Sunscreens Made Simple - Neera R. Nathan, MD, MSHS Instructor of Dermatology Harvard Medical School - Massachusetts General Hospital ...
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Sunscreens Made Simple
Neera R. Nathan, MD, MSHS
Instructor of Dermatology
Harvard Medical School
Clinical Investigator, Manstein Lab
Cutaneous Biology Research Center
Massachusetts General Hospital
Disclosures
Neither I nor my spouse/partner has a relevant
financial relationship with a commercial interest
to disclose.
Objective • To help healthcare professionals of all backgrounds address some of the most common sunscreen questions encountered in clinical practice
Common Sunscreen Questions • What does “broad spectrum” mean? • What’s the difference between “chemical” and “physical” sunscreen? • Is sunscreen safe for me? • Is sunscreen safe for the environment? • Is higher SPF better? • Is the sunscreen in my make-up enough?
Decode the Sunscreen Label
What Does “Broad-Spectrum” Mean?
• “Broad-spectrum” sunscreen
– Protects against harmful ultraviolet rays, including:
• UVA (protection against skin aging1)
• UVB (protects against sunburns)
– What does it NOT protect against?
• Visible light (exacerbate dark spots!)
1Yaar, M., & Gilchrest, B. (2007). Photoageing: Mechanism, prevention and therapy. British Journal of
Dermatology, 157(5), 874-887. doi:10.1111/j.1365-2133.2007.08108.x
What Is Visible Light?
• Comes from both natural
(sunlight) and artificial
sources (device screens)
• Exacerbate post-
inflammatory
hyperpigmentation or
melasma1
– Especially true for people with
dark skin tones
1Impact of long wavelength UVA and visible light on melanocompetent skin. (2008). Journal of Investigative
Dermatology, 58(2). doi:10.1016/j.jaad.2007.10.513
How Do You Block Visible Light?
• Tinted sunscreen
– Look for pigmentary titanium
dioxide or iron oxide on the
label
– Range of shades and various
formulations
• Photoprotective clothing
Decode Sunscreen Label
What’s the Difference Between “Chemical”
and “Physical” Sunscreen?
• May be misnomers1 and the term
“chemical” has a negative connation
• Organic (“chemical”) UV filters
– i.e. ensulizole, octisalate, homosalate,
octocrylene, octinoxate, oxybenzone,
avobenzone
– Broad-spectrum (UVA & UVB)
• Usually combination of organic
filters used to achieve this
– Generally rub on clear
• Includes spray-on formulations
1Geisler,
A. N., Austin, E., Nguyen, J., Hamzavi, I., Jagdeo, J., & Lim, H. W. (2021). Visible light Part Ii.
photoprotection against visible and ultraviolet light. Journal of the American Academy of Dermatology.
doi:10.1016/j.jaad.2020.11.074Decode the Sunscreen Label
What’s the Difference Between “Chemical”
and “Physical” Sunscreen?
• Inorganic (“physical”) UV filters
– I.e. titanium dioxide and zinc oxide
– Reflect & absorb UV
– Broad-spectrum (UVA & UVB)
• When large particles, have
some protection against visible
light
– Can be very chalky
• Usually nanosized
1Geisler,
A. N., Austin, E., Nguyen, J., Hamzavi, I., Jagdeo, J., & Lim, H. W. (2021). Visible light Part Ii.
photoprotection against visible and ultraviolet light. Journal of the American Academy of Dermatology.
doi:10.1016/j.jaad.2020.11.074Are Sunscreens Safe?
• There is not currently evidence to suggest that use of sunscreens
containing organic filters legally sold in the United States are
unsafe
– Results of two JAMA studies1,2 suggest that certain sunscreens
containing organic (“chemical”) UV filters are systemically absorbed
• Unclear significance, if any, for human health
– In vitro and animal studies have shown that high levels of oxybenzone
may cause endocrine disruption3
– The FDA and the AAD still recommend sunscreen use along with other
photoprotection while further research is being conducted
– Oxybenzone is a known contact allergen in humans
1 Matta, M. K., Zusterzeel, R., Pilli, N. R., Patel, V., Volpe, D. A., Florian, J., . . . Strauss, D. G. (2019). Effect of sunscreen application under maximal use
conditions on plasma concentration of sunscreen active ingredients. JAMA, 321(21), 2082. doi:10.1001/jama.2019.5586
2Matta, M. K., Florian, J., Zusterzeel, R., Pilli, N. R., Patel, V., Volpe, D. A., . . . Strauss, D. G. (2020). Effect of sunscreen application on plasma
concentration of sunscreen active ingredients. JAMA, 323(3), 256. doi:10.1001/jama.2019.20747
3 S. Kim, K. ChoiOccurrences, toxicities, and ecological risks of benzophenone-3, a common component of organic sunscreen products: a mini-
review
Environ Int, 70 (2014), pp. 143-157Are Sunscreens Safe?
• Inorganic (“physical”) UV blockers are generally
recognized as safe and effective (GRASE) per
FDA
– Titanium dioxide and zinc oxide do not get
absorbed into the bloodstream
– Best for sensitive skin
• Little guidance on photoprotection from visible
light, including tinted sunscreens
1https://www.fda.gov/news-events/fda-voices/shedding-more-light-sunscreen-absorptionWhat About Coral Reefs? https://www.thenationalnews.com/uae/environment/hope-for-coral-reefs-after-scientists-find-resilient-species-1.885462
Are Sunscreens Safe for
the Environment?
– Beginning January 2021, Hawaii has banned OTC sales of
sunscreens containing two organic filters due to concern
over coral bleaching1
• Oxybenzone and octinoxate
• In vitro evidence that organic filters are toxic to coral
larvae, but at doses much higher than what is present in
the environment2
– Organic UV filters has been found in different types of fish3
• Concern over bioaccumulation
– Organic UV filters also found in water sources and is
difficult to remove in treatment plants3
1Geisler,A. N., Austin, E., Nguyen, J., Hamzavi, I., Jagdeo, J., & Lim, H. W. (2021). Visible light Part Ii. photoprotection against visible and ultraviolet light. Journal of the
American Academy of Dermatology. doi:10.1016/j.jaad.2020.11.074
2Downs C.A., Kramarsky-Winter E., Segal R., et. al.: Toxicopathological effects of the sunscreen UV filter, oxybenzone (benzophenone-3), on coral planulae and cultured
primary cells and its environmental contamination in Hawaii and the U.S. Virgin Islands. Arch Environ Contam Toxicol 2016; 70: pp. 265-288.
3Schneider, S. L., & Lim, H. W. (2019). Review of environmental effects of oxybenzone and other sunscreen active ingredients. Journal of the American Academy of
Dermatology, 80(1), 266-271. doi:10.1016/j.jaad.2018.06.033Recommendations for People
Concerns About Sunscreen Safety
1. Wear photoprotective clothing, including
sunglasses and hats, and cover as much
exposed skin as possible
– Look for clothing with an ultraviolet protection
factor (UPF) of 50+
• Measures protection through clothing
• Blocks UV and visible light
2. Apply SPF30+ sunscreens with inorganic
(“physical”) filters to remaining exposed skinSun Protective Clothing
Slide adapted from Dr. A. Shadi KouroshDecode Sunscreen Label
Is Higher SPF Better?
• The American Academy of Dermatology
(AAD) recommends broad-spectrum SPF 30+
sunscreen to exposed skin everyday1
– When worn as directed, someone who burns in 10
minutes could stay outside 30x longer (5 hours)
without burning while wearing SPF30 sunscreen
– Blocks 97% of UVB (causes sunburn)
1https://www.aad.org/public/everyday-care/sun-protection/sunscreen-
patients/sunscreen-faqsIs Higher SPF Better?
• To achieve the SPF on the label, sunscreen needs to be applied
at a dose of 2mg/cm2
– “teaspoon” rule suggests use of 1 teaspoon to head/neck, 2
teaspoons to the torso, 2 teaspoons to each extremity1
• Functionally, most individuals UNDER-APPLY sunscreen
– As such, effective SPF used is usually less than the
SPF on the label
– Even though differences in protection between SPF30 and
SPF100 are small (97% v 99%), over time, cumulative
increase in UV damage may add up
1Stenberg, C. (1985). Sunscreen application and its importance for the sun protection factor. Archives of Dermatology, 121(11), 1400-1402.
doi:10.1001/archderm.121.11.1400
2Geisler, A. N., Austin, E., Nguyen, J., Hamzavi, I., Jagdeo, J., & Lim, H. W. (2021). Visible light Part Ii. photoprotection against visible and ultraviolet light. Journal of the
American Academy of Dermatology. doi:10.1016/j.jaad.2020.11.074Is The Sunscreen in
My Make-Up Enough?
• Cosmetic formulations contain pigments that
provide modest UV and visible light
protection through oxidation that affects skin
color1
• Many foundations are formulated with SPF
• Tinted Moisturizers
• BB/CC Creams: “Beauty Balm” - All-in-
one moisturizer, foundation and
sunscreen (inorganic filter), some with
anti-oxidants +/- “Color Corrector”
Remember the “teaspoon” rule
• Most users do not apply enough product
amount to achieve coverage listed on label
• “teaspoon” rule
• Layering with broad-spectrum or tinted
sunscreen may be best option
Slide adapted from Dr. A. Shadi Kourosh
1Geisler, A. N., Austin, E., Nguyen, J., Hamzavi, I., Jagdeo, J., & Lim, H. W. (2021). Visible light Part Ii. photoprotection against
visible and ultraviolet light. Journal of the American Academy of Dermatology. doi:10.1016/j.jaad.2020.11.074Common Sunscreen Questions • What does “broad spectrum” mean? • What’s the difference between “chemical” and “physical” sunscreen? • Is sunscreen safe for me? • Is sunscreen safe for the environment? • Is higher SPF better? • Is the sunscreen in my make-up enough?
Thank you!
Please email me with any questions:
nnathan2@mgh.harvard.edu
Dr. A. Shadi Kourosh
Dr. Dieter MansteinYou can also read
