1 research outputs found
New Insight into Biomarkers of Human Mercury Exposure Using Naturally Occurring Mercury Stable Isotopes
Human exposure to
methylmercury (MeHg) and elemental mercury vapor
(Hg<sup>0</sup><sub>(g)</sub>) are often estimated using total Hg
concentrations in hair and urine, respectively. We investigated whether
Hg stable isotopes could be used to better distinguish between exposure
to Hg<sup>0</sup><sub>(g)</sub> versus MeHg. We found that hair from
North American dental professionals was characterized by high positive
Δ<sup>199</sup>Hg values (mean = 1.86‰, 1 SD = 0.12‰, <i>n</i> = 11). This confirms that among people who regularly consume
fish, total Hg concentrations in hair reflect exposure to MeHg. In
contrast, we found that urine from the same individuals was characterized
by a range of Δ<sup>199</sup>Hg values (0.29 to 1.77‰,
2 SD = 0.06‰, <i>n</i> = 12) that were significantly
correlated to the number of dental amalgams in each individual’s
mouth. We hypothesize that fish-derived MeHg is demethylated within
the body, causing mass-dependent fractionation and the excretion of
inorganic Hg in urine. Mercury in urine therefore represents a mixture
of demethylated fish-derived MeHg and amalgam-derived inorganic Hg.
We estimate that the majority (>70%) of Hg in urine from individuals
with <10 dental amalgams is derived from ingestion of MeHg in fish.
These data suggest that within populations that consume fish, urine
total Hg concentrations may overestimate Hg exposure from personal
dental amalgams