticles and the bacteria (Note: Links have been removed),

It is essential to note that interactions between NPs and bacteria in the intestines may be dependent on numerous factors: the surface charge of the NPs and bacteria, the chemical composition and surface charge of the digested food, and variability in diet. These factors may ultimately correlate to effects seen in humans on an individual basis. In fact, similar work has demonstrated that exposing common NPs found in food to stomach-like conditions will change their surface chemistry from negative to neutral or positive, causing the NPs to interact with negatively charged mucus proteins in the gastrointestinal tract and, in turn, affecting the transport of NPs within the intestine (McCracken et al., 2013). The purpose of this work was to measure responses of the microbial community during the NP exposures. Based on previous research, it is anticipated that the NPs altered by stomach-like conditions would also cause changes in the gut environment (McCracken et al., 2013).

Here’s some of what they discovered,

Our initial hypothesis, that NPs induce phenotypic changes in a gut microbial community, was affirmed through significant measurable effects seen in the data. Tests that supported that NPs caused changes in the phenotype included hydrophobicity, EPM, sugar content of the EPS, cell size, conductivity, and SFCA (specifically butyric acid) production. Data for cell concentration and the protein content of the EPS demonstrated no significant results. Data were inconclusive for pH. With such a complex biological system, it is very likely that the phenotypic and biochemical changes observed are combinations of responses happening in parallel. The effects seen may be attributed to both changes induced by the NPs and natural phenomena associated with microbial community activity and other metabolic processes in a multifaceted environment such as the gut. Some examples of natural processes that could also influence the phenotypic and biochemical parameters are osmolarity, active metabolites, and electrolyte concentrations (Miller and Wood, 1996; Record et al., 1998).

Here’s the concluding sentence from the abstract,

Overall, the NPs caused nonlethal, significant changes to the microbial community’s phenotype, which may be related to overall health effects. [emphasis mine]

This research like the work I featured in a June 27, 2013 posting points to some issues with researching the impact that nanoparticles may have on our bodies. There was no cause for immediate alarm in 2013 and it appears that is still the case in 2015. However, that assumes quantities being ingested don’t increase significantly.

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.