A recent study has found that most of sunscreens available fail to provide the necessary protection. I have a few friends who prefer to forgo the sunblocks entirely out of fear for the dangerous chemicals that them might contain. How do you pick the sunscreen that actually works and that is not damaging?

Is it even necessary to use a sunblock?

UVB rays cause sunburn and skin cancer; UVA rays cause aging and likely skin cancer. Because both cause damage to the skin, Sutton says, it's important to pick a sunscreen with broad spectrum protection that shields out both types of rays.

Some ingredients work better for our skin protection:

Two ingredients favored by EWG scientists are zinc oxide and titanium dioxide, for two reasons, Sutton says. "They protect us over this broad range of ultraviolet A (UVA) and UVB." And these ingredients don't tend to break down as easily as other sunscreen ingredients, according to the EWG.

Zinc oxide and titanium dioxide are classified by experts as physical blockers, which work by reflecting rays away from the skin. Other sunscreen ingredients, such as oxybenzone, are chemical blockers, which work by absorbing rays and preventing them from penetrating....

"The physical blocking sunscreens are by far the better sunscreens vs. the chemical sunscreens," says Sonia Badreshia-Bansal, MD, a dermatologist in Danville, Calif.

Newer sunscreen formulas include the ingredients avobenzone and Mexoryl SX... but 40% of Mexoryl can degrade within two hours, Sutton says.

Another new sunscreen addition, Helioplex, is a stabilizer used in sunscreens that combine avobenzone (a UVA sunscreen) and oxybenzone (a sunscreen that blocks UVB and some UVA). While they may be more stable, Helioplex products trigger the same concerns from EWG scientists as do other chemical blockers -- the risk of upsetting hormonal balance, Sutton says.

Harmful chemicals that can actually provide some health risks:

Sutton thinks some ingredients are definitely hazardous, including oxybenzone. "We have animal studies that indicate we should be concerned about hormone disruption," she says. "Oxybenzone is found to have weak estrogenic effects in fish."

Which sunblocks are safe?

Sunscreens using physical blockers (titanium dioxide, zinc oxide) are preferred by EWG scientists and the doctors interviewed by WebMD.

For shopping help, see EWG's list of recommended brands at Top 10 sunscreens. Or ask your doctor to suggest a brand.

Choose a sunscreen with an SPF of 30 or higher, Badreshia-Bansal says. And know that SPF applies only to UVB rays.

Best sunscreens for children and infants

Best for kids, says Sutton, are sunscreens that contain zinc oxide or titanium dioxide at levels of at least 7% and with an SPF of 30 or higher.... According to the American Academy of Pediatrics, parents should keep babies younger than 6 months out of direct sunlight as much as possible.

Spray sunscreens vs. cream

...most experts say creams offer better coverage and are more likely to be used properly. "The problem with sprays and actually with powders is inhalation. You can actually inhale these small particles and they can potentially damage your lungs," she says.

What about clothing?

Clothing helps but won't replace sunscreen, says Treadwell. And not all clothing is created equal when it comes to shielding from the sun's rays. "Clothing works as long as it is a tight weave," she says.

You can test the weave to see if it is tight enough, says Began. "If you shine a strong flashlight through, you shouldn't see light on the other side."

Sunscreens with physical blockers can be a little messy, stain clothing.

Shop around for different brands, Began says. "Everyone's skin reacts differently to the different vehicles [used in the sunscreens],"... Or you can look on the thickness as a blessing. The physical blocking screens "leave a little sheen on the skin," she says. So it's easy to see where you have missed.

Other tips:

Use enough sunscreen, and use it correctly, experts say. "Make sure you are applying at least an ounce to all sun-exposed areas," says Badreshia-Bansal. She recommends reapplying every two hours.

"I recommend my patients put the sunscreen on about 30 minutes to an hour before they go out the door and then reapply again when they are out in the sun," Began says. "And then, if they have a lot of sweating or have done some swimming, anything that may have decreased the concentration, they should reapply it."

You can use the SPF as a rough guide to how long the sunscreen will protect you, she says. If you use a 30 SPF, for instance, and generally burn in 10 minutes without sunscreen, you can expect about 300 minutes or five hours of protection, she says.

"We absolutely recommend wearing hats and being in the shade," Treadwell says. "And staying out of the sun [as much as possible] from 10 to 4." And wear sunglasses to protect your eyes.

Check out WebMD site for more details: 8 Burning Questions About Sunscreens: Experts Give Advice on Choosing and Using Sunscreens