I was just reading this:
http://breakingnews.ewg.org/2012sunscreen/sunscreens-exposed/sunscreens-exposed-9-surprising-truths/
I'm not sure who EWG is but they source lot's of government and academic studies.
The effectiveness of sunscreens to protect against cancer and aging is questionable.
Sunscreens effectively reduce sunburn, but that may make cancer risk worse because you stay out in the sun more.
Effective sun protection is clothing (broad brimmed hat, long shirt and pants), staying in the shade, and avoiding mid day sun
Titanium and zinc is more effective. I've tried these and don't like them because they come off and make white everything that touches my skin. There's a question about the safety of accidentally inhaling it.
Avobenzone is better than oxybenzone. Retinol may cause cancer.
There are some other chemicals used in Europe that may be more effective but they're not allowed in the USA
You need at least 30 minutes of mid day sun per week to produce vitamin D.
etc. etc…
