An article by Stefan Rakete et al at the Institute and Clinic for Occupational, Social and Environmental Medicine, University Hospital in Munich, Germany and three related institutions was published in the March 2022 issue of the Journal of Environmental Monitoring and Assessment.
It reported on the development of a direct atomic absorption assay to measure mercury levels from dried blood samples collected on Mitra® devices with VAMS® technology. The paper is entitled “Mercury biomonitoring in German adults using volumetric absorptive microsampling.” It describes the development and validation of an assay comparing mercury (Hg) levels in dried VAMS blood samples and paired with venous blood.
The co-authors saw a strong correlation between both sample types and reported that VAMS sampling used in combination with direct mercury analysis was an accurate and viable alternative for human biomonitoring of Hg.
A critical part of the study was to measure sample stability and they found that the choice of storage medium was key to keeping the samples stable.
Exposure to mercury can occur a number of ways, including through ingestion of seafood containing methylmercury and through mining (especially mining mercury). Exposure to the element may also occur through certain dental amalgams, some skin whitening creams, or as a result of burning of fossil fuels.
Exposure to Hg can cause many physiological effects, leading to disorders in the cardiovascular and nervous systems. Indeed, prenatal exposure to Hg is of great concern as it may negatively impact healthy brain development in fetuses.
Moreover, Hg exposure can cause negative effects in the kidneys and reproductive systems.
A recent paper published in Nature Communications estimated that the global human health cost of exposure to methylmercury alone was $117 billion and accounted for 29,000 deaths.
Methylmercury is an organometallic form of mercury, formed by specific microorganisms. Once synthesized, the methylmercury enters and accumulates in the food chain.
Two other forms of mercury are elemental Hg, and inorganic mercury compounds. Elemental Hg is found in several sources, such as in fluorescent light bulbs and emissions from burning fossil fuels. Inorganic mercury compounds or salts can occur naturally or for use in industry, as well as in some skin whitening creams.
Although mercury can be detected and analyzed in urine and hair, the gold standard for monitoring mercury is venous blood.
However, Stefan Rakete et al highlighted in their published paper that venous blood sampling has been associated with relatively high logistical costs for human biomonitoring, especially in remote African, Asian, and Latin American countries.
The study authors underlined the fact that access to a trained phlebotomist for venous blood draws in remote areas and logistics for cold chain shipping of samples were the main challenges for biomonitoring.
Due to these challenges, Rakete et al proposed that microsampling might be of great interest as dried microsamples can often be collected remotely, finger-stick blood collection is minimally invasive, and dried samples do not often require cold-chain shipping.
Although dried blood spot (DBS) with filter cards has been the most popular microsampling method to date and has shown some success in Hg analysis, the authors also noted that there have been reports of background contamination and hematocrit dependency.
They stated that volumetric blood collection with VAMS has a number of benefits over DBS, including the fact that “VAMS enables relatively easy and ergonomic blood collection.”
Because Mitra devices with VAMS had not been previously used for Hg monitoring under field conditions, the research group embarked on comparing paired venous and capillary blood from non-occupationally exposed adults using a direct mercury analysis technique.
Measurement of environmental contaminants for public health and epidemiological studies are key to helping to improve the health of millions globally. An efficient way to collect samples from ‘hard to reach’ regions and from vulnerable populations (such as children) is critical to the success of future studies.
The study conducted by S. Rakete et al demonstrated that such an approach using VAMS offers efficiency and has real merit. However, it is important to minimize unwanted environment sample contamination prior to and during studies. For example, it was observed in this study that using a zip-lock bag, compared to an acid-washed vial, introduced unwanted contamination during a stability study. Use of gas impermeable bags (including desiccant), as supplied in Mitra Collection Kits, may help to mitigate this issue. Furthermore, use of desiccant is crucial especially in highly humid environments to prevent microbial damage of the sample.
This study paper was summarized for our readers by James Rudge, PhD, Neoteryx Technical Director. This is curated content. To learn more about the important research outlined in this review, visit the original article published in the Journal of Environmental Monitoring and Assessment.
Image Credits: mercury level testing-iStock, Neoteryx
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