"We're going to stand by 0.08 as the law," she said.

'Pretty harsh'

Clarifying alcohol's effect on the body can be tricky.

Generally speaking, the liver, brain, pancreas and stomach break down and eliminate alcohol through enzymes that convert the substance into water and carbon dioxide, the U.S. Department of Health and Human Services reports.

During that conversion, one of the enzymes metabolizes into "a highly toxic substance and known carcinogen," acetaldehyde. That substance and an alcohol-metabolizing enzyme known as cytochrome contribute to the development of cancers in the respiratory tract, liver, colon or rectum and breast, Health and Human Services research shows.

Alcohol's effect on the brain is considered harmful but somewhat uncertain. In its 24-page "Beyond Hangovers: Understanding alcohol's impact on your health," even the National Institute on Alcohol Abuse and Alcoholism states, "There still is much we do not understand about how the brain works and how alcohol affects it."

What research does show is that alcohol can slow communication between chemical neurotransmitters that carry messages between the brain's estimated 100 billion neurons. Some research indicates that acetaldehyde may contribute to that impairment. Lab animals that received acetaldehyde exhibited impaired coordination and memory and sleepiness, according to research published in 2006 in the journal Alcohol Research & Health.

Brain regions most vulnerable to alcohol include the cerebellum, which controls motor skills; the limbic system, where memory and emotion are centered; and the cerebral cortex, which connects to the nervous system and deals with the ability to think, plan, remember, solve problems and interact socially.

The metabolism of alcohol varies based on genetics, including variations in those enzymes, and environmental factors such as the amount a person drinks and his or her diet, the Department of Health and Human Services states.

"Regardless of how much a person consumes," a department report notes, "the body can only metabolize a certain amount of alcohol every hour," an amount "that varies widely among individuals and depends on a range of factors, including liver size and body mass."

That wide variance may contribute to lawmakers' reluctance to embrace 0.05 as the new drunk.

No Illinois legislators are pitching bills to lower the legal level of intoxication, said state Rep. John D'Amico, D-Chicago, chairman of the Vehicles and Safety Committee.

"You don't want anybody driving drunk, obviously," D'Amico said. "But this would be limiting everybody to one beer. That'd be pretty harsh."

He also said the lower level "would have a domino effect." Restaurants, bars and sports stadiums would suffer.

Call for ignition interlocks

Illinois Secretary of State White, considered a leader in fighting drunken driving, is taking a pass on tinkering with the 0.08 level (adopted in 1997), a spokesman said. White is planning instead to push for legislation that would expand for repeat offenders the use of ignition interlocks — in-car breath testers that prevent the engine from running if alcohol is detected on the driver's breath, the spokesman said.

Wider use of ignition interlocks is central to MADD's efforts, too. J.T. Griffin, the organization's senior vice president of public policy, said MADD supports 0.08 as the limit of legal intoxication in large part because research over 50 years shows definitively that everyone is seriously impaired at that level. Impairment below 0.08 becomes a little more uncertain.

Griffin said pushing to make 0.08 the law "was such a tough battle to fight. We sort of established it as the across-the-board level."

MADD is taking a more practical approach — including recommending that ignition interlocks be mandatory for all DUI offenders — in continuing its fight against drunken driving. Twenty-one states and four counties in California require interlocks for all drunken driving offenders. In Illinois, first-time DUI offenders must obtain one if they want to drive.

"We're doing a lot of really positive things," Griffin said, "and we feel like we've got a lot of momentum. To shift to 0.05 really goes against what we're doing."

Like many, Griffin said impairment happens below 0.08, but "what that level is, I don't really know."

Which is why Brown's work at the simulator may be illuminating. He said he's downloaded the data file from a key 2008 project that focused on blood alcohol levels and impaired driving and will begin re-crunching the analysis in a couple of weeks. He may have preliminary results in October, he said.

But getting there won't be as exciting as watching the pod slide, tilt and spin in the research center.

"This," Brown said, "mainly involves sitting in front of a computer screen."