April 26, 2017

expert reaction to study looking at inhalation of gold nanoparticles as a model of air pollution nanoparticles

Publishing in ACS Nano scientists report that inhalation of tiny particles of pollution could be associated with an increased risk of cardiovascular disease.

These comments accompanied a briefing.

Dr Zongbo Shi, Air Pollution Scientist at the University of Birmingham, said:

“This is a very well designed, robust and high quality study and the results unequivocally showed that nanoparticles can travel from lungs to blood vessels and different organs. This research provides a missing linking or mechanism between airborne nanoparticles exposure and their adverse health effects. It also helps to explain why nanoparticles can travel to human brain as detected in a recent study published in PNAS.¹”

¹  http://www.pnas.org/content/113/39/10797.abstract

Prof. Frank Kelly, Professor of Environmental Health at King’s College London, said:

“This elegant study by Miller and colleagues goes a long way in plugging a gap in the mechanistic understanding of how small particles contribute to vascular injury and disease.

“Using gold nanoparticles and very sensitive detection techniques they circumvent previous problems associated with tracking radiolabelled particles and the uncertainty if the label remained with the particle in transit. By using particles of varying sizes, they demonstrate the transition of particles from the airways into the circulation and subsequently distribution throughout the body. Of note, they found that very small particles (<20μm) accumulated in the body at a greater rate than larger (40μm) particles.

“If these findings with gold particles reflect the movement of exhaust generated carbon particles, then the increased production of very small particles by modern engine technologies is a cause for further concern.”

Prof. Peter Dobson, Professor Emeritus at the University of Oxford, said:

“This is an ambitious study that attempts to use gold particles of different sizes to model the effect of airborne particulates on cardiovascular disease. It is however inappropriate because the gold does not represent the chemistry that is present in and on airborne particulates from combustion and other anthropological sources. The protocols used for the human experiments are very risky because the small gold particles they used are known to be cytotoxic.  The methodology used for the animal experiments is also not appropriate, because the mice were fed on a high fat diet to promote lesions and the nanoparticles were introduced by direct instillation into the lung rather than by inhalation. Unfortunately this is a consequence of the need to accelerate the experiments so care is needed in interpreting the results and applying them to air pollution.

“The study detracts from conclusions reached over 10 years ago by some of the same authors which used carbonaceous particles that are more representative of soot. So the claim in the Press Release for this being the ‘first’ is wrong.

“It is quite a large study, but it is fragmented. The gold nanoparticles made by spark generation for the tests on humans will be very different to the citrate-coated gold supplied by a colloidal route from BBI.  So the mechanism identified is of minimal relevance to the real world.”

Prof. Stephen Holgate FMedSci, MRC Clinical Professor of Immunopharmacology at the University of Southampton, said:

“It is clear from this study that acute episodic exposure to gold nanoparticles has a deleterious effect on cardiovascular disease. As the authors point out, there are also implications for inhaled nanoparticulates from air pollution.

“Beyond acute exposure, what is of great future importance is the effect of chronic exposure to such particles and how early in life these cardiovascular effects begin since air pollution affects human health across the life course.”

Prof. Jeremy Pearson, Associate Medical Director at the British Heart Foundation, which funded the study, said:

“There is no doubt that air pollution is a killer, and this study brings us a step closer to solving the mystery of how air pollution damages our cardiovascular health. More research is needed to pin down the mechanism and consolidate the evidence, but these results emphasise that we must do more to stop people dying needlessly from heart disease caused by air pollution.

“Crucially, individual avoidance of polluted areas is not a solution to the problem. Government must put forward bold measures to make all areas safe and protect the population from harm.”

* ‘Inhaled nanoparticles accumulate at sites of vascular disease’ by Mark R. Miller et al. will be published in ACS Nano at 13:00 UK time on Wednesday 26 April 2017, which is also when the embargo will lift. 

Declared interests

Prof. Frank Kelly: receives funding for his research into health impacts of air quality from research councils, NIHR and the EU. Frank is the air quality and health advisor (unpaid) for the Healthy Air Campaign. Frank is also Chair of COMEAP (DH’s Committee on the Medical Effects of Air Pollution) and is a member of AQEG (Defra’s Air Quality Expert Group).

Prof. Dobson: is Chair of the FENAC NERC facility, and is consultant to a company that makes products to reduce diesel emissions (Energenics Ltd)

Prof. Holgate: is RCP Advisor on Air Quality and Chair of RCP Report Every Breath We Take: The Lifelong Impact of Air Pollution

Dr Zhi: no conflicts.