.Upfront: Coming to a boil

Debate about using glyphosate to control plants in Marin heats up

by Peter Seidman

A recent report from an international health organization has bolstered the argument that a commonly used herbicide should be dropped from use on Marin public lands, say opponents of relying on chemicals to control non-native vegetation.

The debate about whether the county and the county’s largest water district should use the herbicide glyphosate to control plants that easily overrun native vegetation in parks and open space has lasted for decades.

Proponents of using the herbicide (which routinely is called a pesticide) say that it’s the most effective way to control non-native plants, from a cost-benefit basis as well as a practical basis. Land managers in the Marin County Open Space District say that it’s nearly impossible to eradicate non-natives such as broom varieties using mechanical means and hand pulling. The proponents say that applying glyphosate judiciously creates little risk to the environment.

Opponents of using glyphosate say that’s just not true. They point to studies that show a causal relationship between glyphosate and health hazards. Proponents, however, point to studies that show the opposite—that glyphosate is safe.

The issue has bubbled for decades, periodically coming to a boil. The temperature of the debate increased recently when the county planned to apply glyphosate judiciously to control vegetation in the Ring Mountain Preserve between Corte Madera and Tiburon.

The debate over whether to use glyphosate had focused on the Marin Municipal watershed. Protecting the county’s main watershed and reducing fire danger from non-native plants on Mount Tam is one thing, say opponents of chemical control, but using glyphosate in the Ring Mountain Preserve is unacceptable and endangers visitors.

Anti-pesticide proponents are circulating a petition calling on the Board of Supervisors to come out against using the pesticide. At a recent board meeting, Supervisor Katie Rice, who represents the preserve area, said that the county should review its integrated pest management plan. The county is already committed to a reduction of pesticides in parks, but the Open Space District has no such similar mandate, although land managers in the county view using glyphosate as a last resort.

The Marin Municipal Water District (MMWD) has been reviewing its non-native control policies, and the district board is expected to take up the issue soon.

What makes this time different from all other times is a report from the cancer research group of the World Health Organization. In March, the International Agency for Research on Cancer (IARC) said that its most recent investigation of glyphosate data shows that the chemical is a “probable carcinogen.” That’s an increase in the hazard level from the organization’s previous classification of glyphosate as a “possible carcinogen.” That increase adds immediacy to the call to stop using the chemical in Marin.

Almost as soon as the report went public, critics from the chemical industry blasted the research, saying that IARC cherry-picked data contained in previous studies. The controversy continues, but opponents of using glyphosate in Marin say the IARC report should be viewed as just one more nail in the glyphosate coffin.

Glyphosate is the most commonly used herbicide in the world. It’s a Monsanto product that has made billions for the company. Glyphosate is a common application on lawns and driveways and sidewalks and median strips. Monsanto has engineered glyphosate-resistant crop seeds, which allow farmers to use high doses of the chemical to control weeds and increase crop yields. The high doses also result in glyphosate showing up as residue in crops, as well as animals and humans, critics say. Proponents of its use say that the amounts detected pose no potential harm. Opponents beg to differ.

Proponents of using glyphosate say that it can be safely applied topically to plants rather than by spraying, and the topical application is safer. They also say that the chemical has a short half-life. Former Fairfax Mayor and current board member of the Ross Valley Sanitary District Frank Egger disagrees. He’s been a strong glyphosate opponent. “The half-life of glyphosate is much longer than we’ve been led to believe,” he says. “All of the studies that have been done in the past have been industry-run. For years, the Environmental Protection Agency (EPA) has relied on the pesticide industry to determine safety.”

The EPA is at the end of a routine re-evaluation of glyphosate and is expected to release its report soon. The agency delayed issuing a report until it could evaluate the results of the World Health Organization’s report citing the increased cancer hazard of glyphosate. The EPA results could come just as the Marin Municipal Water District begins discussing staff recommendations for vegetation management.

Egger played a major role in rallying Fairfax behind a move to block herbicide use in the watershed, a strategy that district officials say has resulted in the increased spread of non-native vegetation, creating a high fire danger.

Egger and civic activist Bill Rothman played leading roles in the Marin Safe Drinking Water Coalition’s move to convince the district’s board to stop using herbicides in 2005. Egger ran for a spot on the MMWD board in 2008 as a strong anti-pesticide candidate. He was unsuccessful in that bid.

The brooms, Scotch, French and Spanish, have infested the watershed along with other flora such as yellow starthistle and pampas grass. But it’s the brooms that pose the greatest fire threat, as well as damage to the biodiversity of the district’s approximately 22,000 acres of watershed.

The issue of how the district should battle non-natives stretches back to 1994, when a consultant delivered a study to the district that formed the basis for a management plan focused on husbanding the watershed. Then, in 2003, spurred by a continuing increase in fire danger on the watershed, the district adopted an integrated pest management policy aimed at keeping the fuel load suppressed, and at the same time maintaining the ecology of the watershed.

Using a variety of conventional tools, including hand and mechanical removal and controlled burns, the district fought the infesting flora. It also looked at some unconventional methods, including goats that might graze the non-natives. That didn’t work because goats ate every native species they could find before munching on invasive species. The tool that caused the most controversy in the policy was the district’s use of “reduced risk” herbicides. The limited use of those chemicals “in areas away from reservoirs and streams,” was part of the 2003 integrated management policy.

An EPA evaluation found that glyphosate degrades quickly in the soil and does not “migrate” and contaminate water easily, findings that make it a good candidate for use on a watershed. Egger, Rothman and others, however, refute the suppositions.

Larry Bragman currently serves on the MMWD board and is another strong critic of using glyphosate. He also has a unique take on how the district—and the county—should deal with non-native species.

As for the argument that glyphosate degrades to a safe state, Bragman points to New York, where the New York attorney general sued Monsanto “for making that claim,” Bragman says, “and Monsanto lost. They were sued for false advertising.” Proponents of using chemical means to control vegetation also say that it’s far more cost effective to use chemicals along with other methods of control than to take the chemical tool out of the toolbox. “It depends on how broadly you analyze the budget,” Bragman says. “It may save the agency some money. But the actual cost is going to be externalized to the community. There’s no doubt that chemicals save public agencies some money.” But assuming the World Health Organization is correct, he adds, the additional cost of health problems resulting from glyphosate use should be a critical element in a renewed evaluation.

“When conflicting viewpoints exist about husbandry on public property, political and scientific,” Bragman says, “we’ve got to use the precautionary principle. I don’t think we should be rolling the dice with public health.”

In looking at how the district (and by extrapolation other agencies also) should control non-native species, Bragman says, “We need to change the paradigm from eradication to management. Broom, for example, has been around Marin for a long time and has become part of the county’s ecology. I think land management public agencies should embrace a change in perspective. It’s going to take additional investment, but I think it can be done.”

Bragman suggests that managing broom by mechanical means could become a job-creating mechanism. Work “in ecological management needs to be valued,” and can produce local jobs that would add economic benefit to the community.

Pacific Sun
The Pacific Sun publishes every Wednesday, delivering 21,000 copies to 520 locations throughout Marin County.


  1. With controversy and arguments pushing in both directions, and with public health, the water supply and the local ecosystem at stake, prudent public policy would demand that we play it safe, and take the least risk-laden route. Therefore, since it’s not clear whether glyphosate is a carcinogen or not, the least risky route, is to not use glyphosate at all. Prudence demands that alternative, less questionable and unproven methods be used.

    Common sense would dictate that if something has “-cide” in its name (pesticide), then it’s a bad thing when it comes to living beings and a living ecosystem, and common sense should tell you that you’d have to be an insane moron to want to continue using glyphosate. So if you insist on continuing to use glyphosate, evenutally Darwinisim will take care of you, just don’t drag the rest of us down with your sinking ship along the way.


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