Colorado middle schools reported a 24 percent increase in drug-related incidents last year, according to USA Today. School-based experts tell the newspaper they believe the jump is directly related to marijuana legalization. Recreational sales of marijuana began on January 1, 2014.

Schools do not report which kinds of drugs are involved in the incidents, the article notes. State legislators are now asking school districts to keep track of which drugs they are finding.

John Simmons, the Denver Public Schools' Executive Director of Student Services, says schools in his city saw a seven percent increase in drug incidents, from 452 to 482. Almost all of the incidents were related to marijuana, he said.

Middle schools across the state reported a total of 951 drug violations, the highest number in a decade. School officials say while marijuana use has long been a problem, more students are trying it now that it is more easily available and socially accepted.

"Middle schoolers are most vulnerable to being confused about marijuana," said Dr. Christian Thurstone, attending physician for the Denver Health Adolescent Substance Abuse Treatment program. "They think, 'Well, it's legal so it must not be a problem.'"

The group representing the nation's pediatricians issued a statement this week opposing the legalization of marijuana. The drug can be harmful to adolescent health and development, according to the American Academy of Pediatrics (AAP).

The group said it supports the compassionate use of marijuana for some children who suffer from debilitating or terminal illnesses, HealthDay reports. The AAP also supports decriminalizing marijuana, in conjunction with programs designed to prevent marijuana use and to provide early treatment for adolescents with marijuana use problems.

The AAP noted marijuana can cause memory and concentration problems that may lead to difficulties in school. Marijuana can impair motor control, coordination and judgment, leading to an increased risk of accidental injury and death, the group stated in a news release. Regular marijuana use is also associated with psychological problems, worse lung health, and an increased risk of drug dependence in adulthood, the AAP said.

The group expressed concern about legalization of marijuana and its effect on teens. "Making it more available to adults - even if restrictions are in place - will increase the access for teens," said Dr. Seth Ammerman, a member of the AAP Committee on Substance Abuse and an author of the policy statement. "Just the campaigns to legalize marijuana can have the effect of persuading adolescents that marijuana is not dangerous, which can have a devastating impact on their lifelong health and development."

The AAP said it opposes medical marijuana "outside of the usual process by the Food and Drug Administration to approve pharmaceutical products." It noted there has been little research on medical marijuana for adults, and there have been no published studies on marijuana involving children. The group supports further study of marijuana for medical conditions.

D.C. Mayor Muriel E. Bowser on Tuesday vowed that the nation's capital will not become another Amsterdam when marijuana legalization takes effect on Thursday. Bowser said she would ask the D.C. Council to approve emergency legislation to prohibit private clubs from following the model of Amsterdam coffee shops, where pot could be openly exchanged.

The move could rein in a potential free-for-all when a voter-approved measure to legalize marijuana takes effect on Thursday.

"Residents spoke loud and clear when they voted to legalize small amounts of marijuana in the District of Columbia," Bowser said. The task now, she said is, "to implement in a safe, fair and transparent way."

Although voters overwhelmingly approved legalization in November, Congress blocked the District the following month from enacting laws to regulate sales of the drug.

D.C. officials have contended that the congressional interference did not halt the voter approved measure, known as Initiative 71. Bowser's office said for the first time Tuesday that Initiative 71 will take effect at 12:01 a.m. on Thursday. That marks the end of a 30-day congressional review period in which conservatives in Congress could have moved to quash the measure outright. House Republicans have said they believe Initiative 71 was blocked by the spending restriction in December. The issue could be left to courts to decide.

Until then, Bowser and D.C. Police Chief Cathy L. Lanier laid out the contours of how District police plan to respond to the law change.

As specified in the ballot measure, District residents and visitors will be able to possess up to two ounces of marijuana - about a Ziploc bag's worth. Residents will also be able to cultivate the plant in their homes - up to six seedlings each and up to three plants to maturity. D.C. police will stop ticketing for possession, which last year was downgraded to a civil offense instead of a criminal one in the city. The department will also stop using the existence of marijuana on a person or in a home as rationale for investigating other potential criminal behavior.

Police, however , will attempt to draw a bright line prohibiting public use, said Police Chief Cathy L. Lanier. D.C. police will be instructed to continue ticketing for public smoking of marijuana, a ticket akin to drinking in public, punishable by up to 60 days in jail and a $500 fine.

Smoking in public restaurants, clubs or anywhere else that the public is invited to enter will also remain against the law, Lanier said. And growing pot will be permitted only indoors.