In episode #11 (season 2) of CSI: Crime Scene Investigation, a woman poisons her husband with the chemical sodium selenite. Strange as it may sound, this exotic murder weapon, and it's close cousin, sodium selenate, are listed as "nutrients" on the labels of most mass-marketed vitamins. Even though both sodium selenite and selenate are classified as dangerous and toxic to the environment by regulatory bodies such as the Environmental Protection Agency (EPA) and the European Union, they are the primary forms of this mineral - selenium - sold on the mass market today.
In fact, most mass-market vitamins contain chemicals that the EPA does not allow in our public drinking water at levels above 50 parts per billion per liter. According to the EPA's Maximum Contaminant Level (MCL) standards, the highest allowable level of selenium in public drinking water is 50 parts per billion (equivalent to 50 micrograms per liter). To get a sense of how small an allowable limit this is, 50 parts per billion is equivalent to a tablespoon of water in an Olympic-size swimming pool.
How can vitamin manufacturers advertise something as being a "nutrient" when the EPA—out of concern for our health—has barred it from our drinking water at all but exceedingly minute levels? Have sodium selenite/selenate really been shown to be toxic? A brief perusal of toxicology reports from the Hazardous Substances Databank (toxnet.nlm.nih.gov) and PUBMED (pubmed.gov) shows that both forms can be carcinogenic and genotoxic and may contribute to reproductive and developmental problems in animals and humans. The question is not whether these minerals have toxicity, but rather at what level they overwhelm our capacity for their detoxification and/or biotransformation into non-toxic metabolites?
A word should be said here about the differences that exist between inorganic minerals and biologically active ones:
The selenium that is found in foods like brazil nuts, mustard seeds, and fresh produce grown in selenium-rich soil, is infinitely different from unbound forms being put into some multivitamins. In fact, sodium selenite/selenate can cause DNA damage associated with cancer and birth defects, whereas the selenium found within food, or laboratory chelated forms like selenomethionine, has chemopreventive properties.
The basic principle that explains this difference is that when you isolate a nutrient or vitamin out of the food complex within which it is naturally found, and where it is inseparably bound to thousands of known and unknown food factors (e.g., enzymes, lipids, protein chaperones, glyconutrients, etc.) it is no longer as beneficial to life and in some cases harmful to it. This is especially true in the case of vertebrate mammals who are equipped to get their minerals from the plants they ingest or through the biotransformation of inorganic minerals to organic ones by microflora in their gastrointestinal tracts.
The primary reason that sodium selenite/selenate are preferred by some vitamin manufacturers over safer, more beneficial forms like chelated or yeast-grown selenium is because it is more profitable to use raw materials of lower quality.
"You get what you pay for" is a saying that almost always rings true for dietary supplements. Buying industrial waste products, or chemicals that are considered hazardous waste, and repackaging them as "dietary supplements" can be extremely profitable.
Indeed, this is not the first time in American history that such a hoax has been perpetrated on the public. The FDA-approved use of fluoride in our drinking water and the use of radioactive cobalt-60 culled from nuclear reactors for the irradiation of conventional food illustrates how industrial waste products with known toxicity are eventually converted into commodities or technologies "beneficial to health."
Whereas initially these substances have very high disposal costs for the industries that excrete them into our environment, the liability is converted — through the right combination of lobbying, miseducation and "checkbook science" –- back into a commodity, with the environment and consumer suffering health and financial losses as a result.