Found in health stores as a supplement, selenium has been found to be required for the proper function of the human body – in tiny amounts.(1) While small concentrations are found naturally in foods, which are normally enough to sustain us, a number of controversial claims have been made that link elevated levels of selenium to health benefits for humans that range from cancer prevention to HIV/AIDS resistance. Overall, however, the recommended daily limit for adults is 55 micrograms per day, with an upper limit at 400 micrograms per day. Exceeding this amount may put a person at risk of selenosis: symptoms can include a garlic odor on the breath, gastrointestinal disorders, hair loss, sloughing of nails, fatigue, irritability, and neurological damage. Extreme cases of selenosis can result in cirrhosis of the liver, pulmonary edema, and death. (2)
On the other side of the healthy/hazardous equation, however, is the effect of selenium on aquatic life. According to the EPA in the United States (3), selenium concentrations in drinking water must be below 50 parts per billion (50 micrograms per litre), and levels of selenium in saltwater above 127 micrograms per litre can lead to skeletal deformities in fish. (4)
Consumers have to be careful, however, as supplements often come in comparatively large-dose tablets, such as the 200 microgram tablets from Nature’s Way (5). This would mean that having more than a single tablet could push a person over their daily intake limit – and that each discarded tablet could render 1.5 litres of ocean water hazardousto aquatic life, or 4 litres of freshwater contaminated beyond levels recommended for human consumption.
Commercially, selenium is most often found as a by-product of such activities as refining copper and the creation of sulfuric acid. Uses for selenium range from tinting glass to creating electrical (DC) power surge protectors and solar cells. Environmental bodies do their best to keep a close eye on industrial producers, and regulations cover the maximum concentrations that companies are allowed to discharge into lakes, rivers and other water bodies. As always, however, a lower concentration does not always mean that the company is discharging any less of a pollutant – it simply means that the same amount of pollutant has been diluted into a bigger tank of water before being released.
The bottom line? Selenium can be healthy for humans in small doses – but concentrations can quickly add up, and improper disposal can endanger ourselves as well as the fish we eat.
(1) National Institute of Health http://ods.od.nih.gov/factsheets/selenium
(2) Agency for Toxic Substances and Disease Registryhttp://www.atsdr.cdc.gov/toxprofiles/tp92-c3.pdf
(3) Environmental Protection Agencyhttp://water.epa.gov/drink/contaminants/basicinformation/selenium.cfm
(4) Environmental Protection Agencyhttp://water.epa.gov/scitech/swguidance/standards/criteria/aqlife/pollutants/selenium/questions.cfm
(5) Nature’s Way http://www.naturesway.com/Products/Minerals/41081-Selenium-200-mcg.aspx
