Conventional sunscreens often contain estrogenic toxins like parabens and phthalates, so many parents are switching to the more natural varieties. Sunscreens that contain titanium dioxide or zinc oxide will block the suns rays just as effectively as their more toxic counterparts.
It is still important to apply these sunscreens every 2 hours, and also after prolonged swimming.
Check out the 2014 Safe Sunscreen Guide from the Environmental Working Group.