A ground-breaking study Glyphosate remains in forest plant tissues for a decade or more scheduled to be published in Volume 493 of Forest Ecology and Management, shows that glyphosate persists in vegetation on sprayed cutblocks for much longer than previously known, rendering existing regulations around public notifications of past spraying on crown land inadequate.

Signage on sprayed blocks typically warns the public to avoid sprayed blocks for 48-72 hours. Despite years of requests by Stop the Spray BC, there is no public database of sprayed blocks and no requirement to provide signage in the years after spraying.

However, glyphosate translocates into root systems of perennial herbaceous plants like raspberries and blueberries and was present in 26% of fruit the following year at levels deemed “unfit for human consumption if assessed in the marketplace.” Contamination of vegetation is documented 12 years after spraying.

“Spraying crown land to take out fire-resistant species like Trembling Aspen and Paper Birch, species that have commercial value, that sequester more carbon, that reflect more solar radiation, that support more biodiversity, is already a counter-productive practice,” says Stop the Spray BC spokesperson James Steidle.

“To add insult to injury, we are wantonly contaminating the forest ecosystem for over a decade, exposing wildlife and humans to unknown risks, that we haven’t even monitored up till now, for a purpose that will make our forests less diverse, less adaptive, and more likely to fail. I’m not sure how much more unprofessional and negligent it could get.

This is a massive discredit to the entire profession of forestry and the institutions and individuals that have recklessly, yet firmly, stood by this practice since 1984 when the BC government approved broadcast spraying of untested glyphosate formulations with unknown additives on BC forests.”

The study also notes the implications to wildlife:
“Residual glyphosate in fruits in the year following treatment with GBH could have chronic implications for wildlife such as birds, bears, and other mammals consuming large quantities of berries in forest cutblocks.”

Roughly 7-10% of harvested land-area in BC are aerially sprayed with glyphosate, not including backpack spraying. 90-99% of spraying is carried out in Northern BC, so the percentage of cutblocks sprayed in Prince George forest district is much higher than the provincial average. Approximately 15-20% of all area harvested in Prince George forest district are sprayed, although exact figures of area harvested in Prince George are not released by government. The highest spraying is wherever Canfor harvests.

Notable quotes from study:
“The persistence of glyphosate and AMPA within perennial forest plant tissues is a source previously unaccounted for, and the knowledge that these residues remain in plant tissues for much longer than previously suspected, even at very low concentrations, must be considered by forest professionals when making vegetation management decisions.

Further, whether or not glyphosate and its metabolic products are considered harmful to flora or fauna at low concentrations, any compound deliberately added to the environment by humans should be accounted for appropriately. That some control samples unexpectedly contained residues further highlights the fact that even at very low application rates such as those experienced by understory plants through spray drift, trace amounts of glyphosate and AMPA may be stored within plant tissues for twelve years or more.”

“In fruit samples collected from the SBS BEC zone one year after treatment, a greater number of raspberries were detected with residue than blueberries: 90% of raspberries (n = 19) and 70% of blueberries (n = 10) contained glyphosate, and 68% of raspberries and none of the blueberries contained AMPA. Raspberry fruit samples had an average glyphosate residue concentration that was ten times greater than blueberry fruit samples (0.074 μg g−1 compared to 0.007 μg g−1 for blueberries) (χ2(1) = 9.064, p = 0.002), and significantly greater AMPA as well (χ2(1) = 10.970, p < 0.001). Of the thirteen raspberry fruit samples, in which glyphosate residue was detected at levels > MQL, the average glyphosate concentration was 0.105 μg g−1, ranging from 0.057 to 0.21 μg g−1, and five of these samples (26%) contained glyphosate at concentrations greater than the maximum residue limit (MRL) of 0.1 μg g−1, set by the Government of Canada for foods (Health Canada, 2012, Kolakowski et al., 2020).”

“It may therefore be asked whether these concentrations are considered safe for wildlife to consume, especially considering that large areas of forested land are cleared and treated with GBH every year. Moose have been observed to preferentially browse in cutblocks 7–11 years after treatment with GBH, probably since the conditions at that time include a favourable combination of forage and conifers for bedding and cover (Eschholz et al. 1996). Whether persistent glyphosate in plant tissues in these areas might have an effect on the health of moose and other wildlife species is not known.”

“Although fruit contained the least residue of all tissue types on average, 26% of fruit samples contained concentrations greater than the 0.1 μg g−1 MLR used by the Canadian Food Inspection Agency to assess glyphosate residue content in foods. These 26% of fruit samples would be deemed unfit for human consumption if assessed in the marketplace. Residual glyphosate in fruits in the year following treatment with GBH could have chronic implications for wildlife such as birds, bears, and other mammals consuming large quantities of berries in forest cutblocks.”
Read the full study here.

James Steidle
Stop the Spray BC