20 | New Scientist | 27 July 2019SUMMER has returned to the
northern hemisphere, and many
will be reminded to slather on the
sunscreen to keep sunburn at bay.
But after recent developments,
some may hesitate, wondering if
sunscreen is totally safe.
In the past five months, the
US body that regulates sunscreen
has declared that 12 active
ingredients used in sunscreens
might not actually be safe. And
in a study published in May, the
organisation found that four
of these ingredients enter the
bloodstream through the skin.
The revelations have come
from the US at least partly because
sunscreens there are, unusually,
regulated as over-the-counter
drugs. But similar products are
sold around the world. And
sunscreens may be only the tip
of the iceberg, with generalcosmetics starting to come under
scrutiny too.
There is no need to drastically
change your behaviour just yet
as none of the commonly used
ingredients have been decidedly
declared unsafe, but questions
remain. Why are these concerns
only coming now? And how
worried should we be about the
stuff we put on our skin?
In most countries, sunscreens
are classified as cosmetic products.
In the European Union, they
are subject to rules on which
ingredients can be used, and
must pass tests for skin and eye
irritation, for example.
In the US, however, sunscreens,
including cosmetics marketed
with a sun protection factor, are
regulated like drugs because they
make specific health claims: to
reduce the chances of sunburn,
skin ageing and skin cancers. The
US Food and Drug Administration
(FDA) issues rules for industry to
follow and new drugs must“There is some evidence that
oxybenzone may be a hormone
disruptor, and act as a very weak
oestrogen,” says Kim Harley
at the University of California,
Berkeley. Some cancers have
an oestrogen component. “The
issue is that there’s so much we
don’t know,” she says.
Similar questions have been
raised about the other ingredients.
The FDA issued new proposed
rules in February this year, saying
that only two of the original
16 “safe” ingredients can actually
be considered safe and effective:
zinc oxide and titanium dioxide.
Of the remaining ingredients,
two will be banned, while the rest,
including oxybenzone, have big
question marks over them.
Then, in May, the FDA published
a study looking at four of these
ingredients, again including
oxybenzone. Researchers
including Theresa Michele, who
directs the organisation’s Division
of Nonprescription Drugs, applied
one of four sunscreen products
to 24 volunteers, following the
products’ instructions for
maximal use, four times a day
for four days. They then looked
for traces of the chemicals in the
volunteers’ blood.
Not only did all four chemicals
turn up in the blood, they did so
at levels that demand further
research to make sure they aren’t
causing cancer, says Michele.
Dermatologist Kanade Shinkai,
based at the University of
California San Francisco Medical
Center, says she thought
sunscreen would pass through the
skin. But what was a surprise was
that it was absorbed after the first
application and that it persists for
days, she says.
So, is it time to throw out your
sun protection? Not so fast. “I
think sunscreen is important
because we know the sun causesSun protectionKO
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News Insight
Sunscreen safety fears
Common ingredients in sunscreens have question marks hanging over
them. Should we be worried, asks Jessica Hamzelouundergo rigorous clinical trials in
people, but because sunscreens
were already marketed before
these rules took effect, their safety
has been reviewed after the fact.
Although the first sunscreens
came onto the market in the 1920s,
it took the FDA 50 years to issue
any regulations. In 1978, it finallyissued a tentative set of rules and
updated them in 1999, listing
16 active ingredients as safe.
However, these ingredients are
now coming under scrutiny.
Take oxybenzone, for example,
which is widely used in
sunscreens. In 2008, the US
Centers for Disease Control and
Prevention found traces of it in
the urine of 97 per cent of the 2500
people it tested. Other studies have
found the chemical in breast milk.“Only two of the original
16 ‘safe’ ingredients can
actually be considered
safe and effective”Sunscreen protects the
skin, but we know less
about its other effects