Minnesota regulators, for the first time, are considering banning or restricting a controversial class of insecticides that has been linked to honeybee deaths.

The possibility, disclosed this week by the state Department of Agriculture in a revised outline for a study of the chemicals, followed an outpouring of public concern over the dramatic decline in honeybee populations in recent years.

"Obviously people are very interested in this," said Gregg Regimbal, an official with the department's Pesticide & Fertilizer Management Division. "It's a very complex issue and it's highly charged."

More than 400 citizens wrote the agency earlier this year with comments on the proposed review of a class of insecticides called neonicotinoids, which have been linked to bee deaths around the world.

Regimbal said the public response was heavy, with many commenters wanting to know why the study, as originally outlined by the agency, didn't include the possibility of banning the chemicals.

A revised outline published this week states that the range of state action could include "restrictions on or cancellation of products."

"We wanted to make sure it was clear that it's in our authority … and that that would be an option," Regimbal said.

Lex Horan, a Minneapolis-based organizer for Pesticide Action Network of North America, said a suspension, restriction or ban in Minnesota is plausible if the state conducts a careful study of neonicotinoids and their effects on pollinators and other insects.

He said people who wrote to the agency are heartened by the revised outline, including other aspects of the upcoming review.

"The state needs to take this seriously," Horan said. "They put out a strong scoping document because of the feedback they received."

The in-depth review will take more than six months.

The outcry included a letter submitted in May by 17 DFL legislators, who insisted that the department broaden the scope of its review. The 2013 Legislature called for the Agriculture Department to review the chemicals, and the group of 17 was irked that the agency's initial outline didn't mention the possibility of a ban or other restrictions.

"The Legislature did not intend that the Department would simply rubber stamp U.S. EPA's decisions," they wrote, a reference to a review underway at the federal Environmental Protection Agency. Signers included Rep. Jean Wagenius, DFL-Minneapolis, who is chair of the House Environment, Natural Resources and Agriculture Finance committee.

Insecticide use in Minnesota is governed by both state and federal law. The EPA is also reviewing the effects of neonicotinoids on bees and other pollinators, while New York, Oregon, Canada and Europe all have placed bans or restrictions on them.

The chemicals are now the most widely used class of insecticides in the world, according to the state Agriculture Department, and studies have found that they can damage the navigation and reproduction abilities of honeybees and bumblebees, even at low concentrations. Honeybees alone pollinate more than $15 billion worth of crops in the United States.

Horan said the backlash against neonicotinoids was heightened by a recent EPA finding that neonicotinoid seed treatments in soybeans provide little or no overall benefits to soybean production for most farmers.

The pesticides, which work as neurotoxins on many agricultural pests, are used to protect a broad range of crop seedlings including corn, sugar beets, potatoes and cereals.