The
Honest Company sunscreen contains only one active ingredient, zinc oxide, a
naturally occurring mineral known for its UV reflecting properties. (The second
lawsuit cites false advertisement for
claims of using only “natural” substances when apparently synthetic components
were included. And although zinc oxide exists naturally as zincite, it is likely
that the zinc oxide used in sunscreen is synthesized in the lab). Zinc oxide is
an effective broad-spectrum sunblock, protecting against both UVA and UVB
radiation, but adequate concentrations must be used. If you’ve ever felt like
your sunscreen just wouldn’t rub in, you’ve likely used zinc oxide, as its
large particles leave a white, opaque residue many sunscreen users dislike.
Indeed, last year, the Honest Company sunscreen contained 20% zinc oxide, and many consumers complained of the undesirable aesthetic characteristics. This year, the Honest Company more than halved the zinc oxide concentration, reducing it to 9.3%. Although this change may have improved the sunscreen’s aesthetic properties, it most certainly reduced its ability to effectively block the sun’s UV radiation.
Zinc
oxide, and its cousin, titanium dioxide, comprise inorganic sunscreen
components. These particles reflect most of the radiation, but can absorb some
of the energy. Newer sunscreen formulations typically use the nanoparticle
version of these components, reducing the pasty appearance produced by the
older, larger particles. Many sunscreens mix these minerals with the other
class of sunscreen components: organic
molecules. Organic in this sense means “carbon-containing”, and refers to
synthetic molecules made of carbon backbones. In addition to the inorganic
components, some organic sunscreen molecules also provide broad-spectrum
protection. However, the chemical structure of other molecules absorbs narrower
wavelengths, so these are more effective when mixed with other narrow-spectrum
or broad spectrum ingredients. The goal of mixing sunscreen components is to
provide a broad-spectrum, photo-stable sunscreen that has acceptable aesthetic
properties and increases the safety and effectiveness of the sunscreen.
Forbes’ contributor David Korr noted that perhaps the formulation contributed to the sunscreen failure. The sunscreen label directed users to shake well before using, likely to redistribute to zinc oxide particles throughout the lotion. However, it is possible that many people skipped this step, resulting in some very heavy and greasy applications and other light and useless applications. So, formulation and proper consumer use indeed influence the effectiveness of sunscreen.
Forbes’ contributor David Korr noted that perhaps the formulation contributed to the sunscreen failure. The sunscreen label directed users to shake well before using, likely to redistribute to zinc oxide particles throughout the lotion. However, it is possible that many people skipped this step, resulting in some very heavy and greasy applications and other light and useless applications. So, formulation and proper consumer use indeed influence the effectiveness of sunscreen.
Other
common misuses of sunscreen are applying too little or failing to reapply often
enough. The FDA tests sunscreen at 2.0-2.2 mg of sunscreen per square
centimeter of skin. To adequately cover an entire average-sized adult human
body, at least 1.0 ounce (2 tablespoons or the volume of a shot glass), is
needed.
In 2011,
the FDA mandated higher standards for sunscreen
labeling,
requiring full compliance by the end of 2012. Under the new regulations, only
sunscreens containing ingredients that absorb both UVA and UVB radiation can be
classified as “broad-spectrum”. A sunscreen product with SPF (Sun Protection
Factor) 15 or greater can state that it protects against all forms of sun
damage, including sunburn, premature skin aging, and skin cancer. Those with
SPF 2-14 can only state that they have been shown to prevent sunburn.
Additionally, “waterproof” can no longer be used; rather if appropriate, labels
can specify “water-resistant” with the length of time (either 40 or 80 minutes)
before reapplication is needed. Keep in mind that these changes did not remove
other sunscreens from the market, but merely mandated what they can claim.
Avoiding painful sunburns requires proper use of sunscreen—most importantly, actually using sunscreen whenever you are exposed to the sun for extended periods of time. |
UV radiation is more energetic than visible light, but not as energetic as X-rays; thus, it penetrates the top layers of skin, but not beyond that. |
UVA rays can penetrate deeper into the skin, reaching the dermis layer, whereas UVB penetration is limited to the epidermis. |
Contributed
by: Julia van Rensburg, Ph.D.
Narayanan DL, Saladi RN, & Fox JL (2010). Ultraviolet radiation and skin cancer. International journal of dermatology, 49 (9), 978-86 PMID: 20883261
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