Safety of Oxybenzone: Putting Numbers Table. Years of Daily Sunscreen Application Required by an Average US Woman to Reach Systemic Levels Into Perspective of Oxybenzone per Unit of Body Mass Equivalent to Those Given to Immature Rats10 xybenzone, an organic UV-B and short-wave UV-A filter, has been available for over 40 years1; Scenario Scenario Scenario it is widely used in sunscreens and other con- Characteristic 1 2 3 O 2 sumer products in the United States. The Centers for Dis- Body surface area covered, % 100 100 25 ease Control and Prevention has estimated the preva- Application dose, mg/cm2/d211 lence of oxybenzone exposure in the general US Application amount required, 30.00 15.00 3.75 population to be 96.8%.3 In the past few years, oxyben- mL/d Time required, y 34.6 69.3 277.0 zone has received increasing attention as a potentially harmful compound. Initial concerns arose when a re- port demonstrated systemic absorption of oxybenzone in humans at a rate of 1% to 2% after topical applica- For the purposes of this estimation, a generous in-use dose of 1 mg/cm2 was used,13-16 and it was assumed that cov- tion.4 Similar or higher rates of cutaneous absorption in 5-9 erage of 25% of the human BSA was limited to the face, human subjects have been observed. The potential for neck, hands, and arms.17 biological effects, however, were first published in a study 10 by Schlumpf et al demonstrating uterotropic effects in Results. The numbers of years of daily application re- immature rats after oral administration of oxybenzone; quired to obtain the equivalent amount of sunscreen un- it should be noted that the estrogenic effect detected was der the 3 scenarios are listed in the Table. less than 1 million-fold of estradiol, the positive control used. Nonetheless, this study has served as the basis for Comment. Our results indicate that both the application considerable concern among the public. regimens and time periods required to obtain systemic In assessing the potential for hormonal disruption in levels of oxybenzone equivalent per unit of body mass are humans, we decided to place into perspective the doses essentially unattainable. Our assumption is more conser- 10 of oxybenzone used by Schlumpf et al to achieve the vative. For instance, the bioavailability of the oxybenzone- 23% increase in uterine size reported in immature rats. containing rat chow used by Schlumpf et al10 may not have We performed 2 calculations: (1) we determined the been 100%, and we did not take into account the excretion equivalent amount of sunscreen required to be used topi- of oxybenzone in humans. In fact, oxybenzone has not been cally in humans to achieve the effective cumulative demonstrated to accumulate in the plasma even after amount of oxybenzone orally administered to imma- several days of topical application.6,9,18 Most relevant to this ture rats; and (2) we determined the number of years of discussion, however, is that in a human study, oxybenzone daily application required to obtain the equivalent lev- did not demonstrate significant endocrine disruption, even els of oxybenzone that the experimental animals were ex- with application of a formulation containing 10% oxyben- posed to. zone.6 In fact, after 40 years of use, we are not aware of any published study that demonstrates acute toxic effects Methods. The oral dose of oxybenzone used by Schlumpf in humans with systemic absorption of oxybenzone. 10 et al was 1525 mg/kg/d over a 4-day period. The effec- We do not intend for this exercise to serve as a basis tive cumulative dose was 6100 mg/kg. To calculate an from which to legitimize the extrapolation of data from equivalent amount of sunscreen, the following assump- immature rats to humans. In fact, basic scientific prin- tions were applied to the formula: (1) the weight of an ciples regarding the complexities of each respective bio- average woman in the United States was assumed to be logical system preclude this. Nonetheless, we hope that 11 74.6 kg ; (2) the absorption rate of topically applied oxy- this analysis helps to place into perspective the doses re- 4-9 benzone, 10%, was assumed to be approximately 2% ; ported by the in vivo study from which inappropriate con- and (3) the maximum concentration of oxybenzone in clusions have been drawn and considerable controversy sunscreen sold within the United States was assumed to has developed. be 6% (wt/vol), or 60 mg/mL.12 Steven Q. Wang, MD ([6100 mg of Oxybenzone/kgϫ74.6 kg]/2%)ϫ(1 mL of Mark E. Burnett, BS Sunscreen/60 mg of Oxybenzone)=379 217 mL Henry W. Lim, MD We then calculated the number of years of daily appli- Accepted for Publication: November 30, 2010. cation that would be required to apply 379 217 mL of sun- Author Affiliations: Dermatology Service, Memorial screen under 3 different scenarios: Sloan-Kettering Cancer Center, New York, New York (Dr Wang and Mr Burnett); Henry Ford Hospital, Detroit, Scenario 1: 100% body surface area (BSA) coverage at a stan- Michigan (Dr Lim). dard dose of 2 mg/cm2 would require 30 mL (10 950 mL/y with daily application). Correspondence: Dr Wang, Dermatology Service, Memo- Scenario 2: 100% BSA coverage at a dose of 1 mg/cm2 would rial Sloan-Kettering Cancer Center, 136 Mountain View requires 15 mL (5475 mL/y). Blvd, Basking Ridge, NJ 07920 ([email protected]). Scenario 3: 25% BSA coverage at a dose of 1 mg/cm2 would Author Contributions: All authors had full access to all require 3.75 mL (1369 mL/y). of the data in the study and take responsibility for the ARCH DERMATOL/ VOL 147 (NO. 7), JULY 2011 WWW.ARCHDERMATOL.COM 865 ©2011 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/02/2021 integrity of the data and the accuracy of the data analy- ules and/or dots, red dots and/or red lines, and scarlike sis. Study concept and design: Wang and Burnett. Acqui- structures in the center of the lesions.1 Herein, we re- sition of data: Wang and Burnett. Analysis and interpre- port 3 cases of porokeratosis of Mibelli dermoscopically tation of data: Burnett and Lim. Drafting of the manuscript: clearly showing multiple pores. Wang and Burnett. Critical revision of the manuscript for important intellectual content: Wang, Burnett, and Lim. Report of 3 Cases. Case 1. An 88-year-old man pre- Statistical analysis: Lim. Study supervision: Wang and Lim. sented with a 30-year history of multiple brown plaques. Financial Disclosure: None reported. No family history of porokeratosis was reported. Clini- cal examination revealed that brown, round, sharply de- 1. Food and Drug Administration. Sunscreen drug products for over-the- counter human use: tentative final monograph: proposed rule. Fed Regist. marcated annular plaques up to 3 cm in size were wide- 1993;58(90):28194-28302. spread on the trunk and extremities (Figure 1). 2. National Library of Medicine. Household Products Database. Bethesda, MD: Dermoscopic evaluation of the lesions showed a brown National Institutes of Health; 2010. 3. Calafat AM, Wong LY, Ye X, Reidy JA, Needham LL. Concentrations of the rim along on periphery of the lesions (Figure 2A). The sunscreen agent benzophenone-3 in residents of the United States: Na- fine pigment network, dots and/or globules, and the small tional Health and Nutrition Examination Survey 2003-2004. Environ Health Perspect. 2008;116(7):893-897. shining white or brown spots were mainly observed within 4. Hayden CG, Roberts MS, Benson HA. Systemic absorption of sunscreen af- the brown band. ter topical application. Lancet. 1997;350(9081):863-864. Staining of the skin surface with whiteboard marker 5. Sarveiya V, Risk S, Benson HA. Liquid chromatographic assay for common sunscreen agents: application to in vivo assessment of skin penetration and (the furrow ink test) clearly revealed the rims along the systemic absorption in human volunteers. J Chromatogr B Analyt Technol inside and outside of the peripheral band and multiple Biomed Life Sci. 2004;803(2):225-231. open pores with keratotic plugs (Figure 2B). Further- 6. Janjua NR, Mogensen B, Andersson AM, et al. Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate, and 3-(4-methyl- more, the furrow ink test highlighted the differences in benzylidene) camphor after whole-body topical application and reproduc- texture on the skin surface in some lesions. The texture tive hormone levels in humans. J Invest Dermatol. 2004;123(1):57-61. 7. Gustavsson Gonzalez H, Farbrot A, Larko¨ O. Percutaneous absorption of ben- was diminished and flattened in the periphery and finer zophenone-3, a common component of topical sunscreens. Clin Exp Dermatol. in the central portion of the lesions compared with nor- 2002;27(8):691-694. mal skin. Some pores corresponded to hair openings, 8. Jiang R, Roberts MS, Collins DM, Benson HA. Absorption of sunscreens across human skin: an evaluation of commercial products for children and adults. which were confirmed pathologically (Figure 3 and Br J Clin Pharmacol. 1999;48(4):635-637. Figure 4). Although the pores were observed in almost 9. Gonzalez H, Farbrot A, Larko¨ O, Wennberg AM. Percutaneous absorption all lesions, the number and distribution varied in each of the sunscreen benzophenone-3 after repeated whole-body applications, with and without ultraviolet irradiation. Br J Dermatol. 2006;154(2):337- lesion. 340. Case 2. An 89-year-old man presented with a 2-year 10. Schlumpf M, Cotton B, Conscience M, Haller V, Steinmann B, Lichten- steiger W. In vitro and in vivo estrogenicity of UV screens.