We also share a report from cardiologists that suggests you might (or might not) want to check your waist and hip measurements, and a laboratory study with some encouraging news about brain tumor treatments.
US AIR POLLUTION EXPOSURE IN PREGNANCY IS LARGELY DUE TO WILDFIRES
Wildfires are now the leading source of unhealthy levels of air pollution for pregnant women in the United States, researchers say.
They studied roughly 64.5 million pregnancies in 48 states between 2003 and 2019, analyzing neighborhood exposure to tiny airborne particles 2.5 micrometers or less in diameter that travel deep into the lungs and bloodstream.
The major sources of PM2.5 pollution are vehicle exhaust, industrial emissions, and wildfires.
Prenatal exposure to PM2.5 declined substantially between 2003 and 2019, but the contribution of wildfire smoke more than doubled, from around 3.7% to 8.2% overall.
By 2019, wildfire smoke was the dominant contributor to high-pollution days experienced during U.S. pregnancies, researchers reported in Frontiers in Environmental Health.
By 2019, approximately 65% of "exceedance days" — during which PM2.5 pollution exceeded 35 micrograms of particles per cubic meter — were due to wildfire air pollution.
Wildfire smoke is linked with adverse birth outcomes, the researchers noted.
The data pertain only to the U.S., so the researchers cannot directly speak to the experience in Europe, where record-breaking heat waves are contributing to some of the most damaging wildfires in the continent’s history.
However, the contribution of wildfire smoke and other air pollutants to adverse birth outcomes has been documented in both the U.S. and Europe, said senior study author Michel Boudreaux from the University of Maryland.
“While individuals can do some things to reduce their exposure (air filtration, masking, etc), governments and communities need to play an active role by ensuring that people have access to clean air shelters, that homes, workplaces, and schools have air filtration, and ensuring that people that are exposed have access to high-quality medical care.”
ABDOMINAL FAT PREDICTS HEART DISEASE RISK BETTER THAN BMI
The size of a person’s midsection is a better predictor of heart disease risk than body mass index, researchers say.
Overweight and obesity — risk factors for heart disease — have traditionally been diagnosed on the basis of BMI, a ratio of weight to height.
But studies have shown that visceral fat surrounding abdominal organs is more strongly associated with chronic diseases like heart disease and diabetes than subcutaneous fat located directly under the skin.
BMI does not account for distribution of body fat – and not accounting for waist circumference or waist-to-hip ratio can lead to misclassification of cardiovascular disease risk, the researchers reported in the Journal of the American College of Cardiology.
Individuals with normal weight who had elevated central adiposity and high waist-to-hip ratio — meaning their waist is large compared to their hips — had higher risks across most outcomes, study leader Dr. Michael Blaha of Johns Hopkins University said in a statement.
His team looked at data collected over the course of 20 years from more than 260,000 people.
Among individuals with normal weight or overweight, those with high waist circumference and high waist-to-hip ratio had 15% to 50% greater risks for fatal and non-fatal strokes and heart disease.
Those with obesity and low waist circumference had generally similar outcomes compared with those who had normal weight and low waist circumference.
“It is time to abandon a sole focus on body mass index,” said Dr. Harlan Krumholz, editor-in-chief of the journal, who was not involved in the study.
“This enormously important study, based on data from hundreds of thousands of participants in large-scale cohort studies, authoritatively shows that waist circumference and waist-to-hip ratio provide critical information about cardiovascular risk,” Krumholz said in a statement.
“Where fat is distributed matters, and these simple measures should be part of routine cardiovascular risk assessment.”
RESEARCHERS FIND BRAIN-TUMOR VULNERABILITY
After surgery for an incurable brain cancer, there’s a brief window during which drugs can cross through the brain’s protective barrier and reach remaining cancer cells that are likely to trigger recurrence, studies in mice suggest.
Surgery to remove a glioblastoma is usually done within days of diagnosis, followed by chemotherapy and radiation starting four to six weeks later.
Some cancer cells are inevitably left behind, and the delay gives them time to grow. Chemoradiation is only modestly effective at eliminating such residual cells, and tumors recur.
After removing glioblastomas in mice, the researchers discovered that where the tumor had been taken out — the so-called resection margin — the blood-brain barrier was disrupted during the immediate postoperative hours and again 48 to 72 hours afterward.
During those periods, nanoparticles carrying drugs could accumulate at the resection margin, which is where tumors are most likely to recur, according to a report in Science Translational Medicine.
Delivery of nanoparticles containing the chemotherapy agent doxorubicin was enhanced during those peak periods of postoperative blood-brain barrier disruption, inhibiting tumor recurrence.
“For the first time, we’ve shown that glioblastoma surgery briefly exposes a vulnerability we can exploit,” study coauthor Dr. Thomas Kisby of the University of Manchester in the UK said in a statement.
“If treatment is timed during specific windows we identified, it is able to halt the disease significantly before it regrows.”
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