As Connecticut pools and shoreline beaches open up and hot summer days start to set in, you may be reaching for a bottle of SPF to protect against UVA and UVB rays, but before you slather on the lotion, do you really know what’s inside that bottle?

According to a new study, a cancer-causing chemical may be lurking in your go-to brand of sunblock.

Valisure, a New Haven pharmaceutical testing lab, found concentrations of benzene, designated a Group 1 carcinogen by the International Agency for Research on Cancer, in 27% of the nearly 300 sunscreen and after-sun products tested.

Those findings have prompted U.S. Sen. Richard Blumenthal to demand more Food and Drug Administration oversight of sunscreens, calling for the FDA to issue an administrative order before September to address the issue.

According to the Centers for Disease Control and Prevention, benzene is formed in nature and manufactured by humans. Natural sources of benzene include volcanoes and forest fires. The chemical is a natural part of crude oil, gasoline and cigarette smoke, and is used to make types of lubricants, rubbers, dyes, detergents, drugs and pesticides, according to the CDC.

“The FDA has a responsibility to look into these products and determine for the American public what dangers there are, how can they be minimized, and whether they are safe and effective and properly labeled,” Blumenthal said.

Samples contaminated with benzene included products from brands such as Neutrogena, CVS and Sun Bum. However, it’s important to note that when Valisure tested different bottles of the same product, the concentrations of benzene were not the same. For example, the highest concentration of benzene detected in CVS Health’s After-Sun Aloe Vera Gel was 4.71 parts per million, according to Valisure. In another sample of the same product, no benzene was present.

“The problem we’re seeing appears to be contamination from the manufacturing process and not an inherent problem with sunscreen,” Valisure CEO David Light said.

According to the American Cancer Society, studies have shown that benzene exposure can lead to leukemia and bone marrow damage. When benzene use is unavoidable, the FDA requires concentrations of less than two parts per million and states that benzene “should not be employed in the manufacture of drug substances, excipients, and drug products because of their unacceptable toxicity or their deleterious environmental effect.”

“Skin absorption is particularly concerning for benzene in sunscreens since FDA studies have shown that sunscreen ingredients are found in high levels in the blood,” Light said. “Even a low concentration of benzene could result in a very high total exposure since sunscreen is often used multiple times a day and in large amounts.”

Blumenthal and Light urged the public to continue using sunscreen, however, which is crucial in preventing skin cancer. In 2018, the CDC reported that nearly 84,000 people were diagnosed with Melanomas of the skin and 8,199 people died of skin cancer.

Jessica Altro, owner of MamaBear Organics in Collinsville, makes and sells her own sunscreen.

Feeling frustrated and misled by her kids’ sunscreens with names like “pure,” “organic” or “simple” with ingredient lists that were anything but, Altro started making and selling handmade sunscreen with 10 all-natural ingredients in 2019.

She said that recalls and studies such as Valisure’s reduce the public’s trust in big store brands of sunscreen.

“People come in, and they search the ingredients, and I’m like ‘Literally, what you see in my ingredients is what it is.’ There’s nothing hidden. There’s nothing toxic. There’s nothing potent in it. I think it just comes down to trusting the product and the maker,” Altro said.