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.”

As Dr. Kalyanam Shivkumar pondered how to fix the human heart, he was given a gift laced with horror.

Shivkumar, a cardiac electrophysiologist known as “Shiv” to friends and co-workers at UCLA, was trying to better understand the intricate details of nerves in the chest. He hoped doing so might help him improve treatments for cardiac arrhythmias — aberrant rhythms of the heart — that can prove dangerous and even deadly.

A Canadian colleague sent him a set of anatomy books renowned for the beauty and detail of their drawings, but tipped him off that the “atlas” had an appalling history.

Shivkumar was aghast to learn it was the work of an ardent Nazi whose Vienna institute had dissected the bodies of prisoners, many executed for political reasons after Austria was annexed to Nazi Germany in 1938.

“Every time I open up that book,” he said, “my sense is revulsion.”

Shivkumar is a big thinker, an erudite physician quick with an apt quotation, whose Westwood office is stacked with Sanskrit volumes of the Mahabharata alongside books about late Bruins basketball coach John Wooden.

As he waded into the scholarly debate over using the tainted atlas, the doctor bristled at hearing others praise its illustrations as “unsurpassable.” Much of the soul searching among physicians had revolved around when and how to use it. Shivkumar wanted to put those questions to bed.

“Could we be better?” he asked. “Could we not be making something that’s completely untainted?”

That question would launch Shivkumar on a quest that has lasted more than a decade and is expected to endure for years. He wants to surpass the anatomical atlas created by Dr. Eduard Pernkopf, a fervent supporter of the Nazi regime whose work was fueled by the dead bodies of its victims.

His passion project at the UCLA Cardiac Arrhythmia Center is called Amara Yad, a mashup of Sanskrit and Hebrew meaning “immortal hand.” The work has relied on the generosity of people who have willed their bodies for use at UCLA, as well as hearts that were donated but could not be used for transplant.

So far, Amara Yad has completed two volumes focused on the anatomy of the heart and is enlisting teams at other universities for more. The plan is to draft a freely available, ethically sourced road map to the entire body that eclipses the weathered volumes of watercolors from Pernkopf and honors the Nazis’ victims.

Anatomists have told him, “‘You’re crazy. It’s impossible. How could you ever surpass it?’” Shivkumar said of the Pernkopf atlas in a speech last year before members of the Heart Rhythm Society.

But “can it be beaten? The answer is yes.”

For decades, the origins of the Pernkopf Atlas were unknown to many who turned to its pages for guidance. Swastikas tucked into signatures of an illustrator were airbrushed out in later editions. Its history began to trickle out in journals in the 1980s.

When Dr. Howard Israel finally learned of its roots, he was horrified. Israel, an oral surgeon at Columbia University and self-described “very ordinary American Jew,” told the New York Times he had been relying on the book since he was a medical student.

‘’I felt stupid at using the book,” he told the newspaper, “that I could possibly have benefited from something that sounded so evil.” He and another physician enlisted the Holocaust remembrance group Yad Vashem and publicly pushed for the University of Vienna to investigate whose bodies were depicted in its pages.

The resulting probe found no evidence that the anatomy department under Pernkopf — who had ascended to become dean of the medical faculty at the University of Vienna in 1938 — had received bodies from the Mauthausen concentration camp, as some had wondered.

But the institute had been given at least 1,377 bodies of executed people, most of them sentenced to death for political reasons. Among the charges that led to their executions: “crimes of resistance” and “high treason.”

Using the bodies of executed people was “a centuries-old practice in anatomy,” preferred because anatomists could time their work swiftly after a scheduled death, said Dr. Sabine Hildebrandt, an anatomy educator at Harvard Medical School. What was new under the Nazis, she said, was the sheer number of executions.

The institute “was drowned in bodies,” and “the source for these bodies was mostly connected with the apparatus of repression of the Nazi regime,” said historian Herwig Czech, a member of the Lancet Commission on Medicine, Nazism, and the Holocaust, at a recent forum.

By the time those findings emerged, the publisher of the anatomy book had stopped printing it.

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1. A stack of volumes of the Pernkopf atlas on a shelf in Dr. Kalyanam Shivkumar’s UCLA office. 2. Erich Lepier, one of the Pernkopf atlas illustrators, repeatedly included a swastika after the cursive R in his signature. (Allen J. Schaben / Los Angeles Times)

Yet use of the atlas persisted. Hildebrandt said that a decade ago, dental students in her classes “were basically giving each other thumb drives with bootlegged copies of the head and neck.”

Other anatomical atlases exist, but these illustrations had especially fine details, including of the nerves extending beyond the brain and spiral cord. One survey of nerve surgeons found that 13% of respondents were using the atlas. Among those who have publicly grappled with it is Dr. Susan Mackinnon, a surgery professor at Washington University School of Medicine in St. Louis known as a pioneer in nerve regeneration.

“I used this textbook for years before I knew the history of it,” she said. “My brain is contaminated with that. I can’t undo that.”

Mackinnon sought ethical guidance. Rabbi Joseph Polak, a Boston University assistant adjunct professor of health law who survived the concentration camps as a child, said one dilemma involved a patient in excruciating pain.

Polak recalled that the patient had told Mackinnon that “if you can’t find the nerve to stop the pain, then I want my leg amputated.” The rabbi walked through Jewish teachings that applied to the ethical quandary and conferred with other experts, penning a set of recommendations called the Vienna Protocol.

Among his urgings to doctors: If you use these drawings, make it clear to patients where they came from.

The Third Reich wanted “to extinguish them and to extinguish eventually all memory of them,” the rabbi said of Holocaust victims, speaking at a recent forum about the atlas. But when a doctor tells patients about what happened to the people depicted in the drawings, he said, “they’re being called out of that darkness.”

Mackinnon now keeps the atlas locked away. In the rare cases she feels she needs to consult it to operate, she tells patients and co-workers about the man behind it. His firings of Jewish doctors. The grim details in its pages — shorn hair, emaciated bodies — that began to raise suspicions about its terrible origins.

The only reason to use it, she said, is to save someone from misery — and only if “nothing else will help you.”

“Could we be better” than Pernkopf? Shivkumar asked. “Could we not be making something that’s completely untainted?”

(Allen J. Schaben / Los Angeles Times)

Shivkumar said his goal is to eliminate the need to consult those pages at all. Inside UCLA’s Center for the Health Sciences in Westwood, he showed off a donated heart, prepped and ready for its close-up in a corner of the lab outfitted with a black backdrop and brilliant lights.

A spent heart normally wilts like a deflated balloon, but this one had been pumped with chemicals to imitate the fullness of life. The team first puts the organs to use in research, then carefully dissects them for imaging.

Bringing out a bisected piece of a heart, Dr. Shumpei Mori displayed how its inner architecture could be captured on camera, threading a catheter through the organ as a co-worker snaked in an endoscope.

“The internal structure is really fine and delicate,” said Mori, a specialist in cardiac anatomy who had jumped at the chance to do something new in the field.

“Even Pernkopf simplified the anatomy” in its drawings, Mori said. “What we are doing is more complicated.”

Dr. Shumpei Mori holds a detailed model of a heart. “Even Pernkopf simplified the anatomy,” he said. “What we’re doing is more complicated.”

(Allen J. Schaben / Los Angeles Times)

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The camera is far from their only tool: The team has generated 3-D images to illustrate the dimensions of the inner structures of the heart; done CT scans to produce hand-held models; and used sophisticated imaging from a microscope to reveal the lattice of nerves connecting to the organ — part of the signaling system that Shivkumar calls “the internet of the human body.”

In another lab, Mori carefully unzipped a bag on a metal gurney to reveal the stripped-down interior of a cadaver diligently dissected over a year and a half, its rib cage cracked open like a weighty book. Shivkumar pointed out the pale web of nerves stretching up through the neck. Mori had painted them yellow by hand.

The human body might seem like well-traveled territory, but as physicians work to find less invasive ways of healing, such as attacking a cancer with ultrasound, Shivkumar said there is “a volcanic desire for this kind of information.” Snip the right nerve, he said, and you can avert the need for a heart transplant.

“Pernkopf never did nerves like this,” he said with pride.

Amara Yad is also an act of “moral repair” meant to honor the victims, said Dr. Barbara Natterson-Horowitz, a UCLA cardiologist and evolutionary biologist who helped support the project. The Nazi atlases “were like documents of death. The atlases that Shiv is creating are really living, interactive tools to support life.”

When Shivkumar decided to launch the project, he had been inspired by the words of USC emeritus professor of rheumatology Dr. Richard Panush, who had pushed to set the atlas aside in the library of the New Jersey medical center where he had worked, moving it to a display case that explained its history.

Panush said the old atlas should be preserved only as “a symbol of what we should not do, and how we should not behave, and the kind of people that we cannot respect.”

Doctors need to know that history to understand their own moral fallibility, Hildebrandt said. Physicians in Nazi Germany “still thought they were doing the right thing,” she said, even as they failed to see some people as human.

Rabbi Polak stressed that doctors at the time “had the deepest, most profound respect of the masses.”

Yet when the Nazis took power, “it turned out that a vast proportion of them were moral sleazeballs,” Polak said. “They were the first to join when they saw that it could promote their careers.”

Model hearts line a bookshelf at UCLA. The Amara Yad project is working with other universities to tackle other parts of human anatomy.

(Allen J. Schaben / Los Angeles Times)

Shivkumar said that beyond making new tools for physicians, the Amara Yad project is working with Oxford University to develop an accompanying curriculum that will explore ethical failures in medicine. Pernkopf’s anatomy book is only one example.

The history of the atlas “invites the contemplation of how doctors and medical scientists and anatomists are related to a regime,” said Sari J. Siegel, who heads the Center for Medicine, Holocaust and Genocide Studies at Cedars-Sinai. Thinking about it underscores that “medicine is political.”

“It can’t be divorced from the larger contexts in which it exists.”

Shivkumar, born to a Hindu family in the southernmost state of India, is used to people wondering why he became “possessed” with this project. He recalls first learning about the Holocaust from a photographer friend of his grandfather, a former newspaper editor once imprisoned for sedition against the British Empire.

He was 11 when the photographer showed him images dating to World War II, and it chilled him “to see that human beings could be so brutal to other humans.” As a child, his parents had told him they owed the world because their part of India was lucky to be long spared from such conflict.

In Amara Yad, we “get a rare opportunity in history to correct an unbelievably depressing stain that was placed in our field,” he told the Heart Rhythm Society.

It irritates him to think of the abundant resources that a Nazi had at hand to do this sort of work. “Imagine having five Shumpeis!” he exclaimed at one point, gesturing at his colleague who hand painted the nerves. At UCLA, the project has piggybacked on ongoing research and relied on donations. He is hoping to garner $500,000 annually to continue and expand the work.

But Shivkumar likes to quote the Emperor Ashoka on that point: “To do good is difficult. One who does good first does something hard to do. … Truly, it is easy to do evil.”

My resident describes our next emergency room patient — a 32-year-old female with severe, crampy mid-abdominal pain, vomiting and occasional loose stools. The symptoms have been present for nearly a week, and there is tenderness to both sides of the upper abdomen. It could be a gallbladder problem, the resident says, hepatitis, pancreatitis, diverticulitis or an atypical appendicitis. She proposes routine blood tests along with an ultrasound and an abdominal CT scan.

This is the time-honored approach to an undifferentiated patient complaint: Generate a list of possible diagnoses, decide which represent a “reasonable” concern and use the results from further testing to conclude what’s going on. Yet increasingly the second phase of this process — evaluating which diagnoses represent a reasonable concern — is getting short shrift. It is the heavy lift of any patient encounter — weighing disease probabilities, probing for details. It’s often simpler, and faster, to cast a wide net, click the standard order for blood work and imaging, and wait for the results to pop up.

The issue of the “busy doctor ordering too many tests” has plagued medicine for decades. Now, as hospitals inject algorithms and technology into their workflow, it’s much worse. Medicine is moving inexorably away from the deductive arts, becoming more technology- and test-dependent and less patient-centric.

Go to an emergency room today and you will likely be met within minutes by a doctor whose sole role is to perform a “rapid medical evaluation.” The provider asks a few questions, ticks boxes on a computer screen and, shazam, you are in line for the most likely series of tests and scans, all based on typically a less than 60-second encounter.

This strategy seems obvious. When workups are initiated as soon as the patient arrives, wait times go down, patient satisfaction goes up, and fewer patients leave out of frustration before even being seen. These are the metrics that put smiles on administrators’ faces and give hospitals high marks in national surveys.

But is it good doctoring? Without the luxury of time, these gateway providers typically lump patients into broad, generic categories: the middle-aged person with chest pain, the short-of-breath asthmatic, the vomiting pregnant patient, the septuagenarian with cough and fever, and so forth. The diagnosis is then reverse-engineered with tests to cover all possible bases for that particular complaint.

In essence this is flipping the script on traditional doctoring while incentivizing doctors to use testing as a surrogate for critical thinking, dumbing down the practice of medicine and throwing gasoline on the problem of over-testing.

Since rapid evaluation became the norm, use of laboratory, CT and ultrasound services at my hospital has increased nearly 20%. Just the other day, a pregnant woman in my ER went through a full battery of time-consuming, expensive and invasive tests even though she’d been through all of them at another hospital the day before. As far as I can tell, the only reason we did that was because that’s what an algorithm told us to do.

This has real effects on patients. Contrary to popular perception, more tests may not supply more answers. That’s because the accuracy of any test depends on the likelihood that the patient has the disease in question before the test is performed. Testing performed without the appropriate indication or context can produce incidental or even spurious results that may have your doctor looking in entirely the wrong direction.

The basic problem with hospitals’ growing obsession with efficiency is this: Algorithmic systems treat all patients the same, expecting precise, like-for-like responses to every question with just the right amount of detail. Except every patient is unique. And they tend to give up their stories at their own pace, in broken, non-linear fits and starts, sometimes conflating truth and fiction in ways that can be counterproductive and frustrating, but also uniquely human. I am often reminded of Jack Webb in the old TV series “Dragnet” imploring a witness to offer “just the facts, ma’am, just the facts.” In real life, whether from situational stress, self-delusion, superstition, health illiteracy, mental illness, drugs or alcohol, my patients’ initial version of their complaint is rarely “just the facts” or the final word on the subject.

A colleague recently described her role in a clinical encounter as 9 parts translator to 1 part doctor. One question leads to another, and then another, and another until she successfully translates the patient’s lived experience into a language modern medicine and its algorithms might begin to understand. My experience is similar. Properly choreographed, the doctor-patient interaction becomes a pas de deux — two people in sync, jointly trying to solve a puzzle with each sharing their perspective and expertise. In the transition to front-loaded care, I worry health decisions will be made with information that may be incomplete or, at times, totally unreliable.

Algorithmic medicine also seems tailor-made for an AI takeover. The logic is obvious. Use “big data” to assist doctors and nurses struggling to keep up with the demands of modern medicine. AI can ensure a level, consistent floor of care that avoids errors of omission by considering a deliberately broad list of diagnostic possibilities. In an ideal world, a synergy of human and machine intelligence could amplify the patient-doctor encounter. As likely, AI will lead doctors to abdicate judgment and responsibility to the automated response of the machine.

And so, I complimented my resident on her list of concerns but suggested that we spend a little more time with the patient. The story of her symptoms didn’t feel complete. I recommended my resident grab a chair and simply ask the patient about her life. What emerged was the chaotic picture of an exhausted part-time student by day, working two evening waitressing jobs and surviving on pizza, pasta and energy drinks. She had always had a “fragile stomach.”

Our list of reasonable diagnoses was expanding and contracting, replaced with irritable bowel syndrome, food intolerances, gut motility issues, all overlying a stressed individual barely keeping it together. The labs, ultrasound or CT scan initially proposed now seemed irrelevant.

The result: The patient got out of the hospital faster. She received helpful suggestions about stress reduction, diet and sleep habits. She got an appointment with a primary care physician and avoided thousands of dollars in tests. Had we just relied on tests instead of asking a few more questions, there is a good chance we would have missed the best approach to her problem entirely.

ER waiting rooms and wards are bursting at the seams, and the streamlining of care has never felt more essential. But this is not an excuse for doctors to relinquish their humanity or their “method.” We should tweak the process: Allow more time for doctors to get the story right, do less testing until we have weighed the risks and rewards, prioritize asking questions rather than merely looking for answers.

Sociologists coined the term “pre-automation” to describe the transitional phase in which humans lay the groundwork for automation, often by acting in increasingly machine-like ways. As providers, we must not fall in line.

Put another way, with AI primed to take on a substantial role in how doctors deliver care, we should remind ourselves: If we behave like machines, we certainly won’t be missed when machines replace us.

Eric Snoey is an ER doctor at Alameda Health System-Highland Hospital in Oakland.