The US Environmental Protection Agency has rejected a petition from the Natural Resources Defense Council (NRDC) asking the agency to review and limit the use of the herbicide glyphosate “to prevent unreasonable adverse effects” to the monarch butterfly.
In the petition, filed in February 2014, NRDC sought an immediate review of glyphosate and its impact on the pollinator, as well as measures to limit the herbicide's use. NRDC said the herbicide, often used on genetically modified corn and soybeans, has killed much of milkweed that monarchs use for forage.
“The agency at this time has not determined that glyphosate causes unreasonable adverse effects to the monarch butterfly,” noted EPA in its response.
The agency did say it plans to issue a Federal Register Notice to seek public input on the overlap in pesticide use for weed management, including use in agricultural and non-agricultural areas, and the areas where the monarch butterfly and its resources are present.
EPA is conducting a re-registration review of the product, which is required for every 15 years for each registered pesticide to determine whether it continues to meet standards set by the law.
In its response, EPA cited work already in progress to protect the butterfly as a result of the White House Pollinator Task Force Plan issued last month and ongoing international work with Mexico and Canada to protect the monarch's migration pathway.
“The primary concern for monarch butterflies is the reduced availability of milkweed which is necessary for their life-cycle,” the letter stated. “Therefore focusing on glyphosate may only result in intensified use of other herbicides that may be just as detrimental to monarch butterflies or pose other human health or ecological risk.”
The monarch migrating population has dropped by more than 90 percent since 1995. However, the 2014 population was estimated to be two or three times as large as 2013's record low.
EPA last reviewed the safety of glyphosate in 1993, but NRDC said in a statement that since then, “its use has increased 10-fold, yet the agency has never considered the herbicide's impact on monarchs.”
NRDC sued the EPA in October to block its approval of a dual herbicide produced by Dow AgroSciences known as Enlist Duo, citing the loss of monarch butterflies. The product is a combination of glyphosate and another herbicide known as 2,4-D.