For the folks that couldn't be bothered to take the time to RTFA, the Biodegradability of the balloons per the article
StPaulHusker linked to is being called into question.
I don't have a problem with the tradition as long as there is enough helium and the balloons are truly biodegradable. But if one or the other is seriously in question, it's time to do the responsible, mature thing and find a new tradition.
And there's a thread about this on the Politics tab since some folks can't help but dip into the ole' echo chamber when a topic like the environment comes up.