Selenium health hazards

The selenium concentration in most natural waters is very low, often less than 1 ag and frequently just a few ng Hence, selenium from drinking water only constitutes a health hazard in exceptional circumstances (Fordyce et al., 2000a Vinceti et al., 2000). However, occasionally much greater concentrations are found. Groundwaters containing up to 275 JLg have been reported from aquifers in China and 1,000 xg selenium from selenifer-ous aquifers in Montana, USA (Table 9). Selenium concentrations of up to 2,000 p,gL or more have also been reported in lakes from... 

Selenium is both a toxic and an essential element. The toxicity depends greatly on the species. Selenium is a cumulative toxic substance and can be a serious health hazard when present in high concentrations in food and water. However, at very low levels, pg/kg it is recognized as an essential trace element in animal nutrition. 

Eisler, R. 2000. Selenium. Pages 1649-1705 in Handbook of Chemical Risk Assessment Health Hazards to Humans, Plants, and Animals. Volume 3, Metalloids, Radiation, Cumulative Index to Chemicals and Species. Lewis Pubhshers, Boca Raton, Florida. 

Control of metalloid content in natural objects, foodstuff and pharmaceuticals is an important task for modern analytical chemistry. Determination of elements such as Arsenic is necessary for evaluation of object toxicity, since their content in environment may exceed MCL (maximum contaminant level), posing hazard to human health. Elements such as Selenium in definite doses are healthy, but in greater quantities they produce toxic effect. 

A number of metals and their compounds have been found to pose health risks to humans, other animals, and plants. When they occur in air, these metals are sometimes regarded as pollutants. Title III of the 1990 Amendments to the Clean Air Act, for example, lists the following elements and their compounds as "hazardous air pollutants antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, and selenium. 

Some epidemiological studies report data from populations exposed to selenium in the food chain in areas with high selenium levels in soil. It is likely that selenite, selenate, and the selenium found in food and in dietary supplements comprise the majority of selenium compounds to which oral, off-site selenium exposures will occur at or near hazardous waste sites. Aside from the variation in effective dose, the health effects from exposure to selenate, selenite, and dietary selenium are not expected to differ greatly. However, oral exposures to many other compounds of selenium could occur (primarily through soil or edible plant ingestion) if those compounds were deposited at the site, or if local environmental conditions greatly favor transformation to those forms. Heavy metal selenides, aluminum selenide, tungsten diselenides, and cadmium selenide are used in industry and may end up in waste sites. 

The National Occupation Hazard Survey (NOHS), conducted by the National Institute for Occupational Safety and Health (NIOSH), estimated that 108,682 workers in 15,127 plants were potentially exposed to selenium in the workplace in 1970 (NOHS 1976). These estimates were derived from observations of the actual use of selenium (1% of total estimate), the use of trade name products known to contain selenium... 

The industrial hazards of Se were recognized in 1945 [41], Since then many cases of acute and chronic selenosis in humans via consumption of selenium compounds or by inhalation have been recorded [7,42], It is, however, interesting to note that in areas of the United States where chronic selenosis has occurred among livestock there have been no clear-cut cause-effect relationships in terms of toxicity for human health [43]. 

Yuan, X., Tang, C., 2001. TTie accumulation effect of lead on DNA damage in mice blood cells of three generations and the protection of selenium. J. Environ. Sci. Health A. Tox. Hazard Subst. Environ. Eng. 36, 501—508. 

SPECIALTY FOODS AND HIGHLY POTENT NUTRITIONAL SUPPLEMENTS. It is fortunate that most consumers are not able to purchase pure mineral salts and to mix them into their foods, because without special measuring equipment and experience in preparing such mixtures, it is very easy to add toxic excesses of trace elements like iodine and selenium to foods. However, even some of the products that are sold by health food stores may have undesirable, or even toxic effects, because they are very rich in certain minerals. The potentially hazardous products may be considered as highly potent nutritionai suppiements, in order to distinguish them from the less potent specialty foods, which are usually safe in the amounts consumed. Table M-27 shows the approximate amounts of these minerals that are provided by various specialty foods and nutritional supplements. 

Toxicology Inh. may cause nose or throat irritation, dizziness, drowsiness may cause skin irritation ing. may cause Gl discomfort, loss of coordination, dizziness, fatigue excessive vapors may irritate eyes Heavy metal content (ppm) antimony < 0.3, arsenic < 0.3, cadmium < 0.7, chromium < 2.5, copper < 2.5, lead < 0.3, mercury < 0.03, selenium < 0.7, zinc <0.1, nickel < 1.5 TSCA listed Precaution Use safety glasses, impervious gloves Hazardous Decomp. Prods. CO, COj HMIS Health 1, Flammability 1, ReadivityO Storage Keep away from excessive heat or open flame Dapro DF 1492 [Elementis Spec.]... 

---