What is selenium?
Selenium is a metal. It's found in natural deposits as ores containing other elements (sulphide, silver, copper, lead, and nickel). Processed selenium is used to make:
- electronics
- pharmacy products
- glass products
- pesticides
- rubber
- pigments for plastic, paints, enamel, ink, and rubber
Where is selenium found?
Most rocks and soil contain selenium. It's released in to 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 smelted
- other metals are refined
Selenium also comes from:
- run-off and industrial wastewater from copper and lead refineries
- municipal 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 that they are exposed to.
How does selenium get into my water?
- There is selenium in water (in very small amounts) from natural rock weathering and soil erosion.
- Mining operations often contaminate surface and groundwater with selenium.
Does selenium affect my health?
Selenium is a nutrient people need at low levels. Being exposed to high levels can cause health problems. Eating food with high levels of selenium (e.g., 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 (in drinking water) can cause hair loss, brittle nails, and neurological problems.
How do I know if there is selenium in my drinking water?
If routine monitoring shows selenium levels over the maximum acceptable concentration (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 selenium in drinking water?
According to Health Canada, the Canadian drinking water guideline for selenium is 0.05 milligrams per litre (mg/L).
What if there's a high level of selenium in drinking water?
If there is a problem with selenium in any public water supply, customers must be told right away. Another water source must also be supplied to prevent health risks.
If a consumer/well owner is concerned about unsafe levels of selenium in drinking water:
- use water from another safe source (e.g., municipal system, bottled water) to drink, cook, and brush teeth. If your well water selenium level is higher than 0.05 mg/L, it is 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
- NSF/ANSI standard 58 on reverse osmosis drinking water systems
- NSF/ANSI standard 53 on drinking water treatment units (with specific selenium removal)
After you have installed your system, have the treated water tested for selenium to make sure your system is working properly. Monitor and maintain your water treatment equipment according to manufacturer instructions.
If you have any questions about selenium in water, call Environmental Public Health.
