WASHINGTON — One in 12 full-time workers in America acknowledges having used illegal drugs in the past month, the government reports.

Most of those who report using illicit drugs are employed full-time, with the highest rates among restaurant workers, 17.4%, and construction workers, 15.1%, according to a federal study being released yesterday. About 4% of teachers and social service workers reported using illegal drugs in the past month, which was among the lowest rates.

Federal officials said the newest survey is a snapshot and was not designed to show whether illicit drug usage in the workplace is a growing problem or a lessening one. The current usage rate is 8.2%. Two previous government surveys reflected a usage rate of 7.6% in 1994 and 7.7% in 1997, but those studies involved a much smaller sample of interviews.

The latest study comes from the Substance Abuse and Mental Health Administration, an agency within the Health and Human Services Department.

The data is drawn from the agency’s annual surveys in 2002, 2003 and 2004 of the civilian, non-institutionalized population. Each survey included interviews with more than 40,000 people, who were each paid $30 to participate.

Joe Gfroerer, an agency official, said most of the illicit drug use involved marijuana.

Anne Skinstad, a researcher and clinical psychologist, called the survey’s results “very worrisome” because there are fewer treatment programs than there used to be to assist employees and employers with a dependence on drugs.

However, testing programs for drug use are fairly prevalent, with 48.8% of full-time workers telling the government that their employers conducted testing for drug use.