A weekly roundup of public health news
Uninsured Americans still pay heavily into U.S. health care
Despite lacking coverage, uninsured Americans pay almost two-thirds as much toward the U.S. healthcare system as people with insurance, new research in Health Affairs finds.
The study, published in the journal’s September issue, found uninsured people under age 65 paid about 64% as much toward healthcare in 2023 as insured people. Because they did not pay insurance premiums, taxes made up most of their contributions.
Nearly all U.S. adults contribute to healthcare through some combination of federal and state income taxes, Medicare payroll taxes, insurance premiums and out-of-pocket medical costs. But how much people pay — and how those costs affected their finances — vary widely by income, insurance and health status, the study said.
Researchers estimated healthcare contributions using 2023 federal data for U.S. tax filers. Median contributions rose sharply with income, totaling about $740 per person among the lowest-income fifth of filers to more than $26,000 among the highest-income fifth.
However, direct medical expenses took a greater toll on people with fewer resources. Out-of-pocket spending represented about 1% of income among the lowest-income group, compared with 0.3% among the highest-income group.
Older adults and people in fair or poor health also had higher out-of-pocket costs. Median annual spending reached $2,250 among older adults and $1,725 among people in poor health. People with employer-sponsored insurance paid about $1,710 out of pocket annually.
About 26.4 million U.S. adults lacked health insurance at some point in 2023, accounting for 8% of the population, according to the U.S. Census Bureau. Young adults had the highest uninsured rate, at 14%, while 11% of working-age adults overall lacked coverage.
Nearly two-thirds of adults who went without health insurance in 2023 were people of color. American Indian and Alaska Native people were most likely to lack coverage, at about 19%, followed by Hispanic people, and Native Hawaiian and Pacific Islander people.
Extreme rainfall fuels surges in microplastic pollution
Heavy rainfall from extreme weather is spreading microplastic pollution — and ferrying health risks along with it, new science shows.
A Sept. 10 study in Science finds heavy rainfall can create surges of microplastics into waterways, impeding water quality and ultimately threatening the human food supply.
Rivers carried about 263,000 metric tons of microplastics into oceans around the world in 2022, considerably more than many previous estimates, the research found. Plastic use and poorly managed waste were major factors determining where concentrations were highest, while weather helped drive shorter-term changes. Much of the waste came from rivers in developing countries.
Rivers and other waterways are major routes carrying pollution from land to the ocean. Microplastics, which are defined as plastic particles smaller than 5 millimeters, can accumulate from cities, farms, roads and floodplains before being swept downstream, contaminating coastal environments and marine food webs.
Rainfall can dramatically speed up that movement. Researchers warned that climate change could worsen the problem as extreme rain becomes more frequent and intense, sending concentrated bursts of pollution downstream and into oceans.
As microplastics are flushed through waterways, they are carrying more than just debris, more new science shows. A research review published Aug. 28 in Energy & Environment Nexus found microplastics can pick up heavy metals, pesticides and other pollutants, then release them after being eaten by fish or other organisms.
The risks can vary by the size, type and age of the plastic. Polystyrene, for example, can attract some chemical pollutants at rates as much as 47 times higher than some other plastics. Older, worn-out particles can become more effective carriers as their surfaces change.
The smallest particles may pose particular concerns, the review said. Nanoplastics, which are smaller than 1 micrometer, can cross biological membranes, allowing them and the pollutants they carry to move beyond the digestive tract and potentially reach organs such as the liver, spleen and brain. Larger microplastics can also develop communities of microorganisms on their surfaces, including disease-causing bacteria and antibiotic resistance genes that can travel through water and food chains.
As much as 40 million metric tons of microplastics enter the environment each year, largely from paints, cosmetics and the breakdown of larger plastic products. About 430 million tons of plastic were produced globally in 2024. That total is projected to more than triple by 2060.
Hot days are extending beyond summer
As the world warms with climate change, extreme heat is increasingly stretching beyond the summer season.
While dangerously hot days used to mainly happen during the summer, they are now occurring more often just before and after, bracketing the season in heat, according to a study in AGU Advances.
Extreme heat seasons have expanded significantly across about half of the world’s land area over the past 45 years. In the western U.S., eastern China, northern Africa and eastern Europe, extreme heat has increased more in the months following the traditional heat season. Western Europe, southern Africa and northwestern India experienced larger increases ahead of their usual heat seasons.
Researchers highlighted Phoenix, Arizona, as one example of how temperatures are changing. From 2015 to 2024, the median date of the city’s extreme dry heat in the city moved 10 days later compared with the 1980s. Humid heat, meanwhile, shifted earlier.
The expansion in high heat days can pose health risks. Early heat can strike before people have physically adjusted to warmer weather or communities have prepared their cooling plans. Heat that lingers after summer can draw out exposure following months of already-hot weather.
Longer heat seasons can also overlap with other hazards. In the western U.S., later heat can coincide with wildfire season, while in the Southeast it can overlap with hurricane season and resulting power outages.
The findings came as the contiguous U.S. experienced its warmest summer ever recorded. Temperatures for June through August, known as meteorological summer, were the warmest in 132 years, the National Oceanic and Atmospheric Administration confirmed Sept. 9. Record-breaking heat extended across much of the Southwest, with Arizona, New Mexico, Utah and Colorado each recording their warmest summer on record.
Nighttime low temperatures were higher than average across the contiguous U.S., preventing communities from cooling down.
Last month, the average U.S. temperature was 3.5 degrees above the 20th-century average, making it the hottest August ever on record, NOAA said. Notable weather events in August included Lake Mead in the Southwest dropping to its lowest recorded level, drought occurring in 59% of the nation, flash flooding in Hawaii and the burning of 15,000 acres in a Nevada wildfire.
Other recent public health news of note includes:
• Being exposed to air pollution for long periods can stress the heart, a new analysis in BMC Public Health says. Researchers found heart rate variability — changes in the time gap between heartbeats — declines more rapidly after about three hours of air pollution exposure. People who have cardiovascular conditions or who work outdoors for long periods should take note, they said, as lower heart rate variability is linked to a higher risk of heart disease and cardiac events.
• Heat waves that occur in the ocean can have impacts on human health, new findings show. Marine heat waves, which are defined as extended periods of high ocean temperatures, are becoming more frequent, longer lasting and more intense as the climate warms. While their main impact is on ocean ecosystems, they can also lead to more intense storms and flooding for people living on coastlines, increase algae blooms and damage fisheries and seafood supplies, a recent study in Nature Sustainability says. New research released earlier this summer in the Proceedings of the National Academy of Sciences linked marine heat waves with increased deaths, wasting and stunting in children.
• People who have lung cancer are more likely to have microplastics in their lungs, according to new findings presented at the European Respiratory Society Congress on Sept. 6. Researchers found patients with lung cancer were more likely to have detectable microplastics and more of the material than people without the disease. Polypropylene and polyethylene plastics, which are used in packaging, textiles and consumer products, were the most common types found. Microplastics commonly enter the lungs through inhalation.
The Watch is written by Michele Late, who has more than two decades of experience as a public health journalist.ore than two decades of experience as a public health journalist.
