Tag Archives: inhalation

German scientists battle tough mucus

A December 15, 2017 news item on ScienceDaily highlights cystic fibrosis research being done in Germany,

Around one in 3,300 children in Germany is born with Mucoviscidosis [cystic fibrosis; CF]. A characteristic of this illness is that one channel albumen on the cell surface is disturbed by mutations. Thus, the amount of water of different secretions in the body is reduced which creates a tough mucus. As a consequence, inner organs malfunction. Moreover, the mucus blocks the airways. Thus, the self regulatory function of the lung is disturbed, the mucus is colonized by bacteria and chronic infections follow. The lung is so significantly damaged that patients often die or need to have a lung transplant. The average life expectancy of a patient today is around 40 years. This is due to medical progress. Permanent treatment with inhaled antibiotics play a considerable part in this. The treatment can’t avoid the colonization by bacteria completely but it can keep it in check for a longer period of time. However, the bacteria defend themselves with a development of resistance and with the growth of so-called biofilms underneath the layer of mucus, which mostly block off the bacteria in the lower rows like a protective shield.

A complex way to the Pathogens

Scientists of the Friedrich Schiller University Jena, Germany succeeded in developing a much more efficient method to treat the airway infections which are often lethal. Crucial are nanoparticles that transport the antibiotics more efficiently to their destination….

A December 15, 2017 Friedrich Schiller University Jena press release (also on EurekAlert), which originated the news item, expands on the theme,

“Typically, the drugs are applied by inhalation in the body. Then they make a complicated way through the body to the pathogens and many of them don’t make it to their destination,” states Prof. Dr Dagmar Fischer of the chair for Pharmaceutical Technology at the University of Jena, who supervised the project together with her colleague Prof. Dr Mathias Pletz, a pulmonologist and infectious diseases physician, from the Center for Infectious Diseases and Infection Control at the Jena University Hospital. The project was supported by the Deutsche Forschungsgemeinschaft. First of all, the active particles need to have a certain size to be able to reach the deeper airways and not to bounce off somewhere else before. Ultimately, they have to penetrate the thick layer of mucus on the airways as well as the lower layers of the bacteria biofilm.

Nanoparticles travel more efficiently

To overcome the strong defense, the researchers encapsulated the active agents, like the antibiotic Tobramycin, in a polyester polymer. Thus, they created a nanoparticle which they then tested in the laboratory where they beforehand had simulated the present lung situation, in a static as well as in a dynamic state, i. e. with simulated flow movements. Therefore Pletz’s research group had developed new test systems, which are able to mimick the situation of the chronically infected CF-lung. The scientists discovered that their nanoparticle travels more easily through the sponge-like net of the mucus layer and is finally able to kill off the pathogens without any problems. Moreover, an additionally applied coating of polyethylenglycol makes it nearly invisible for the immune system. “All materials of a nanocarrier are biocompatible, biodegradable, nontoxic and therefore not dangerous for humans,” the researcher informs.

However, the Jena scientists don’t know yet exactly why their nanoparticle fights the bacteria so much more efficiently. But they want to finally get clarification in the year ahead. “We have two assumptions: Either the much more efficient transport method advances significantly larger amounts of active ingredients to the center of infection, or the nanoparticle circumvents a defense mechanism, which the bacterium has developed against the antibiotic,” the Jena Pharmacist Fischer explains. “This would mean, that we succeeded in giving back its impact to an antibiotic, which had already lost it through a development of resistance of the bacteria.”

“More specifically, we assume that bacteria from the lower layers of the biofilm transform into dormant persisters and hardly absorb any substances from outside. In this stadium, they are tolerant to most antibiotics, which only kill off self-dividing bacteria. The nanoparticles transport the antibiotics more or less against their will to the inner part of the cell, where they can unfold their impact,” Mathias Pletz adds.

Additionally, the Jena research team had to prepare the nanoparticles for the inhalation. Because at 200 nanometers the particle is too small to get into the deeper airways. “The breathing system filters out particles that are too big as well as those which are too small,” Dagmar Fischer explains. “So, we are left with a preferred window of between one and five micrometers.” The Jena researchers also have promising ideas for resolving this problem.

Coating of Nanoparticles enhances the impact of Antibiotics against Biofilms

The scientists from Jena are at this point already convinced to have found a very promising method to fight respiratory infections of patients with mucoviscidosis. Thus they may be able to contribute to a higher life expectancy of those affected. “We were able to show that the nanoparticle coating improves the impact of the antibiotics against biofilm by a factor of 1,000,” the pulmonologist and infectious diseases physician is happy to say.

It’s exciting news and I wish the researchers great success. Perhaps, one day, they will publish a paper about their work.

nanoIndEx publishes guidance document on assessing exposure to airborne nanomaterials

Lynn Bergeson’s June 21, 2016 posting on Nanotechnology Now announced a newly published guidance document from the European Union’s nanoIndEx,

… The guidance document summarizes the key findings of the project, and is intended to present the state of the art in personal exposure assessment for nanomaterials. The conclusions section states: “Unfortunately, many nanotoxicological studies have used excessive, unrealistically high doses of [manufactured nanomaterials] and it is therefore debatable what their findings mean for the lower real-world exposures of humans. Moreover, it is not clear how to establish realistic exposure dose testing in toxicological studies, as available data on occupational exposure levels are still sparse.” According to the guidance document, future studies should focus on the potentially adverse effects of low-level and realistic exposure to manufactured nanomaterials, especially through the use of exposure doses similar to those identified in environmental sampling.

You can find the 49pp PDF here or here. To whet your appetite, here’s a bit from the introduction to the “Exposure to Airborne Nanomaterials; A Guidance Document,”

… While human exposure to MNMs may in principle occur during any stage of the material’s lifecycle, it is most likely in workplaces, where these materials are produced or handled in large quantities or over long periods of time. Inhalation is considered as the most critical uptake route, because the small particles are able to penetrate deep into the lung and deposit in the gas exchange region. Inhalation exposure to airborne nanomaterials therefore needs to be assessed in view of worker protection.

Exposure to airborne particles can generally best be assessed by measuring the individual exposure in the personal breathing zone (PBZ) of an individual. The PBZ is defined as a 30 cm hemisphere around mouth and nose [2]. Measurements in the PBZ require instruments that are small and light-weight. The individual exposure specifically to MNMs [manufactured nanomaterials, sometimes also known as engineered nanomaterials or nanoparticles] has not been assessable in the past due to the lack of suitable personal samplers and/or monitors. Instead, most studies related to exposure to MNMs have been carried out using either bulky static measurement equipment or not nanospecific personal samplers. In recent years, novel samplers and monitors have been introduced that allow for an assessment of the more nanospecific personal exposure to airborne MNMs. In the terminology used in nanoIndEx, samplers are devices that collect particles on a substrate, e.g. a filter
of flat surface, for subsequent analysis, whereas monitors are real-time instruments that deliver
information on the airborne concentrations with high time resolution. Scientifically sound investigations on the accuracy, comparability and field applicability of these novel samplers and monitors had been lacking. … (p. 4 print; p. 6 PDF)

There’s also a brief description of the nanoindEX project in the Introduction,

The three-year project started on June 1st, 2013, and has been funded under the frame of SIINN, the ERA-NET [European Research Area Network] for a Safe Implementation of Innovative Nanoscience and Nanotechnology [SINN]. The aim of the project was to scrutinise the instrumentation available for personal exposure assessment concerning their field readiness and usability in order to use this information to generate reliable data on personal exposure in real workplaces and to eventually widely distribute the findings among the interested public. This Guidance Document you are holding in your hands summarises the key findings of the project. (p. 5 print; p. 7 PDF)

As I understand it, the area of most concern where nanotoxicology is concerned would be inhalation of nanoparticles into the lungs as the body has fewer protections in the respiratory tract than it has elsewhere, e.g. skin or digestive system.

Study nanomaterial toxicity without testing animals

The process of moving on from testing on animals is laborious as new techniques are pioneered and, perhaps more arduously, people’s opinions and habits are changed. The People for the Ethical Treatment of Animals (PETA) organization focusing the research end of things has announced a means of predicting carbon nanotube toxicity in lungs according to an April 25, 2016 news item on Nanowerk (Note: A link has been removed),

A workshop organized last year [2015] by the PETA International Science Consortium Ltd has resulted in an article published today in the journal Particle and Fibre Toxicology (“Aerosol generation and characterization of multi-walled carbon nanotubes [MWCNTs] exposed to cells cultured at the air-liquid interface”). It describes aerosol generation and exposure tools that can be used to predict toxicity in human lungs following inhalation of nanomaterials.

An April 25, 2016 PETA press release on EurekAlert, which originated the news item, explains further without much more detail,

Nanomaterials are increasingly being used in consumer products such as paints, construction materials, and food packaging, making human exposure to these materials more likely. One of the common ways humans may be exposed to these substances is by inhalation, therefore, regulatory agencies often require the toxicity of these materials on the lungs to be tested. These tests usually involve confining rats to small tubes the size of their bodies and forcing them to breathe potentially toxic substances before they are killed. However, time, cost, scientific and ethical issues have led scientists to develop methods that do not use animals. The tools described in the new article are used to deposit nanomaterials (or other inhalable substances) onto human lung cells grown in a petri dish.

Co-authors of the Particle and Fibre Toxicology article are scientists from the PETA Science Consortium , The Dow Chemical Company, Baylor University, and the U.S. NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM).

“Promoting non-animal methods to assess nanotoxicity has been a focus of the PETA International Science Consortium”, said Dr. Monita Sharma, co-author of the publication and Nanotechnology Specialist at the Consortium, “we organized an international workshop last year on inhalation testing of nanomaterials and this review describes some of the tools that can be used to provide a better understanding of what happens in humans after inhaling these substances.” During the workshop, experts provided recommendations on the design of an in vitro test to assess the toxicity of nanomaterials (especially multi-walled carbon nanotubes) in the lung, including cell types, endpoints, exposure systems, and dosimetry considerations. Additional publications summarizing the outcomes of the workshop are forthcoming.

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

Aerosol generation and characterization of multi-walled carbon nanotubes exposed to cells cultured at the air-liquid interface by William W. Polk, Monita Sharma, Christie M. Sayes, Jon A. Hotchkiss, and Amy J. Clippinger. Particle and Fibre Toxicology201613:20 DOI: 10.1186/s12989-016-0131-y Published: 23 April 2016

This is an open access paper.

Call for proposals to create in vitro inhalation tests for nanomaterial toxicity

I got an email announcement (March 17, 2015) which has acted as a spur to my desire to follow up on my Deux Seurats: one (was an artist) and one (is an inquiry into scientifically sound alternatives to animal testing) of December 26, 2014 post.

First, here’s a March 16, 2015 PETA (People for the Ethical Treatment of Animals) International Science Consortium (PISC) press release which describes a practical and scientific initiative for finding alternatives to animal testing,

Today, the PETA International Science Consortium Ltd. put out a request for proposals (RFP) to identify facilities that can develop an in vitro test that, when used in an integrated approach, has the potential to replace the current test conducted on animals to assess the inhalation toxicity of nanomaterials.

The RFP follows a workshop, organized by the Science Consortium and held at U.S. Environmental Protection Agency headquarters in Washington, D.C., that brought together scientific experts from government, industry, academia, and nonprofit organizations from around the world. The goal of the workshop was to make specific recommendations on the design of this in vitro test, including cell types, endpoints, exposure systems, and dosimetry considerations required to develop the in vitro model.

Based on the recommendations from the workshop, the RFP seeks facilities to develop a method that can assess the induction of pulmonary fibrosis in cells co-cultured at the air-liquid interface following exposure to aerosolized multi-walled carbon nanotubes. The Science Consortium will fund this work.

“For both scientific and ethical reasons, there is interest in developing a non-animal method that is faster, cheaper, and more relevant to the human situation,” says the Science Consortium’s Dr. Amy Clippinger.

The long-term vision is to include this in vitro test in a battery of in silico and in vitro assays that can be used in an integrated testing strategy, providing comprehensive information on biological endpoints relevant to inhalation exposure to nanomaterials to be used in the hazard ranking of substances in the risk-assessment process.

The request for proposals can be found here. The proposal deadline is May 29, 2015.

For more information, please visit PISCLTD.org.uk.

I see the research focus is on multi-walled carbon nanotubes. This makes sense since research has shown that long fibres act like the asbestos fibres they resemble when found in the lung.

Second, I’m hoping to follow up my Deux Seurats piece soon with the tentatively titled, The trouble with mice and … .

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.

Toxicology convo heats up: OECD releases report on inhalation toxicity testing and Nature Nanotechnology publishes severe critique of silver toxicity overanalysis

This has to be one of the rawest reports I’ve seen and that’s not a criticism. The OECD (Organization for Economic Cooperation and Development) has released no. 35 in its Series on the Safety of Manufactured Nanomaterials titled, INHALATION TOXICITY TESTING: EXPERT MEETING ON POTENTIAL REVISIONS TO OECD TEST GUIDELINES AND GUIDANCE DOCUMENT.

This report is the outcome of a meeting which took place in fall 2011 according to the July 4, 2012 news item on Nanowerk,

The expert meeting on Inhalation Toxicity Testing for Nanomaterials was held on 19-20 October 2011 in The Hague, hosted by the Netherlands, with the aim of discussing the results of the OECD Sponsorship Programme (under the responsibility of SG3) on this specific topic and addressing issues relevant to inhalation toxicity. Fifty experts from the WPMN as well as the OECD Working Group of the National Coordinators for the Test Guidelines programme (WNT) participated in the meeting.

This is a partial list of recommendations from the report,

Recommendations raised by the speakers for the discussion

7. Various recommendations were raised by the speakers that served as points for discussion. These recommendations do not necessarily reflect a general agreement. …

• “Provide explicit guidance for the generation of aerosols (sample preparation) based on the exposure scenario”. Hans Muijser

• “Generation of a test atmosphere should have workplace characteristics, but should be adapted to adjust for rodent respirability”. Günter Oberdörster

• “A choice for a dry aerosol or a liquid aerosol should depend on the given test substance and planned test approach (hazard- or risk driven)”. Otto Creutzenberg

• “Aerosol characterization should include size distribution, mass, number and morphology of the material”. Günter Oberdörster

• “Mass concentration is not sufficient for comparison of nanomaterials of the same chemical composition”. Flemming Cassee

• “Dry powders will appear as agglomerate upon aerosolization, which needs to be addressed in the sample preparation guidelines”. Flemming Cassee

• “Dissolution behaviour of the test substance should be assessed in physiological fluids mimicking various lung-specific pH ambiences (neutral, acid)”. Otto Creutzenberg

• “Data analysis should include interpretation of aerosol characteristics, NOAEL, risk assessment implications, mode of action and a strategy for dosimetric extrapolation to humans. The inclusion of biokinetic data is important”. Günter Oberdörster

• “Include biokinetics in the guidance, since different distribution patterns in the whole organism are likely dependent on physicochemical characteristics of nanoparticle aerosols and the dose at the target site will therefore be different. This will allow the assessment of accumulation of nanomaterials in the body at low exposure levels and long-term exposure. A way to perform it is by radiolabelled materials, chemical elemental analysis to determine organ concentrations and transmission electron microscopy”. Wolfgang Kreyling. Others who have suggested inclusion of biokinetics or recognized the importance were Otto Creutzenberg, Frieke Kuper, Günter Oberdörster and David Warheit. (p. 13)

You actually see who made the recommendations! Speakers discussed carbon nanotubes, titanium dioxide, cerium oxide, zinc oxide and more, all of which you can read about in summary form in this 38 pp. report.

Meanwhile, Nature Nanotechnology has published an incendiary commentary about nanosilver and the latest request by the European Commission for another study.  Michael Berger has devoted a July 4, 2012 Nanowerk Spotlight article to the commentary,

A commentary by Steffen Foss Hansen and Anders Baun in this week’s Nature Nanotechnology (“When enough is enough”  [behind a paywall]) pointedly asks “when will governments and regulatory agencies stop asking for more reports and reviews, and start taking regulatory action?”

Hansen and Baun, both from the Technical University of Denmark’s Department of Environmental Engineering, take issue with yet another scientific opinion on nanosilver that has been requested by the European Commission in late 2011: “SCENIHR – Request for a scientific opinion on Nanosilver: safety, health and environmental effects and role in antimicrobial resistance” (pdf). Specifically, the EC wants SCENIHR to answer four questions under the general heading of ‘Nanosilver: safety, health and environmental effects, and role in antimicrobial resistance’.

“Most of these questions – and possibly all of them – have already been addressed by no less than 18 review articles in scientific journals, the oldest dating back to 2008, plus at least seven more reviews and reports commissioned and/or funded by governments and other organizations” Hansen tells Nanowerk. “Many of these reviews and reports go through the same literature, cover the same ground and identify many of the same data gaps and research needs.”

Here’s a prediction from Hansen and Baun as to what will be in the next report due in 2013  (from the Nature Nanotechnology commentary When enough is enough in 7, 409–411 (2012) published online  July 1, 2012 [Note: I have removed links and footnotes]),

… we predict that the SCENIHR’s upcoming review will consist of five main sections summarizing: the properties and uses of nanosilver; human and environmental toxicity; microbial resistance; risk assessment; and research needs. We also predict that the SCENIHR’s report will say something along the following lines: “Nanosilver is reportedly one of the most widely used nanomaterials in consumer products today but the scale of production and use is unknown. The antibacterial properties of nanosilver are exploited in a very diverse set of products and applications including dietary supplements, personal care products, powdered colours, textile, paper, kitchenware and food storage.” And like many previous reviews and reports, the new report is likely to cite the Consumer Product Inventory maintained by the Project on Emerging Nanotechnologies.

We acknowledge that answering the question of how to regulate the use of nanosilver is not easy given the different views of the different stakeholders in this debate and the complex regulatory landscape associated with the many applications of nanosilver. …

Arguably, we all want that the pros and cons of regulatory policy options be based on the best available science while taking broader socio-economical and ethical aspects into consideration before deciding on the appropriate regulatory measures concerning human and environmental exposure to nanosilver. Although it is common for independent scientific experts to be commissioned to gather, analyse and review the available scientific information, and to provide recommendations on how to address a given risk, we do not see the need for further reviews. It is time for the European Commission to decide on the regulatory measures that are appropriate for nanosilver. These measures should then be implemented wholeheartedly and their effectiveness monitored.

I predict this commentary will provoke some interesting responses and I will try to add the ones I can find to this posting as they become available.

ETA July 6, 2012: Dexter Johnson weighed in with his July 5, 2012 posting (Note: I have removed a link),

What may make the matter even worse is that we may already have a pretty substantial framework—in the US, at least—on which to base nanosilver regulations, which dates back to the 1950s. It concerned what was called at the time collodial silver, which is essentially what today is called nanosilver.

But getting back to current stagnant state of affairs, it’s hard to know exactly what’s causing the paralysis. It could be concern over implementing regulations in a depressed economy, or just a fear of taking a position. But in both these instances, the lack of action is making the situation worse. …