EXPERT REACTION: World-first study shows increased atmospheric CO2 levels damage young lungs, in mice

Embargoed until: Publicly released:
Peer-reviewed: This work was reviewed and scrutinised by relevant independent experts.

Experimental study: At least one thing in the experiment was changed to see if it had an impact on the subjects (often people or animals) – eg: changing the amount of time mice spend on an exercise wheel to find out what impact it has on weight loss.

Animals: This is a study based on research on whole animals.

Australian researchers who have conducted the first study looking at the direct health impacts of predicted carbon dioxide levels say the results are worrying and highlight the urgent need for more research into the issue. Conducted in mice, the study found that exposure to about 900ppm of CO2, a level predicted by the end of the century, had a direct impact on both the lung function and lung structure of mice that had been living in that environment throughout pregnancy, early life, and into early adulthood.

Journal/conference: Environmental Health Perspectives

Link to research (DOI): 10.1289/EHP7305

Organisation/s: Telethon Kids Institute, Curtin University, The University of Western Australia, The Australian National University

Funder: The authors declare they have no actual or potential competing financial interests.

Media release

From: Telethon Kids Institute

World-first study shows increased atmospheric CO2 levels damage young lungs

Australian researchers who have conducted the first study looking at the direct health impacts of predicted carbon dioxide levels say the results are worrying and highlight the urgent need for more research into the issue.

Researcher Associate Professor Alexander Larcombe, who is a member of the Wal-yan Respiratory Research Centre – which is a powerhouse partnership between Telethon Kids Institute, Perth Children’s Hospital Foundation and Perth Children’s Hospital – said humans had evolved to breathe atmospheric carbon dioxide at about 300 parts per million.

“Current levels are just over 400ppm, and climate change modelling predicts that within our lifetimes it is likely to increase to about double that,” Assoc Prof Larcombe said.

“There is a lot of research that looks at the environmental and health impacts of climate change, but none that focus solely on the health effects of breathing in higher levels of carbon dioxide in the atmosphere.”

Conducted in mice – which the researchers say are naturally able to better tolerate increased CO2 levels due to their burrowing habits – the study found that exposure to about 900ppm of CO2 had a direct impact on both the lung function and structure of mice that had been living in that environment throughout pregnancy, early life, and into early adulthood.

“The lung damage included altered alveoli, which is the critical part of the lung that helps with gas exchange – meaning they could have had more difficulty breathing,” Assoc Prof Larcombe said.

“We also saw some changes in the actual physical structure of the lungs and both of these changes meant the lungs weren’t functioning as they should.”

Interestingly, the lungs of adult mice that were not exposed to elevated CO2 during early life did not show signs of impairment, which the researchers believe is because their lungs were fully formed before being exposed to the higher levels of CO2.

The University of Western Australia researcher Dr Caitlin Wyrwoll, who is a co-author on this study, described it as important work because it offered “the first insight into the fact that these higher levels of CO2 exposure were indeed affecting the health of developing lungs”.

“This work has shown us that exposure to these predicted CO2 levels in pregnancy and early life is likely driving changes in lung function when the mice are adults. This therefore could be an opportunity to focus in on this period and help to protect lung development, and therefore improve the health outcomes later in life,” Dr Wyrwoll said.
She said more research in this area was critical to fully understand the potential health impact on our children in the future.

“The lungs are the first organs that we would expect to see affected, and it gives us a clue that other systems in the body might also be affected,” Dr Wyrwoll said.

“We need to do further research into how it affects the respiratory system, as well as how the bones and the kidneys are developing, but also how the brain is working.”

Perth Children’s Hospital Foundation chief executive Carrick Robinson said the Foundation was proud to support the Wal-yan Respiratory Research Centre.

“This is another example to highlight why it is so important to fund respiratory researchers here in WA. The Wal-yan powerhouse partnership is dedicated to funding the very best people – and Associate Professor Larcombe is an exemplary example of that,” Mr Robinson said.

-Ends-

Key Points
- This is was a pilot study assessing health impacts across a lifetime spent in an environment where CO2 levels are higher.
- The research team tracked two groups of mice (one a control) for about 14 weeks, which allowed the baby mice to become young adults.
- The team would like to conduct this study over a longer period, where in addition to looking at the lungs they would also look at other systems such as brain and kidney function.
- This was a collaboration between Telethon Kids Institute and The University of Western Australia and The Australian National University.
- The paper was published in Environmental Health Perspectives today, January 13. It will be available to view this evening via: https://ehp.niehs.nih.gov/ehp7305

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Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Professor Graeme Zosky is Deputy Director of the Menzies Institute for Medical Research and a Professor of Physiology in the Tasmanian School of Medicine, University of Tasmania

This is the first study to show a link between early-life exposure to future levels of atmospheric carbon dioxide and impaired lung growth. The findings of the study imply that the primary effect is on body growth and lung stiffness in females. Early deficits in growth and lung stiffness are strong predictors of future risk for chronic lung disease and we know that these deficits are unlikely to improve later in life. This has implications for lung health in the community as carbon dioxide levels continue to increase in the coming decades. This work adds to the growing body of evidence regarding the effects of carbon emissions on community health and shows that we need to act now to reduce the burden of disease in future generations.

Last updated: 13 Jan 2021 12:38pm
Declared conflicts of interest:
Graeme has published work previously with Alexander Larcombe, Luke Berry and Caitlin Wyrwoll (all authors on the study).
Associate Professor Ben Mullins is from the School of Public Health at Curtin University

This study used an animal (mouse) model to investigate the physiological effects of future atmospheric carbon dioxide levels - likely to occur as soon as 50 years into the future (2070), according to some climate models.

The work investigated mice from gestation through to adulthood – though preliminary, the research demonstrates significant potential consequences for perinatal physiological development and lung function under future climate change scenarios.

Coupled with recent research on the impacts of temperature extremes and in-utero exposure to bushfire smoke, the results are even more concerning and underline the need for further research on health impacts of climate change as well as options for mitigation.

Last updated: 13 Jan 2021 12:33pm
Declared conflicts of interest:
Ben has previously collaborated with the research's lead author, who also holds a fractional appointment at Curtin University.
Professor Ian Rae is an expert on chemicals in the environment at the School of Chemistry at the University of Melbourne. He was also an advisor to the United Nations Environment Programme on chemicals in the environment and isĀ former President of the Royal Australian Chemical Institute

Animal lungs are used to handling carbon dioxide. It is generated deep in the body where nutrient substances are consumed, and it is carried to the lungs by the blood, and expelled when the animal breathes out. For a human, the expelled air has a carbon dioxide concentration about 100 times that of the air that is breathed in.
 
A research group in Western Australia has reported the results of pilot studies with baby female mice who were exposed for several weeks, as they matured, to air containing carbon dioxide concentrations of about 900 ppm - a bit over double the concentration of 'natural' air that we all breathe. Lung damage was observed in these mice, but not in mice that were only exposed as adults, suggesting that development of lung tissue is affected by the increased concentration of carbon dioxide. The researchers were surprised at this, especially because mice live in burrows, where heavy gases like carbon dioxide can collect, so they must often be exposed to high concentrations and it would be expected that their bodies could cope with modest increases in the concentration.
 
Much higher concentrations of carbon dioxide are known to cause serious damage to animals breathing it, but 900 ppm, although high on the 'greenhouse gas' scale, is quite low by the standards of submarines, spacecraft and crowded poorly-ventilated rooms.
 
The authors say that carbon dioxide concentrations of 900 ppm are predicted, by some models, to be reached by 2100, and so there is an urgency about finding out more by extending the pilot study. However, I think the 900 ppm prediction is at the upper end of the range of predictions, so we (and the mice) shouldn't be too worried. The pilot study used very small number of animals and a serious study would need to use more, which may pose a problem for the researchers when they seek ethics permission to proceed on such a non-urgent study.
 
While the biological work was carefully done, there was no statement in the published paper that the carbon dioxide was free of impurities (such as the much more poisonous carbon monoxide). That could be a worry.

Last updated: 13 Jan 2021 11:12am
Declared conflicts of interest:
None declared.

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