Majority of sexual assaults drug facilitated

May 11 2006

Almost 62 percent of sexual assaults were found to be drug facilitated, and almost 5 percent of the victims were given classic 'date-rape' drugs, according to a new study at the University of Illinois at Chicago.

An estimated 100,000 sexual assaults are committed in the United States each year, and the FBI says that number could be three times higher if all cases were reported, said Adam Negrusz, associate professor of forensic sciences in the UIC College of Pharmacy.

Negrusz, lead author of the study titled "Estimate of the Incidence of Drug-Facilitated Sexual Assault in the U.S.," said individuals who use drugs, with or without alcohol, are thought to be at a significantly higher risk for sexual assault.

"In some cases the substances are taken voluntarily by the victims, impairing their ability to make decisions," Negrusz said. "In other cases the substances are given to the victims without their knowledge, which may decrease their ability to identify a dangerous situation or to resist the perpetrator."

In about 80 percent of the cases the victim knows the assailant, he said, "while only 20 percent of sexual assaults are opportunistic."

The study, funded by the National Institute of Justice, can be accessed via the National Criminal Justice Reference Service at www.ncjrs.gov

The study collected data from 144 subjects who sought help in clinics located in Texas, California, Minnesota and Washington state. The subjects were from all ethnic backgrounds and ranged in age from 18 to 56, with a mean age of 26.6.

Each clinic was provided with sexual assault kits and asked to enroll willing sexual assault complainants. Subjects provided two urine samples and a hair specimen and completed a questionnaire that asked them to describe the assault and any drugs they were using.

"The urine and hair specimens were analyzed for about 45 drugs that have either been detected in sexual assault victims or whose pharmacology could be exploited for drug-facilitated sexual assaults," Negrusz said.

Two types of drug-facilitated sexual assault were identified: presumed surreptitious drugging, or willful drug use by the subject.

According to Negrusz, 61.8 percent of the subjects were found to have at least one of the 45 analyzed drugs in their system; 4.9 percent tested positive for the classic date-rape drugs, and 4.2 percent of the subjects had been drugged without their knowledge.

Four of the unwittingly-drugged victims, Negrusz said, tested positive for Rohypnol, a tranquilizer 10 times more potent than Valium that has been banned in the United States.

When the subject's voluntary drug use was queried, 35.4 percent were likely to have been impaired at the time of the sexual assault.

"This study demonstrated the need for toxicological analysis in sexual assault cases," Negrusz said, noting the high percentage of subjects who tested positive for drugs. "It also demonstrated that sexual assault complainants severely underreport their illegal drug usage. This could be corrected if the administering nursing staff was better educated on taking a truthful drug history."

The study also confirmed that drug-facilitated sexual assault is more often due to the subject's own drug use, he said, rather than surreptitious drugging by the perpetrator.

Robert Gaensslen, professor and head of the UIC forensic science program, and Matthew Juhascik, who received his doctoral degree in biopharmaceutical sciences from UIC, assisted with the study.