University of
Rochester
Amid growing alarm
over the plastic that pollutes our environment, biomedical and optics
researchers at the University of
Rochester are working to better understand the prevalence
of microplastics in drinking water and their potential impacts on human health.
They are collaborating
with SiMPore, a company
that uses nanomembrane technology initially developed at the University, to
devise ways to quickly filter and identify particles of plastic 5 mm or smaller
in drinking water samples. They will then test the ability of these particles
to cross a microscale barrier that simulates the lining of a human intestine.
“We want to see to
what extent the particulates that you consume in your drinking water can pass
through your gut and into your other organs,” says Greg Madejski, a
postdoctoral fellow in the laboratory of James McGrath,
professor of biomedical
engineering.
Madejski is coordinating the research with the lab of Wayne Knox, professor of optics. Both McGrath and Knox are affiliated with the Materials Science Program.
Madejski is coordinating the research with the lab of Wayne Knox, professor of optics. Both McGrath and Knox are affiliated with the Materials Science Program.
Microplastics are used
as ingredients in cigarette filters, textile fibers, and cleaning or personal
care products. Others result when larger plastic items are worn down by sun,
wind, and waves. They can be found on mountaintops and at the bottom of the
oceans; in the air we breathe and in the water we drink.
Exactly how many microplastics are absorbed by humans, and how much harm it is causing them has been hard to assess because the particles— below 100 microns—are so small and difficult to detect.
Exactly how many microplastics are absorbed by humans, and how much harm it is causing them has been hard to assess because the particles— below 100 microns—are so small and difficult to detect.
“These are particles
that you couldn’t pick up with tweezers; that you can’t even see with the naked
eye,” Madejski says. They elude the “traditional method of skimming the surface
of water with a plankton net and collecting everything,” he says.
Instead the
researchers will filter water through sheets of silicon nitride a hundred times
thinner than the diameter of a human hair. These SiMPore nanomembranes, based
on prototypes initially created in the McGrath lab, have micron-sized slits in
them.
“That allows us to catch micron-sized debris,” Madejski says. “And because the sheets are so thin, you can filter a significant amount of water through them without a lot of pressure.”
“That allows us to catch micron-sized debris,” Madejski says. “And because the sheets are so thin, you can filter a significant amount of water through them without a lot of pressure.”
The layer of
microscopic debris that accumulates on the surface of the membranes is analyzed
in various ways to determine how much of it consists of microplastic particles.
The particles can be
stained with Nile Red dye, for example, which adheres to plastics. Raman
microscopy, used in the Knox lab, shines a bright laser on the material to
obtain chemical bond information—basically “a molecular fingerprint of what
that material is,” Madejski says. “It doesn’t work as well with fluorescent
material, which many plastics are, but it can clearly identify 10-micron
polystyrene beads, for instance.”
The researchers also
hope to use X-ray photoelectron spectroscopy and energy-dispersive X-ray
spectroscopy techniques to further study the composition of microplastic
particles.
“The beauty of
nanoscale membranes is you can adapt them for a wide range of characterization
tools,” Madejski says.
Particles that are
identified as microplastics will be separated out and “fed” to Caco2 human
epithelial cell lines that are widely used as a model of the intestinal
epithelial barrier. This will help determine the extent to which the particles
are absorbed into the body.
Working with David
Rowley of the City of
Rochester Water Bureau, water samples are being analyzed at
every stage of the city’s 35-mile long gravity-fed water purification and
supply system, which stretches from high elevation Hemlock Lake, where the city
draws its water, through pipes and reservoirs, and ultimately reaching
destinations like the drinking fountains and faucets in the labs and hallways
of Goergen Hall on the University’s River Campus.
There is an urgency to
learning more about the prevalence of microplastics and their potential impacts
on human health, says Madejski, who recently attended a workshop on
microplastics at the Woods Hole Oceanographic Institute.
“One thing to keep in
mind is that over the last 70 years or so we’ve produced about 4 billion tons
of plastic; in the next decade or so, we’re due to double that amount,”
Madejski says.
The project is funded
with a National Institutes of Health Small
Business Innovation Research award, which provides
early-stage capital for technology commercialization. The program allows
US-owned and operated small businesses to engage in federal research and
development that has a strong potential for commercialization.