The Ocean Conservancy assembled nearly 600,000 volunteers recently to pick up trash from coastlines around the world. Considering that we are pelted nearly daily with "reports" about how much plastic packaging there is in the various garbage patches around the world, I was quite surprised by this graphic of the most commonly found items:
The filters of most butts are made of cellulose di-/tri-acetate which has a specific gravity of about 1.3, which suggests that the butts sink rather than float and hence have a difficult time making their way to the great garbage patches.
The efforts to fight pollution are mostly based on visibility of the pollution. "Out of sight, out of mind" is never more true. The butts sink and it's tough to get people fired up about them, even though they are the most common type of ocean trash. But plastic packaging floats and is visible, and it will remain visible even if it is biodegradable. And that's why I don't believe biodegradable plastics will do anything to change public perception about plastic waste. As long as people can see the plastic waste on the coastline, the biodegradability will do nothing to change their perception of it.
Since plastic pollution is leading to cities banning bags and bottles, the same logic would lead us to also be considering a ban on cigarettes. Somehow I don't see that happening, as the tobacco industry is far more powerful than the plastics industry in lobbying against such bans.