The use of glyphosate, the active ingredient in commonly used herbicides RoundUp and Aquamaster, is being re-evaluated by the county parks department in light of local protests against glyphosate and a recent reclassification of glyphosate as “probably carcinogenic” by the World Health Organization’s International Agency for Research on Cancer.
Marin County Parks recently announced that it plans to eliminate herbicides in regional parks and near county buildings and limit applications to road medians, 34 Open Space preserves and agricultural lands. The parks department will determine in coming months whether to reduce glyphosate use in its integrated pest management plan, or IPM, which the county applies to its 16,000-acre Open Space District.
In light of the reconsideration, supervisors called for feedback from county staffers and residents at a workshop on Tuesday, which drew nearly 200 people. As part of the county parks presentation, Dr. Susan Kegley, head of the environmental consulting firm Pesticide Research Institute, gave a presentation on glyphosate and its new classification.
Though the supervisors took no action, the parks department reaffirmed its conviction that pesticides should be used on parklands, but in limited amounts under strict application guidelines.
“I see a lot of pesticide-free stickers and you should know that we share that goal,” said Chris Chamberlain, county parks superintendent. “We use herbicides in a very judicious manner as a last resort.”
Mr. Chamberlain estimated that the county parks’ use of glyphosate amounted to less than one percent of applications countywide, with the vast majority attributable to unregulated residential use.
Ms. Kegley, the consulant, outlined the process for how glyphosate came to be labeled “probably carcinogenic” and posited that high levels of exposure to glyphosate—at least enough to possibly cause cancer in humans—were more likely to occur from constantly eating foods treated with glyphosate rather than the occasional romp through county parklands.
“I think exposures to once-a-year treatments are quite manageable compared to annual dietary exposure,” she said.
She noted that children were more susceptible to accumulating toxic levels of glyphosate in their systems, mostly from what they eat. Additionally, the label “probably carcinogenic” encompasses a motley of mundane activities, such as taking Tylenol, eating French fries and potato chips, and visiting tanning beds or hair salons, Ms. Kegley said.
According to Ms. Kegley, the vast majority of the data used by the World Health Organization involved high-exposure tests on rats and mice, which were found to have contracted non-Hodgkins lymphoma, hairy cell leukemia, testicular tumors, pancreatic islet cell adenoma and thyroid cancer.
In early September, the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment issued a “notice of intent” to list glyphosate as known to cause cancer, signaling a 30-day public comment period before the designation became official. But after requests from the Monsanto Company, the Joint Glyphosate Task Force, and the Agricultural Council of California, the comment period was extended to Oct. 20.
Since at least 2010, Aquamaster has been the chemical of choice for the county’s vegetation-control projects, mostly to curb grasses and weeds on medians. In a 2014 report, the county noted that it spot-sprayed 741 ounces of Aquamaster. That’s down from 1081 ounces used in 2013.
A critical stakeholder in the pesticide debate is the county fire department, which uses glyphosate to reduce fuel sources in fire-prone areas, most especially Mount Tamalpais. “Glyphosate is not the only way to manage fuel breaks. But right now, we have such a fire problem in this county that we need all of the tools in the toolbox,” Fire Chief Jason Weber said.
Some opined that the county should beef up manual-removal efforts while continuing to use pesticides to halt the spread of invasives. Chileno Valley beef rancher Mike Gale has long battled thistle—a plant unpalatable to cows—which swarms his grasslands. Though he’d like to see pesticides curbed, keeping a small amount of pesticides in play couldn’t hurt.
“The elimination of glyphosate should be the goal,” said Mr. Gale, a former Marin Organic board member. “But, unfortunately, that is not a practical way to deal with the problem once it’s established. Don’t take all the options off the table.”
Yet pesticide opponents pointed to the example of the Marin Municipal Water District, which in July decided to ban RoundUp on its 21,000 acres.
“My feeling is that if the water district is banning glyphosate, you certainly can,” said Lindsay Vurek of Lagunitas.
Still others called for the county to ban glyphosate not only on public lands, but also on private property and from being sold in stores.
Supervisor Steve Kinsey was attending a meeting of the California Coastal Commission, which he chairs, on Tuesday. But he issued a statement that expressed his support for the current IPM and limited use of herbicides.
“We live in a complex world where our choices are rarely ‘either/or,’” Supervisor Kinsey’s letter read. “This is true in this instance as well, and we should be willing to skillfully manage the limited use of herbicides while we also explore less toxic means to achieve our goals.”