What is selenium?
Selenium is a metal. It's found in natural deposits, usually in materials that also have other elements like sulphide, silver, copper, lead, and nickel. Processed selenium is used to make:
- electronics
- pharmacy products
- glass products
- pesticides
- rubber
- colours (pigments) for plastic, paints, enamel, ink, and rubber
Where is selenium found?
Most rocks and soil contain selenium. It's released into air, water, and soil naturally and when it's manufactured.
Selenium dust can enter the air when:
- coal and petroleum fuels are burned (combustion)
- metal is separated from its natural source using heat (smelting)
- other metals are refined
Selenium also comes from:
- run-off and industrial wastewater from copper and lead refineries
- municipal (city or town) wastewater
- hazardous waste disposal sites
Most people are exposed to low levels of selenium every day through food, water, and air. Food is the highest source of selenium exposure.
How does selenium get into my drinking water?
- There is a very small amount of selenium in water from natural rock weathering and soil erosion.
- Mining operations often contaminate surface and groundwater with selenium.
How does selenium affect my health?
Selenium is a nutrient that people need at low levels. But being exposed to high levels can cause health problems.
Eating food with high levels of selenium (like grains or vegetables grown in soil with high levels of selenium) for a short time can cause nausea, vomiting, and diarrhea.
Being exposed to high levels of selenium for a long time can cause hair loss, brittle nails, and problems with your brain and nerves.
How do I know if there is selenium in my drinking water?
Your water can be tested to see how much selenium is in it. Learn more about
testing your drinking water in Alberta.
The maximum acceptable concentration (MAC) is the highest amount of a metal in drinking water that is safe for a person to drink. If routine testing shows selenium levels over the MAC, your water supplier has to decrease the amount of selenium to a safe level.
If you have a private water source, test your water regularly to make sure it is safe. Make sure to have your water sample tested by an accredited lab.
What is the standard for levels of selenium in drinking water?
According to Health Canada’s
Guidelines for Canadian Drinking Water Quality, the MAC for selenium is 0.05 mg/L (milligrams per litre).
What should I do if there are high levels of selenium in my drinking water?
If you are concerned about unsafe levels of selenium in your drinking water:
- Use water from another safe source to drink, cook, and brush your teeth. Safe water sources include municipal water systems or bottled water. If the selenium level in your well water is higher than 0.05 mg/L, it is still safe to use the water to bathe and wash dishes.
- Talk to a professional water specialist to install a certified water treatment unit to remove selenium.
Any treatment device must be certified to meet these standards:
- NSF/ANSI standard 62 on drinking water distillation systems. Distillation boils water, catches the steam, and condenses it to liquid while leaving the selenium out.
- NSF/ANSI standard 58 on reverse osmosis drinking water systems. Reverse osmosis forces water through a membrane that filters out minerals like selenium.
- NSF/ANSI standard 53 on drinking water treatment units (with specific selenium removal).
After you have installed your system, have your treated water tested for selenium to make sure your system is working properly. Monitor and maintain your water treatment equipment according to the manufacturer’s instructions.
Where can I learn more?
If you have any questions about selenium in drinking water, contact Alberta Health Services
Environmental Public Health.
