Home' Australian Pharmacist : Australian Pharmacist December 2014 Contents Australian Pharmacist December 2014 I © Pharmaceutical Society of Australia Ltd.
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the possible instability of the chemicals
in the sunscreen, check the expiry date
of the preparations. Discard and do not
use if it has expired.
Nanoparticles range in size between
one and 100 nanometres.
sunscreens contained micro-sized
particles (200–500 nanometres)
requiring a thick application to provide
a barrier to reflect and scatter UV rays.
Although effective, they were not
visually appealing due to the thick,
opaque, white layer on the skin. By the
1990s, nano-sized particles of metal
oxides were included in sunscreens
making these preparations invisible on
the skins and increasing their use.5
Sunscreens contain nanoparticles
(20–100 nanometres) of titanium
dioxide and zinc oxide that absorb and
reflect/scatter UV radiation.
health safety concerns were raised
about the use of nanoparticles in
sunscreens. It was suggested that the
metal oxide nanoparticles in sunscreen
could penetrate the skin, generate
free radicals and cause cancers.
However, recent Australian research
using imaging techniques to observe
the body’s response to zinc oxide
nanoparticles, showed that although
nanoparticles are absorbed by the
body, the body has the capacity to both
identify and remove these particles
before they enter the blood stream.
This research demonstrated that
although nanoparticles can penetrate
human skin, the body’s immune system
breaks down the nanoparticles directly
removing the risk of free radical and
Prof Ian Oliver from
Cancer Council Australia, stated ‘this
research shows us conclusively that the
nanoparticles in sunscreen are unlikely
to cause harm to beach-goers’.
on these findings, nanoparticles are
considered safe for humans.
Additionally sunscreens with titanium
dioxide nanoparticles are generally
coated with dimethicone or silica which
prevents clumping of these particles
and inhibit free radical generation.
Pharmacists are encouraged to provide
current and evidence-based information
to consumers about nanoparticles in
sunscreens to combat this negative
image. Childhood exposure to the sun is
an important contributing factor to skin
Sunscreens are considered safe
and recommended for use in adults and
in children, including babies.
There is further information on the
Therapeutic Goods Administration (TGA)
Sun protection factor
The amount of sun protection provided
by a sunscreen is rated using the
worldwide sun protection factor (SPF)
system. This system determines the
ratio of UV radiation dose for minimal
erythema (redness) to appear after
sunscreen has been applied, compared
to the minimal erythemal dose (MED)
without sunscreen. The SPF system
rates a sunscreen’s effectiveness of
preventing sunburn (due to UVB rays)
not its effectiveness at blocking UVA
rays.5 See Box 1.
When testing sunscreens, an application
of 2 mg/cm2 is applied to the skin. This is
a thick application and people do not
usually apply this amount of sunscreen.
Therefore, the expected sun protection
will not be achieved unless there is an
adequate application. An adult should
apply approximately 30 mL of sunscreen
for full body coverage.
The maximum SPF is 50+ indicating
that during testing, the sunscreen
has provided a SPF of at least 60.
Sunscreens are no longer referred to
as waterproof but as water resistant
meaning the sunscreen will not come off
the skin during swimming or exercise,
as long as it is not wiped off. However,
even if a sunscreen is described as being
‘4 hours water resistant’, it must be
reapplied every two hours to maintain
the same level of protection.
pharmacists are recommending a
sunscreen and SPF for a consumer, their
skin type (as some skin types burn more
easily), family history of skin cancer, and
the activity they are planning should be
A sunscreen with a higher SPF rating will
block more UVB rays but will not double
or triple the length of time a person can
be exposed to the sun before burning
occurs.9 See Table 2.
Currently, there is no international
standard for rating the ability of a
sunscreen to block UVA rays. Most
countries use in-vitro persistent pigment
darkening methods to determine the
UVA protection factor (UVA-PF).
Australia, the method is defined by
the International Organization for
Standardization (ISO) standard, ISO
Broad-spectrum sunscreen became
available in Australia in the mid-1990s.
Before this, only UVB-based sunscreens
For a sunscreen to be labelled ‘broad
spectrum’, it must have a4:
• minimum SPF of 8
• UVA-PF at least 1/3 of the labelled SPF
and/or critical wavelength ≥370 nm.
As the SPF increases, the UVA-PF
increases proportionally. Any sunscreen
labelled SPF ≥30 must have a UVA-PF of
at least 1/3 of the labelled SPF and be
Table 1. UV index – level, warning and action
is generally not
in the sun for
long periods of
and use sun
8, 9, 10 Very high
Adapted from the Bureau of Meteorology.
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