Updated

When we think of Fourth of July, we tend to think of barbeques, fireworks and summer fun. But Fourth of July is also known for one other thing as well: It’s the deadliest weekend of the year for fatal car accidents.

According to the National Highway Traffic Safety Administration (NHTSA)—which has been tracking car crash statistics for a quarter of a century—Fourth of July almost always tops the list as the deadliest weekend on our nation’s highways.

According to NHTSA statistics, 392 people were killed in motor vehicle traffic crashes during the 2010 Fourth of July holiday period (the latest statistics available). Of those fatalities, 39 percent were in crashes that involved at least one driver or motorcycle operator with a blood alcohol concentration (BAC) of .08 grams or higher.

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But those statistics beg a further question: how many of those accidents involved drivers who had been drinking yet were under the legal threshold of .08 BAC? Indeed, the question that we really need to be asking is should a person with a BAC of .06 or .07 be legally driving?

And a further very significant question: Would lowering the legal threshold to .05 make a difference in the number of lives lost in fatal car crashes every year?

These are the questions currently being hotly debated as a result of the recent recommendation by the National Transportation Safety Board that all states reduce their legal threshold for drunken driving to .05. Much of the debate currently focuses on what we might consider semantic issues of "drunk" versus "buzzed" driving. Should "buzzed" driving be allowed?

Here's what we know: Alcohol — any amount of alcohol — negatively affects the Central Nervous System; this includes impairment of vision, lack of muscular coordination and lengthened reaction time. A new National Highway Transportation and Safety Administration chart shows that a person with .05 BAC experiences "reduced coordination, reduced ability to track moving objects, difficulty steering, (and) reduced response to emergency driving situations."

Most importantly, alcohol also impairs a person's judgment and removes inhibitions.
Put in real terms, a 180-pound man might consume four beers in one hour and have a BAC of .073-legal to drive under today's .08 threshold. A 140-pound woman who has had three glasses of wine in two hours will have a BAC of .063 — also legal to drive under today's standards.

Are we okay with this? Would you want your 21-year-old, 180-pound son getting behind the wheel of a car after he has had four beers in one hour?

It's also important to note that these BAC numbers don't factor in intervening variables, such as how tired a person is or how much they've eaten, both of which affect the impact of the alcohol in a person's system.

As a clinician and academic who specializes in the treatment of addiction, and as the Clinical Director of the Dunes, a high-end comprehensive addiction treatment program in East Hampton, New York, I certainly do not advocate a draconian zero-tolerance approach to alcohol and substance use--for people who don't have a drinking or drugging problem; if a person does indeed have a substance problem, then abstinence via recovery and treatment is the prescribed way to go.

Our experience has shown us that public policy can and has affected public health.

We know that when the legal drinking age was raised by federal decree in 1984, highway fatalities were significantly reduced. The NHTSA estimates that over 25,000 lives were saved through 2008 — almost a thousand lives a year.

In the current debate, a study by the Insurance Institute for Highway Safety has estimated 7,082 deaths would have been prevented in 2010 if all drivers on the road had blood alcohol content below .08 percent. Those are real lives.

Will lowering the BAC threshold actually affect people's behavior? For those with a drinking problem, probably not. But for the recreational drinker — who might plan their evening around a limited number of drinks — the answer is yes.

With the current BAC threshold of .08, we are putting even the casual drinker at risk because essentially we are condoning driving when one has drunk alcohol to a point of impairment. When that 180-pound man is on his (legal) fourth beer, not only is his driving ability impaired, but his judgment on whether or not he can drive — or drink more — is also impaired.

Is he "drunk"? Does that matter? If a person is killed by an alcohol impaired driver, does it really matter if we consider them "drunk" or "buzzed"?