Selenium lethal

Early JL, Schnell RC. 1982. Effect of glutathione depletion on selenium lethality and hepatic drug metabolism in male rats. Toxicol Lett 11 253-257. 

The bad guys, shown in pink in Figure 2.8, are toxic, often lethal, even in relatively small quantities. Several of the essential trace elements become toxic if their concentrations in the body increase. Selenium is a case in point. You need about 0.00005 g/day to maintain good health, but 0.001 g/day can be deadly. That s a good thing to keep in mind if you re taking selenium supplements. 

Waddell, B. and T. May. 1995. Selenium concentrations in the razorback sucker (Xyrauchen texanus) substitution of non-lethal muscle plugs for muscle tissue in contaminant assessment. Arch. Environ. Contamin. Toxicol. 28 321-326. 

What do the ions of the following elements have in common calcium, Ca chlorine. Cl chromium, Cr cobalt, Co copper, Cu fluorine, F iodine, I iron, Fe magnesium. Mg manganese, Mn molybdenum, Mo nickel, Ni phosphorus, P potassium. K selenium, Se sodium, Na sulfur, S zinc, Zn They are all dietary minerals essential for good health, but can be harmful, even lethal, when consumed in excessive amounts. 

LD50 and LD75, concentrations at which the dose of selenium is lethal in 50% and 75% of animals, respectively. 

It is widely recognized that dietary selenium (Se) exhibits a protective effect against Hg toxicity (Sumino et al. 1977). Reduction of the lethal and neurotoxic effects of methylmercury compounds has been noted. The reason... 

Elemental selenium (selenium[0]) is rarely found naturally, but it is stable in soils. Selenates (selenium[+6]) and selenites (selenium[+4]) are water soluble and can be found in water. Sodium selenate is among the most mobile forms of selenium because of its high solubility and inability to adsorb to soil particles. More insoluble forms, such as elemental selenium, are less mobile therefore, there is less risk for exposure. Because of greater bioavailability, water-soluble selenium compounds are probably more lethal than elemental selenium by any route. Selenium is found in nature complexed with multiple compounds, and although various forms are discussed in the profile, many others exist. Plants can contain organic selenium in the form of the amino acids selenomethionine and selenocysteine, along with the dimethyl selenides. Elemental selenium can be oxidized to form selenium dioxide. While the products of oxidation might be expected at the soil surface, elemental selenium would be the expected predominant form in deep soils where anaerobic conditions exist. Selenium sulfides, used in some antidandruff shampoos, are not very water soluble and, therefore, like elemental selenium are relatively immobile in the environment. 

In animals, the acute lethality of hydrogen selenide and elemental selenium dust when inhaled has been investigated. In guinea pigs exposed to hydrogen selenide for 2,4, or 8 hours, 5/16 died within 10 days of exposure at 12 mg selenium/m3, 3/16 died at 6 mg selenium/m3, and 8/16 died at 6 mg selenium/m3, respectively (Dudley and Miller 1941). 

The LD50 and lethal LOAEL values from each reliable study following oral exposure to elemental selenium dust, selenium dioxide dissolved in water (selenious acid), sodium selenate, sodium selenite, potassium selenate, and dietary selenium for each species and exposure duration are recorded in Table 3-2 and plotted in Figure 3-2. The LOAEL values for death in rats and mice following acute and intermediate oral exposures to selenium sulfide or selenium disulfide are recorded in Table 3-3 and plotted in Figure 3-3. 

Administration of lethal doses of selenium sulfide particles in carboxymethylcellulose by gavage has been reported to cause irregular breathing in mice (Henschler and Kerschner 1969), but not in rats (Cummins and Kimura 1971). No respiratory effects were seen in mice administered 464 mg selenium sulfides/kg/day or in rats administered 31.6 mg selenium sulfides/kg/day by gavage once daily for 13 weeks (NTP 1980c). 

Cheng W-H, Ho Y-S, Valentine BA, et al. 1998. Cellular glutathione peroxidase is the mediator of body selenium to protect against paraquat lethality in transgenic mice. J Nutr 128 1070-1076. 

Miller WT, Williams KT. 1940. Minimum lethal dose of selenium as sodium selenite for horses, mules, cattle and swine. Journal of Agricultural Research 60 163-173. 

Sodium selenite (selenium trioxide) CASRN 10102-18-8 White powder Mean lethal dose of selenite salts In dogs 4 mg/kg. Human ingestion of 1-5 mg/kg sodium selenite caused moderate toxicity. 

The lethal effects of methylmercury in various species of mammals are influenced by ambient temperature, dietary selenium, ethanol, and especially hypertension. Tests with a genetic strain of rat with high blood pressure showed that this strain was more sensitive to methylmercury than were control strains they died earlier and with higher tissue mercury burdens. Because hypertension and borderline hypertension is common among human inhabitants of mercury-polluted areas, with estimates as high as 56% among individuals 40 years old and older, more research seems warranted on the role of hypertension as a significant... 

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