A weekly roundup of public health news
Farmers use far more nitrogen than needed, raising health risks
U.S. corn and soybean farmers are using far more nitrogen fertilizer than their crops need, polluting waterways and damaging the environment, a new report from the Union of Concerned Scientists finds.
As much as half of the nitrogen applied to the 179 million acres of corn and soybean crops grown in the U.S. each year is not taken up by plants, according to the Feb. 10 report. Left unused, the excess nitrogen can wash into waterways, potentially contaminating drinking water.
Long-term exposure to nitrates in drinking water can raise risks for colon, bladder and ovarian cancers. Infants given formula prepared with nitrate-contaminated water face the risk of methemoglobinemia, also known as “blue-baby syndrome,” a potentially fatal condition that reduces oxygen in the bloodstream.
Groundwater in several states regularly exceeds U.S. Environmental Protection Agency standards for nitrate contamination, authors noted. Runoff from farms in the Midwest flows into the Mississippi River and contributes to a seasonal “dead zone” in the Gulf of Mexico. In 2025, that dead zone stretched about 4,400 square miles.
Fertilizer overuse also contributes to climate change. When excess nitrogen stays in soil, microbes convert some of it into nitrous oxide and other gases that are released into the atmosphere, where they can spur global warming. Nitrogen fertilizer use was responsible for roughly 120 million metric tons of heat-trapping emissions in 2023, report authors estimated.
Farmers often overapply nitrogen fertilizer to avoid lower-than-expected yields. Over time, repeated overuse of fertilizer can degrade soil health, reducing soils’ ability to replenish nutrients and pushing farmers to apply even more fertilizer to maintain yields — a cycle the report describes as a “fertilizer treadmill.”
Review finds nurse-led hospital care on par with doctors
Nurses can safely provide many types of hospital care traditionally delivered by doctors, according to a new Cochrane review.
Published Feb. 12 in the Cochrane Database of Systematic Reviews, the review looked at studies of hospital care provided to more than 28,000 patients in 20 countries, finding little to no difference in deaths, quality of life or patient safety.
The studies compared care provided by junior and senior doctors with that delivered by nurses — including advanced nurse practitioners, clinical nurse specialists and registered nurses. Nurses in the study worked in areas such as cancer, cardiology, obstetrics-gynecology and respiratory care.
Overall, the review found little to no difference between nurse-led and doctor-led clinical care. In some areas, nurses came out slightly ahead of doctors, including management of diabetes, medication and eczema.
The level of nurse training and responsibility differed across studies, which may influence outcomes, reviewers said. When considering nurse grade, they found fewer patient safety problems when care was delivered by specialist nurses.
The growing aging population, more complex health needs and doctor shortages have caused strain in hospitals in the U.S. and in many parts of the world. Some health systems are turning to nurses to take on duties traditionally performed by doctors to address problems.
The U.S. is predicted to have a shortfall of nearly 142,000 physicians by 2038, according to the Health Resources and Services Administration, including doctors in primary care, cardiology and anesthesiology.
Power outages during heat waves can turn indoors dangerous
When blackouts occur during heat waves, staying home can be unsafe, a new study finds.
Researchers examined what would happen if a major heat wave struck at the same time as a citywide power outage. Focusing on Austin, Texas, as a test case, they analyzed indoor heat risk for each of the city’s 213,000 single-family homes. The findings, published in Building and Environment, show that most houses could quickly become dangerous without air conditioning.
The study matched homes to about 720 building models based on factors such as year of construction, size, window type and number of floors. They then recreated conditions from a historical three-day heat wave in which outdoor temperatures exceeded 110 degrees and simulated a power grid failure.
The results showed stark differences by age. Under today’s climate conditions, about 85% of single-family homes in Austin would pose significant heat risk to an elderly person during a combination heat wave and blackout, researchers found. For younger people, the share of homes reaching that level of risk is smaller, about 15%.
But as temperatures rise in future scenarios under climate change, vulnerability would spread, the study found. Nearly every single-family home showed some level of heat risk, and the share of homes posing risk to younger residents would increase sharply.
As homes vary in how they are built, outdoor temperatures alone may not reliably predict how hot it will become inside. Well-insulated houses with modern windows may heat up more slowly, while older homes with cracks and single-pane windows can warm rapidly once cooling systems shut down.
Austin faces a doubling of heat waves by the end of the century, according to climate projections. Researchers said their method can be applied to other cities, allowing officials to identify which homes and neighborhoods face the greatest risk during extreme weather events.
Other recent public health news of note:
• Hair extensions may contain far more hazardous chemicals than previously recognized, according to a new study in Environment & Health. Researchers analyzed more than 40 popular products, including synthetic and human hair extensions, finding all but two samples contained hazardous substances. The study detected chemicals linked to cancer, hormone disruption and developmental problems in the products, which are widely used by Black women.
• Public trust in the Centers for Disease Control and Prevention remains at its lowest level, according to a recent KFF Poll conducted weeks after the Trump administration reduced the number of recommended routine childhood vaccines by about a third. Just 47% of adults said they trusted the agency at least “a fair amount” to provide reliable vaccine information — down more than 10 percentage points since the start of the administration. A separate survey by the Annenberg Public Policy Center found most Americans still consider the MMR, flu and COVID-19 vaccines safe, though support has eroded slightly.
• South Asian adults in the U.S. develop heart disease risk factors earlier than other population groups, even though many report healthy habits, according to a study published in the Journal of the American Heart Association. At ages 45 to 55, researchers found that South Asian Americans had higher rates of prediabetes, Type 2 diabetes and high blood pressure than their white, Chinese and Hispanic peers, and similar or slightly lower rates of high blood pressure compared to Black adults. At age 45, South Asian men were nearly eight times more likely than white men to have prediabetes, and women had about triple the risk.
The Watch is written by Michele Late, who has more than two decades of experience as a public health journalist.