Abstract
Venous blood is a preferred matrix for the determination of total mercury (Hg) in human biomonitoring but has some drawbacks such as the requirement for an uninterrupted cold chain for transport and storage and the need of medical personnel for sample collection. Therefore, we tested and implemented a simpler and less expensive method for measuring Hg in human blood using dried blood spots (DBS). For method development, we investigated the influence of different storage conditions (temperature, storage vessel, time) on DBS samples. For method validation, we compared DBS and venous blood and investigated whether DBS sampling is suitable for measuring Hg in the general population in countries with low Hg exposure such as Germany. Based on our results, we found that pre-cleaned glass tubes were most suitable for storage of DBS samples, as this allowed the samples to remain stable for at least 4 weeks even at high temperatures (40 °C). When comparing venous blood and DBS, a very good correlation (r = 0.95, p < 0.01, Spearman-Rho) and high precision of DBS (mean relative standard deviation 8.2% vs. 7.2% in venous blood samples) were observed. Comparing the recoveries of both matrices in different concentration ranges, the variation of the recoveries decreases with increasing Hg concentration. The mean recoveries also decreased with increasing Hg concentration. Overall, we found comparable results for DBS and venous blood using direct Hg analysis. Furthermore, we demonstrated that DBS are suitable for Hg biomonitoring in the general population in Germany and improved the storage conditions for the DBS.
Highlights
Mercury (Hg) is a toxic metal and a hazard for humans and the environment (UNEP, 2013)
Since dried blood spots (DBS) samples in studies and human biomonitoring, especially in areas with poor infrastructure, usually cannot be measured immediately after sample collection, the stability of Hg is an important prerequisite for its applicability
We demonstrated that it is advisable to use human blood for method development instead of certified reference materials to study the stability of Hg in DBS samples during storage
Summary
Mercury (Hg) is a toxic metal and a hazard for humans and the environment (UNEP, 2013). Hg can occur in the elemental, inorganic (e.g., HgCl2), or organic form (e.g., methylmercury), with each species having different toxicodynamic properties (Bernhoft, 2012; Bose-O’Reilly et al, 2010). The major anthropogenic sources of Hg emissions are the burning of fossil fuels and artisanal and smallscale gold mining (ASGM) activities (UNEP, 2019). In ASGM areas, the use of elemental Hg is a major source of Hg exposure (Bose-O’Reilly et al, 2017; Nyanza et al, 2019; Sundseth et al, 2017). The main source of Hg exposure is the consumption of fish, e.g., tuna, which may contain a high amount of organic Hg due to the accumulation in the food chain (Bose-O’Reilly et al, 2010; Sundseth et al, 2017)
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