Which sunscreen should you choose? - Mary Poffenroth
Sunscreen comes in many forms,
each with its own impacts on your body
and the environment.
With so many options,
how do you choose which sunscreen
is best for you?
To answer that question,
we first have to understand
how sunscreens work.
Sunlight is composed
of electromagnetic waves
and is our primary source
of ultraviolet radiation,
which has a shorter wavelength than
visible light and carries more energy.
UVA,
UVB,
and UVC are classified according
to their wavelengths.
Short wavelength UVC
never reaches the Earth's surface,
but UVB and UVA do.
Medium wavelength UVB rays
can enter the skin's superficial layers
and long length UVA rays
can penetrate into the deeper layers.
UVB in small amounts actually helps
us make vitamin D,
which enables our bodies to build
and maintain strong bones.
However, prolonged exposure to UVA
and UVB can damage DNA,
age your skin,
and promote the development
of potentially deadly skin cancer.
Sunscreen protects your skin
either physically by deflecting UV rays
with an inorganic blocker
like zinc oxide or titanium dioxide,
or chemically by using carbon-based
compounds to absorb UV photons
that are then harmlessly
dissipated as heat.
So, what differentiates one sunscreen
from another?
When we choose a sunscreen,
we can compare application method,
the SPF,
and the active ingredients.
Sprays can be convenient to put on,
especially when you're wet,
but a recent study found that most people
don't apply a thick enough layer
to get full protection.
And the possible health risks of inhaling
sunscreen compounds from a spray cloud
might make you consider reaching
for that bottle of lotion instead.
Opt for a sunscreen with an SPF
of at least 15, although 30 is better.
SPF is a nonlinear scale of how much
UVB radiation is needed
to give protected skin a sunburn.
SPF 15 does a pretty good job by blocking
93% of UVB rays.
You get a slight increase as SPF goes up,
with SPF 30 blocking 97%,
and 50 blocking 98%.
SPF is based on the quantity
of solar exposure.
So how much time you have before
you start to burn
really depends on a long list of factors,
including your genetics,
and when, where, and how
you spend your time in the sun.
Even though US marketed sunscreens
have been deemed safe by the FDA,
scientists are still researching
the effects of many active ingredients
on the human body.
So if you're worried
about potential irritants,
look for mineral-based formulas
with zinc oxide or titanium dioxide.
Even though they may go on
a bit thick at first,
they're less irritating than carbon-based
chemical sunscreens.
These mineral-based sunscreens
are preferential for the environment, too.
If you plan on catching rays
while splashing in a river or the ocean,
keep in mind that carbon-based
chemical sunscreens
can harm marine life.
Take coral reefs, for example.
Although they cover less than 1%
of the Earth's underwater surface,
they're home to nearly 25% of all
fish species,
making them the most diverse
and productive marine ecosystems.
Research shows that carbon-based
chemical sunscreen ingredients,
like oxybenzone, butylparaben,
octinoxate, and 4MBC
contribute to a stress condition called
coral bleaching in corals,
which are living creatures.
Exposure to these organic compounds
results in the death
of the coral's symbiotic algae.
In addition to providing
a reliable food source,
these algae give coral their brilliant
rainbow of colors.
Without them, corals turn a bleached white
and are susceptible to disease
and possibly death.
And once the coral dies,
the entire reef ecosystem
is not far behind.
So you're now ready to make an informed
choice when picking out your next sunscreen.
SPF is clearly labeled on the front.
On the back under "active ingredients,"
you can find whether zinc oxide,
titanium dioxide,
and those coral-harming components
are present.
Taking a bit more time to check
can be well worth it
for both you and the environment.
