Posted on March 26, 2024 by SF Forest Alliance
It’s that time of the year! San Francisco smiles with wildflowers. The yellow oxalis is the harbinger of spring.
It’s also the time that we find toxic pesticides beings sprayed in “Natural Resource Areas” – typically Triclopyr, though we don’t actually know which ones are being used here. This is Corona Heights above the Randall Museum.
This is also from Corona Heights, east side by the fence circling the hill.
GLEN CANYON, TOO
These pictures are from Glen Canyon, at the Christopher Park entrance. They warn of the usage of Vastlan, which has triclopyr as the active ingredient.
This one’s also from Glen Canyon, at the Amber street entrance. It also warns of the use of Vastlan, i.e. triclopyr.
WHAT’S WRONG WITH TRICLOPYR?
Triclopyr is one of the most toxic pesticides used by San Francisco Recreation and Parks Department, and it’s used almost exclusively in the so-called “Natural Resource Areas.” For over a decade, it was used as Garlon, classified as a Tier 1 (most hazardous) pesticide; then in 2019, with a new formulation Vastlan, it was reclassified as Tier II and is being used even more broadly.
There is limited non-corporate research on triclopyr (the active ingredient in Garlon). The companies making these products don’t always identify or publicize their dangers. In 2003, Dow was fined for misleading the public about the danger of one of its products. More recently, Monsanto may have interfered with the Environmental Protection Agency’s assessment of Roundup. The main source of information is the chapter on Triclopyr in the Marin Municipal Water District Report on herbicides. (You can read that here as a PDF: Chap4_Triclopyr_8_27_08 . It’s technically written. Here is another paper that is more accessible for the layperson: Caroline Cox Triclopyr 2000 )
Usually, when looking at herbicides, researchers start by looking at Acute Toxicity – how much would it take to kill or injure you immediately. Separately, they look at Chronic Toxicity – a longer-term impact. What should also be followed, but often isn’t, is the long-term effects of low-level exposure. This is an issue with Garlon.
What stands out when attempting to research Garlon is how much is not known, particularly about the effects of repeated low-level exposure. There simply isn’t that much research out there, and few human studies. “Although triclopyr has been registered in the US since 1979, there are still very few studies on triclopyr that are not part of the EPA registration process.” Most of the research that exists is on Garlon 4. What was used on Twin Peaks was Garlon 4 Ultra – similar but not mixed in kerosene. It was mixed in a less flammable but apparently equally toxic methylated seed oil. Nowadays, what is used is Vastlan, which still has triclopyr as its active ingredient.
What is known about triclopyr makes uncomfortable reading.
- Triclopyr is poisonous enough that it can be used to commit suicide. There’s a paper in French about the effects of triclopyr and another chemical, fluoxypyr. The “Google Translate” version of its conclusion: These results are consistent with ingestion of potentially fatal triclopyr and fluroxypyr. To our knowledge, no blood concentration has been described so far in a context of voluntary ingestion for fluroxypyr, however a case has already been described for triclopyr of the same order of magnitude.
- Garlon “causes severe birth defects in rats at relatively low levels of exposure.” The rats were born with brains outside their skulls, or without eyelids. “Maternal toxicity was high” and exposed rats also had more failed pregnancies.
- Rat and dog studies showed damage to the kidneys, the liver, and the blood. It’s insidious, because there’s no immediate effect that’s apparent. If someone’s being poisoned, they wouldn’t even know it. In a study on six Shetland ponies, high doses killed two ponies in a week, and two others were destroyed.
- About 1-2% of Garlon falling on human skin is absorbed within a day. For rodents, its absorbed twelve times as fast. Too bad for the gophers…
- It isn’t considered a carcinogen under today’s more lenient guidelines, but would have been one under the stricter 1986 guidelines.
- Dogs may be particularly vulnerable; their kidneys may not be able to handle Garlon as well as rats or humans. “The pharmacokinetics of triclopyr is very different in the dog, which is unique in its limited capacity to clear weak acids from the blood and excrete them in the urine.” Dow Chemical objected when EPA said that decreased red-dye excretion was an adverse effect, so now it’s just listed as an “effect.”
- There was insufficient information about Garlon’s potential effect on the immune system, or as an endocrine disruptor.
- It very probably alters soil biology. “There is little information on the toxicity of triclopyr to terrestrial microorganisms. Garlon 4 can inhibit growth in the mycorrhizal fungi…” (These are funguses in the soil that help plant nutrition.) No one knows what it does to soil microbes, because it hasn’t been studied.
- It’s particularly dangerous to aquatic creatures: fish (particularly salmon); invertebrates; and aquatic plants.
It doesn’t generally kill adult honeybees, but there are no studies of other insects. [ETA: Some studies show slight “acute toxicity” to honeybees.] - Garlon can persist in dead vegetation for up to two years.
Given all this evidence, it isn’t a chemical that we would want in our parks – or watersheds. We’d rather have the wildflowers (or “weeds”).
