In a new 400-page analysis that blows through the current state of scientific knowledge on the health risks and benefits of marijuana, one of the strongest conclusions is that it can effectively treat chronic pain in some patients.

The sweeping report, released Thursday by the National Academies of Science, Engineering, and Medicine, covered more than 10,000 scientific studies and came to nearly 100 other conclusions. Those mostly highlight unanswered questions and insufficient research related to health effects of marijuana, as well as several risks. However, the firm verification that marijuana does have legitimate medical uses—supported by high-quality scientific studies—is a significant takeaway in light of the Drug Enforcement Administration’s decision in August to maintain marijuana’s listing as a Schedule I drug. That is, a drug that has no medical use.

The new report also strongly concludes that the Schedule I listing creates significant administrative barriers for researchers wishing to conduct health research on marijuana and its components—an issue Ars has previously reported on

“It is often difficult for researchers to gain access to the quantity, quality, and type of cannabis product necessary to address specific research questions on the health effects of cannabis use,” concluded the authors, a panel of experts led by Marie McCormick, a pediatrician and public health researcher at Harvard.

In a public presentation of their findings, the report’s authors repeatedly refused to comment on the DEA’s scheduling of marijuana, noting that the issue was outside the scope of their scientific review.

The massive report falls at a hazy time for enforcement of that scheduling. Despite the federal prohibition, dozens of states have enacted or passed laws allowing for medical and recreational use of marijuana. The Obama Administration was lenient in its enforcement of the federal law, largely leaving states alone. However, it’s unclear how President-elect Donald Trump’s Administration will handle the situation.

"I won't commit to never enforcing federal law… I think some of [the Obama-era guidelines] are truly valuable in evaluating cases… Using good judgment about how to handle these cases will be a responsibility of mine. I know it won't be an easy decision, but I will try to do my duty in a fair and just way."

The issue was floated during the ongoing confirmation hearings for Senator Jeff Sessions, Trump’s nominee for attorney general. Sessions has previously been critical of the Obama Administration’s stance on the issue, but when asked about it in a hearing Tuesday, he said:

The authors of today’s report are hopeful that their evidence-based conclusions will steer discussions, policies, and decisions moving forward.

The other big takeaways of the report include:

Cannabis and cannabinoids were effective at treating chronic pain, particularly that related to multiple-sclerosis. The substances were also effective for treating chemotherapy-related nausea and vomiting in cancer patients

Cannabis and cannabinoids use is not linked to cancers that arise from smoking, such as lung and neck cancers. However, smoking may increase respiratory problems, like chronic phlegm, if it’s done on a regular basis.

Smoking marijuana while pregnant can result in lower birth weights, but it’s unclear if there are long-term effects in children. States in which cannabis use is legal report upticks in accidental poisonings of children compared with states that don’t allow for use.

There’s not enough research to know how marijuana use relates to heart attack, strokes, or diabetes. But there’s some evidence that smoking pot could trigger a heart attack.

There’s a little evidence that marijuana could have anti-inflammatory effects, but otherwise there’s not enough research to know how cannabis and cannabinoids affect the immune system or those who are immune-compromised.

Using marijuana may increase the risk of developing mental health issues, such as schizophrenia, anxiety, and to a lesser extent depression.

There’s a little evidence that using marijuana increases the risk of using other drugs—mostly tobacco. However, the committee found a clear link between people who use marijuana and those prone to developing substance dependence.