Q&A: Geosciences’ Michael Hochella discusses study involving toxic nanoparticles produced by burning coal
Virginia Tech scientists have discovered that incredibly small particles of an unusual and highly toxic titanium oxide produced from burning coal can cause lung damage in mice after a single exposure and long-term damage in just six weeks. The potential that the same nanoparticles could be toxic to humans is high.
Tests were headed by Irving Coy Allen, a professor with the Virginia-Maryland College of Veterinary Medicine, with collaborators from across Virginia Tech and researchers from a host of other universities in the United States and China. The findings were published in the scientific journal Frontiers in Immunology.
They follow a 2017 study by Virginia Tech geologist Michael Hochella, a University Distinguished Professor Emeritus in the Department of Geosciences, part of the College of Science at Virginia Tech.
He and a team of researchers found that burning coal -- when resulting smoke is not captured by high-end filters found in U.S. power plants -- emits metallic-like particulates known as titanium suboxide nanoparticles, or Magneli phases, into the air. Such nanoparticles were found by Hochella’s team of scientists in ash collected from the city streets, sidewalks, and in standing water in Shanghai.
Below, are edited excerpts from an email Q&A exchange with Hochella, now living in Montana.
Q: These studies resulted from you ‘accidentally’ discovering the nanoparticles in a 2014 coal ash spill in the Dan River in North Carolina. What would you hope people, and especially governments, do with this new information?
A: These Magneli phases have been distributed literally around the world without us knowing it. In the Nature Communications paper, we did an approximation of how much. Briefly, we started with the Industrial Revolution [starting roughly 1760] when coal burning went up dramatically. Since that time, we estimate that worldwide, humans have produced -- unknowingly and unintentionally -- roughly a gigaton of these nanoparticles. That's a billion tons. Now, not all of that will have gone up in the atmosphere, as electrostatic precipitators on stacks of coal burning power plants started being used in the 1920s in the United States. But today, air quality can still be horrible in many countries due to coal burning, and that air pollution travels the world. This study reminds us that even in the 21st century, we still don't know all the pollutants that are in our environment. In terms of coal, we know that it is the largest polluting fuel we use, and the nanoparticle issue just adds to this problem. It serves as another reason to continue to try to decrease coal use worldwide. In developing countries, that is particularly hard because it is so cheap.
Q: What additional studies would you want to see happen in the near future? Those showing potential effects on people, animals, plant life?
A: Our studies to date beg the need for human studies of inhaled Magneli phases. Such studies are always done by the bio/medical communities, but when materials and earth sciences collaborators are not included, the studies, historically, are not as useful. This is becoming well known. It is critical that we join forces to make these studies more useful and meaningful, just like this latest study with Dr. Allen.
Q: From all of this work, from the first discovery of the titanium suboxide nanoparticles in the Dan River to now, what has surprised you the most?
A: 1) Curiosity science is still absolutely essential, because you never know what you will find, and what it might mean, and 2) that my initial prediction was actually correct -- that the toxicity testing would turn out to give us bad news. For the latter, I had a strong feeling that due to the “odd” electronic behavior of Magneli phases in lab experiments, and that because they were so exceedingly rare on the planet until we started burning coal, that evolved biological systems would not be equipped to handle these things through natural selection.
Q: Do you wish to add anything?
A: As human civilization moves forward in time, with more pressures on the planet -- which are already dramatic, but will clearly get even more dramatic -- we need to double our efforts to do the needed science, eventually working through political action to keep the populace as safe and healthy as possible.