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Estimation of global recoverable human and animal faecal biomass

Abstract

Human and animal faeces present persistent threats to global public health and also opportunities for recovery of resources. We present the first global-scale accounting of recoverable faeces (livestock animal and human) from 2003 to 2030 using country-specific human and animal population estimates and estimated species-specific faeces production by human or animal body mass. We also examine global coverage of domestic livestock animals and sanitation facilities to describe the distribution of onsite versus offsite hazards from animal and human faeces. In 2014, the total mass of faeces was 3.9 × 1012 kg per year, increasing by >52 × 109 kg per year since 2003 and anticipated to reach at least 4.6 × 1012 kg in 2030. Annual global production of faeces from animals (primarily cattle, chickens and sheep) was about four times that from humans. Ratios of animal faeces to human faeces continue to increase (geometric mean of 4.2:1 for 2003 versus 5.0:1 for 2014 versus a projected 6.0:1 for 2030). Low-income populations bear the greatest burden of onsite faeces, mostly from animals in or near the domestic environment. This analysis highlights the challenges of resource recovery from concentrated and dispersed sources of faeces, and the global public health policy needed for safe management of animal faeces.

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Fig. 1: Country-level estimates for percentage of the world’s faeces production in 2014.
Fig. 2: Country-level animal faeces to human faeces ratios.
Fig. 3: Country-level animal faeces to human faeces ratios, 2003–2014.

Data availability

All data on animal sizes and population estimates were obtained from tables or figures in manuscripts listed and publicly available datasets (DHS data available from the DHS programme: https://dhsprogram.com/data/; MICS data available from UNICEF: http://mics.unicef.org/). A final dataset of the faeces estimates supporting this manuscript is available from the corresponding author upon request.

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Acknowledgements

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

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D.B. and J.B. conceived of the analysis. D.B., P.Y., D.H. and J.B. planned the analysis. D.B. and P.Y. obtained data and conducted the analysis. D.B. wrote the initial manuscript and created all figures and tables. D.B., P.Y., A.L., D.H. and J.B. contributed edits and sections to the manuscript.

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Correspondence to Joe Brown.

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Supplementary Figures 1–3, Supplementary Methods, Supplementary Discussion, Supplementary Tables 1–3, Supplementary References 1–2

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Berendes, D.M., Yang, P.J., Lai, A. et al. Estimation of global recoverable human and animal faecal biomass. Nat Sustain 1, 679–685 (2018). https://doi.org/10.1038/s41893-018-0167-0

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