Pro-marijuana tweets are reaching hundreds of thousands of American teens and young adults several times a day, a new study concludes. The researchers say they are concerned about their findings because young people can be especially influenced by social media, HealthDay reports.

“I’ve been studying what is influencing attitudes to change dramatically and where people may be getting messages about marijuana that are leading them to believe the drug is not hazardous,” lead author Patricia Cavazos-Rehg of the Washington University School of Medicine in St. Louis said in a news release. “As people are becoming more accepting of marijuana use and two states have legalized the drug for recreational use, it is important to remember that it remains a dangerous drug of abuse.”

Cavazos-Rehg analyzed tweets sent between May 1 and December 31, 2013, by a pro-marijuana Twitter account with about 1 million followers, called Weed Tweets@stillblazintho. The account posted an average of 11 tweets a day during the study period. The researchers determined 82 percent of the tweets were positive about marijuana, 18 percent were either neutral or were not about marijuana, and 0.3 percent were negative.

Using information from a data analysis firm, the researchers found 73 percent of those receiving the tweets were under age 19. Almost 20 percent were 16 or younger. About 22 percent were 20 to 24 years of age, and only 5 percent were 25 or older.

“These are risky ages when young people often begin experimentation with drugs,” said Cavazos-Rehg. “It’s an age when people are impressionable and when substance-use behaviors can transition into addiction. In other words, it’s a very risky time of life for people to be receiving messages like these.”

Their findings appear in the Journal of Medical Internet Research.