Long-term and season-specific changes in the concentrations of trace elements and sulfur in a human body over twelve years by means of quantitative analyses of beard samples collected every day — A case study

In this paper, we measured more than 4200 beard samples collected from a single person every day over a 12-year period and analyzed them based on a standard-free method. It was found that the sulfur concentration remained almost constant from a long-term perspective but showed small periodic elevations. Silicone, phosphorus and rubidium showed significant periodic changes with a cycle of several years. While manganese, strontium and molybdenum seemed to show long-term changes, there were no significant differences due to their large standard deviations. Concerning seasonal changes, silicone and phosphorus showed decreasing trends in summer, albeit without significant differences. The bromine concentration showed clear seasonal variations, rising in winter and falling in summer, suggesting the possible influence of seasonal changes in the elemental components in the airborne particles that pass over to Japan from the Asian Continent. These findings confirmed that beard analyses are useful not only for evaluating changes in trace element concentrations in the human body but also for clarifying the main pathways of the intake of these elements.