Gaia: astronomers to release most accurate data ever for nearly two billion stars

ROYAL ASTRONOMICAL SOCIETY

Research News

    SHARE

 PRINT  E-MAIL

IMAGE: A DIAGRAM OF THE TWO MOST IMPORTANT COMPANION GALAXIES TO THE MILKY WAY, THE LARGE MAGELLANIC CLOUD OR LMC (LEFT) AND THE SMALL MAGELLANIC CLOUD (SMC) MADE USING DATA FROM... view more 

CREDIT: ESA/GAIA/DPAC

On 3 December an international team of astronomers will announce the most detailed ever catalogue of the stars in a huge swathe of our Milky Way galaxy. The measurements of stellar positions, movement, brightness and colours are in the third early data release from the European Space Agency's Gaia space observatory and will be publicly available. Initial findings include the first optical measurement of the acceleration of the Solar system. The data set, and early scientific discoveries, will be presented at a special briefing hosted by the Royal Astronomical Society.

Launched in 2013, Gaia operates in an orbit around the so-called Lagrange 2 (L2) point, located 1.5 million kilometres behind the Earth in the direction away from the Sun. At L2 the gravitational forces between the Earth and Sun are balanced, so the spacecraft stays in a stable position, allowing long-term essentially unobstructed views of the sky.

The primary objective of Gaia is measure stellar distances using the parallax method. In this case astronomers use the observatory to continuously scan the sky, measuring the apparent change in the positions of stars over time, resulting from the Earth's movement around the Sun.

Knowing that tiny shift in the positions of stars allows their distances to be calculated. On Earth this is made more difficult by the blurring of the Earth's atmosphere, but in space the measurements are only limited by the optics of the telescope.

Two previous releases included the positions of 1.6 billion stars. This release brings the total to just under 2 billion stars, whose positions are significantly more accurate than in the earlier data. Gaia also tracks the changing brightness and positions of the stars over time across the line of sight (their so-called proper motion), and by splitting their light into spectra, measures how fast they are moving towards or away from the Sun and assesses their chemical composition.

The new data include exceptionally accurate measurements of the 300,000 stars within the closest 326 light years to the Sun. The researchers use these data to predict how the star background will change in the next 1.6 million years. They also confirm that the Solar system is accelerating in its orbit around the Galaxy.

This acceleration is gentle, and is what would be expected from a system in a circular orbit. Over a year the Sun accelerates towards the centre of the Galaxy by 7 mm per second, compared with its speed along its orbit of about 230 kilometres a second.

Gaia data additionally deconstruct the two largest companion galaxies to the Milky Way, the Small and Large Magellanic Clouds, allowing researchers to see their different stellar populations. A dramatic visualisation shows these subsets, and the bridge of stars between the two systems.

Dr Floor van Leeuwen of the Institute of Astronomy at the University of Cambridge, and UK Gaia DPAC Project Manager, comments: "Gaia is measuring the distances of hundreds of millions of objects that are many thousands of light years away, at an accuracy equivalent to measuring the thickness of hair at a distance of more than 2000 kilometres. These data are one of the backbones of astrophysics, allowing us to forensically analyse our stellar neighbourhood, and tackle crucial questions about the origin and future of our Galaxy."

Gaia will continue gathering data until at least 2022, with a possible mission extension until 2025. The final data releases are expected to yield stellar positions 1.9 times as accurate as those released so far, and proper motions more than 7 times more accurate, in a catalogue of more than 2 billion objects.

##

Images and movies

A diagram of the two most important companion galaxies to the Milky Way, the Large Magellanic Cloud or LMC (left) and the Small Magellanic Cloud (SMC) made using data from the European Space Agency Gaia satellite. The two galaxies are connected by a 75,000 light-years long bridge of stars, some of which is seen extending from the left of the SMC.

Credit: ESA/Gaia/DPAC

Movies [available after the embargo expires]

Our Solar Neighbourhood

Since 2013 the European Space Agency Gaia satellite has been measuring the positions and characteristics of nearly two billion stars in our Milky Way galaxy. This movie is a flythrough of the nearest 326 light years to the Sun, a region of space that contains around 300,000 stars.

Credit: ESA/Gaia/DPAC

The Large and Small Magellanic Clouds

Data from the European Space Agency Gaia space observatory help us understand the different stellar populations in the two main companion galaxies to the Milky Way, the Large and Small Magellanic Clouds. This animation moves from an image of the Milky Way to the two systems, shows the separate populations of stars in each one. It then illustrates the dramatic bridge of stars connecting the LMC and SMC, spanning 75,000 light years.

Data sets provided by Merce Romero-Gomez. Video based on the paper: Gaia Early Data Release 3: structure and properties of the Magellanic Clouds by Gaia Collaboration, X. Luri et al., A&A 2020 (in press).

Credit: ESA/Gaia/DPAC

Further information

The Gaia Early Data Release 3 will be freely available to the scientific community and the wider public after 1100 GMT on Thursday 3 December.

Institutes in the UK have played a pivotal role in a wide range of aspects of the new Gaia data release. At the Royal Observatory Edinburgh, supported by Leicester University, software for the pre-processing of the data was prepared and tested; at the Institute of Astronomy (IoA) in Cambridge the photometric data was processed and prepared for publication, and at the Mullard Space Science Laboratory work is continuing on the software for the processing of the spectroscopic data produced by the mission. The UK activities in the Gaia project are supported by grants from the UK Space Agency and the Science and Technology Facilities Council.

Gaia space telescope measured the acceleration of the Solar System

UNIVERSITY OF HELSINKI

Research News

    SHARE

 PRINT  E-MAIL

IMAGE: THE STREAM OF STARS ACROSS THE SKY. view more 

CREDIT: (ESA AND GAIA DPAC)

The Gaia space telescope has measured the acceleration of the Solar System when it orbits the center of our Milky Way galaxy. The Solar System motion relative to the stars agrees with the results by Finnish astronomers in the 19th century.

Moreover, the observational data by Gaia improves satellite navigation. Finnish researchers are participating in this massive endeavor, that results in three-dimensional mapping of our galaxy, to be completed in 2024.

Today, Dec. 3, 2020, the European Space Agency (ESA) released observational data from the Gaia telescope (Gaia Early Data Release 3 or EDR3), in continuation to the DR1 and DR2 releases of the years 2016 and 2018. Gaia accrues accurate knowledge about, for example, the Milky Way stars, distant extragalactic quasars, and the asteroids of our Solar System.

Quasars are bright, star-like objects that allow for the determination of planet Earth's orientation in space. With the help of their precise positions measured by Gaia, a new high-precision reference system can be constructed for defining the positions of stars, Solar System objects, and also satellites.

"The knowledge accrued by Gaia affects the precision of satellite navigation in the future. The satellite positions and Earth orientation in space are determined in a reference frame tied to the directions of quasars. The precision and state of the art of the reference frame are critical for the precision in navigation," says Professor Markku Poutanen at the Finnish Geospatial Research Institute FGI, National Land Survey of Finland.

The precise observations of quasars resulted, for the first time, in a successful computation of the acceleration of the Solar System.

"The acceleration of the Solar System towards the center of the Milky Way, as measured by Gaia, is (2.32±0.16) x 10-10 m/s2 or, roughly, two one-hundred-billionth parts of the gravitational acceleration caused by the Earth on its surface, " summarizes Astronomy Professor Karri Muinonen at the Department of Physics, University of Helsinki, also Research Professor at the Finnish Geospatial Research Institute FGI.

Gaia in the research of asteroids

Gaia's data processing is carried out within the European DPAC network (Data Processing and Analysis Consortium) with more than 300 researchers. Solar System researchers at the University of Helsinki take part in the Gaia data processing in several different ways.

"We are responsible for the daily computation of orbits for asteroids discovered by Gaia. Based on these computations, ground-based follow-up observations are organized," describes Muinonen.

"Before data releases, we take part in the validation of Gaia observations of asteroid positions, brightnesses, and spectra. Our research with Gaia data focuses on asteroid orbits, rotation periods and pole orientations, masses, shapes, and surface structural and compositional properties. In the computation of collision probabilities for near-Earth asteroids, the precision of reference frames is completely central," continues Muinonen.

Asteroid observations by Gaia were published in DR2 in spring 2018 (14 099 asteroids). In the forthcoming DR3 release in spring 2022, there will be position and brightness data for tens of thousands of asteroids and, for the first time, asteroid spectra will also be released.

Years of work and billions of stars

The EDR3 data has been collected by Gaia from the end of July 2014. The data includes, for example, position and brightness data of 1,81 billion stars and color data of 1,55 billion stars from the time period of 34 months. Furthermore, the data more than triples the number of quasars observed for precise reference frames to 1,61 million.

EDR3 is a remarkable improvement, in terms of both numbers and precisions, as compared to the earlier releases. The newest release gives hints about the gigantic nature of the forthcoming DR3 release in spring 2022 and the final DR4 release after 2024.

Gaia observes astronomical objects systematically in the so-called L2 Lagrange point some 1,5 million kilometers from the Earth in the anti-sun direction. Gaia observes about two billion stars with a precision, at best, of one hundred millionths of a degree. The result will be a three-dimensional map of our galaxy.

Stellar motion in the future

Based on the Gaia data, researchers' have modeled the motion of stars in the Milky Way. They have produced an animation for the motion of 40 000 randomly selected stars on the sky 1.6 million years into the future.

"In the animation, short and long trails describe changes in stellar positions with 80 000 years. The former are mostly related to distant stars, whereas the latter are solely due to the nearby stars. Every now and then, short trails expand into long ones, and long trails shrink into short ones. This is also related to the changing distances of the stars," says Muinonen.

In the end of the animation, stars appear to be removed from the left and collected to the right. This is due to the Solar System's motion relative to the stars. A similar phenomenon can be seen when moving from a center of a forest islet to its boundary: the trees in the front gradually disappear whereas they seem to be collected in the back.

"This shows the average motion of the Solar System with respect to the surrounding stars. From the Finnish point of view, it is intriguing that the motion documented by Gaia agrees with the pioneering research about the Solar System's motion by Friedrich Wilhelm August Argelander (1799-1875) in the 19th century at the Helsinki Observatory," concludes Muinonen.

Argelander was the first astronomer, who unequivocally calculated the direction of Solar System motion in space. He worked at the Observatory, University of Helsinki, then the Imperial Alexander University. He had made the observations at the Turku Observatory in 1827-1831 before the observatory moved to Helsinki. In Helsinki, he compiled the stellar catalog entitled "DLX stellarum fixarum positiones mediae ineunte anno 1830" that, as the title says, included the precise positions of 560 stars.

Movement of quasars is actually the movement of Solar System

More accurately, the apparent stellar streams include the information about the motion of the stars and the Solar System about the center of the Milky Way. The Gaia quasar observations allow for the determination of the acceleration related to this orbital motion.

Gaia has measured the apparent motions of quasars on the sky. These motions are tiny, about one thousandth part of the motion of stars 3000 light years from us. The apparent stream of quasars is directed toward the center of the Milky Way, that is, in the direction where the acceleration of the Solar System is pointing. Gaia has, in essence, measured the absolute motion of the Solar System relative to the distant universe. This motion derives from the gravitational forces by the Milky Way and all other objects in the universe.

CAPTION

Figure: The acceleration of the Solar System is revealed in the apparent motion of the distant quasars toward the center of the Milky Way. In reality, the quasars do not have proper motion.

CREDIT

(ESA and Gaia DPAC)

###

Animation: The stars' predicted motion across the sky. (ESA and Gaia DPAC) https://youtu.be/cEsfqFDSpm0

Read more:

Gaia EDR3 (3. 12. 2020) data release, home page:

https://www.cosmos.esa.int/web/gaia/early-data-release-3

http://www.esa.int/Science_Exploration/Space_Science/Gaia

More information:

Professor Karri Muinonen, University of Helsinki and National Land Survey, karri.muinonen@helsinki.fi, +358 50 415 5474, Asteroid shapes, rotations, and surface properties from Gaia photometry

Professor Markku Poutanen, National Land Survey, markku.poutanen@maanmittauslaitos.fi, +358 40 718 2152, Reference frames

Docent Mikael Granvik, University of Helsinki and Luleå Institute of Technology, mikael.granvik@helsinki.fi, +358 50 521 7209, Asteroid orbit and mass computation from Gaia astrometry

Docent Antti Penttilä, University of Helsinki, antti.i.penttila@helsinki.fi, +358 50 524 0968, Asteroid compositional analyses from Gaia spectroscopy

 

Supercomputer simulations could unlock mystery of Moon's formation

DURHAM UNIVERSITY

Research News

    SHARE

 PRINT  E-MAIL

Volume 90%

 

VIDEO: A CROSS SECTION OF A 3D SIMULATION RUN BY RESEARCHERS INVESTIGATING HOW A COLLISION BETWEEN THE EARLY-EARTH AND A MARS-SIZE OBJECT MIGHT HAVE LED TO THE FORMATION OF THE MOON.... view more 

CREDIT: SERGIO RUIZ-BONILLA

Astronomers have taken a step towards understanding how the Moon might have formed out of a giant collision between the early Earth and another massive object 4.5 billion years ago.

Scientists led by Durham University, UK, ran supercomputer simulations on the DiRAC High-Performance Computing facility to send a Mars-sized planet - called Theia - crashing into the early Earth.

Their simulations produced an orbiting body that could potentially evolve into a Moon-like object.

While the researchers are careful to say that this is not definitive proof of the Moon's origin, they add that it could be a promising stage in understanding how our nearest neighbour might have formed.

The findings are published in the journal Monthly Notices of the Royal Astronomical Society.

The Moon is thought to have formed in a collision between the early Earth and Theia, which scientists believe might have been an ancient planet in our solar system, about the size of Mars.

Researchers ran simulations to track material from the early Earth and Theia for four days after their collision, then ran other simulations after spinning Theia like a pool ball.

The simulated collision with the early Earth produced different results depending upon the size and direction of Theia's initial spin.

At one extreme the collision merged the two objects together while at the other there was a grazing hit-and-run impact.

Importantly, the simulation where no spin was added to Theia produced a self-gravitating clump of material with a mass of about 80 per cent of the Moon, while another Moon-like object was created when a small amount of spin was added.

The resulting clump, which settles into an orbit around the post-impact Earth, would grow by sweeping up the disc of debris surrounding our planet.

The simulated clump also has a small iron core, similar to that of the Moon, with an outer layer of materials made up from the early Earth and Theia.

Recent analysis of oxygen isotope ratios in the lunar samples collected by the Apollo space missions suggests that a mixture of early Earth and impactor material might have formed the Moon.

Lead author Sergio Ruiz-Bonilla, a PhD researcher in Durham University's Institute for Computational Cosmology, said: "By adding different amounts of spin to Theia in simulations, or by having no spin at all, it gives you a whole range of different outcomes for what might have happened when the early Earth was hit by a massive object all those billions of years ago.

"It's exciting that some of our simulations produced this orbiting clump of material that is relatively not much smaller than the Moon, with a disc of additional material around the post-impact Earth that would help the clump grow in mass over time.

"I wouldn't say that this is the Moon, but it's certainly a very interesting place to continue looking."

The Durham-led research team now plan to run further simulations altering the mass, speed and spinning rate of both the target and impactor to see what effect this has on the formation of a potential Moon.

Co-author Dr Vincent Eke, of Durham University's Institute for Computational Cosmology, said: "We get a number of different outcomes depending upon whether or not we introduce spin to Theia before it crashes into the early Earth.

"It's particularly fascinating that when no spin or very little spin is added to Theia that the impact with the early Earth leaves a trail of debris behind, which in some cases includes a body large enough to deserve being called a proto-Moon.

"There may well be a number of possible collisions that have yet to be investigated that could get us even closer to understanding just how the Moon formed in the first place."

###

The research was carried out with Durham University's Institute for Data Science and the School of Physics and Astronomy at the University of Glasgow, UK.

The high-resolution simulations were run using the SWIFT open-source simulation code. They were carried out on the DiRAC Memory Intensive service ("COSMA"), hosted by Durham University on behalf of the DiRAC High-Performance Computing facility.

The research was funded by the Science and Technology Facilities Council, part of UK Research and Innovation.

The impact of Neandertal DNA on human health

ESTONIAN RESEARCH COUNCIL

Research News

 

IMAGE: MICHAEL DANNEMANN

NOT A NEANDERTHAL  view more 

CREDIT: JÜRI PARIK 

A researcher at the University of Tartu described new associations between Neandertal DNA and autoimmune diseases, prostate cancer and type 2 diabetes.

Modern humans migrated out of Africa more than 60,000 years ago and met and interbred with Neandertals and other archaic human groups. As a consequence, we can find that a few percent of the genomes of people outside of Africa contain traces of archaic ancestry. Large-scale resources with genetic and medical data are needed to find out how this archaic remains affect modern human health. Most previous studies have examined European population-specific cohorts. However, the Neandertal DNA content is quite different between Europeans and Asians and our knowledge limited about non-European Neandertal DNA. A new study by Senior Research Fellow of Evolutionary and Population Genomics Michael Dannemann analyzed Neandertal associated phenotypes in an Asian cohort and compared it to those discovered in a European cohort.

This study provides evidence that the impact of Neandertal DNA on the immune system has not been population-specific. "My findings show that while the Neandertal DNA in European and Asian populations differ they both contain variants that increase the risk of autoimmune diseases like dermatitis, Graves' disease and rheumatoid arthritis," said Dannemann.

Another disease for which associations were found in both populations was prostate cancer. Dannemann said that the difference is here that this gene variant had a protective effect which means it reduces the risk for prostate cancer.

Of particular interest were the Neandertal associations with type 2 diabetes, a disease influencing many people today. The result of this study showed that Neandertal-linked associations were only found in Asians and showed evidence for an over-proportional effect on this disease given the Neandertal DNA content in this population.

However, given the different associated archaic variants in both European and Asian cohorts, the results of this study also suggest that the effects of how Neandertal DNA influences immunity might be population-specific. "This is highlighting the importance of studying a wider range of ancestries to help us to ascertain how the phenotypic legacy of Neandertals influences modern humans today," added Dannemann.

###

The study is part of the project "Center for Genomics, Evolution and Medicine". The Center for Genomics, Evolution and Medicine (cGEM) aims to apply advancements in genomic medicine in an evolutionarily-aware framework to account for different evolutionary pathways of populations which have led to differences in susceptibility to common diseases, like metabolic and cardiovascular diseases and cancers.

Peanut treatment lowers risk of severe allergic reactions in preschoolers

UNIVERSITY OF BRITISH COLUMBIA

Research News

 

IMAGE: EXPOSING CHILDREN TO A SMALL, REGULAR DOSE OF PEANUTS IN A REAL-WORLD SETTING (OUTSIDE OF A CLINICAL TRIAL) IS EFFECTIVE IN REDUCING THE RISK OF ALLERGIC REACTIONS. view more 

CREDIT: CREDIT: VLADISLAV NIKONOV/UNSPLASH

It's a peanut-filled world--or at least it can feel that way for kids with peanut allergies. But a new study by researchers at the University of British Columbia and BC Children's Hospital gives hope to parents and kids who face real danger from exposure to peanuts.

"There's a common misperception about peanut allergies--that it's not a serious health issue. Although the risk of a fatal reaction to peanuts is low in patients with peanut allergy, it has a major impact on quality of life and many families feel hopeless in dealing with what can seem like an unmanageable problem," said the study's senior author Dr. Edmond Chan, head of the division of pediatric allergy and immunology at UBC's faculty of medicine and clinical investigator at BC Children's Hospital Research Institute.

The study, recently published in the Journal of Allergy and Clinical Immunology: In Practice, is the first to demonstrate that exposing children to a small, regular dose of an allergen (in this case, peanuts) in a real-world setting (outside of a clinical trial) is effective in reducing the risk of allergic reactions.

The treatment method, known as oral immunotherapy, involves gradually increasing the amount peanuts (or peanut products) given to the child. One treatment aim is to reach desensitization, whereby the child can ingest a full serving of peanuts without triggering a dangerous reaction. Another goal is protection in the event of an accidental exposure, and lessening or eliminating the need for epinephrine injections in response to reactions. To sustain their level of immunity, the child must continue to eat peanut products on a regular basis.

Over the course of this study, 117 preschool-age children--between the ages of 9 months and five years--with peanut allergies from across Canada received a daily maintenance dose of 300mg of peanut protein--equivalent to about one peanut or a quarter teaspoon of peanut butter.

After one year, the researchers found that nearly 80 per cent of the preschoolers were able to eat 15 peanuts (equivalent to 4000mg of peanut protein) without reaction during an allergist-supervised oral challenge. And almost every child (more than 98 per cent) who participated in the study could eat three to four peanuts without reaction, which is enough to protect from 99 per cent of accidental exposures.

Although some children in the study (21.4 percent) experienced an allergic reaction during the allergist-supervised oral challenge, the reactions were mild (14.5 per cent) or moderate (six per cent). Two children received epinephrine for moderate reactions. There were no severe reactions.

This study follows another analysis by the same researchers last year that was the first to demonstrate the safety of peanut oral immunotherapy for a large group of preschool-aged children when offered as a routine treatment in a hospital or clinic rather than within a clinical trial.

"Now, thanks to oral immunotherapy, these kids can accidentally eat something with peanut butter in it--like a cookie or cake--and not suffer a reaction, which is wonderful news for the families," said the study's lead author Dr. Lianne Soller, UBC allergy research manager based at BC Children's Hospital.

For Ravinder Dhaliwal, oral immunotherapy has been a game changer for her family and six-year old daughter, Saiya, who was diagnosed with a peanut allergy when she was still an infant.

"Before starting therapy, our lives were filled with anxiety because every outing revolved around her food allergies," said Ravinder. "Now, we can go to a restaurant or a birthday party without being in constant fear."

As one of the participants in the study, Saiya started receiving maintenance therapy in the spring of 2018, eating a small amount of peanut product every day. One year later, she was able to eat 20 peanuts in a sitting without having a reaction.

Today, Saiya is not only eating peanut butter sandwiches three times a week--she is enjoying the flavour of peanut products for the first time in her life and asking for them as a treat.

"Having gone through oral immunotherapy, I don't feel scared anymore--it's like having a shield to protect my child. The experience has been empowering for all of us," said Ravinder.

According to Chan and Soller, the earlier children undergo oral immunotherapy, the better. If left unchecked, peanut allergies most often become life-long and reactions can become more severe, which can result in social isolation, bullying, and anxiety.

###

No 'one-size-fits-all solution' for children exposed to domestic violence, researchers say

Case Western Reserve University study surveyed social service professionals at more than 100 Ohio agencies to assess service needs

CASE WESTERN RESERVE UNIVERSITY

Research News

 

CLEVELAND--Some of the most affected by domestic violence are also the youngest. Each year, more than 6% of all children in the United States are exposed to domestic violence and require intervention services from various agencies, according to the Centers for Disease Control.

A team of researchers at Case Western Reserve University surveyed 105 agencies throughout Ohio to better understand service, policy and research needs--and get feedback about potential strategies to protect children from intimate partner violence.

The study's key findings yielded recommendations to include emotional and coping skills as vital parts of childhood education--not unlike how math and reading are incorporated into school curricula, according to the study's co-author Kristen Berg, a postdoctoral researcher at the university's School of Medicine and graduate of the Jack, Joseph and Morton Mandel School of Applied Social Sciences.

"Kids should be provided appropriate education from very early ages about healthy relationships, with both the self and others, and all of their ingredients," she said. "Things like understanding how to identify their own emotions, how to cope with those emotions, learning how to attune to others' emotions, safe dating behaviors, consent-based communication--from school curricula that explicitly emphasize social and emotional intelligence."

A rapidly growing body of research nationally--including at the Mandel School--has revealed that children who have been exposed to domestic violence are more likely than their peers to experience a wide range of difficulties, from fear and low self-esteem, to anger and oppositional behavior and feeling isolated in social relationships.

Berg said there's also evidence that those exposed to domestic violence tend to have higher rates of depression and anxiety, over-activated stress responses, and both victimization by and perpetration of dating violence during adolescence. Families affected by domestic violence also often experience housing instability or substance misuse, and children's education and peer relationships may be disrupted due to moves in and out of the family home.

None of this comes as a surprise to researchers or the social service professionals they surveyed.

"But that's notable in and of itself," Berg said. "By now, there have been decades of calls by clinicians and researchers to reduce fragmentation among service systems in order to best care for trauma-exposed kids and families. Our participants' responses suggest that we haven't quite figured out how to remove barriers that are thwarting that collaborative approach."

In addition, the research showed that service providers highlighted needs for increased trauma-informed care and better collaboration among service providers.

"While there might not be a one-size-fits-all solution, there are places we can start," said Megan Holmes, founding director of the Center on Trauma and Adversity and an associate professor at the Mandel School, who co-authored the study.

Gut microbiome snapshot could reveal chemical exposures in children

Study of how semi-volatile organic compounds affect bacteria and fungi reveals new relationships and bacteria used for bioremediation in children's guts

DUKE UNIVERSITY

Research News

Researchers at Duke University have completed the most comprehensive study to date on how a class of persistent pollutants called semi-volatile organic compounds (SVOCs) are associated with the gut microbiome in human children.

The results show that certain SVOCs are correlated with the abundance of bacterial and fungal species living in the human digestive tract and may affect them differently, providing a potential mechanism for measuring exposure to a wide variety of these substances. The study also suggests that exposure to toxic halogenated compounds, chemicals containing carbon and a halogen such as chlorine and bromine, may create a niche for bacteria that feed off of them - bacteria that are not usually found in the human gut.

"We found bacteria that researchers use for soil bioremediation to remove chlorinated solvents, which is not an organism that you would expect to find in somebody's gut," said Claudia Gunsch, the Theodore Kennedy Professor of Civil and Environmental Engineering at Duke. "The reason it's used in soils is to detoxify and remove chlorines, which suggests that maybe that's also exactly why they're in these guts."

The results appear online on October 30 in the journal Environmental Science & Technology Letters.

"We want to understand the impacts of exposure to SVOCs on our gut microbiome and how that translates to positive or negative health outcomes," Gunsch said. "But right now it's a big black box that we don't understand."

SVOCs are a broad class of odorless chemicals that are emitted from building materials and consumer products, often slowly evaporating and settling on dust particles and water droplets. Almost everyone in the developed world is exposed regularly to at least some of these compounds, due to their common use in industrial and consumer products.

The thought that these chemicals might have effects on the human microbiome and impact health is relatively new, and the research to uncover what these may be and why they occur is still in its infancy. One important line of work is aimed at children because they typically have higher exposure rates, due to spending more time playing on dusty floors where SVOCs accumulate, and because their growing bodies are more susceptible to novel environmental stressors.

One avenue for causing turbulence in a growing child's life is through affecting the gut microbiome. Made up of the complex communities of bacteria and fungi growing and living together throughout the human digestive tract, the gut microbiome has been shown to have a clear importance to childhood development as well as adult health. While some studies have already shown that certain SVOCs have an impact on the gut microbiome of children, the chemicals studied are just a tiny fraction of those that people are exposed to.

"In theory, perturbations in the gut microbiome of children might be associated with long-term health impacts," added Courtney Gardner, assistant professor of civil and environmental engineering at Washington State University, who conducted the study while still a member of Gunsch's laboratory. "But before we can really study any of them for clear causations, we need to get a sense of which SVOC classes seem to be the most negatively associated with microbiome communities."

In their first explorative foray into this field, Gunsch, Gardner and their colleagues at Duke measured the levels of dozens of SVOCs circulating in the bodies of almost 80 children between the ages of three and six. They also characterized each of the children's gut microbiome and then looked for relationships between the differences they found and exposures to SVOCs.

There wasn't any shortage of data to work with, as the researchers found 29 SVOC compounds in more than 95% of the samples taken. They also found relationships between the compounds present in children's blood or urine and the relative amounts of key microbes, including 61 bacteria and 24 fungi. After working through the various biomarkers and relationships, the researchers came away with two interesting insights.

The first was that children with high levels of halogenated SVOCs have some unusual guests in their guts.

The researchers also found that while some SVOCs had a negative effect on bacteria in the gut microbiome, others had a positive effect. With more research into exactly how these various chemicals affect the different species of the gut in their own ways, this work may provide the possibility of using a snapshot of the gut's microbial community as a window into what SVOCs a child has been exposed to.

"It's currently really complicated and expensive to measure what chemicals people have been exposed to if you don't already know what you're looking for," said Gunsch. "By contrast, this is pretty simple. If we could get a reliable snapshot of SVOC exposure just by sequencing a microbiome's genetic signature, we could use that to help us understand more about the health impacts these chemicals have on our children and ourselves."

###