A colony of the soft coral known as the "bent sea rod" stands bleached on a reef off of Islamorada, Florida. Hard and soft corals are presently bleaching- losing their symbiotic algae Ð all over the coral reefs of the Florida Keys due to unusually warm ocean temperatures this summer. Months with waters warmer than 85 F have become more frequent in the last several decades compared to a century ago, stressing and in some cases killing corals when temperatures remain high for too long. TUESDAY, APRIL 12, 2016
Kelsey Roberts/USGS
A colony of the soft coral known as the "bent sea rod" stands bleached on a reef off of Islamorada, Florida. Hard and soft corals are presently bleaching- losing their symbiotic algae Ð all over the coral reefs of the Florida Keys due to unusually warm ocean temperatures this summer. Months with waters warmer than 85 F have become more frequent in the last several decades compared to a century ago, stressing and in some cases killing corals when temperatures remain high for too long. TUESDAY, APRIL 12, 2016
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(CNN) —  

It took just one day of use for several common sunscreen ingredients to enter the bloodstream at levels high enough to trigger a government safety investigation, according to a pilot study conducted by the Center for Drug Evaluation and Research, an arm of the US Food and Drug Administration.

The study, published Monday in the medical journal JAMA, also found that the blood concentration of three of the ingredients continued to rise as daily use continued and then remained in the body for at least 24 hours after sunscreen use ended.

The four chemicals studied avobenzone, oxybenzone, ecamsule and octocrylene – are part of a dozen that the FDA recently said needed to be researched by manufacturers before they could be considered “generally regarded as safe and effective.”

So, should you stop using sunscreen? Absolutely not, experts say.

“Studies need to be performed to evaluate this finding and determine whether there are true medical implications to absorption of certain ingredients,” said Yale School of Medicine dermatologist Dr. David Leffell, a spokesman for the American Academy of Dermatology. He added that in the meantime, people should “continue to be aggressive about sun protection.”

“The sun is the real enemy here,” said Scott Faber, senior vice president for government affairs at the Environmental Working Group, or EWG, an advocacy group that publishes a yearly guide on sunscreens.

“It’s not news that things that you put on your skin are absorbed into the body,” Faber said. “This study is the FDA’s way of showing sunscreen manufacturers they need to do the studies to see if chemical absorption poses health risks.”

The need to screen

According to the Skin Cancer Foundation, more Americans are diagnosed with skin cancer each year than all other cancers combined. Around the world, melanoma ranks as the 19th most common cancer in both men and women, the World Cancer Research Fund says.

In the United States, sunscreens were originally approved as an over-the-counter solution to sunburn. They came in two types: one using chemical combos to filter the sun, the other using minerals to block the sun such as titanium dioxide or zinc oxide, which leave a telltale white coating. With many people not wanting to sport a white tint, the popularity of the chemical sunscreens soared.

Because of the way they were used at the time, there wasn’t a lot of concern about a potential health impact. But that soon changed, and the FDA began to ask the industry for safety testing, said David Andrews, senior scientist at the EWG.

“They were originally used in small quantities to prevent sunburn on vacation,” Andrews said. “Now they recommend applying these every day, applying them to large parts of your body. And the FDA began raising concerns.”

A small study of sunscreen chemicals

The new FDA study enrolled 24 healthy volunteers who were randomly assigned to a spray or lotion sunscreen that contained avobenzone, oxybenzone or octocrylene as ingredients or a crème sunscreen that contained the chemical ecamsule.

The volunteers were asked to put their assigned sunscreen on 75% of their bodies four times each day for four days. Thirty blood samples were taken from each volunteer over seven days.

Of the six people using the ecamsule cream, five had levels of the chemical in their blood considered statistically significant by the end of day one. For the other three chemicals, especially oxybenzone, all of the volunteers showed significant levels after the first day.

“Looking through the results tables of the study, one thing about oxybenzone stood out,” Andrews said. “Oxybenzone was absorbed into the body at about 50 to 100 times higher concentration than any of these other three chemicals they tested.”