Drug and alcohol overdoses killed more than 500 people in Maryland in 2001, with overdose-related deaths increasing nearly 16 percent over the five years starting in 1997, according to a new University of Maryland study.

The Center for Substance Abuse Research reported that 559 Maryland residents died from overdoses in 2001, up from 482 in 1997. Among researchers' other findings:

* Although drug overdoses still kill more men than women by a 4 to 1 ratio, drug deaths among women grew 76 percent -- from 68 to 120 -- during the study's five-year period.

* The racial composition of drug and alcohol overdose victims shifted, with whites making up the majority of such deaths. Fatal overdoses among whites grew 27 percent from 1997 to 2001, compared with less than a 5 percent increase among African Americans during that period. Whites now represent 52 percent of all overdose deaths in Maryland; African Americans, 46 percent.

* The number of drug and alcohol deaths in Montgomery County remained relatively stable -- 21 in 1997 and 23 in 2001. Prince George's County logged a decrease, from 38 to 25.

* The Baltimore metropolitan area accounted for 80 percent of the state's fatal drug and alcohol overdoses in 2001. That area -- which included Anne Arundel and Howard counties -- also had some of the highest rates of heroin addiction in the nation.

* The percentage of drug and alcohol overdose deaths in the Washington metropolitan area was much lower -- 9 percent. That area included Montgomery and Prince George's.

* Southern Maryland -- which included Calvert, Charles and St. Mary's counties -- registered a 2 percent increase in overdose deaths during the five-year period. That compared with a 47 percent increase for Anne Arundel, Baltimore, Harford and Howard counties.

* Marijuana is still the drug of choice among juvenile offenders -- nearly 50 percent tested positive. From 1994 to 2001, total emergency department admissions involving marijuana increased 132 percent in the Baltimore metropolitan area.

* The rate of alcohol- and drug-related deaths in Maryland was above the national average in 2000, the most recent year for which such figures are available, researchers said. Then, there were 17.5 deaths per 100,000 versus 12.2 deaths per 100,000 nationally.

"We need to pay attention to these numbers," said Eric Wish, director of the center, known as CESAR, and a professor of criminology at the university. "There are some striking trends here that need explanation."

The center conducted the study as part of Maryland's Drug Early Warning System, which has been tracking overdose statistics for several years. It bases findings on three sources: interviews with recently arrested juvenile offenders; interviews with professionals in drug treatment, law enforcement and education; plus traditional indicators of the area's drug culture, such as treatment admission data.

"This kind of information can give authorities . . . the first indication that something's changed in the drug scene," said Erin Artigiani, CESAR's deputy director of policy and governmental affairs.

"But interpreting the numbers can be tricky," she said. "We can't assume drug use itself is rising. Changes in the purity of street drugs, for example, can influence overdose rates."

Artigiani said researchers compile data but do not provide theories.

"We simply monitor substance abuse across the state and identify trends," Artigiani said. "We offer a snapshot of substance abuse, but we can't speculate why it's happening."

Once the Drug Early Warning System detects an emerging drug-use trend, it disseminates the data to state, county and local governments. CESAR researchers say, for example, that the prescription painkiller OxyContin, and other forms of the drug oxycodone, may be gaining in popularity as an alternative to heroin. Ecstasy, the widely used club drug, appears to be getting a foothold in homes and other locations.

"We've got some pretty solid leads here," Wish said. "This is the first word, not the last, but it does look like ecstasy and OxyContin are establishing themselves more firmly in the Baltimore drug scene."

OxyContin, a mainstream pain remedy approved by the Food and Drug Administration, was prescribed more than 6 million times in 2001, but it has come under intense scrutiny recently as its abuse has become widely documented.

Two Northern Virginia doctors have been implicated in alleged, widespread conspiracies to put the drugs on the black market. The nationwide investigation, which involves more than a dozen federal agencies and scores of local and state law enforcement officials, is also focusing on more than a half-dozen deaths possibly connected to prescriptions written by the doctors, including a woman who died in Fairfax County in 2000 and another -- Mary Ruth Nye, 45 -- who died of a suspected overdose in Prince William County eight weeks ago.

The Drug Enforcement Administration cites 146 cases nationally in which OxyContin was verified as the direct cause of death or a contributing factor and 318 deaths in which OxyContin was most likely involved -- a total of 464 deaths linked by investigators to the drug.

With ecstasy, Artigiani said, "Our interviews with young offenders suggest that ecstasy has moved beyond the raves, the party scene, where it debuted. Now it's gaining popularity as a drug consumed at home and other locations."