As a holistic nutritionist I am sometimes asked difficult questions along the lines of "how bad is this?" and "what's worse?" and I constantly ask these questions myself. To be honest, our food supply as well as cosmetics and skincare are flawed on both sides of the conventional/organic world. My role is to help you make the healthiest decisions while keeping your priorities and goals in mind.
For most of my life, I would not touch sunscreens or sunblocks. I felt that the sun is too crucial to our health and didn't want to slather on chemicals, heat them up and bake them into my body (I also just looooved to tan). I still feel this way, however I now have hyperpigmentation that I can't ignore and I wish I would have at least used something on my poor little face.
While it's true that we have evolved with the sun and require it for adequate vitamin D, it's also true that sun really ages your skin...and it's true that we don't yet know enough about the long term effects of applying all of the chemicals found in sunscreens. As a skin care therapist, I must concede and admit that you should at least use a little something on your face and décolleté to protect it from premature aging.
The takeaway? In my own personal opinion, is moderation. I would suggest sunblock (physical barrier) vs. sunscreens (chemical barrier) as I think they are healthier and offer more protection. So far the best product I've come across has been G.M. Collin's tinted mineral BB Cream in SPF 25 (not a paid endorsement of any kind) made with Zinc Oxide and Titanium Dioxide.