You can ask to have glass lenses instead of plastic. I like the light weight of the plastic, and I insist on the anti-scratch coating, or I'd be buying new ones every couple of months.

The warnings about various plastics are interesting. They are coming at the same time that various cancers are being connected to belated virus reactions. We have known for some time about the Human Pappiloma Virus causing common forms of cervical cancer. Now there is research that may suggest a connection between chickenpox and measles and later incidence of liver and lung cancers.