Sunscreen use not associated with significant risk of benzene exposure, study finds

A recent study has reported sunscreen use to be not a significant contributor to benzene exposure. 

USA: Reported users of sunscreen were less likely to have increased levels of blood benzene, according to a recent study in the Journal of the American Academy of Dermatology. This suggests that the application of topical sunscreen may be associated with a low risk of systemic benzene absorption. 

Sunscreens are used widely as photoprotective agents and are available as over-the-counter drugs by the US Food and Drug Administration. Results from a recently conducted study by a pharmaceutical testing company Valisure found elevated benzene levels in 78 batches of sunscreen and after-sun care products, with some containing nearly 3 times the concentration limit fixed by the US FDA i.e 2 parts per million. Benzene is a known human carcinogen of all exposure routes whose exposure is strongly linked to hematologic malignancies. In this context, it becomes important to understand systemic benzene exposure in relation to sunscreen use. 

Against the above background, Rebecca I. Hartman, Harvard Medical School, Boston, Massachusetts, and colleagues aimed to examine the association between sunscreen use and blood concentrations of benzene in a retrospective cross-sectional analysis. 

For achieving their objective, they used data from the National Health and Nutrition Examination Survey (2003-2006; 2009-2018) for adults aged 20 years. 10,861 adults were identified with data on blood benzene and self-reported sunscreen use. Sunscreen use was determined by answering either "always," "most of the time," "sometimes," "rarely," or "never" to the question, "When you go outside on a very sunny day, for more than one hour, how often do you use sunscreen?"

Blood concentration of benzene was determined by capillary gas chromatography and mass spectrometry with selected-ion monitoring detection. Blood concentration was defined as either below or above the lower limit of detection (LLOD) (0.024 ng/mL). 

The authors found that sunscreen users of any frequency were less likely to have elevated blood concentrations of benzene than never users suggesting a risk of systemic benzene exposure from sunscreen use may be low. 

"It is possible that other factors may more strongly influence systemic benzene concentrations, including second-hand cigarette smoke, chemical products, gasoline emissions, and occupational exposures.  Although quality control screening of sunscreen products is important, addressing other sources of benzene may be more beneficial from a public health standpoint," the authors added. 

Limitations include lack of respondent detail on last application of sunscreen and total daily sunscreen use, unknown timing of blood draws relative to sunscreen use, and lack of urine benzene levels. Additionally, the data set included 2003-2006 and 2009-2018 data, prior to recent reports of benzene found in sunscreen

"Further work is necessary to characterize the systemic absorption of benzene due to sunscreens and to identify appropriate quality control measures," they concluded.