Montana State University

Rise in paraquat use leads to warnings for pesticide applicators, dealers in Montana

August 26, 2014 -- MSU News Service

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Tel: (406) 994-4571

BOZEMAN – As weeds like kochia develop resistance to glyphosate herbicides, more Montanans are turning to herbicides that contain the active ingredient paraquat, says Montana State University Pesticide Education Specialist Cecil Tharp.

Paraquat is very effective as a broadspectrum herbicide, but unlike glyphosate products, it is highly toxic to humans, Tharp said. Just a few drops to one teaspoon can kill the average 160-pound person. As a result, Tharp warns applicators to be aware of the personal protective equipment requirements that are listed on the product label. He also reminds dealers that they aren’t required to suggest personal protective equipment to customers, but if they do, they must be sure to read the product labels to give accurate advice.

“Due to the risks, applicators shouldn’t simply ask dealers, retailers, friends, family or neighbors for the required personal protective equipment,” Tharp said. “They should always read and follow the pesticide product label. That is the ultimate source and contract for applicators to follow.”

Most herbicide products used in Montana require only minimal personal protective equipment, but products that contain paraquat require much more personal protective equipment, Tharp said. Some common paraquat products are Gramoxone SL, Bonedry, Paraquat Concentrate and Firestorm.

“Neglecting to follow the product label personal protective equipment requirements puts you and your workers, handlers and possibly family at risk to poisoning,” Tharp said, noting that paraquat is a Category 1 for toxicity, the highest level given on product labels.

Personal protective equipment requirements are always listed on the pesticide product label, and they are updated periodically, Tharp said. The recommendations for paraquat products are currently aimed at two groups: applicators-handlers and mixers-loaders.

Applicators and other handlers must wear long-sleeve shirts and long pants, chemically resistant gloves, protective eyewear, NIOSH-approved particulate filtering respirators equipped with N, R, P, or HE class filter media.

In addition to those items, mixers and loaders must wear chemically resistant aprons and face shields. All users must select only the type of respirator recommended on the pesticide label.

Personal protective equipment is often available where pesticide products are sold, but not always, Tharp said. For more information on vendors that carry personal protective equipment, applicators can ask their local pesticide dealer or go online to or

For more information, contact Cecil Tharp at or (406) 994-5067.

Evelyn Boswell, (406) 994-5135 or