A group of Maine police chiefs is denouncing the marijuana legalization question on the November ballot as a poorly written proposal that would negatively affect families and communities.

The Maine Chiefs of Police Association plans to formally announce its opposition Friday and outline concerns about public safety and public health as voters prepare to head to the polls to legalize recreational marijuana use for adults. If approved in November, Question 1 would establish a system to regulate and tax marijuana for purchase by adults 21 and older.

“We’re concerned about the effect (legalization) may have on the communities and the youth after looking at what’s happened in Colorado,” said Falmouth Police Chief Edward Tolan, incoming president of the association. “That’s what prompted us to take this position as police chiefs.”

Tolan declined to discuss the chiefs’ concerns in detail before a Friday morning news conference, but said many involve impaired drivers and children being exposed to edible marijuana products.

A second major law enforcement association in Maine will meet later this month to discuss legalization and determine if it will also take a position on the referendum question. Sagadahoc County Sheriff Joel Merry, president of the Maine Sheriffs’ Association, said the Sept. 30 meeting will be the first time the state’s county sheriffs will meet formally to discuss the issue. It will include a presentation from Scott Gagnon, chair of Smart Approaches to Marijuana Maine, which opposes legalization, and Casco Bay CAN, a coalition focused on preventing youth substance abuse.

“I can tell you there’s been a lot of discussion among individual sheriffs about the repercussions if it were to pass,” he said. “We do value the will of the voter, but we have this extreme sense of responsibility on what is safe and healthy for our communities. I know some individuals have paid very close attention to what has happened in other states that have legalized the recreational use of marijuana, particularly Colorado and Washington.”

Recreational marijuana is legal in Washington state, Colorado, Alaska, Oregon and the District of Columbia. California, Arizona, Nevada and Massachusetts also will have legalization votes in November.

Law Enforcement Against Prohibition, a national group of current and former members of law enforcement, announced in July that it supports Maine’s legalization proposal. The organization has no members in Maine.

Opposition to marijuana legalization from the law enforcement community doesn’t surprise Rep. Mark Dion, a Portland Democrat and former Cumberland County sheriff who supports the legalization proposal. He sees Question 1 as an opportunity for law enforcement and the public to discuss rational drug policy and hopes that discussion can take place without fear.

“We shouldn’t fear the possibility of change,” he said. “We’ve been on an arc toward legalization since the 1970s when we were a leader in decriminalization.”

While Dion believes there are other crimes that need the attention of police officers, he said he understands the “legitimate concerns” law enforcement has about responsible consumption and impaired driving.

“I hear that, but Maine law already addresses that. It may not be as clean of a line as with alcohol, but they’re making arrests for drug-impaired driving,” he said.

David Boyer, the campaign manager for the Campaign to Regulate Marijuana Like Alcohol, the group promoting Question 1, said he encourages law enforcement to look at data from states where marijuana is legal.

“The sky hasn’t fallen in Colorado. It’s working there,” he said. “There have been valuable law enforcement resources spent enforcing failed marijuana laws. By regulating and making marijuana legal for adults, we can free up time and money for police to focus on serious violent crimes.”

Much of the discussion in Maine so far has centered on driving while impaired. During the last legislative session, lawmakers considered a proposal to establish a blood level limit to determine impairment, but the bill died after it was unanimously rejected by the House. During public hearings on the bill, medical marijuana patients and advocates testified against setting a limit similar to the one in Washington and Colorado. They argued that the blood level limit is arbitrary, not backed by science and unfairly targets medical marijuana patients who have higher levels of THC in their systems but are not impaired.

“There is no way to determine if someone is under the influence of the drug when using marijuana,” Tolan said. “We don’t have any testing procedures in Maine other than a drug recognition expert.”

Data from the Colorado Department of Transportation shows a 10 percent rise in traffic fatalities in 2015, but a report from the department made no connection to marijuana. The department blamed the majority of the fatalities on risky behaviors such as not wearing a seatbelt, riding motorcycles without helmets, speeding or driving while impaired or distracted.

In Washington state, the percentage of drivers involved in fatal crashes who had recently used pot rose from 8 percent to 17 percent from 2013 to 2014, according to a report by the AAA Foundation for Traffic Safety.

A report released this month by the Rocky Mountain High Intensity Drug Trafficking Area, which is run by the U.S. Office of National Drug Control Policy, says average marijuana-related traffic deaths in the three years since Colorado legalized recreational marijuana were 48 percent higher than the average over the previous three years. During the same time, total traffic deaths increased 11 percent, according to the report.

Legalization advocates question the data released by Rocky Mountain High Intensity Drug Trafficking Area, saying it is not an objective government report. Boyer said that there is no evidence to show that legalizing pot results in more traffic crashes and that the presence of marijuana in a car or in a person’s system does not necessarily indicate impairment.

When it comes to youth access to marijuana, legalization advocates say a regulated market can lead to a drop in teen use because stores check IDs. But opponents worry that normalizing marijuana use will lead more kids to try it.

Marijuana consumption by Colorado high school students dropped slightly after the state legalized adult use and is lower than the national average, according to a biannual poll by the Colorado Department of Public Health and Environment. According to the department, 21.2 percent of students surveyed in 2015 had used marijuana in the past 30 days, down from 22 percent in 2011. The national average for teen marijuana use is 21.7 percent.

Emergency room visits and poison-control calls for children 9 and younger who had consumed marijuana increased after recreational stores opened in 2014, according to a study published in July by the JAMA Pediatrics medical journal. The study found that twice as many children went to the Children’s Hospital Colorado emergency room per year in 2014 and 2015 as they did before marijuana stores opened. Sixteen children 9 or younger went to that ER for exposure to marijuana. Marijuana-related calls to poison-control make up about two of every 1,000 calls, according to the study.