Tension over weed control measures reached a head in Mancos last week after the town applied the herbicide 2,4-D to Boyle Park. Residents who showed up to the park to protest said the compound presents unnecessary health risks to children and other park visitors.
The town said traditional herbicides like 2,4-D are necessary to comply with state laws about weed control. Residents said 2,4-D, which is not organic, causes health problems including a higher risk of cancer, but experts and regulators are not so sure.
The herbicide kills broadleaf weeds without affecting grass. It has been commercially available since 1945 and in 2001 was the third-most popular herbicide in the United States.
The Colorado Noxious Weed Act requires Mancos to control “noxious” weeds, including species found in Boyle Park such as hound’s-tongue, bindweed and thistle.
In May, a letter from Montezuma County Noxious Weed Department Director Bonnie Loving implored the town to control weeds in public areas and advised the town that organic methods were “not the most feasible or efficient way to go about it.”
“In conclusion, the organic herbicides are not efficient or feasible for a town’s goals,” Loving wrote.
Three residents who attended the Town Board meeting on Oct. 10 asked trustees to reconsider their decision to spray Boyle Park, but were told the decision had been discussed and made May 9.
And a letter to the board from Mancos Parks manager Terry Jennings in May stated that the cost of a certified organic treatment could be six times the cost of traditional methods and more than three times the cost of a “combination organic based” solution.
In 2015, Mancos released a report detailing a 10-year plan to decrease the number of traditional methods that some residents have opposed. The report said traditional methods “may still be required in some areas,” especially those with low foot traffic.
“The Town assumes that all pesticides are potentially hazardous to human and environmental health,” the 2015 report states. “Therefore, reasonable non-pesticide alternatives shall be given preference over chemical controls.”
Lily Russo has pointed out in emails to trustees and The Journal that 2,4-D was one of the two main ingredients in Agent Orange, an herbicide used by the U.S. military during the Vietnam War and blamed for health problems among Vietnamese citizens and U.S. soldiers.
However, experts generally agree that the main health problems of Agent Orange were from 2,4,5-T, the mixture’s other ingredient, while the problems attributed to 2,4-D were much more mild.
The link to cancer is weakAlthough 2,4-D studies have suggested a wide range of plausibilities, the consensus among regulators holds that the compound has not proved to be harmful to humans, given appropriate usage.
In 1987, the World Health Organization classified 2,4-D as “possibly carcinogenic,” also known as group 2B. In 2015, WHO reaffirmed this classification, citing “moderate evidence” that the compound was linked to immunosuppression and “strong evidence” that it caused oxidative stress, a state of chemical imbalance that has been linked to cancer in separate research.
However, the agency also said in its 2015 review that it did not observe “strong or consistent increases” in cancer risk related to 2,4-D exposure.
Although WHO findings provide expert opinions, they don’t have direct regulatory effects.
The European Union has approved regulated use of 2,4-D since 2002, and in 2011 affirmed that the usage limits were safe for consumers. In the U.S., the Environmental Protection Agency has found that 2,4-D is safe when used as directed.
The EPA has approved use of pesticides containing 2,4-D since 1948. In 1992, the agency categorized the compound as group D: “not classifiable as to human carcinogenicity.” Group D is one step above the category for compounds that have “no evidence” of being carcinogenic and one below the “possibly carcinogenic” category that parallels WHO’s 2B category.
Since 1992, the EPA has reviewed studies exploring any possible link between cancer risk and exposure to 2,4-D at least three times, each time finding that data do not support a conclusion that links human cancer to 2,4-D exposure.