Science
Pregnant? Researchers want you to know something about fluoride
Adding fluoride to drinking water is widely considered a triumph of public health. The Centers for Disease Control and Prevention says the cavity-prevention strategy ranks alongside the development of vaccines and the recognition of tobacco’s dangers as signal achievements of the 20th century.
But new evidence from Los Angeles mothers and their preschool-age children suggests community water fluoridation may have a downside.
A study published Monday in JAMA Network Open links prenatal exposure to the mineral with an increased risk of neurobehavioral problems at age 3, including symptoms that characterize autism spectrum disorder. The association was seen among women who consumed fluoride in amounts that are considered typical in Los Angeles and across the country.
The findings do not show that drinking fluoridated water causes autism or any other behavioral conditions. Nor is it clear whether the relationship between fluoride exposure and the problems seen in the L.A.-area children — a cohort that is predominantly low-income and 80% Latino — would extend to other demographic groups.
However, the results are concerning enough that USC epidemiologist Tracy Bastain said she would advise pregnant people to avoid fluoridated water straight from the tap and drink filtered water instead.
“This exposure can impact the developing fetus,” said Bastain, the study’s senior author. “Eliminating that from drinking water is probably a good practice.”
About 63% of Americans receive fluoridated water through their taps, including 73% of those served by community water systems, according to the CDC. In Los Angeles County, 62% of residents get fluoridated water, the Department of Public Health says.
The data analyzed by Bastain and her colleagues came from participants in an ongoing USC research project called Maternal and Developmental Risks from Environmental and Social Stressors, or MADRES. Women receiving prenatal care from clinics in Central and South Los Angeles that cater to low-income patients with Medi-Cal insurance were invited to join.
Between 2017 and 2020, 229 mothers took a test to measure the concentration of fluoride in their urine during their third trimester of pregnancy. Then, between 2020 and 2023, they completed a 99-question survey to assess their child’s behavior when their sons and daughters were 3 years old.
Among other things, the survey asked mothers whether their children were restless, hyperactive, impatient, clingy or accident-prone. It also asked about specific behaviors, such as resisting bedtime or sleeping alone, chewing on things that aren’t edible, holding their breath, and being overly concerned with neatness or cleanliness.
Some of the questions the mothers answered addressed health problems with no obvious medical cause, including headaches, cramps, nausea and skin rashes.
Among the 229 children — 116 girls and 113 boys — 35 were found to have a collection of symptoms that put them in the clinical or borderline clinical range for inward-focused problems such as sadness, depression and anxiety. In addition, 23 were in the clinical or borderline clinical range for behaviors directed at others, such as shouting in a classroom or attacking other kids, and 32 were deemed at least borderline clinical for a combination of inward and outward problems.
What interested the researchers was whether there was any correlation between a child’s risk of having clinical or borderline clinical behavioral problems and the amount of fluoride in his or her mother’s urine during pregnancy.
They found that compared to women whose fluoride levels placed them at the 25th percentile — meaning 24% of women in the study had levels lower than theirs — women at the 75th percentile were 83% more likely to have their child score in the “clinical” or “borderline clinical” range for inward and outward problems combined. When the researchers narrowed their focus to children in the clinical range only, that risk increased to 84%, according to the study.
The researchers also found that the same increase in fluoride levels was associated with an 18.5% increase in a child’s symptoms related to autism spectrum disorder, as well as an 11.3% increase in symptoms of anxiety.
The amount of fluoride needed for mothers to go from the 25th to the 75th percentile was 0.68 milligrams per liter. As it happens, that’s nearly identical to the 0.7 mg per liter standard that federal regulators say is optimal for preventing tooth decay.
Bastain said that allowed the researchers to compare what might happen to children in two parallel universes: a typical one where their mothers consumed fluoridated water during pregnancy, and an alternate one where they didn’t.
“You can use it as a proxy for if they lived in a fluoridated community or not,” she said.
What that thought experiment shows is that children in the fluoridated community face a higher level of risk. That said, it’s not clear when that risk becomes high enough to be worrisome.
“We don’t know what the safe threshold is,” Bastain said. “It’s not like you can say that as long as you’re under the 75th percentile, there are no effects.”
The study authors’ concerns about the effects of fluoride on developing brains didn’t come out of nowhere.
The National Toxicology Program — a joint effort of the CDC, the National Institutes of Health, and the Food and Drug Administration — has been investigating the issue since 2016. In a report last year that reviewed an array of evidence from humans and laboratory animals, a working group concluded “with moderate confidence” that overall fluoride exposure at levels at or above 1.5 mg per liter “is consistently associated with lower IQ in children.”
The working group added that “more studies are needed to fully understand the potential for lower fluoride exposure to affect children’s IQ.”
A 2019 study of hundreds of mothers in Canada — where 39% of residents have fluoridated water — found that a 1-mg increase in daily fluoride intake during pregnancy was associated with a 3.7-point reduction in IQ scores in their 3- and 4-year-old children.
And among hundreds of pregnant women in Mexico, a 0.5-mg-per-liter increase in urinary fluoride went along with a 2.5-point drop in IQ scores for their 6- to 12-year-old children, researchers reported in 2017.
Bastain and her colleagues write their study is the first they are aware of that examines the link between prenatal fluoride exposure and neurobehavioral outcomes in children in the United States. The results are sure to be controversial, Bastain said, but there’s a straightforward way for pregnant people to reduce the possible risk.
“It’s a pretty easy intervention to get one of those tabletop plastic pitchers” that filter out metals, she said. “Most of them do a pretty good job of filtering out fluoride.”
Science
Video: NASA Announces Artemis III Crew
new video loaded: NASA Announces Artemis III Crew
transcript
transcript
NASA Announces Artemis III Crew
NASA announced the crew of Artemis III mission, which will fly to low-Earth orbit to test rendezvous and docking maneuvers with one or two lunar landers.
-
“I am excited to welcome you as the next crew in the Artemis journey to successfully return to the moon — this time to stay.” “I’m honored by the role that I’ve been given. I’m also very humbled by the task in front of us. But first and foremost, I’m grateful.” “So with that, the Artemis II crew, comrade, hands you the baton. You got the controls.” “As you know, we had a significant anomaly at our Launch Complex 36A on May 28. We’ve redoubled our efforts and are moving forward.”
By Alisa Shodiyev Kaff
June 9, 2026
Science
Santa Monica Mountains’ last steelhead trout survived the Palisades fire — and even had babies
Scientists feared the Santa Monica Mountains’ last remaining steelhead trout were dead, smothered by debris flows unleashed by the Palisades fire.
But the endangered fish surprised them: A team of biologists recently spotted 30 of the rare trout — and 21 babies — in Topanga Creek.
“There was a lot of happy dancing in the creek,” said Rosi Dagit, principal conservation biologist for the Resource Conservation District of the Santa Monica Mountains, which works with public and private landowners to conserve natural resources.
That’s because the steelhead here are endangered, at both the state and federal levels. Once, they swam in most streams of the Santa Monicas, but their numbers plummeted amid overfishing and coastal development. Increasingly frequent wildfire has further stressed their habitat. Topanga Creek, a biodiversity hot spot, is home to their last known population in the mountains that stretch from the Hollywood Hills to Point Mugu in Ventura County.
The trout that were spotted, including this one, are part of a distinct Southern California population that’s listed as endangered at the state and federal levels.
(RCDSMM Stream Team)
The California Department of Fish and Wildlife spearheaded a complex mission to rescue trout threatened by the Palisades fire that sparked in January 2025.
Time was of the essence. The fire hadn’t yet been fully contained. But rain was on the way, which would sweep massive amounts of sediment from the denuded hillsides into the water. Fish are often killed this way.
Crews stunned the fish with electricity, scooped them up in buckets, trucked them to a hatchery and ultimately moved them to Arroyo Hondo Creek in Santa Barbara County.
Within days, Topanga Creek was choked with mud. Some assumed the fish left behind were goners.
But in March, the conservation district’s team found four. The following month, when water conditions were clearer, they saw more.
“These fish continue to amaze me,” said Kyle Evans, environmental program manager for the state Department of Fish and Wildlife, who had seen the damage to the creek. “I had seen populations get wiped out in similar situations. So when I heard, I was thrilled.”
Evans surmises the fish that survived were in an area of the creek where less charred material and sediment were swept in.
“These fish likely hunkered down, were hiding under some rocks or places to try to get away from the main concentration of flow,” he said. “And luckily they weren’t buried.”
The ones that were spotted were fairly small, around 6 to 14 inches. Rainbow trout and steelhead trout are the same species, but with different lifestyles. If the fish remain in freshwater, they’ll be considered rainbows. However, they can migrate to the ocean and become steelhead, where they typically grow larger before returning to their natal waters to spawn.
Topanga Creek hasn’t fully recovered from the damage it sustained, but scientists say it’s looking better. Surveys last year were “so depressing,” Dagit said, with very few animals, and stretches that were essentially transformed into flat roads from all the sediment buildup. Some of the riparian canopy burned right down to the creek.
Then came 32 inches of rain over the last nine months, scouring out and moving sediment, creating deeper pools. Dagit said they recently found newt egg masses for the first time in years, as well as a few adult newts and many frogs. Plants that provide cover are starting to recover.
She provided photos comparing certain pools last year and this year, some dramatically transformed. In September 2025, the Shrine Pool could have been an overgrown hiking trail. This April, it was filled with shallow water.
The Shrine Pool in September 2025, left, and the same location in April 2026, right, with RCDSMM’s Isaac Yelchin donning a wetsuit.
(RCDSMM Stream Team)
Topanga Creek is home to another endangered fish, the small but hardy northern tidewater goby, often described as cute. Not long before the trout operation, Dagit led a rescue of hundreds of these fish too. Many were repatriated to the lagoon at the mouth of the creek in a moving ceremony last June.
There’s still the matter of what to do with the trout that were moved to Santa Barbara County last year. Evans would like to bring them home to the Santa Monicas at some point, but isn’t sure if it will happen. On one hand, they could bolster the small, genetically isolated surviving population. On the other, they might inadvertently bring in a disease or bacteria. There is some time to decide. Evans estimates the creek still needs to recover for two to three more years.
For now, the fish are functioning fine in their adopted creek. Experts worried the trauma wrought by the move would disrupt their spawning process, but they had babies that spring. This year, they spawned again.
Science
Pacifica pier cracks, another coastal casualty as seas continue to rise
The Pacifica Municipal Pier was shut down and taped off Thursday after city workers noticed cracks running through the landmark structure and concrete chunks falling into the ocean.
It’s just one of many coastal California structures that have recently crumbled under pressure from a rising and relentless ocean.
Officials from the small, beach city south of San Francisco said the pier was closed due to “cracking, separation, and displacement of the concrete walkway and structural elements.”
It will stay closed while structural engineers asses its safety.
Photos taken by city employees show a wide crack that runs from top to bottom and across the structure as well. Other photos show a large horizontal crack under the foundation of a small restaurant on the pier, the Chit Chat Cafe.
The cafe was also shut down.
This is not the first time the 53-year-old pier has shown signs of stress. In 2021, part of it was shut down after handrails along the edge collapsed. And in 2023, after a series of storms pummeled the Central California coast, damaging parts of the pier, the structure was partially closed for more than year.
Those same storms caused extensive damage in Aptos and Capitola, 70 miles south, where piers and waterfront infrastructure were swept away or damaged.
In 2024, a 150- to 180- foot section of the Santa Cruz wharf was ripped off by powerful waves.
At least 10 of the state’s dozens of coastal public piers were closed for part or all of 2024 due to structural damage sustained in winter storms since 2022. At least five others have longer-term upgrades planned to address structural issues.
“These things are costly to maintain,” said Zach Plopper, senior environmental director at Surfrider. “They are a part of our California coastal culture in many ways, but we’re going to need to reckon with, one, the state that they’re in, and two, the continuous and worsening threats they’re going to experience,”
He said most of the piers were constructed in the early 1900s, and they weren’t built to withstand decades of rough seas, storms and rising sea level.
“With this incoming El Niño, which is forecasted to be significant, and this marine heat wave we’re in the midst of, we’re kind of in uncharted waters as far as what this winter could bring in terms of storms and swells to the California coast, and we’re likely going to see a lot more damage,” he said. “Not just piers, but roads and other coastal infrastructure up and down the state.”
There was no storm in Pacifica earlier this week, so no single event could be blamed for the destruction.
However, a 2025 report from an outside engineering firm, GHD, found that several sections of the pier were in “poor” or “serious” condition, and they recommended closure before anticipated storms or events that could “subject the piles to high winds, swells and large waves.”
The firm found several areas of the pier where concrete was missing and rebar was exposed and corroding.
“The pier has continued to experience high winds and large waves in a harsh marine environment,” the engineers wrote in the report, noting that continuous exposure to seawater or marine spray was “detrimental” to the structure.
A 2023 city report estimated it would cost $19 million to repair.
That same year, a state law was enacted to require local governments along the California coast to plan for sea level rise in the coming decades.
Sea level has risen some 8 inches, on average, along the coast in the past 150 years, Plopper said, and researchers anticipate another foot in the next 25 years.
“We’re going to see profound shifts on our coastline, none that we have ever experienced before, and building static structures on the coast just doesn’t work all that well,” he said. “We’re going to have to make some really hard decisions.”
-
Business21 seconds agoPrimm is a spooky shell of its former self. But the gambling oasis may have found a savior
-
Entertainment5 minutes agoHiker who died in Runyon Canyon ID’d as Hollywood screenwriter, pal of Caitlyn Jenner
-
Politics15 minutes agoSupporters of L.A. County healthcare sales tax declare victory
-
Sports27 minutes agoUSC freshman linebacker Talanoa Ili joins lawsuit seeking to upend new NIL system
-
World35 minutes agoWho has the most and fewest judges in the EU?
-
News55 minutes agoIn Nevada, Trump’s policies are making things tough for Republican Gov. Joe Lombardo
-
New York2 hours agoThis Parking Spot Is Free. Should It Be?
-
Los Angeles, Ca2 hours agoO.C. Uber customer says driver asleep in Tesla on 405 Freeway