Long-term monitoring of mercury in young German adults: Time trend analyses from the German Environmental Specimen Bank, 1995-2018

As highlighted in the Minamata Convention, Mercury (Hg) in its various forms poses a substantial risk to human health and the environment. The health relevance of Hg is also recognized by the European Human Biomonitoring Initiative (HBM4EU), which classifies Hg as a priority substance, since considerable knowledge and data gaps on Hg exposure levels and their changes over time still exist in Europe. The German Environmental Specimen Bank (German ESB) provides valuable policy relevant data and long-term trends of substance exposure on a national level for international comparison and evaluation. In this study we analysed data of the German ESB on Hg exposure of young adults aged 20 to 29 including data on urinary Hg levels from 1995 to 2018 and whole blood Hg levels from 2001 to 2010. Results show a clear decrease in both, about 86% in urine total daily Hg excretion from 1995 (0.76 μg/L) to 2018 (0.11 μg/L) (n = 10,069) and about 57% in blood concentrations of Hg from 2001 (1.76 μg/L) to 2010 (0.77 μg/L) (n = 4085). Over the investigated timeframe only a few values exceeded the toxicologically derived health based guidance value HBM I for blood and urine, with these exceedances decreasing over time in line with the general trend. The factors mostly influencing Hg excretion identified in this study are dental amalgam as well as fish and seafood consumption. Besides other factors (e.g. age and sex), also airborne Hg exposure appears to be a low but evident influencing factor in Germany. Although a considerable decrease in internal Hg exposure is recognized in the last decades, the current low-level exposure may cause adverse health effects especially to vulnerable groups such as pregnant women and children. To further elucidate and evaluate current exposure sources and to reduce human exposure to Hg, continuous environmental and human biomonitoring is needed.