Air pollution and blood clots

A new study from the School of Public Health shows a link between air pollution and potentially life- threatening blood clotting diseases.

Venous thromboembolism encompasses deep vein thrombosis, where blood clots occur deep in a vein, and pulmonary embolism, where blood clots travel to the lungs. These diseases affect about one in a million people in the U.S. annually and are the third most common vascular diagnosis after heart attack and stroke. 

Researchers tracked more than 6,600 participants from six communities in the U.S. over 17 years to assess longterm exposure to four air pollutants: fine particulate matter, nitrogen dioxide, nitrogen oxides, and ozone. They found:

• Exposure to fine particulate matter, which occurs after events like forest fires, increased risk of blood clot diseases by 43 percent. Those exposed to nitrogen dioxide were 2.8 times more likely to experience a blood clot disease. Nitrogen oxides were associated with a 2.3 times greater risk of developing a blood clot disease.
• The associations were consistent across people who smoked or had preexisting respiratory diseases. 

“What’s striking from our study is the increase in serious blood clotting disease with exposure to some of the most common types of pollutants in the air we breathe,” said Pamela Lutsey, a professor in the School of Public Health and lead author. “It’s clear that air pollution’s health effects extend beyond respiratory diseases and impact blood clot risks, even in otherwise healthy individuals without prior respiratory issues.”

Published in Blood in December 2024.

Zebra mussel impact on walleye lakes

A recent U of M study found that invasive zebra mussels alter aquatic ecosystems and are associated with elevated mercury concentrations in fish. Mercury, a potent neurotoxin, poses a serious threat to both aquatic life and human health.

Researchers at the College of Food, Agricultural and Natural Resource Sciences and others studied 21 Minnesota walleye lakes to assess the impact of zebra mussels.  They compared mercury concentrations of fish from lakes with and without zebra mussels and sampled water, zooplankton, invertebrates, and fish from both nearshore and open water zones. They found:

• Walleye exhibited 72 percent higher mercury concentrations in lakes invaded by zebra mussels. Average-sized walleye were more than twice as likely to exceed mercury thresholds tied to human health.
• Walleye in infested lakes reached mercury concentrations exceeding the Minnesota Department of Health threshold of 0.22 parts per million at a significantly smaller size (14 inches vs. 18 inches).
• Yellow perch exhibited 157 percent higher mercury concentrations. Average-sized yellow perch had a 50 times higher risk of exceeding mercury thresholds.
• Increased mercury concentrations in fish add to a growing list of known negative effects of invasive zebra mussels. 

“We were surprised to find such a large effect of zebra mussels in fish-tissue mercury concentrations, and we are eager to conduct further research to understand exactly the mechanism behind these patterns,” said senior author Gretchen Hansen, an associate professor in the Department of Fisheries, Wildlife and Conservation Biology. 

These results do not mean that fish are unsafe to eat, but point to a need to assess contaminant loads in fish harvested for consumption in lakes invaded by zebra mussels.

Published in Science of the Total Environment in December 2024.

Grasses vs. buckthorn

Buckthorn is one of Minnesota’s most widespread invasive species. Each year millions of dollars are spent trying to remove it from the state’s woodlands and forests. Most attempts offer only a temporary reprieve. 

New U of M research suggests that seeding native plants alongside invasive removal efforts may help. Researchers found that heavily seeding native grasses, like Virginia wildrye, alongside buckthorn removal efforts greatly reduces the number and size of new buckthorn trying to reclaim the site.

Among the findings:

Returning buckthorn were 47 percent less abundant and 81 percent smaller in areas where grasses were established—about a 90 percent decrease returning from seed overall.

Seeding is most effective in woodlands with enough light to support vigorous grass growth. Grasses do not establish well in dark forests but can form nearly impenetrable thickets in more open woodlands.

Seeding must be paired with other management strategies that prevent larger trees from resprouting.

“There are no easy solutions when it comes to buckthorn, but this work clearly demonstrates that by investing in native biodiversity we can make our natural areas more resistant to invasion in a way that means less time and money combating those invaders, fewer herbicides put into our environment, and healthier ecosystems overall,” said lead author Mike Schuster, a researcher in the College of Food, Agricultural and Natural Resource Sciences. 

Published in Ecological Engineering in January 2025.

If you liked this story, Minnesota Alumni magazine publishes four times a year highlighting U of M alumni and University activities. Early access to stories and a print subscription are benefits of being an Alumni Association member. Join here to receive a printed copy at home.