1 : 1
m
o l a r
r a t i o
Potential Se deficiency
Hypothetical potential Se toxicity
(Hg deficiency)
Hypothetical potential Hg toxicity
(Se deficiency)
Molar concentration of mercury
Molar concentration of selenium
Hypothetical
optimal range
Figure 14.3 Mercury and selenium display a multi-faceted antagonistic relationship in marine
mammals, including the formation of an insoluble mineral (HgSe, tiemmanite) occasionally resulting in a near 1:1 molar correlation (i.e., Koeman et al. 1973; Koeman et al. 1975; Brookens et al. 2007).
As noted by Khan and Wang (2009) the 1:1 molar ratio can potentially be viewed as Se deficient if
Hg–Se is not bioavailable, wherein selenium is unable to participate in Se-dependent detoxification
processes (i.e., glutathione peroxidase, selenoproteins). We emphasize that, somewhat counterintuitively, with high concentrations of Se seen in marine mammals (see Figure 14.2) that potential
selenosis could occur in marine mammals as a result of Hg deficiency. (Adapted from Khan, M. and
Wang, F., Environ. Toxicol. Chem., 28, 1567, 2009.)