We get two kinds of rays from the sun. One is UVB, and the other is UVA. UVB rays can cause sunburn and cancer. UVA can cause skin cancer, and early wrinkling and skin aging. This ray is also what the body is exposed to in a tanning bed.
Most brands of sunscreen (or sunblock) will protect from sunburn (UVB). A brand that offers "broad spectrum" protection is supposed to protect you from both UVA and UVB rays. "Only 15% of 952 products analyzed met [Environmental Working Group's] EWG's criteria for safety and effectiveness, blocking both UVA and UVB radiation, remaining stable in sunlight, and containing few if any ingredients with significant known or suspected health hazards." (1)
Only brands whose active ingredient is zinc oxide or titanium dioxide (or both) have been proven to be safe. Either of these will block harmful sun rays. These are also natural elements. Other ingredients used in sunscreens are chemicals that absorb the harmful rays — and the skin absorbs the chemicals because they break down in the sun, and some may also build up in the body.
"Zinc oxide and titanium dioxide are stable compounds that provide broad spectrum UVA and UVB protection, while the available studies consistently show very little or zero penetration of intact skin by these compounds ..." (1)
The safety of those with different active ingredients (especially those containing oxybenzone, micronized titanium dioxide, nano titanium dioxide, micronized zinc oxide, or nano zinc oxide) has not been proven. When zinc oxide or titanium dioxide is micronized or reduced to nano scale, it no longer blocks the bad rays but instead is absorbed by the body. When sunscreen is offered as a spray or pump, the ingredients have been micronized or nanonized and are then able to be inhaled.
An EWG study shows that "consumers who use sunscreens without zinc and titanium are likely exposed to more UV radiation and greater numbers of hazardous ingredients than consumers relying on zinc and titanium products for sun protection. We found that consumers using sunscreens without zinc and titanium would be exposed to an average of 20% more UVA radiation — with increased risks for UVA-induced skin damage, premature aging, wrinkling, and UV-induced immune system damage — than consumers using zinc- and titanium-based products. They contain four times as many high hazard ingredients known or strongly suspected to cause cancer or birth defects, to disrupt human reproduction or damage the growing brain of a child. They also contain more toxins on average in every major category of health harm considered: cancer (10% more), birth defects and reproductive harm (40% more), neurotoxins (20% more), endocrine system disruptors (70% more), and chemicals that can damage the immune system (70% more)." (1)
According to Dr. Cameron Hayden (University of Queensland, Australia), "It would be prudent not to apply oxybenzone to large surface areas of skin for extended and repeated periods of time, unless no alternative protection is available. There may be additional concern for young children who have less well-developed processes of elimination and have a larger [skin] surface area per body weight than adults, with respect to systemic availability of a topically applied dose." But this is exactly how sunscreen is used. (2)
Products whose active ingredient is zinc oxide or titanium oxide appear to be the safest for use by adults, males and females alike, and children. Below is a list of the safest sunscreens, in alphabetical order, and links to some (many of which probably not in every store) are provided.