First measurements of the methane concentration and its carbon stable isotope composition in the breath of Costa Ricans
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Germain Esquivel-Hernández
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Mario Villalobos-Forbes
Abstract
Breath research has demonstrated that mammals, including humans, produce methane (CH4) due to microbial activity in the gastrointestinal tract under anoxic conditions. Overall, humans are classified as methane producers if they exhale methane concentrations at least 1 ppmv higher than the environmental level. Here, we present the first measurements of CH4 concentration and its carbon stable isotope composition (δ13C-CH4) in the breath of Costa Rican individuals. Samples were collected from a total of 51 volunteers aged between 5 and 72 years, using Tedlar bags, and analyzed using laser spectroscopy. We found that 56 % and 62 % of female (N = 14) and male (N = 16) individuals, respectively, can be considered as methane producers and emitted CH4 concentrations up to 37.9 ppmv with δ13C-CH4 values up to −75.0 ‰. The δ13C-CH4 values also confirmed that the exhaled methane was produced by all the individuals evaluated. Despite our data being preliminary, our work can be useful for future breath studies in Latin American populations that incorporate isotopic techniques (e.g., laser spectroscopy and isotope ratio mass spectrometry) and consider how dietary factors or intestinal microbiota may influence levels of methane emission among different age groups.
Funding source: Universidad Nacional Costa Rica and World Bank Group
Award Identifier / Grant number: Grant 8194-CR-UNA
Acknowledgments
We kindly thank all participants who provided breath samples for our study. The authors thank Dr. Maarten De Moor, OVSICORI-UNA, for the access to the calibration standards.
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Research ethics: This study was conducted in accordance with the Declaration of Helsinki. Ethics approval was also obtained from the Scientific Ethics Committee of Universidad Nacional Costa Rica (UNA-CECUNA-ACUE-030-2020).
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Informed consent: All participants were informed about the purpose and nature of the study and gave their consent to participate in the study.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: The authors state no conflicts of interest.
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Research funding: The authors acknowledge the funding provided by Universidad Nacional Costa Rica and the World Bank which was essential to acquire the laser carbon isotope analyzer used in this study (Grant 8194-CR-UNA).
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Data availability: The data that support the findings of this study are available from the corresponding author, [GEH], upon reasonable request.
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