By: Leah Stokes & Noelle Selin
Mercury is a toxin that harms human health. People become exposed to mercury primarily by eating fish. In some communities, where artisanal and small-scale gold mining (ASGM) occurs, exposure can be quite high. This is because people may breathe in mercury fumes from the process.
It is possible to tell how much mercury a person has been exposed to by testing their hair, blood and urine. Estimating mercury exposure through hair samples is primarily a measure of methylmercury — the most toxic form of mercury. But, it may also be influenced by the hair surface’s exposure to emissions. For example, if a person using mercury to capture gold stands over the amalgam (the mixture of mercury and gold) while they are burning off the mercury, it is likely that some of this mercury could end up on their hair.
At INC2, the second round of the mercury treaty negotiations in Chiba, Japan in early 2011, delegates and observers were able to measure the mercury concentration in their hair. We both sent in samples, and found out that Noelle had a concentration of 1.39 ppm while Leah had a concentration of 0.75 ppm. These values are close to, or below the WHO and the US EPA guidance values for mercury in hair: 1.8 ppm and 1.2 ppm respectively.* Many other delegates at the negotiations had mercury concentrations around 4.00 ppm, which is above these guidance values. For most people, mercury concentrations in hair reflect fish consumption, and Leah is mostly a vegetarian, while Noelle is from New England and loves fish.
Arnika, a Czech non-governmental organization (NGO), and a member of both International POPs Elimination Network (IPEN) and Zero Mercury Working Group (ZMWG), has posted a website where people around the world are reporting the mercury concentrations in their hair. These individuals then reflect on this information in light of the current negotiations, sending a message to delegates.
Amanda Giang and Julie van der Hoop compiled the self-reported data from Arnika’s website, to give you a sense of how mercury concentrations in hair can vary across countries.
* Note: The WHO and EPA actually give their recommendations in terms of daily oral intake of methylmercury. Amanda Giang converted these values to hair mercury concentrations using conversion factors developed by Rice et al. (2010), Stern (2005), and Allen et al. (2007).
Thanks so much for covering the happenings at INC5,. It’s so great to see others interested in this topic and I appreciate you giving a day by day reporting on INC5.
After reading your blog entry, there are few statements I would like to provide additional information for your consideration for future articles, that could clear up some long held misconceptions.
“People become exposed to mercury primarily by eating fish”.
According to The World Health Organization, Dental amalgam has been identified as the largest single source of continuous Hg exposure for members of the general population who possess amalgam fillings (WHO, 1991; Heath Canada, 1996). In the USA that represents roughly 122 million Americans. A significant portion of the population. Additionally, WHO (1991) estimated 1 – 3 micrograms per day of mercury exposure from fish (if one ate fish everyday), where as dental amalgam was 3 – 17 ug/day (WHO 1991) or 1 – 27 ug/day (WHO 2003).
so perhaps that statement should read, “People become exposed to methylmercury primarily by eating fish”.
the article goes on to state: “It is possible to tell how much mercury a person has been exposed to by testing their hair, blood and urine. Estimating mercury exposure through hair samples is primarily a measure of methylmercury — the most toxic form of mercury.”
If one were to compare the EPA’s Reference Concentration Dose (RfD) for methylmercury ( 0.1 μg Hg/kg-day) VS that of mercury vapor (from element mercury) (0.048 Hg/kg-day) one would find that according to our regulatory agencies, mercury vapor would be considered more toxic. Unfortunately, while most people might test, hair, blood or urine for exposure to mercury vapor (which primarily ends up as inorganic mercury), those pathways are all minor excretory pathways. According to a large body of scientific literature 70% – 90% of inorganic mercury leaves in the feces.
this study, from found: The relationship between urinary mercury and airborne concentrations of elemental mercury is only reliable down to concentrations of about 10 µg/m3 and therefore not an accurate measure for understanding exposure of persons due to most environmental air concentrations, which are well below 10 µg/m3.
I really appreciate your continued coverage of INC5 and I look forward to reading more of your blog posts.
<a href="http://www.mercuryexposure.info" title="Mercury Exposure – a guide to dental amalgam"
<a href="http://www.youputwhatinmymouth.com" title="You Put What In My Mouth ?"