A new study on sunscreen is sparking national concern over the ingredients in the products used to protect our skin from UVA and UVB exposure. New research from the Center for Drug Evaluation and Research (CDER), a wing of the Food and Drug Administration has demonstrated that certain chemicals in some sunblock products can enter the body’s bloodstream after just one day of use, CNN reports.

Published earlier this week in the medical journal JAMA, the study examined four ingredients common in chemical sunscreens—avobenzone, oxybenzone, ecamsule and octocrylene—that were recently flagged by the FDA over lack of data on their safety and efficacy. The CDER study enrolled 24 healthy volunteers who were randomly assigned to spray or spread different types of sunscreen over 75% of their bodies four times each day for four days. Thirty blood samples were taken from subjects over seven days and evaluated for changes.

Five out of six study participants who used ecamsule cream had levels of the chemical in their blood researchers considered statistically significant after just one day of use. As for the three other chemicals, all participants showed significant levels after one day of use. Oxybenzone in particular was absorbed at about 50 to 100 times higher concentration than any of the other chemicals.

Researchers are somewhat concerned, since studies have shown that oxybenzone may be linked to, for example, lower testosterone levels in adolescent boys, hormone changes in men and shorter pregnancies and/or low birth weight in babies. Oxybenzone is also known to be a common allergen—and products containing the substance have been banned by some reef sites because of their links to coral bleaching.

But cancer and skin cancer safety experts say this does not mean people should stop using sunscreen. And Scott Faber, senior vice president for government affairs at the Environmental Working Group, notes, “It’s not news that things that you put on your skin are absorbed into the body,” but he points out that this study could serve as a reminder to manufacturers to do studies to determine whether such chemicals pose a legitimate health risk.

In response to the study, the Skin Cancer Foundation issued a press release, saying in part: “The sunscreen ingredients currently FDA-approved have been used in the U.S. for many years, and there is no evidence that these ingredients are harmful to humans. There is, however, substantial evidence showing that sunscreen helps reduce skin cancer risk, as well as skin aging.”

Cancer experts also noted that the report itself concludes that additional research is needed to determine the effects of potential absorption of sunscreen ingredients into the bloodstream—reiterating that people should continue to use sunscreen and not abandon sun-safe behaviors, such as seeking shade, wearing hats and sunglasses, and avoiding the sun between 10 a.m. and 2 p.m.

For those worried about the effects of chemical sunscreen ingredients, including pregnant and nursing women, experts recommend choosing products with zinc oxide and titanium dioxide, which are naturally occurring minerals present in many over-the-counter products. Consumers can also refer to the Environmental Working Group’s annual list of safe sunscreens, ranked both by efficacy and relative level of concern posed by its ingredients.

To learn more about sun exposure and cancer risk, click here.