The Brief

Whether it's our bloodstream, brain, or lungs, microscopic fragments of plastic seem to turn up every time scientists scour a new corner of the human body.

The male reproductive organs are no exception.

New research published this month finds microplastics can build up in the testicles of humans and dogs — raising more questions about the potential health impacts of these particles.

Animal studies have shown exposure to microplastics can impact sperm quality and male fertility, but scientists are still in the early stages of translating this work to human health.

"Microplastics are everywhere," says Dr. John Yu, a toxicologist in the College of Nursing at the University of New Mexico and lead author of the study. "The quantification of those microplastics in humans is the first step to understanding its potential adverse effects."

When he set out to do the study, Yu didn't expect microplastics would have penetrated the male reproductive system so extensively, given the tight blood-tissue barrier around those organs. To his surprise, the research team unearthed a wide range and heavy concentration of microplastics in the testicles of about two dozen men and close to 50 dogs.

The results may also be relevant to a well-documented global decline in sperm count and other problems related to male fertility. This trend has been linked to a host of environmental and lifestyle factors, including certain endocrine-disrupting chemicals found in plastics.

The growing numbers of studies like this one are "compelling and should be a wake up call for policymakers," says Tracey Woodruff, director of the Environmental Research and Translation for Health Center at the University of California, San Francisco.

How much and what kind of plastics were in the testicles?

This is the largest study to measure how much of these microplastics that permeate the water, food and even air end up in the most intimate recesses of male reproductive anatomy.

It follows a smaller analysis, published last year by a team in China, that detected microplastics in about half a dozen human testicles and in semen.

For the current study, researchers at the University of New Mexico collected the testicles from autopsies of people ranging in age from 16 to 88 and from nearly 50 dogs after they were neutered at local veterinary clinics.

Dogs can function as "sentinel" animals for disease and harmful chemical exposure because they're so embedded in the human environment, plus canine spermatogenesis is more similar to the human process of producing sperm than lab rats, says Yu.

Instead of trying to count each microplastic particle, the researchers were able to quantify the total amount of plastic by dissolving all the biological tissue and separating out the solids.

About 75% of what remained was plastic.

Polyethylene, or PE, made up a large portion of that. It's the most widely used plastic in the world, showing up in packaging, bags and any number of products.

Matthew Campen, who has examined these tiny particles up close, describes them as "shard-like, stabby bits" because of the way they've become "old and brittle and fragmented."

"What they do in the body, we don't know," says Campen, a professor at the UNM College of Pharmacy and one of the authors of the study, "Obviously, little tiny particles can disrupt the way cells behave."

Polyvinyl chloride — what's in PVC piping — emerged as another prominent culprit and was the second most common in the dog testicles. Vinyl chloride is classified as a carcinogen and long-term exposure, for example in drinking water, can increase the risk of cancer.

What's more, Yu and his team found a correlation between lower sperm count in the dog testicles and the presence of PVC (the analysis couldn't be done on the human samples because of how they had been stored).

There was also an association between greater levels of PVC and decreased weight of the testicles. The same was seen with Polyethylene terephthalate, or PET, another common source of plastic, which recent research suggests may be harmful.

Woodruff says weight is a somewhat "crude" marker for the effects on testicular health, although it's frequently used by regulatory agencies to evaluate the impacts of chemicals.

Implications?

The research comes with many caveats and cannot prove microplastics directly cause problems with male fertility. Nonetheless, Yu says the results are "concerning" and lay the foundation for more targeted studies on the "relationship between microplastic exposure and its potential impact on sperm."

An emerging body of evidence suggests microplastics can have toxic effects on reproductive health.

In a 2022 review of the evidence for the state of California, Woodruff and her colleagues concluded that microplastics were "suspected" to harm sperm quality and testicular health, but she says that may soon tip over from "suspected" to "likely" because more high-quality studies are being published.

"In the history of looking at chemical or environmental health issues, at the beginning you see these indicators of health harms and then those that have some type of evidence behind them just tend to grow," says Woodruff, "I anticipate we're just going to see more health harms from these microplastics."

In the University of New Mexico study, the concentration of microplastics in human testicles was on average three times higher than in dogs.

Campen says there are still many unknowns, like what specific concentration would pose a threat to health, or how that might vary depending on the kind of microplastic or where they accumulate in the body.

"We're just at the tip of the iceberg," says Campen, who has used this same technique to quantify the levels of microplastics in other tissues and organs.

The amount in the testicles is considerably higher than what was discovered in placenta, and second to what they observed in the brain, says Yu.

Exactly how the microplastics are making their way into the testicles requires further study. Campen suspects they could be "hitchhiking" through the gut via tiny fat particles that get metabolized and then fan out across the body.

It's plausible the build-up of microplastics in the testicles could affect reproductive health in any number of ways. Yu says microplastics could physically disrupt spermatogenesis, mess with the barrier between the testicles, or be a vehicle for harmful chemicals.

They could lead to inflammation and cause oxidative stress, which down the road might affect fertility, says Dr. Sarah Krzastek, a urologist at Virginia Commonwealth University.

"It's probably one more piece of the puzzle of things that are contributing to declines in male fertility over the years as these environmental exposures keep accumulating," she says, "We don't know the clinical ramifications of that yet."

Richard Lea, a reproductive biologist at the University of Nottingham, calls the findings "alarming."

"Having something unnatural like that in the testes is not particularly good news for good reproductive health," says Lea.

In his lab, Lea has found that exposure to phthalates, which are chemicals that can leach from plastics, can reduce the ability of sperm to swim and increase the fragmentation of DNA in the sperm head. This is one likely contributor to the decline in sperm quality in household dogs over the last several decades, a trend that mirrors what's seen in humans.

Of course, the testicles are just one part of the male reproductive system.

Lea says there's now research showing these chemical contaminants can affect the hormonal control of reproduction, at different levels in the body, including in the brain.

How to study a substance that is ubiquitous

Dr. Shanna Swan, a reproductive epidemiologist who has documented the global decline in sperm count, says she's concerned about the accumulation of microplastics. But it's not yet clear finding them in the testicles rather than other parts of the body is more worrisome from the standpoint of reproductive health.

For example in her work, she's looked at how prenatal exposure to endocrine-disrupting chemicals like phthalates can affect male reproductive function and "lead to lifetime of reproductive damage."

Swan says a limitation running through many of the recent studies on microplastics is that the samples may be inadvertently exposed to microplastics in the environment and that leads to skewed impressions of what was actually present in the person.

She notes there were similar quality control issues nearly a quarter century ago when scientists first started measuring phthalates in human tissues.

"I think there have to be a lot of caveats saying this is really the beginning," says Swan, a professor at the Icahn School of Medicine at Mount Sinai, "It's suggestive, it's important, and it's preliminary."

The University of New Mexico researchers developed a quality control process to protect the samples from being accidentally exposed to microplastics as much as possible. Campen says there's so much plastic in the human body, the amount that might contaminate the samples is "trivial."

More broadly, though, he acknowledges the field faces some huge challenges moving forward — especially as they try to draw a stronger link between these tiny particles and a decline in reproductive health or disease.

"A lot of the problem is they're so ubiquitous. There are no proper controls anymore. Right? Everybody's exposed," he says.

The federal government has drastically scaled back the number of recommended childhood immunizations, sidelining six routine vaccines that have safeguarded millions from serious diseases, long-term disability and death.

Just three of the six immunizations the Centers for Disease Control and Prevention says it will no longer routinely recommend — against hepatitis A, hepatitis B and rotavirus — have prevented nearly 2 million hospitalizations and more than 90,000 deaths in the past 30 years, according to the CDC's own publications.

Vaccines against the three diseases, as well as those against respiratory syncytial virus, meningococcal disease, flu, and COVID, are now recommended only for children at high risk of serious illness or after "shared clinical decision-making," or consultation between doctors and parents.

The CDC maintained its recommendations for 11 childhood vaccines: measles, mumps, and rubella; whooping cough, tetanus, and diphtheria; the bacterial disease known as Hib; pneumonia; polio; chickenpox; and human papillomavirus, or HPV.

Federal and private insurance will still cover vaccines for the diseases the CDC no longer recommends universally, according to a Department of Health and Human Services fact sheet; parents who want to vaccinate their children against those diseases will not have to pay out-of-pocket.

Experts on childhood disease were baffled by the change in guidance. HHS said the changes followed "a scientific review of the underlying science" and were in line with vaccination programs in other developed nations.

HHS Secretary Robert F. Kennedy Jr., an anti-vaccine activist, pointed to Denmark as a model. But the schedules of most European countries are closer to the U.S. standard upended by the new guidance.

For example, Denmark, which does not vaccinate against rotavirus, registers around 1,200 infant and toddler rotavirus hospitalizations a year. That rate, in a country of 6 million, is about the same as it was in the United States before vaccination.

"They're OK with having 1,200 or 1,300 hospitalized kids, which is the tip of the iceberg in terms of childhood suffering," said Paul Offit, the director of the Vaccine Education Center at the Children's Hospital of Philadelphia and a co-inventor of a licensed rotavirus vaccine. "We weren't. They should be trying to emulate us, not the other way around."

Public health officials say the new guidance puts the onus on parents to research and understand each childhood vaccine and why it is important.

Here's a rundown of the diseases the sidelined vaccines prevent:

RSV. Respiratory syncytial virus is the most common cause of hospitalization for infants in the U.S.

The respiratory virus usually spreads in fall and winter and produces cold-like symptoms, though it can be deadly for young children, causing tens of thousands of hospitalizations and hundreds of deaths a year. According to the National Foundation for Infectious Diseases, roughly 80% of children younger than 2 who are hospitalized with RSV have no identifiable risk factors. Long-awaited vaccines against the disease were introduced in 2023.

Hepatitis A. Hepatitis A vaccination, which was phased in beginning in the late 1990s and recommended for all toddlers starting in 2006, has led to a more than 90% drop in the disease since 1996. The foodborne virus, which causes a wretched illness, continues to plague adults, particularly people who are homeless or who abuse drugs or alcohol, with a total of 1,648 cases and 85 deaths reported in 2023.

Hepatitis B. The disease causes liver cancer, cirrhosis, and other serious illnesses and is particularly dangerous when contracted by babies and young children. The hepatitis B virus is transmitted through blood and other bodily fluids, even in microscopic amounts, and can survive on surfaces for a week. From 1990 to 2019, vaccination resulted in a 99% decline in reported cases of acute hepatitis B among children and teens. Liver cancer among American children has also plummeted as a result of universal childhood vaccination. But the hepatitis B virus is still around, with 2,000-3,000 acute cases reported annually among unvaccinated adults. More than 17,000 chronic hepatitis B diagnoses were reported in 2023. The CDC estimates about half of people infected don't know they have it.

Rotavirus. Before routine administration of the current rotavirus vaccines began in 2006, about 70,000 young children were hospitalized and 50 died every year from the virus. It was known as "winter vomiting syndrome," said Sean O'Leary, a pediatrician at the University of Colorado. "It was a miserable disease that we hardly see anymore."

The virus is still common on surfaces that babies touch, however, and "if you lower immunization rates it will once again hospitalize children," Offit said.

Meningococcal vaccines. These have been required mainly for teenagers and college students, who are notably vulnerable to critical illness caused by the bacteria. About 600 to 1,000 cases of meningococcal disease are reported in the U.S. each year, but it kills more than 10% of those it sickens, and 1 in 5 survivors have permanent disabilities.

Flu and covid. The two respiratory viruses have each killed hundreds of children in recent years — though both tend to be much more severe in older adults. Flu is currently on the upswing in the United States, and last flu season the virus killed 289 children.

What is shared clinical decision-making?

Under the changes, decisions about vaccinating children against influenza, covid, rotavirus, meningococcal disease, and hepatitis A and B will now rely on what officials call "shared clinical decision-making," meaning families will have to consult with a health care provider to determine whether a vaccine is appropriate.

"It means a provider should have a conversation with the patient to lay out the risks and the benefits and make a decision for that individual person," said Lori Handy, a pediatric infectious disease specialist at the Children's Hospital of Philadelphia.

In the past, the CDC used that term only in reference to narrow circumstances, like whether a person in a monogamous relationship needed the HPV vaccine, which prevents a sexually transmitted infection and certain cancers.

The CDC's new approach doesn't line up with the science because of the proven protective benefit the vaccines have for the vast majority of the population, Handy said.

In their report justifying the changes, HHS officials Tracy Beth Høeg and Martin Kulldorff said the U.S. vaccination system requires more safety research and more parental choice. Eroding trust in public health caused in part by an overly large vaccine schedule had led more parents to shun vaccination against major threats like measles, they said.

The vaccines on the schedule that the CDC has altered were backed up by extensive safety research when they were evaluated and approved by the FDA.

"They're held to a safety standard higher than any other medical intervention that we have," Handy said. "The value of routine recommendations is that it really helps the public understand that this has been vetted upside down and backwards in every which way."

Eric Ball, a pediatrician in Orange County, Calif., said the change in guidance will cause more confusion among parents who think it means a vaccine's safety is in question.

"It is critical for public health that recommendations for vaccines are very clear and concise," Ball said. "Anything to muddy the water is just going to lead to more children getting sick."

Ball said that instead of focusing on a child's individual health needs, he often has to spend limited clinic time reassuring parents that vaccines are safe. A "shared clinical decision-making" status for a vaccine has no relationship to safety concerns, but parents may think it does.

HHS' changes do not affect state vaccination laws and therefore should allow prudent medical practitioners to carry on as before, said Richard Hughes IV, an attorney and a George Washington University lecturer who is leading litigation against Kennedy over vaccine changes.

"You could expect that any pediatrician is going to follow sound evidence and recommend that their patients be vaccinated," he said. The law protects providers who follow professional care guidelines, he said, and "RSV, meningococcal, and hepatitis remain serious health threats for children in this country."

This story comes from NPR's health reporting partnership with KFF Health News, a national newsroom that produces in-depth journalism about health issues. KFF Health News is one of the core operating programs at KFF, the independent source for health policy research, polling, and journalism.

The National Park Service has updated its policy to discourage visitors from defacing a picture of President Donald Trump on this year's pass.

The use of an image of Trump on the 2026 pass — rather than the usual picture of nature — has sparked a backlash, sticker protests, and a lawsuit from a conservation group.

The $80 annual America the Beautiful pass gives visitors access to more than 2,000 federal recreation sites. Since 2004, the pass has typically showcased sweeping landscapes or iconic wildlife, selected through a public photo contest. Past winners have featured places like Arches National Park in Utah and images of bison roaming the plains.

Instead, of a picture of nature, this year's design shows side-by-side portraits of Presidents George Washington and Trump. The new design has drawn criticism from parkgoers and ignited a wave of "do-it-yourself" resistance.

Photos circulating online show that many national park cardholders have covered the image of Trump's face with stickers of wildlife, landscapes, and yellow smiley faces, while some have completely blocked out the whole card. The backlash has also inspired a growing sticker campaign.

Jenny McCarty, a longtime park volunteer and graphic designer, began selling custom stickers meant to fit directly over Trump's face — with 100% of proceeds going to conservation nonprofits.

"We made our first donation of $16,000 in December," McCarty said. "The power of community is incredible."

McCarty says the sticker movement is less about politics and more about preserving the neutrality of public lands. "The Interior's new guidance only shows they continue to disregard how strongly people feel about keeping politics out of national parks," she said.

The National Park Service card policy was updated this week to say that passes may no longer be valid if they've been "defaced or altered." The change, which was revealed in an internal email to National Park Service staff obtained by SFGATE, comes just as the sticker movement has gained traction across social media.

In a statement to NPR, the Interior Department said there was no new policy. Interagency passes have always been void if altered, as stated on the card itself. The agency said the recent update was meant to clarify that rule and help staff deal with confusion from visitors.

The Park Service has long said passes can be voided if the signature strip is altered, but the updated guidance now explicitly includes stickers or markings on the front of the card.

It will be left to the discretion of park service officials to determine whether a pass has been "defaced" or not. The update means park officials now have the leeway to reject a pass if a sticker leaves behind residue, even if the image underneath is intact.

In December, conservation group the Center for Biological Diversity filed a lawsuit in Washington, D.C., opposing the new pass design.

The group argues that the image violates a federal requirement that the annual America the Beautiful pass display a winning photograph from a national parks photo contest. The 2026 winning image was a picture of Glacier National Park.

"This is part of a larger pattern of Trump branding government materials with his name and image," Kierán Suckling, the executive director of the Center for Biological Diversity, told NPR. "But this kind of cartoonish authoritarianism won't fly in the United States."

The lawsuit asks a federal court to pull the current pass design and replace it with the original contest winner — the Glacier National Park image. It also seeks to block the government from featuring a president's face on future passes.

Not everyone sees a problem with the new design. Vince Vanata, the GOP chairman of Park County, Wyoming, told the Cowboy State Daily that Trump detractors should "suck it up" and accept the park passes, saying they are a fitting tribute to America's 250th birthday this July 4.

"The 250th anniversary of our country only comes once. This pass is showing the first president of the United States and the current president of the United States," Vanata said.

But for many longtime visitors, the backlash goes beyond design.

Erin Quinn Gery, who buys an annual pass each year, compared the image to "a mug shot slapped onto natural beauty."

She also likened the decision to self-glorification.

"It's akin to throwing yourself a parade or putting yourself on currency," she said. "Let someone else tell you you're great — or worth celebrating and commemorating."

When asked if she plans to remove her protest sticker, Gery replied: "I'll take the sticker off my pass after Trump takes his name off the Kennedy Center."

The 83rd annual Golden Globe Awards take place Sunday evening beginning at 5 p.m. at the Beverly Hilton Hotel, and that means parking restrictions and street closures in the city.

Here are places to avoid, as well as some alternative routes:

North Santa Monica Boulevard:

• Westbound lane closures: Complete lane closures, from Wilshire Boulevard to Century Park East through 6 a.m. Monday.
  
• Eastbound lane closures: Complete lane closures, from Century Park East to Wilshire Boulevard from 2 p.m. Saturday through 6 a.m. Monday. 

The city suggests using South Santa Monica Boulevard, which will remain open in both directions. There also are alternative east-west routes such as Olympic, Sunset and Pico boulevards.

Wilshire Boulevard:

• Eastbound/Westbound lane reduction: Lane reductions are in effect and will last through 9 p.m. Wednesday.
  
• Eastbound/Westbound full closure: All of Wilshire Boulevard between Comstock Avenue and North Santa Monica Boulevard will be closed from 10 p.m. Saturday through 6 a.m. Monday.
  
• Eastbound lanes of Wilshire Boulevard: An eastbound closure from Comstock to North Santa Monica Boulevard will occur between 10 p.m. Monday through 6 a.m. Tuesday.

Other streets:

Several other streets like Whittier Drive, Carmelita Avenue, Elevado Avenue and Lomitas Avenue, as well as Trenton Drive and adjacent alleys will have limited closures with local access available only to residents. Closures begin at 10 p.m. Saturday and last through 6 a.m. Monday.

Parking notices:

Residential streets surrounding the venue will be completely restricted, no exceptions made, from 6 a.m. Sunday until 6 a.m. Monday on the following streets:

• Whittier Drive — from Wilshire Boulevard to Elevado Avenue
• Carmelita Avenue — from Wilshire Boulevard to Walden Drive
• Elevado Avenue — from Wilshire Boulevard to Walden Drive
• Trenton Drive — from Whittier Drive to Wilshire Boulevard
• Walden Drive — from Santa Monica Boulevard to Elevado Avenue
• Lomitas Avenue — from Wilshire Boulevard to Walden Drive

Residents without permit parking can obtain parking exemptions by contacting the city of Beverly Hills’ parking exemption line at (310) 285-2548 or online at beverlyhills.org/parkingexemptions.

Demonstrations against this week’s deadly ICE shooting in Minneapolis are planned this weekend across Los Angeles. The protests are being organized by the “ICE Out For Good Coalition” — a network of several groups including the ACLU and 50501.

Here are a some of the planned actions across the city:

Saturday

• Pasadena: Noon to 2 p.m. at Garfield and Colorado Boulevard, across from the Paseo Mall
• Eagle Rock: 1 to 2 p.m. at Colorado and Eagle Rock boulevards
• City of Los Angeles: 2 to 4:30 p.m. in Pershing Square

Sunday

• West Hollywood: 11 a.m. to 1 p.m. at 647 N. San Vicente Blvd., across from the Pacific Design Center.
• City of Los Angeles: Noon to 2 p.m. at The Home Depot on 2055 N. Figueroa St.
• Beverly Hills: 2 and 4 p.m. at 9439 Santa Monica Blvd., between Beverly and Canon drives