Every year, the Environmental Working Group (EWG), a non-profit organization that uses public information to protect health and the environment, puts out a list of safe and reliable sunscreens. The list includes sunscreens from companies like Badger and California Baby, both of which use titanium dioxide as sunblock.
They also found that a form of vitamin A (retinyl palmitate) found in many sunscreens can actually speed the development of skin tumors and lesions in lab animals. Sort of defeats the purpose of sunblock, eh? You can read the full report here.
Last year we posted a great blog about Green Sunscreen and it gives you an excellent review of what to look for in a sunscreen. Personally, I use Badger SPF 30, on both myself and my 16-month-old son, and we have found it to be very effective.