Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.

CNN
 — 

Cruising at a depth of 8,336 meters (over 27,000 feet) just above the seabed, a young snailfish has become the deepest fish ever filmed by scientists during a probe into the abyss of the northern Pacific Ocean.

Scientists from University of Western Australia and Tokyo University of Marine Science and Technology released footage of the snailfish on Sunday filmed last September by sea robots in deep trenches off Japan.

Along with the filming the deepest snailfish, the scientists physically caught two other specimens at 8,022 meters and set another record for the deepest catch.

Previously, the deepest snailfish ever spotted was at 7,703 meters in 2008, while scientists had never been able to collect fish from anywhere below 8,000 meters.

“What is significant is that it shows how far a particular type of fish will descend in the ocean,” said marine biologist Alan Jamieson, founder of the Minderoo-UWA Deep Sea Research Centre, who led the expedition.

Scientists are filming in the trenches off Japan as part of a 10-year study into the deepest fish populations in the world. Snailfish are members of Liparidae family, and while most snailfish live in shallow water, others survive at some of the greatest depths ever recorded, Jamieson said.

During the two-month survey last year, three “landers” – automatic sea robots fitted with high-resolution cameras – were dropped into three trenches – the Japan, Izu-Ogasawara and Ryukyu trenches – at varying depths.

In the Izu-Ogasawara trench, footage showed the deepest snailfish hovering calmly alongside other crustaceans on the seabed.

Jamieson classified the fish as a juvenile and said younger deep sea snailfish often stay as deep as possible to avoid being eaten by bigger predators that swim at shallower depths.

Another clip shot at between 7,500 and 8,200 meters in the same trench showed a colony of fish and crustaceans munching at bait tied to an undersea robot.

Images of the two captured snailfish – identified as Pseudoliparis belyaevi – provide a rare glimpse of the unique features that help the deep sea species survive the extreme environment.

They have tiny eyes, a translucent body, and their lack of swim bladder, which helps other fish float, works to their advantage, Jamieson said.

The professor said the Pacific Ocean is particularly conducive to vibrant activity due to its warm southern current, which encourages sea creatures to go deeper, while its abundant marine life provides a good source of food for bottom feeders.

Scientists would like to know more about creatures living at extreme depths, but cost is the constraint, Jamieson said, adding that each lander alone costs them $200,000 to assemble and operate.

“The challenges are that technology has been expensive and scientists don’t have a lot of money,” he said.

CNN
 — 

The escalating climate crisis is shifting many people’s purchasing patterns and this extends to the $500 billion dollar global beauty industry which is grappling with a range of sustainability challenges across product manufacturing, packaging and disposal.

Strategy and consulting firm Simon Kucher’s Global Sustainability Study 2021 found 60% of consumers around the world rated sustainability as an important purchase criterion, and 35% were willing to pay more for sustainable products or services.

This shift in consumer preferences has propelled many beauty brands to set environmental goals: to move away from single-use and virgin plastics, provide recyclable, reusable and refillable packaging and offer more transparency around products’ ingredients so customers can ascertain how “green” their purchase is.

However, consumers still struggle to understand the sustainability credentials of many products, according to the British Beauty Council. This is because the industry’s clean-up efforts have been inconsistent, and fall short of making a recognizable impact in the absence of collective goal-setting, global strategy and standardized regulations.

Ingredient and branding transparency

There is no international standard for the beauty industry on how much product ingredient information to share with customers — or how to do so. Brands can set their own rules and goals, giving rise to confusion and “greenwashing,” where sustainability claims are often touted but not substantiated.

Companies often use marketing language like “clean beauty” to make it seem like their products are natural, for example, when they may not actually be organic, sustainable or ethically made.

“The term ‘clean beauty’ has become quite dangerous. It’s used to sell more products,” according to British Beauty Council CEO Millie Kendall, who added that such buzzwords are losing traction in the UK as British customers wise up to their shortcomings. “Customers need better marketing information and certification information.”

In a 2021 report calling on the industry to have “the courage to change” their business practices, the British Beauty Council wrote that, all too often, even natural ingredients involved in manufacturing products give way to “over-consumption, non-regenerative farming practices, pollution, waste and neglect.”

“The only way out of this is transparency,” Kendall told CNN.

Jen Lee, chief impact officer at US-based brand Beautycounter, said she continues to see confusion over ingredients among consumers. (In 2013, the company launched and published “The Never List,” which currently cites more than 2,800 chemicals — including heavy metals, parabens and formaldehyde — it claims to never use in its products.)

“Natural vs. synthetic ingredients has been a conversation. People think natural is safer, but it’s not always the case,” Lee explained. “Natural ingredients formulated in the industry can have toxic load. Heavy metals can occur in natural components of the earth.”

“We used to be more natural and organic,” added Sasha Plavsic, founder of makeup brand ILIA Beauty. “What was challenging is (that) raw materials were difficult to source or would come in inconsistently or products wouldn’t perform.”

Most makeup is created and molded at high temperatures, Plavsic explained. Purely organic materials often fall apart in this heat, leading to inconsistent results and subpar product performance. “Not every synthetic is bad,” Plavsic said. “Sometimes, it helps create the best in class formula.”

The industry’s plastic packaging is a particular sustainability challenge — 95% is thrown away and the vast majority is not recycled, according to the British Beauty Council.

The cosmetics business is the fourth biggest plastic packaging user globally — after food and beverage, industrial packaging and pharmaceuticals — and plastic is about 67% of the industry’s packaging volume, according to Vantage Market Research. Beauty giant L’Oreal used 144,430 metric tons of plastic in its packaging material in 2021, for example, according to the Ellen Macarthur Foundation (EMF). Estee Lauder Companies reported its brands produced 71,600 metric tons of plastic in product packaging that same year.

And only 9% of the global plastic waste is recycled, according to a report from the Organisation for Economic Co-operation and Development. The United States only recycles 4% of its plastic waste.

Many brands are trying to phase out harmful plastics from their operations and adopt post-consumer recycled (PCR) plastic. (L’Oreal has set a target of 50% PCR plastic usage by 2025, while Estee Lauder is targeting 25% “or more” PCR plastic — but both are far from achieving their targets.)

“Between 60-70 major global brands have made unprecedented progress” in PCR plastic usage across industries, EMF’s Plastic Initiative Lead Sander DeFruyt told CNN. But DeFruyt stressed that PCR plastic must be adopted in conjunction with brands removing single and virgin plastics from their usage cycles to truly make a difference.

However, PCR plastic is not easy to find — low recycling rates around the world mean there is limited supply. Meanwhile, demand for it is growing demand across industries, DeFruyt said. This competition hikes up its price, which is already higher than virgin plastic.

Hair care brand FEKKAI claims that it used up to 95% PCR content in its packaging, but pricing and supply issues posed a challenge, forcing it to currently aim for containers and packaging that feature at least 50% PCR in its packaging.

“PCR plastic is more expensive than stock plastic. The cost is hard and then sourcing it is too,” founder Frédéric Fekkai told CNN. “PCR is close to our heart, but there is a massive demand, so finding recycled plastic is difficult.”

Beauty retailers plays a pivotal — and under-utilized — role, with control over stocking decisions and supply chains. But many vary when it comes to the standards they set for brands they sell.

“Smaller businesses do more, full stop,” said Jessi Baker, founder of the technology platform Provenance, which helps brands display their sustainability credentials for customers. “They move more nimbly. Some of them are born-good brands — climate friendliness was part of their setup. They don’t need to restructure their entire supply chain. Their culture already has it compared to the larger brands who need to work hard to change.”

Sephora launched its “Clean + Planet Positive” initiative in 2021, which labeled products that met its set criteria. (This is separate from the French retailer’s “Clean at Sephora” program, which is currently facing a consumer lawsuit alleging it carries a significant percentage of products understood by customers to be harmful.) Target launched a similar program in 2022, featuring a “Target Zero” icon for both online and in-store offerings that either have reusable, recyclable, compostable or reduced plastic packaging, or feature waterless or concentrated products.

Still, many steps taken by brands and retailers do not even begin to touch on the waste and pollution generated throughout supply chains, manufacturing and shipping, all huge problems for the industry to grapple with.

The gaps in standardization in the beauty ecosystem can, to some extent, be filled by certifications such as the US-born B Corporation, or B Corp. This accreditation, one of the most well-known in the beauty space, is issued by the non-profit B Lab, which scores a company on a variety of criteria around ethics and sustainability. However beneficial it may be among eco-conscious consumers, though, it is currently completely voluntary for brands to apply for.

Governments and multinationals enforcing regulations and setting a base line for brands to operate from when making sustainability claims would go a long way to making change, many experts and business leaders believe.

Susanne Kaufmann, founder of her namesake beauty brand, says her efforts in Austria would reap better results if more countries around the world had stricter, more uniform garbage disposal laws.

“I package our product in a recyclable material,” Kaufmann said. (Her products’ packaging, which is refillable and reusable, is made from 75% recycled plastic — and is 100% recyclable.) If I send this to the US, the garbage is not separated… and it’s not recyclable,” she explained, referring to inconsistencies in recycling laws across the United States.

And when it comes to ingredients, the European Chemicals Agency lists 2,495 substances banned from use in cosmetic products marketed for sale or use in the bloc. But the US Food and Drug administration only lists 11, making it more challenging for American consumers to find safer, greener options. The Environmental Working Group, a non-profit watchdog, studied lab tests of 51 sunscreen products in 2021 and found that only 35% of products met the EU standard, compared with 94% that passed the US standard.

However, while government can set minimum requirements, Mia Davis, vice president of sustainability and impact at beauty retailer Credo Beauty, says the needle will move in the private sector.

“Regulation can raise the floor a bit. A person who doesn’t know about any (sustainability issues) should still be able to walk into a bodega and get clean products… But that’s never going to be what the market can do,” she said. “Market leadership is key.”

In the absence of bold regulations or global standards on sustainability practices, this “leadership” — undertaken both by brands and customers in the beauty marketplace — is likely to be the most immediately impactful vector for addressing the industry’s climate shortcomings. It will take continued collective advocacy and initiative to see meaningful climate-conscious change.

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.

CNN
 — 

Astronauts who will helm the first crewed moon mission in five decades were revealed on Monday, queuing up the quartet to begin training for the historic Artemis II lunar flyby that is set to take off in November 2024.

The astronauts are NASA’s Reid Wiseman, Victor Glover and Christina Koch, and Jeremy Hansen of the Canadian Space Agency.

Wiseman is a 47-year-old decorated naval aviator and test pilot who was first selected to be a NASA astronaut in 2009. A native of Baltimore, Maryland, he’s completed one prior spaceflight, a 165-day trip to the International Space Station that had launched aboard a Russian Soyuz rocket in 2014. Most recently, Wiseman served as chief of the astronaut office before stepping down in November 2022, making him eligible for a flight assignment.

Wiseman will serve as commander of the Artemis II mission.

Hansen, 47, is a fighter pilot who was selected by the Canadian Space Agency for astronaut training in 2009. From London, Ontario, Hansen is one of only four active Canadian astronauts, and he recently became the first Canadian to be put in charge of training for a new class of NASA astronauts.

He will be the first Canadian ever to travel to deep space.

Glover is a 46-year-old naval aviator who returned to Earth from his first spaceflight in 2021 after piloting the second crewed flight of SpaceX’s Crew Dragon spacecraft and spending nearly six months aboard the International Space Station.

“It’s so much more than the four names that have been announced,” Glover said during the Monday announcement at NASA Johnson Space Center in Houston. “We need to celebrate this moment in human history. … It is the next step in the journey that will get humanity to Mars.”

Glover, born in Pomona, California, served in several military squadrons in the United States and Japan in the 2000s, and he completed test pilot training with the US Air Force. When he was selected for the NASA astronaut corps in 2013, he was working in the US Senate as a legislative fellow. All told, Glover logged 3,000 flight hours in more than 40 aircraft, over 400 carrier arrested landings and 24 combat missions.

Glover’s first mission to space was as part of the SpaceX Crew-1 team, which launched to the International Space Station in November 2020 for a six-month stay on the orbiting laboratory.

Koch, 44, is a veteran of six spacewalks — including the first all-female spacewalk in 2019. She holds the record for the longest single spaceflight by a woman, with a total of 328 days in space. Koch is also an an electrical engineer who helped develop scientific instruments for multiple NASA mission. Koch, a native of Grand Rapids, Michigan, also spent a year at the South Pole, an arduous stay that could well prepare her for the intensity of a moon mission.

The Artemis II mission will build on Artemis I, an uncrewed test mission that sent NASA’s Orion capsule on a 1.4 million-mile voyage to lap the moon that concluded in December. The space agency deemed that mission a success and is still working to review all the data collected.

If all goes to plan, Artemis II will take off around November 2024. The crew members, strapped inside the Orion spacecraft, will launch atop a NASA-developed Space Launch System rocket from NASA’s Kennedy Space Center in Florida.

The journey is expected to last about 10 days and will send the crew out beyond the moon, potentially further than any human has traveled in history, though the exact distance is yet to be determined.

The “exact distance beyond the Moon will depend on the day of liftoff and the relative distance of the Moon from the Earth at the time of the mission,” NASA spokesperson Kathryn Hambleton said via email.

After circling the moon, the spacecraft will return to Earth for a splashdown landing in the Pacific Ocean.

Artemis II is expected to pave the way for the Artemis III mission later this decade, which NASA has vowed will put the first woman and person of color on the lunar surface. It will also mark the first time humans have touched down on the moon since the Apollo program ended in 1972.

The Artemis III mission is expected to take off later this decade. But much of the technology the mission will require, including spacesuits for walking on the moon and a lunar lander to ferry the astronauts to the moon’s surface, is still in development.

NASA is targeting a 2025 launch date for Artemis III, though the space agency’s inspector general has already said delays will likely push the mission to 2026 or later.

The space agency has been seeking to return people to the moon for more than a decade. The Artemis program was designed to pave the way to establishing a permanent lunar outpost, allowing astronauts to live and work deeper into space long term as NASA and its partners map a path to sending the first humans to Mars.

Vanessa Wyche, the director of NASA’s Johnson Space Center, declined to provide details to CNN about the selection process. But she emphasized the diversity of the Artemis II crew, which includes men and women rather than only a staff of White male test pilots as has been the case for historic missions of the past.

“I can tell you, they still all have the right stuff,” Wyche said. “We have requirements different than we did (when we) just had test pilots” on inaugural missions.

Koch said in an interview with CNN’s Ed Lavandera that the group found out they were selected a few weeks ago.

“We were all sent to a meeting that was on our calendars under a different pretext that didn’t sound as lofty as the one it was going to be,” Koch said. “And accidentally two of us were very late to that meeting.”

She said the offer rendered her “speechless.”

“It truly is an honor,” she added. “It’s an honor — not to get myself in the space — but because it’s amazing to be a part of this team that’s going back to the moon and on to Mars.”

An interview with the four astronauts will air on “CNN This Morning” on Tuesday, which starts at 6 am ET.

Editor’s Note: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet initiative has partnered with CNN to drive awareness and education around key sustainability issues and to inspire positive action.

CNN
 — 

Originally a term used by trophy hunters in Africa, the “Big Five” described the animals most challenging to shoot and kill: the lion, elephant, leopard, rhino, and buffalo. Nowadays, it is more loosely used to refer to some of Africa’s largest and most iconic animals.

However, British photographer Graeme Green has reclaimed the narrative, creating a global “New Big Five” for wildlife photography. In 2021, 50,000 people around the world voted for the five animals they would most like to photograph, or see photographed, in the wild. Five animals were crowned the winners: the elephant, polar bear, lion, gorilla and tiger.

This week, sees the publication of “The New Big 5” photography book, which features images of those animals and other at-risk wildlife, from photography legends such as Ami Vitale, Steve McCurry and Paul Nicklen, and essays from famous conservationists and activists including like Jane Goodall and Paula Kahumbu.

Green says that the book celebrates wildlife and is a global call to action on issues impacting wildlife, including habitat loss, poaching, pollution and climate change.

Green was on assignment in Botswana at least a decade ago when he came up with the idea for a project to encourage people to “shoot with a camera, not a gun,” he says.

“I thought this would be a way to get people really focusing on wildlife, thinking about the wildlife they love, thinking about the animals that are at risk.”

In total, the book includes the work of 144 globally renowned wildlife photographers from Ecuador to India. Curating the images took nearly two years of work, says Green.

“I think these are some of the most beautiful and creative images that I’ve seen put together in one book,” says Green. “These are the species that we are at risk of losing.”

According to the UN, nature is declining at an unprecedented rate, with around one million of the planet’s animal and plant species facing extinction. The “New Big 5,” all of which are threatened, act as ambassadors for what is happening in the natural world, says Green.

As well as being a powerful reminder of what we stand to lose, the book also points people towards potential solutions. Featured essays explore the benefits of rewilding and the importance of indigenous communities in conservation.

A chapter on endangered species from bees to blue whales illustrates the alarming threat climate change poses to animals outside of the “New Big 5.” “That’s only the tip of the iceberg – I could have included thousands of pictures because that’s how serious the situation is,” says Green.

Jane Goodall, a leading conservationist who also wrote the afterword to the book, said in a press release that “we have a window of time during which we can start to heal some of the harm we have inflicted on the natural world, but only if we get together and take action now.

“I hope the photos will lead people into the wonderful worlds of these iconic species. Then, perhaps, other people will become involved in helping to create a world where wildlife can flourish for future generations to enjoy,” she said.

“The New Big 5: A Global Photography Project For Endangered Wildlife,” by Graeme Green, published by Earth Aware Editions, is on sale from April 4, 2023.

CNN
 — 

Scientists in Germany say they’ve been able to make a nasal vaccine that can shut down a Covid-19 infection in the nose and throat, where the virus gets its first foothold in the body.

In experiments in hamsters, two doses of the vaccine – which is made with a live but weakened form of the coronavirus that causes Covid-19 – blocked the virus from copying itself in the animals’ upper airways, achieving “sterilizing immunity” and preventing illness, a long-sought goal of the pandemic.

Although this vaccine has several more hurdles to clear before it gets to a doctor’s office or drug store, other nasal vaccines are in use or are nearing the finish line in clinical trials.

China and India both rolled out vaccines given through the nasal tissues last fall, though it’s not clear how well they may be working. Studies on the effectiveness of these vaccines have yet to be published, leaving much of the world to wonder whether this approach to protection really works in people.

The US has reached something of a stalemate with Covid-19. Even with the darkest days of the pandemic behind us, hundreds of Americans are still dying daily as the infection continues to simmer in the background of our return to normal life.

As long as the virus continues to spread among people and animals, there’s always the potential for it mutate into a more contagious or more damaging version of itself. And while Covid infections have become manageable for most healthy people, they may still pose a danger to vulnerable groups such as the elderly and immunocompromised.

Researchers hope next-generation Covid-19 vaccines, which aim to shut down the virus before it ever gets a chance to make us sick and ultimately prevent the spread of infection, could make our newest resident respiratory infection less of a threat.

One way scientists are trying to do that is by boosting mucosal immunity, beefing up immune defenses in the tissues that line the upper airways, right where the virus would land and begin to infect our cells.

It’s a bit like stationing firefighters underneath the smoke alarm in your house, says study author Emanuel Wyler, a scientist at the Max Delbruck Center for Molecular Medicine in the Helmholtz Association in Berlin.

The immunity that’s created by shots works throughout the body, but it resides primarily in the blood. That means it may take longer to mount a response.

“If they are already on site, they can immediately eliminate the fire, but if they’re like 2 miles away, they first need to drive there, and by that time, one-third of the house is already in full flames,” Wyler said.

Mucosal vaccines are also better at priming a different kind of first responder than injections do. They do a better job of summoning IgA antibodies, which have four arms to grab onto invaders instead of the two arms that the y-shaped IgG antibodies have. Some scientists think IgA antibodies may be less picky about their targets than IgG antibodies, which makes them better equipped to deal with new variants.

The new nasal vaccine takes a new approach to a very old idea: weakening a virus so it’s no longer a threat and then giving it to people so their immune systems can learn to recognize and fight it off. The first vaccines using this approach date to the 1870s, against anthrax and rabies. Back then, scientists weakened the agents they were using with heat and chemicals.

The researchers manipulated the genetic material in the virus to make it harder for cells to translate. This technique, called codon pair deoptimization, hobbles the virus so it can be shown to the immune system without making the body sick.

“You could imagine reading a text … and every letter is a different font, or every letter is a different size, then the text is much harder to read. And this is basically what we do in codon pair deoptimization,” Wyler said.

In the hamster studies, which were published Monday in the journal Nature Microbiology, two doses of the live but weakened nasal vaccine created a much stronger immune response than either two doses of an mRNA-based vaccine or one that uses an adenovirus to ferry the vaccine instructions into cells.

The researchers think the live weakened vaccine probably worked better because it closely mimics the process of a natural infection.

The nasal vaccine also previews the entire coronavirus for the body, not just its spike proteins like current Covid-19 vaccines do, so the hamsters were able to make immune weapons against a wider range of targets.

As promising as all this sounds, vaccine experts say caution is warranted. This vaccine still has to pass more tests before it’s ready for use, but they say the results look encouraging.

“They did a very nice job. This is obviously a competent and thoughtful team that did this work, and impressive in the scope of what they did. Now it just needs to be repeated,” perhaps in primates and certainly in humans before it can be widely used, said Dr. Greg Poland, who designs vaccines at the Mayo Clinic. He was not involved in the new research.

The study began in 2021, before the Omicron variant was around, so the vaccine tested in these experiments was made with the original strain of the coronavirus. In the experiments, when they infected animals with Omicron, the live but weakened nasal vaccine still performed better than the others, but its ability to neutralize the virus was diminished. Researchers think it will need an update.

It also needs to be tested in humans, and Wyler says they’re working on that. The scientists have partnered with a Swiss company called RocketVax to start phase I clinical trials.

Other vaccines are further along, but the progress has been “slow and halting,” Poland said. Groups working on these vaccines are struggling to raise the steep costs of getting a new vaccine to market, and they’re doing it in a setting where people tend to think the vaccine race has been won and done.

In reality, Poland said, we’re far from that. All it would take is another Omicron-level shift in the evolution of the virus, and we could be back at square one, with no effective tools against the coronavirus.

“That’s foolish. We should be developing a pan-coronavirus vaccine that does induce mucosal immunity and that is long-lived,” he said.

At least four nasal vaccines for Covid-19 have reached late-stage testing in people, according to the World Health Organization’s vaccine tracker.

The nasal vaccines in use in China and India rely on harmless adenoviruses to ferry their instructions into cells, although effectiveness data for these has not been published.

Two other nasal vaccines are finishing human studies.

One, a recombinant vaccine that can be produced cheaply in chicken eggs, the same way many flu vaccines are, is being put through its paces by researchers at Mount Sinai in New York City.

Another, like the German vaccine, uses a live but weakened version of the virus. It’s being developed by a company called Codagenix. Results of those studies, which were carried out in South America and Africa, may come later this year.

The German team says it’s eagerly watching for the Codagenix data.

“They will be very important in order to know where whether this kind of attempt is basically promising or not,” Wyler said.

They have reason to worry. Respiratory infections have proved to be tough targets for inhaled vaccines.

FluMist, a live but weakened form of the flu virus, works reasonably well in children but doesn’t help adults as much. The reason is thought to be that adults already have immune memory for the flu, and when the virus is injected into the nose, the vaccine mostly boosts what’s already there.

Still, some of the most potent vaccines such as the vaccine against measles, mumps and rubella use live attenuated viruses, so it’s a promising approach.

Another consideration is that live vaccines can’t be taken by everyone. People with very compromised immunity are often cautioned against using live vaccines because even these very weakened viruses may be risky for them.

“Although it’s strongly attenuated, it’s still a real virus,” Wyler said, so it would have to be used carefully.

CNN
 — 

A new study found a moderately higher risk of autism spectrum disorder in children born to pregnant people exposed to tap water with higher levels of lithium, but experts caution that this association does not show a direct link between the two.

About 1 in 36 children in the US is diagnosed with autism spectrum disorder (ASD) each year, according to data from the US Centers for Disease Control and Prevention.

Scientists still don’t know the exact cause of autism, a developmental disorder. Genetics may be a factor, but some have been looking at potential environmental causes, too.

Cases may be on the rise, but that is also unclear. One study published this year on cases in the New York-New Jersey area found that autism diagnosis rates tripled among certain age groups between 2000 and 2016. A 2021 report found similar increases in cases, but the CDC says the increased number of cases is most likely linked to more doctors screening for the condition.

Lithium is an alkali metal that can be found naturally in some food and ground water. It’s used in batteries, grease and air conditioners, as well as in the treatment of bipolar disorder and some blood disorders. Its levels in US drinking water are not regulated, according to the US Geological Survey.

A new study, published Monday in the journal JAMA Pediatrics, found a small association between lithium and autism diagnosis in Denmark, where the researchers say the level of lithium in drinking water is similar to that in American water systems.

The researchers checked a database of people with psychiatric disorders for children born between 2000 and 2013 to find information on 8,842 cases of ASD and 43,864 participants who did not have ASD. They then measured the concentration of lithium in 151 public waterworks that served more than half of the Danish population and mapped out where pregnant people lived in relation.

As lithium levels in water increased, there was a modest increased risk of an ASD diagnosis. Specifically, compared with people at the lowest exposure level, those who had the second and third highest exposure during pregnancy had a 24% to 26% higher risk of ASD diagnosed in children. The group with the highest exposure had a 46% higher risk than those at the lowest level of exposure.

The researchers could not tell how much water the pregnant people drank, but they picked Denmark in part because residents there consume some of the lowest amounts of bottled water in Europe.

Experts say it’s important to note that the research can’t show that lithium exposure leads directly to an autism diagnosis.

Further study is required, said study co-author Dr. Beate Ritz, a professor of neurology in the David Geffen School of Medicine at UCLA, and a professor of epidemiology and environmental health at the UCLA Fielding School of Public Health.

“Any drinking water contaminants that may affect the developing human brain deserve intense scrutiny,” Ritz said in a news release. She added that the research would need to be replicated in other countries to look for a similar connection.

The implications of the findings are complex as far as public health policy is concerned, according to an editorial published alongside the study. Lithium levels in water, at concentrations that the study associated with a potential ASD risk, have also been linked with health benefits such as lower rates of hospitalization for psychiatric disorders and suicide.

“If all these of associations are valid, the wisdom of Solomon will be required to develop guidelines for lithium in drinking water that are maximally protective of the entire population,” wrote Dr. David C. Bellinger, a professor of neurology and psychology at Harvard Medical School. “Until the basic biology of ASD is better understood, it will be difficult to distinguish causal from spurious associations.”

Dr. Max Wiznitzer, director of the Rainbow Autism Center at University Hospitals Rainbow Babies and Children’s Hospital in Cleveland, points to other research on the effects of lithium on pregnant people who take it for mental health disorders. Those studies – which look at people exposed to much higher levels than are found in drinking water – do not show a connection with autism spectrum disorder.

“It’s an interesting association, but causation is definitely not proven,” said Wiznitzer, who was not involved in the new research. “We have to see if there’s a viable and biologically plausible mechanism by which a small amount of lithium in the water supply can somehow do this, yet pharmacologic dosing of lithium in women with bipolar disorder has not been reported to be causing increased risk of ASD.”

Other studies have also suggested connections between ASD and environmental exposures to things like pesticides, air pollution and phthalates. But none of them points to any of these factors as a direct cause of the disorder.

A link between environmental exposure and ASD is hard to prove, Wiznitzer said. With research showing that increased exposure to air pollution raises the risk of giving birth to a child with ASD, for example, he often wonders whether pollution is the determining factor or if it’s just the populations who live in more polluted areas.

“There’s a lot of speculation about about environmental factors, but how many of them are truly causally associated?” Wiznitzer said. “We are bombarded with a variety of environmental stressors in our everyday lives. We have to figure out how to basically safely navigate them, and this is probably not one that’s high on our list.”