Canada establishes guidelines for boron in drinking water

By ES&E Staff

Health Canada has developed a five milligrams per litre maximum allowable concentration for the chemical element boron in drinking water, according to a recent guideline technical document.

The word “boron” is derived from borax, the mineral from which it was isolated. It can enter the environment from the weathering of rocks and soils and seawater spray, as well as from fossil fuel combustion and wastewater discharge.

Typically, boron is found in pesticides, cosmetics and pharmaceuticals; however, when it comes to water it exists pri- soaps, detergents and flame retardants.

In most Canadian drinking water supplies, boron is below 0.1 mg/L. It can be higher in groundwater supplies in areas with naturally-occurring boron. Most of the world’s boron is in the oceans with an average concentration of 4.5 mg/L in seawater, while levels in Canadian coastal waters range from 3.7 to 4.3 mg/L.

The main source for Canadians’ exposure to boron is through food; however, exposure through drinking water can contribute up to 16% of total dietary exposure. Health Canada indicates that a treated water concentration of less than 5

“Lower concentrations can be achieved by some drinking water treatment systems, depending on the source water quality, the type of treatment technology in place, and the operational conditions of the treatment plant,” states the technical document.

Of the more than 200 minerals containing boron, only four (borax, kernite, colemite and ulexite) are commercially important and make up more than 90% of the borates used industrially worldwide, according to Health Canada.

“The only significant mechanism expected to influence the fate of boron in water is adsorption-desorption reactions with soil and sediment, the extent of which depends on the pH of the water, concentration of boron in solution, and the chemical composition of the soil,” according to the new guidelines.

The World Health Organization has set a maximum allowable concentration of 2.4 mg/L, while the U.S. Environmental Protection Agency established a non-enforceable lifetime health advisory

In Canada, the maximum allowable concentration is risk-managed to take into consideration the treatment challenges of lowering it for private wells

Reproduction and development are considered to be the most sensitive health considerations for boron toxicity. Boron is not an essential element, but some studies indicate it may be beneficial to human health, and has been used to treat inflammation, arthritis, menstrual pain

This article is intended to be a preview of the legislation and not a replacement for the actual guidance from the government.

For more information, email: editor@esemag.com