If you’re like most people, you usually don’t step out into the blazing-hot sun unless you’ve slapped on a good amount of spray or lotion to ward off the cancer-causing UV rays that bombard us when we go outside. And for many among us, this isn’t simply a case of slathering on sunscreen when we head to the beach or to an outdoor all-day picnic—no, we need the stuff daily for our day at work, school, or simple outdoor recreation.

But according to new research from the U.S. Food and Drug Administration (FDA), the chemicals in our sunscreen don’t merely sit on top of our skin until we rinse it off. Instead, many of the active ingredients enter our bloodstream at levels far in excess of what was previously believed.

A report published Monday in peer-reviewed journal JAMA found that after applying spray, lotion and cream, there is a “systemic absorption of sunscreen active ingredients” well beyond the FDA’s recommended limits. And while it remains unclear what the effect of this seepage into our bloodstream is, the data supports a need for further FDA investigation to determine exactly what the health impact of these findings are.

Theresa Michele, director of the FDA division of nonsprescription drug products and a coauthor of the study, told Wired:

“Everyone had always thought that because these are intended to work on the surface of the skin that they wouldn’t be absorbed, but they are.” 

The data reveals how in our ongoing fight against skin cancer—the most common malignancy in the U.S. which affects an estimated 3.3 million people per year—we have applied vast amounts of sunscreen, considered an over-the-counter medication in the U.S., without having tested what the health impact could be.

In a release about the study, JAMA Dermatology editor-in-chief Kanade Shinkai and former FDA Chairman Robert Califf noted:

“Sunscreens have not been subjected to standard drug safety testing, and clinicians and consumers lack data on systemic drug levels despite decades of widespread use. Furthermore, appropriately designed trials have not yet been conducted to understand the optimal sunscreen dose needed to achieve a balance of risk and benefit when used to prevent skin cancer and melanoma.”

Researchers looked into the concentration of four active ingredients in 24 participants’ bloodstreams, including avobenzone, ecamsule, octocrylene, and oxybenzone. Participants were told to apply one of four different types of sunscreen—spray, lotion, or cream—four times per day for four days on exposed skin that was uncovered by a swimsuit, as per recommended usage.

Oxybenzone, in particular, reached the plasma concentration threshold a mere two hours after a single application and exceeded 20 ng/mL by the seventh day of the study. What makes this alarming is that the lingering presence of the sun-filtering molecules in the bloodstream remains a mystery in terms of what—if anything—this means for our bodies.

Continuing, Shinkai and Califf explained:

“The study findings raise many important questions about sunscreen and the process by which the sunscreen industry, clinicians, specialty organizations, and regulatory agencies evaluate the benefits and risks of this topical OTC medication. First and foremost, it is essential to determine whether systemic absorption of sunscreen poses risks to human health. Second, the effects of different sunscreen formulations, clinical characteristics (ie, skin type, age, presence of skin diseases that disrupt the skin barrier), physical activity level, and exposure to sun and water on systemic sunscreen levels require further study. “

U.S. sunscreen brands will now have to submit additional data regarding bloodstream absorption to the FDA. If the data shows that sunscreen doesn’t absorb beyond the toxicological threshold, makers won’t have any problem. But in case they do go beyond recommended limits, regulators will want to see what the potential risk is in terms of cancer, harm to the reproductive and endocrine systems, and other possible hazards.

In the meantime experts note that, despite this new research, the beneficial effects of sunscreen far outweigh the deadly risk of skin cancer. If the research gives you pause, however, a wide array of natural mineral based sunscreens are currently on the market, and recipes for homemade natural alternatives can be found online. Protective clothing, hats, and sunglasses can also be used to minimize exposure to carcinogenic rays and, while we should be cautious about which sunscreens to use, the new rules won’t be finalized until November.