No Pesticides Used in Potrero Parks, According to Environment Department

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Last fall, glyphosate – commercially sold as Roundup or Aquamaster – the pesticide most commonly used by the San Francisco Recreation and Parks Department (SFRPD), was classified by the California Environmental Protection Agency (CalEPA) as a known carcinogen.  Glyphosate is a herbicide used to kill unwanted plants, especially annual broadleaf weeds.

CalEPA’s action didn’t go unnoticed. Within months of the classification, a coalition of dog owners, parents, and concerned citizens presented SFRPD with a petition with 11,000 signatures demanding that all use of chemicals containing glyphosate in City parks cease immediately.

Anti-glyphosate activists believe that the herbicide is causing increased cancer cases in dogs, especially related to the nose and mouth.  Many are worried that children, who also have more contact with the ground, may face higher cancer risks as well.  However, despite advocacy efforts the City continues to use glyphosate.

Since the City and County of San Francisco passed the Integrated Pest Management Ordinance (IMP) in 1996, only pesticides placed on the Reduced Risk Pesticide List (RRPL) by the San Francisco Department of the Environment (SFDoE) can be used on City-owned property, and then only as a last resort.

Under IMPO, SFDoE is responsible for determining what pesticides can be used in San Francisco parks, not park managers. SFDOE is charged with protecting the environment, which can require a balancing of different, sometimes competing, needs of people, animals, and plants.

It addition to deciding what pesticides can be used, SFDOE can make it harder to deploy more dangerous pesticides, and easier to use safer ones. To accomplish this, approved pesticides are grouped in three tiers based on their toxicity. Tier III pesticides are considered generally safe. Tier II are identified as moderately toxic, and include products with warnings like “possible cause of cancer, or “toxic.” Tier I pesticides are thought to be highly toxic, and include products with warnings like “known or probable cause of cancer,” or “extremely toxic.”

The tiers determine when a pesticide can be deployed. Tier II pesticides can only be used when there are no Tier III options. Tier I pesticides can just be applied when all Tier II options have failed. 

There are fewer Tier I pesticides than Tier III. Of the 49 pesticides on the 2016 Reduced Risk Pesticide List, 33 are considered non-toxic and defined as Tier III pesticides, 18 are moderately toxic and identified as Tier II, and seven are considered highly toxic, or Tier I.  However, the top three pesticides used by weight are all Tier I. Tier III pesticides, the least toxic, are used the least, while Tier I pesticides, with the greatest toxicity, are used the most. 

This may sound worse than it is. With the exception of glyphosate, SFRPD doesn’t use much pesticide. According to the 2016 RRPL, of the 49 pesticides approved for use in City parks in 2014, only eight were applied in quantities of more than a pound. Of these, four were used in quantities of less than three pounds, including Fiesta, Avenger, Intice Thiquid Ant Bait, and Norform Polaris. Just three pesticides were used in quantities greater than 10 pounds:  Garlon, 12.8 pounds, Aquamaster, 59 pounds, and Roundup, 572 pounds. However, only about four percent of glyphosate is used in parks. The rest is mostly applied to public golf courses and on turf at the airport.

No pesticides were used in Potrero Hill parks in 2014 and 2015.  “According to reports to the Department of the Environment – which manages the City’s IPM program – there was no pesticide use at these sites in 2014 or 2015,” said Sarah Madland, SFRPD director of policy and public affairs. 

Garlon, Aquamaster, and Roundup are Tier I pesticides, with known toxicity issues, even in low doses. Garlon is toxic to fish. Its maker, Dow AgroSciences, recommends that the chemical not be applied directly to, or otherwise permitted to come into direct contact with, cotton, grapes, tobacco, vegetable crops, flowers, fruit or orchard trees, shrubs, or other desirable broadleaf plants. 

Roundup and Aquamaster may pose even greater toxicity risks, especially to animals. Introduced by Monsanto in 1974, glyphosate is the world’s most widely used pesticide. It’s proven remarkably effective against a wide range of plants, often when no other herbicide will work, making it ideal or dealing with invasive species. It’s used on farms by the ton and in home gardens by the gallon. Monsanto has always maintained that Roundup is safe. Until last year, few disagreed.

In 2015, the World Health Organization labeled glyphosate as a known or probable cause of cancer. France banned the use of Roundup in nurseries.  Several countries, including Brazil, Germany, and Bermuda, are considering prohibiting Roundup completely.

Critics of the war against invasive species argue that since the San Francisco Bay Area’s climate is changing, so too should the assortment of plants growing in open spaces and parks. To them, SFRPD is trying to preserve a moment in time that’s already passed. They argue that plants that are best suited to the region now should be encouraged to grow here.

In contrast, proponents of pesticide use argue that invasive species can take over an environment, driving out valuable native species altogether, and severely limiting others.