hat the public thinks is settled science, safe and effective, and thoroughly tested by regulatory agencies may often be an illusionary world divorced from reality. A new pilot study is turning heads, grabbing mainstream headlines and causing the public to ask questions.

Time Magazine writes

In the study, each of 24 people were asked to wear different formulations — a spray, a lotion or a cream — of commercially available sunscreens for four days, and the same amount was applied over 75% of each volunteer’s body surface four times a day. (That’s the maximum dose recommend by most sunscreen manufacturers, who advise reapplying sunscreen every two hours.) Throughout the study period, the researchers took blood samples from the participants — 30 samples per person overall — to look for four common active ingredients which are used in different combinations in sunscreens: avobenzone, oxybenzone, octocrylene and ecamsule.

They found all four of the ingredients are absorbed into the blood at levels that the agency says is worth testing further for possible cancer risk.

“This supports the need for further studies to understand the clinical significance of this,” says Dr. David Strauss, director of the division of applied regulatory science at the Center for Drug Evaluation Research at the FDA and another of the study’s co-authors. “We really have a paucity of data on whether there are adverse health effects of these ingredients or not.”

Each of the four ingredients appeared at levels greater than 0.5 nanogram per mL of blood, which is the level that the International Council for Harmonization, a group of regulatory authorities that looks at scientific and technical issues involving registration of drugs, determined could be linked to higher cancer risk in animal studies.

The purpose of the current study was to establish whether the active ingredients in sunscreens were absorbed into the blood; other studies need to figure out whether the compounds have any effect of people’s health at those levels. “These results mean sunscreens don’t get a get-out-of-jail-free card [because they are used on the skin,]” says Strauss. “They have to be studied like any other drug.”