Last month I posted a story on our website from our sister publication Plastics & Rubber Weekly about a pair of scientists who want governments around the world to classify certain plastic waste as "hazardous." I thought that would be the end of the discussion. But the debate is continuing to get attention, so let's take a closer look.

The issue was raised in the "Comment" column in the periodical Nature. Two California-based graduate students, Chelsea Rochman and Mark Anthony Browne, claimed that labeling some plastics — specifically PVC, polystyrene, polyure­thane and polycarbonate — as hazardous would cut health risks and protect wildlife.

The pair wrote that discouraging use of those polymers "could boost research on new polymers and replace the most problematic materials with safer ones."

The precautionary principle is key to their point — the idea that regulators should take action now and force manufacturers to prove that their materials are safe.

I sympathize with the authors' concern about plastic marine debris. It's a real problem that the global plastics industry was slow to address. But now we're finally starting to see some action. The idea that the answer to this problem is to declare large segments of the plastic industry "hazardous" is, in my opinion, an extreme and unreasonable approach.

First, the safety of PVC, PS, PU and PC have been investigated for years. While the fine details may be debated, the government agencies charged with deciding chemical safety have largely determined that these plastics are not "hazardous."

Second, I don't anticipate that governments will be eager to take on all the legal and regulatory burdens that would result from such a determination. Better to let them focus on materials that clearly are dangerous, rather than keeping them busy with lesser threats.

Is that a common-sense approach? I thought so — and that's why I thought it would be the last word on the subject.

But the idea has legs. I'm seeing more news coverage of the Nature column, including a call for reader comments on the topic from The New York Times' "Rendezvous" blog.

Unfortunately, the fact that two scientists can float an idea like this and have it taken seriously is evidence that the public image of plastics is not nearly as high as many in the industry would like.

Loepp is PN editor and author of "The Plastics Blog."