An estimated 1.3 million Japanese people aged 15 to 64 have used marijuana, surpassing for the first time the number of those who have abused inhalants such as paint thinner, a survey by a national institute showed Sunday.

The National Center of Neurology and Psychiatry in Tokyo's Kodaira has conducted the substance abuse survey biennially since 1995, and the latest one was sent out to 5,000 people in that age bracket between September and October 2017, with 2,899 of them responding.

The national center calculated the estimated figure of 1,331,765 habitual and non-habitual marijuana users, an increase of around 380,000 from the previous survey, based on population ratios and other factors, while the survey showed declines for the numbers of people who have inhaled organic solvents and used so-called "dangerous drugs."

Among the respondents, 1.4 percent said they have used marijuana, up 0.4 points from the previous survey, followed by solvents at 1.1 percent, down 0.4 points, and methamphetamines at 0.5 percent, unchanged from the previous survey.

Since the government has tightened regulations on "dangerous drugs" that can cause effects similar to those of narcotics and stimulants, authorities suspect more people are using marijuana instead of "dangerous drugs."

Police took actions against more than 3,000 people -- a record high -- last year over incidents related to marijuana, including teenagers who were arrested for possessing it, and the Health, Labor and Welfare Ministry's Narcotics Control Department has intensified its activities as well.

There are concerns that young people in particular are susceptible to marijuana use out of curiosity, with some believing marijuana is less harmful than other types of drugs.