Experts have only a hazy idea of marijuana’s myriad health effects, and federal laws are to blame

See the original posting on LA Times Science

More than 22 million Americans use some form of marijuana each month, and it’s now approved for medicinal or recreational use in 28 states plus the District of Columbia. Nationwide, legal sales of the drug reached an estimated $7.1 billion last year.

Yet for all its ubiquity, a comprehensive new…