1. Stability of Human Methanogenic Flora Over 35 Years and a Review of Insights Obtained From Breath Methane Measurements 
Michael D. Levitt, Julie K. Furne, Michael Kuskowski, John Ruddy 
Clinical Gastroenterology and Hepatology 
Volume 4, Issue 2, Pages (February 2006)
DOI: /j.cgh
Copyright © 2006 American Gastroenterological Association Terms and Conditions

2. Figure 1
A comparison of the breath methane concentration of 280 healthy adults obtained in 1970 vs 212 healthy adults studied in Each point represents the breath methane concentration of an individual minus the atmospheric methane concentration. Individuals with values greater than 1 ppm above atmospheric were considered to be methane producers.
Clinical Gastroenterology and Hepatology 2006 4, DOI: ( /j.cgh )
Copyright © 2006 American Gastroenterological Association Terms and Conditions