The CDC says alcohol impairment is a factor in 31% of traffic fatalities.

On Friday and Saturday nights (presumably peak impairment time), checkpoints determine that about 3% of drivers are impaired. http://www.iihs.org/iihs/sr/statusreport/article/48/10/1

I too, as "statistically significant amount" to me means "measurable above detector error."

FWIW, http://www.allergy.org.au/patients/product-allergy/alcohol-a... says:

> The human body constantly produces small amounts of alcohol itself. Normal levels of 0.01 to 0.03 mg of alcohol/100 ml are contained in the blood. By contrast, a blood alcohol limit for driving of 0.05 per cent is equal to around 50 mg of alcohol/100 ml of blood.

Thus, according to my definition, 100% of drivers have a statistically significant amount of alcohol in their blood system, though nowhere near to the level of impairment.

It's not just high, it's ludicrously high. Over the easter weekend in my city, extensive random breath testing of almost 60,000 people caught 58 driving above 0.05 - still too high but orders of magnitude less than the GP's assertion.

One in 10^4 would be (much) more accurate.

Source: http://www.dailytelegraph.com.au/news/breaking-news/nsw-poli...

Impairment is on a continuous scale. Even a totally sober person would have their concentration slightly impaired if say they caught something out of the ordinary in the corner of their eye. If that happens at the wrong time, you have an accident.