We know how difficult it can be to watch a loved one struggle with major illness or chronic pain, and we appreciate the commitment with which families search for effective treatments. In this spirit of hope, a number of families have come forward recently to express their views about potential benefits of medical marijuana. As leaders entrusted to protect and improve the quality of life for all Minnesotans, we urge policymakers to move with caution and to seek clear, empirical evidence when considering the question of legalizing medical marijuana.

Marijuana is not a single drug or active ingredient. It is a complex substance containing more than 400 chemicals. Anecdotal evidence attributes a variety of benefits to marijuana use, but these stories are not backed by an abundance of well-controlled research. This is important because our health system depends on rigorous research to guide decisions, especially in the case of new drugs coming to market.

Even if one is inclined to accept the perspective of those backing medical marijuana, we should not exempt medical marijuana from the same regulatory oversight we require for other drugs. After all, professional ethics require the medical community and government agencies to consistently apply reasonable and effective safeguards to protect patients from untested, unproven and unregulated therapies.

Research into the efficacy of any medication must take into consideration dosage, timing, drug interactions, side effects and other factors. Medical marijuana has not gone through anything close to this rigorous process we require for even minor drugs coming to market. Giving sick people powerful chemicals to treat serious medical conditions in a nonregulated, noncontrolled fashion just doesn't square with modern medical practices, much less our ethics and core values of quality care.

While the benefits of medical marijuana are poorly documented, there's no shortage of evidence regarding marijuana's negative effects on individuals and communities. For example:

• Marijuana can disrupt learning and impair memory;

• Marijuana can exacerbate mental illness;

• Marijuana can increase blood pressure, heart rate and heart-attack risk;

• Marijuana use during pregnancy can harm a baby's brain development;

• Marijuana can impair drivers, causing automobile crashes that kill or injure innocent people;

• Medical marijuana products — where they are legal for medical purposes — can be inaccurately labeled, contain variable levels of the active ingredients, or even contain contaminants such as fungi and pesticides; and

• Marijuana is addictive; 1 in 6 of those who start using in their teens develop dependency.

While some portray medical marijuana as a low-risk wonder drug, there is a steady drumbeat of caution coming from respected organizations in the medical and public-health community, including the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, and the American Society of Addiction Medicine. Academic research also suggests that we think twice before legalizing medical marijuana. A recent major study from Columbia University found states that legalized medical marijuana had higher rates of marijuana abuse and dependence. The study also found that among those ages 12 to 17, marijuana usage rates were higher in states with legalized medical marijuana, compared with those states that do not have such laws.

Given the wealth of evidence showing the health risks and social risks associated with marijuana, Minnesota would be smart to wait for additional scientific research — and watch for evidence coming out of states that have legalized medical marijuana — before moving forward to legalize it here. We can learn a lot from the good and bad experiences of other states.

If the concern is about finding better medical care for patients, better research can help us find which chemicals in marijuana may have therapeutic value. As that information becomes available, we can act to ensure consistent quality, dosing and medical supervision to provide the maximum benefit with minimal risk.

Ed Ehlinger, Lucinda Jesson and Mona Dohman are commissioners of the state departments of Health, Human Services and Public Safety, respectively.