Say you’ve had a beer or two or maybe a cocktail at one of those holiday parties. You feel perfectly capable, get into the car and start driving. A police officer sees you run a red light or notices that a headlight or taillight is off and pulls you over. The officer gives you a routine breath test. It shows only a slight blood alcohol level, far below the illegal level of .08 percent. The officer lets you off with a warning.

So everything is OK, right? Wrong, says recent research. Two groups of scientific researchers have reported in recent weeks that even a small amount of alcohol in the bloodstream can dull the brain’s behavior and make driving hazardous.

(If you are under 21, the “Zero Tolerance Law” kicks in. Since 1995, Maine law says if you are under 21, driving, and found with any measurable amount of alcohol in your body, you will lose your license for one year. But that’s another story.)

Dutch researchers reported in the journal Science that “even relatively small amounts of alcohol can adversely affect the operation of the anterior cingulate cortex.” That’s the portion of the brain that monitors behavior for errors. They found that blood-alcohol concentrations as low as .04 percent causes subjects to flunk a test involving adjusting performance to changed conditions.

Researchers at Texas A&M University reported similar findings. Dr. Maurice Dennis tested 19 men and women with various blood alcohol levels as they drove automobiles. He found that at a .04 percent level the drivers had trouble with skid control, crash simulation and maneuvering through traffic cones. “In a nutshell, what it means is you don’t have to be staggering, fall-down drunk to have driving problems if you’ve been drinking. A person may think to himself or herself, ‘I’ve only had a couple of beers so I can drive okay,’ but their judgment can be severely affected and they don’t even know it.” He found that a 150-pound man can reach the dangerous .04 level with as little as one or two beers. For a 120-pound woman, one beer will do it.

To be safe, that means not drinking at all if you are driving.