Embedded Files
What are the processes governing human exposure?
What are the processes governing human exposure?
The origin of human exposure to MeHg can be broken down to atmospheric exposure and ingestion. Organic mercury in the atmosphere accounts for around 22% the total gaseous mercury, however, from the inhaled MeHg only a small fraction is actually uptaken by the body [4]. In contrast, ingested MeHg is almost entirely absorbed by the body and represents the major exposure route- in contrast, ingested inorganic mercury has a much lower absorption rate.
Box model of MeHg in a rat body: K represents mass transport coefficients and the subscripts represent each compartment: Bl, Br, Cs, Gl, Gt, Ki, Lv and Sk represent blood, brain, carcass, gut tissue, gut lumen, kidney, liver and skin, respectively.
Source: Farris, F. F., Dedrick, R. L., Allen, P. V., & Smith, J. C. (1993). Physiological Model for the Pharmacokinetics of Methyl Mercury in the Growing Rat. Toxicology and Applied Pharmacology, 119(1), 74–90.
Source: Farris, F. F., Dedrick, R. L., Allen, P. V., & Smith, J. C. (1993). Physiological Model for the Pharmacokinetics of Methyl Mercury in the Growing Rat. Toxicology and Applied Pharmacology, 119(1), 74–90.
Once in the body, MeHg bonds to thiol groups in certain proteins (like those having the amino acid cysteine) in the duodenum, entering the circulatory system by combining with hemoglobin and traveling through the body.
Partitioning between the blood, lipids and organs in the body is fairly similar, hence, blood's Hg concentration is a good estimation of mercury accumulated in the body.
MeHg affinity to lipids drives its accumulation in the central nervous system, where it affects enzymes, cell membranes and mitochondrias - giving it its neurotoxin rename.
MeHg is particularly dangerous in pregnant women because after ingested, it easily crosses the placenta and accumulates in the fetuses brain more than in the mother's body, which can lead to malformations and other pregnancy risks.
Page updated
Report abuse