MagChloride Truth


Protecting plants and trees

Millions of gallons of fire retardant are dropped on our nation’s forestlands every year. It is critical that the solution that is used does not present a danger to vegetation and the surrounding forest areas where it is applied.

Products that are fully qualified on the QPL have completed a yearslong testing and evaluation period—which includes testing the retardant’s impact on the environment—and have been determined to be safe.

Today, we have limited data on magnesium chloride-based fire retardants on vegetation – but we can look elsewhere to understand potential issues.

In Liquid Road Deicing Environment Impacta research report published in 1998, the authors stated that magnesium chloride, similar to sodium chloride, may cause growth inhibition, scorched leaves or even plant death. The chloride ions in salt cause adverse effects in vegetation, and with higher concentrations of chloride in magnesium chloride, it is potentially more harmful to vegetation than sodium chloride.

While magnesium is crucial to plant growth, excessive amounts of it in the soil may reduce a plant’s ability to absorb calcium and other needed nutrients. Magnesium chloride is also soluble in water and can exchange with heavy metals in soils potentially releasing them into the environment, another concern that was raised in a report from Public Sector Consultants in 1993.

Meanwhile, in a report researching the impact of magnesium chloride on trees, Colorado State University found that there are similar effects. The report said that once mag chloride enters a tree’s water-conducting system, it accumulates in the margins of leaves or needles. The leaves are weakened or killed, which can potentially lead to the death of the tree. Even low applications of mag chloride on roadsides can grow in concentration in roadside ditches, move off road into drainage areas and have a similar effect.