Sunscreens prevent sunburns, but beyond that simple fact surprisingly little is known about the safety and efficacy of these ubiquitous creams and sprays. FDA's failure to finalize its 1978 sunscreen safety standards both epitomizes and perpetuates this state of confusion. Environmental Working Group's review of the latest research unearthed troubling facts that might tempt you to give up on sunscreens altogether. That's not the right answer - despite the unknowns about their efficacy, public health agencies still recommend using sunscreens, just not as your first line of defense against the sun. EWG says use sunscreen, but look for shade, wear protective clothing and avoid the noontime sun before we smearing on the cream. Here are the surprising facts:

1. There's no consensus on whether sunscreens prevent skin cancer.

The Food and Drug Administration's 2007 draft sunscreen safety regulations say: "FDA is not aware of data demonstrating that sunscreen use alone helps prevent skin cancer" (FDA 2007). The International Agency for Research on Cancer agrees. IARC recommends clothing, hats and shade as primary barriers to UV radiation and writes that "sunscreens should not be the first choice for skin cancer prevention and should not be used as the sole agent for protection against the sun"

2. There's some evidence that sunscreens might increase the risk of the deadliest form of skin cancer for some people.

Some researchers have detected an increased risk of melanoma among sunscreen users. No one knows the cause, but scientists speculate that sunscreen users stay out in the sun longer and absorb more radiation overall, or that free radicals released as sunscreen chemicals break down in sunlight may play a role. One other hunch: Inferior sunscreens with poor UVA protection that have dominated the market for 30 years may have led to this surprising outcome. All major public health agencies still advise using sunscreens, but they also stress the importance of shade, clothing and timing.

3. There are more high SPF products than ever before, but no proof that they're better.

In 2007 the FDA published draft regulations that would prohibit companies from labeling sunscreens with an SPF (sun protection factor) higher than "SPF 50+." Scientists are worried that high-SPF products may tempt people to stay in the sun too long, suppressing sunburns (a late, key warning of overexposure) while upping the risks of other kinds of skin damage. Flaunting FDA's proposed regulation, companies substantially increased their high-SPF offerings in 2010.

4. Too little sun might be harmful, reducing the body's vitamin D levels.

Adding to the confusion is the fact that sunshine serves a critical function in the body that sunscreen appears to inhibit - production of vitamin D. The main source of vitamin D in the body is sunshine, and the compound is enormously important to health - it strengthens bones and the immune system, reduces the risk of various cancers (including breast, colon, kidney, and ovarian cancers) and regulates at least 1,000 different genes governing virtually every tissue in the body. (Mead 2008) Over the last two decades, vitamin D levels in the U.S. population have been decreasing steadily, creating a "growing epidemic of vitamin D insufficiency" (Ginde 2009a). Seven of every 10 U.S. children now have low levels.

5. The common sunscreen ingredient vitamin A may speed the development of cancer.

Recently available data from an FDA study indicate that a form of vitamin A, retinyl palmitate, when applied to the skin in the presence of sunlight, may speed the development of skin tumors and lesions (NTP 2009). This evidence is troubling because the sunscreen industry adds vitamin A to 41 percent of all sunscreens.

The FDA recently conducted a study of vitamin A's photocarcinogenic properties, the possibility that it results in cancerous tumors when used on skin exposed to sunlight. EWG recommends that consumers avoid sunscreens with vitamin A (look for "retinyl palmitate" or "retinol" on the label).

6. Free radicals and other skin-damaging byproducts of sunscreen.

Both UV radiation and many common sunscreen ingredients generate free radicals that damage DNA and skin cells, accelerate skin aging and cause skin cancer. When consumers apply too little sunscreen or reapply it infrequently, behaviors that are more common than not, sunscreens can cause more free radical damage than UV rays on bare skin

7. Pick your sunscreen: nanomaterials or potential hormone disruptors.

The major choice in the U.S. is between "chemical" sunscreens, which have inferior stability, penetrate the skin and may disrupt the body's hormone systems, and "mineral" sunscreens (zinc and titanium), which often contain micronized- or nano-scale particles of those minerals.

After reviewing the evidence, EWG determined that mineral sunscreens have the best safety profile of today's choices. They are stable in sunlight and do not appear to penetrate the skin. They offer UVA protection, which is sorely lacking in most of today's sunscreen products.

EWG has found a number of serious problems with existing products, including overstated claims about their perfomance and inadequate UVA protection. Many of these will be remedied when the FDA's proposed sunscreen rule takes effect. But even after the rule is enacted, gaps will remain. FDA does not consider serious toxicity concerns such as hormone disruption when approving new sun filters, and the new rules would fail to measure sunscreen stability despite ample evidence that many products break down quickly in sunlight.

Environmental Working Group (EWG) works to protect kids and adults from toxic chemicals in our food, water, air and the products we use every day. The above information is from their website.