Stefka - it's lnly confusing because there is so much misinformation around!
Because of the chemical structure alcohol, it gets into the breastmilk pretty rapidly, at the same rate as it gets into your blood - but the amount of alcohol transferred is very low.
The alcohol is diffused out of the breastmilk, back into the bloodstream. I quote:
"Unlike urine, which stores substances in the bladder, alcohol is not trapped in breast milk, but is constantly removed as it diffuses back into the bloodstream."
That quote is from this Canadian medical website:
www.cfpc.ca/cfp/2002/Jan/vol48-jan-clinical-1.asp
So, pumping and dumping, or waiting a long time, is really pointless as Nature does the job for you, at a rate of something like 1-2 hours per unit of alcohol, which is how long the average human body takes to get rid of it, via the liver.
Mothers differ in how worried they are about any of this. Small amounts of alcohol will really not affect the baby in anyway. Larger amounts have been shown to affect let down. Really massive doses of alcohol - far more than most people would ever have at one sitting - might have observable effects on the baby (mainly sedation). But even then, while it is obviously not a good thing in any way at all, the baby would get over it.
There's an element of common sense in all this. You would want to avoid all alcohol if you were expressing for a tiny pre-term baby , I think. A term, healthy baby is different. You'd prob not worry at all about occasional, moderate drinking...and you'd be very sceptical of people who tell you that you should pump and dump, 'cos if they tell you this, they are showing how little they know about how breastfeeding works.
Hope this helps!