Sunscreens have been known to prevent skin damage by reflecting, absorbing, and or scattering UV rays
While sunscreens are widely used as a first line of defence against skin cancer, concerns have been raised against them for their effects on endocrine, reproductive, developmental outcomes. A new study now claims that active ingredients in sunscreen can end up in your bloodstream, posing serious questions whether the cosmetic product needs to be regulated like medicines before use?
The four-group pilot study, led by the US Food and Drug Administration (FDA) researchers and published in the Journal of the American Medical Association (JAMA), involved 24 healthy volunteers, to determine whether the active ingredients — avobenzone, oxybenzone, octocrylene, and ecamsule — of four commercially available sunscreens (not named in the study) are absorbed into the body during maximum sunscreen use (four times per day for four days).
All the four ingredients tested resulted in plasma concentrations exceeding 0.5 nanograms per millilitre (ng/mL) — the threshold established by the FDA for potentially waiving some non-clinical toxicology studies for sunscreens — the clinical effect of which remains unknown.
While "the demonstration of absorption well above the FDA guideline does not mean these ingredients are unsafe, the study findings raise many important questions about sunscreen and the process by which the sunscreen industry, clinicians, specialty organisations, and regulatory agencies evaluate the benefits and risks," Robert Califf and Kanade Shinkai said in an editorial that accompanied the study in JAMA.
Sunscreens have been known to prevent skin damage by reflecting, absorbing, and or scattering ultra-violet (UV) radiation. Although many countries including Australia and the US regulate sunscreens as medicines or drugs and the active ingredients are evaluated for their safety before they are approved for use in sunscreens, little is known about the harms of systemic exposure for most active ingredients.
“Evidence that sunscreen may be systemically absorbed was indicated by studies in humans as early as 1997; in 2008, the Centers for Disease Control and Prevention demonstrated the presence of the common sunscreen ingredient oxybenzone in 97 per cent of urine samples collected as part of the National Health and Nutrition Examination Survey,” the editorial said.
“However, there is a paucity of careful and systematic study of a fundamental aspect of drug development: measurement of blood levels of active sunscreen ingredients over time when the product is used as directed,” it added.
According to the FDA, active ingredients in sunscreens that result in systemic absorption greater than 0.5 ng/mL must undergo nonclinical toxicology assessment including systemic carcinogenicity.
Although users presume that companies manufacturing and selling sunscreens have conducted necessary experiments to support the safety and effectiveness of their products. But, sunscreens have not yet been subjected to standard drug safety testing. Further, decades of widespread use clinicians and consumers lack data on systemic drug levels.
Moreover, no appropriate trials have been designed yet to understand the optimal sunscreen dose needed to achieve a balance of risk and benefit.
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