Studies Opposing
Sunscreen
Studies Supporting
Sunscreen
SUNSCREEN
UVA-Activated Synthesis of Metalloproteinases 1,
3 and 9 Is Prevented by a Broad-Spectrum
Sunscreen.
Sunscreens Containing Physical UV Blockers Can
Increase Transdermal Absorption of Pesticides
Introduction
Sunscreens are widely used as superficial barriers to prevent UV skin damage
and cancers, but also are of concern because dermal absorption is a major
source of human chemical exposure. This study by Brand, R.M., et al (2003) was
conducted to determine whether commercial sunscreens containing physical
UV absorbers titanium dioxide or zinc oxide increase transdermal absorption of
pesticides. For this study, the full thickness dorsal skin of female hairless mice
aged 6-16 weeks were used in accordance to the NIH Guide for the Care and
Use of Laboratory Animals. Four studies were conducted. First was the effect of
sunscreens containing physical UV absorbers on the transdermal penetration of
herbicide 2,4-D. Next, a study to determine if an inhibiting sunscreen could be
made using a solvent and UV absorbers. A third study was to model repeated
application of an SPF 45 sunscreen with a second dose of the pesticide and
sunscreen applied 4.5 hours later, and lastly three other pesticides (paraquat,
malathion, parathion) were tested to see if sunscreens can enhance the
absorption. The results of the first study showed five of nine tested sunscreens
showed significantly increased absorption of the pesticide 2,4-D, while the
remaining 4 also showed an increase but that was not significant. The second
study yielded that the tested UV absorbers and solvent were found to be able to
inhibit 2,4-D transdermal absorption when compared with the control group.
Next, the third study found with reapplication when the skin is not washed there
was a significant increase in the second pulse of pesticide absorption. Lastly,
after a 30 minute treatment with sunscreen, all three additional pesticides
showed significantly increased absorption. Overall, concluding from the data in
this study, sunscreen can increase the transdermal absorption of pesticides 2,4D, paraquat, malathion and parathion especially when not washed between
applications.
Sunscreens are a widely used consumer product for protection from
UV rays. Despite the use of sunscreen by consumers, skin cancer rates
continue to rise in the US. UV exposure can cause photo aging and
even cancers. Both UVA and UVB exposure pose their own threats to
health so it is recommended to use broad or full spectrum sunscreens.
UVA light can reach the dermis layer of the skin and cause alterations
to cells which may become cancerous. UVB light affects the epidermis
or top layer of the skin and causes sunburns. There is controversy over
the efficacy of sunscreen at preventing cancers and controversy for
sunscreen as a form of pollutant. However, there is evidence for
sunscreen to be protective of skin damage and ultimately DNA
damage which leads to cancers.
•
An overlooked consequence of sunscreen use is the threat to marine life it
poses. In the study Sunscreen products as emerging pollutants to coastal
waters by Tovar-Sánchez, A., et al., (2013) the effect of sunscreens introduced
into coastal marine systems in nearshore waters of Majorca Island was
studied. These sunscreens are made of organic and inorganic UV chemical
filters that enter the oceans by humans and affect marine life. These
chemicals do not biodegrade well for they are lipophilic and they are
persistent in the environment. There were three field and laboratory studies
conducted. The first was to get results for UV chemical filter levels in different
samples of surface water in three Majorca Island areas. In August-September
of 2011, the samples were collected from two areas that were near densely
populated beaches and a third location, considered a control, near an open
and scarcely used beach in a pristine area. Secondly, a study was done to
evaluate the contribution of sunscreen to the total dissolved in nearshore
beaches. Lastly, the effect of sunscreens on the growth rate of marine diatom
was tested. A permit for sampling was obtained and no endangered or
protected species were involved in the studies. The results yielded of the first
study that after a chemical analysis was done, three areas around the
Majorca Island showed four of the main chemicals used in sunscreens in the
surface waters. Even in the pristine control area detectable concentrations of
chemicals were measured. This shows a connection between shore activity
and the persistence of these products which contributes to an impact along
the whole Island. The second study showed when sunscreens dissolved in
nearshore beaches some inorganic nutrients were found that can affect
algae growth. Other studies have shown that high concentrations induce a
significant response from phytoplankton. Also discovered in the study was
metals such as aluminum and iron were in the dissolved sunscreen products
which have been shown to limit primary production, or the conversion of
energy by autotrophs to organic substances, in phytoplankton. The species of
marine phytoplankton tested for effects of sunscreen on their growth rate was
Chaetoceros gracilis. In the last study, the concentrations of sunscreen were
made higher than observed levels in the water samples to find a threshold for
toxicity. Even at low sunscreen concentration levels some inhibitory effects
were observed. This study confirms the toxicity of sunscreen on marine
phytoplankton. In conclusion, this study gives evidence of sunscreen as a
potential pollutant with negative effects on marine life and emphasizes the
importance of understanding the radiating effects of our actions and choices
as consumers on this Earth.
•
Survey Results
Tovar-Sánchez, A., Sánchez-Quiles, D., Basterretxea, G., Benedé, J. L., Chisvert, A., Salvador, A., & ... Blasco, J.
(2013). Sunscreen Products as Emerging Pollutants to Coastal Waters. Plos ONE, 8(6), 1-8.
doi:10.1371/journal.pone.0065451
•
35 Participants : Females: 25 Males: 10
Completed by students at Bridgewater State University
Everyday
N%
Brand, R. M., Pike, J., Wilson, R. M., & Charron, A. R. (2003). Sunscreens containing physical UV blockers can increase
transdermal absorption of pesticides. Toxicology & Industrial Health, 19(1), 9-16. doi:10.1191/0748233703th169oa
Sunscreen Products as Emerging Pollutants to
Coastal Waters
Jean, C., et al., (2011) reported research on the efficacy of a broad
spectrum sunscreen in preventing UVA induced -catenin activation and
the stimulation of matrix metalloproteinases. Since UVA radiation reaches
the dermis of the skin, it can stimulate matrix metalloproteinase, or MMP, to
cause degradation which can be cancerous. It has been shown that catenin can signal malignant squamous cell carcinomas and MMP can
help facilitate cancer cell progression. MMPs work in the skin work to break
down collagen and other elastic components which increase photo aging.
This study aimed to test the effect of sunscreen on -catenin translocation,
in which it was found that without protective sunscreen, the -catenin
invaded the nucleus of the cell, which causes cancer progression.
However, with the sunscreen layer, -catenin remained within the cell
membrane, unable to alter and harm the cell. Next, the effects of UVA
induced MMP expression was tested. It was found that cells, specifically
keratinocytes, irradiated through a non-quartz plate showed active
synthesis of MMPs. In contrast, the coating of the quartz plate with
sunscreen proved a reduction in MMP synthesis of MMP-9, MMP-3, MMP-1
by 65%, 80%, and 83% respectively. This study has shown that broad
spectrum sunscreen has significantly reduced the UVA transcription of catenin and the activation of MMPs which both are linked to skin cancers.
How often
sunscreen
is used
2 (5%)
Only
Only
during
while at
the
the beach
summer
N%
N%
Never
12 (34%) 16 (45%)
5 (14%)
Freshma Sophomore
n
N%
N%
Year at
Bridgewater 1 (2.8%)
State
University
10 (28%)
Total Answered
Correctly
N%
SPF stands for Sun
Protection Factor
UVA light can
penetrate to the
dermal layer of the
skin
UVB light can
penetrate to the
epidermal layer of
the skin
Sunscreen works by
absorbing light
30 (85%)
15(42%)
N%
Hours spent in
sun on average
per week
Junior
N%
11 (31%)
Less than 12
hours
N%
12-24 hours
N%
24 or more
hours
N%
Unsure
N%
12 (34%)
19 (54%)
2(5%)
2 (5%)
Yes
N%
No
N%
24 (68%)
11 (31%)
Senior
N%
13 (37%)
Other cosmetics or
products than
sunscreen used that
contain SPF
Total Answered
Incorrectly
N%
Strongly
agree
N%
5 (14%)
20 (57%)
13 (37%)
22 (62%)
5 (7%)
30 (85%)
Belief
sunscree
n use can
prevent
cancer
13
(37%)
Agree
N%
17
(48%)
Unsure Disagree Strongly
N%
N % disagree
N%
2
(5%)
3
(8%)
Conclusion
Based on the research studies reviewed, it is concluded that using sunscreen is a
preventive behavior for skin damage and cancers. According to my survey, 85 percent
of the participants did not know that SPF stood for sun protection factor and also only
7 percent knew that sunscreens work through absorbing light. It was also found that
the majority of the participants are outside on average per week about 12-24 hours, in
which sunscreen should be an integral part. Another important point from the survey
was that 14 percent reported to never use sunscreen. It is believed it would be
beneficial for consumers to understand their own behaviors and level of knowledge
with the threats and precautions of their current choices on the effects of UV light.
Also addressed in the research is the growing potential of sunscreens as pollutants
with implications for marine systems as the trend for populations is to live in coastal
areas. There is an opportunity and need for more studies to explore this implication of
sunscreen use. I concluded from this research the emphasis on the use of broad or full
spectrum sunscreen. With being mindful of sunscreen use and reapplication, one can
best protect themselves from UV light harm. Overall, this research has proven that
sunscreen can prevent cancers and other skin damage.
0
(0%)
Jean, C., Bogdanowicz, P., Haure, M., Castex-Rizzi, N., Fournié, J., & Laurent, G. (2011). UVA-activated synthesis
of metalloproteinases 1, 3 and 9 is prevented by a broad-spectrum sunscreen. Photodermatology,
Photoimmunology & Photomedicine, 27(6), 318-324. doi:10.1111/j.1600-0781.2011.00627.x
DNA Photo Protection Conveyed by Sunscreen
DNA damage is an important part of the process of cancer development
resulting from UV exposure. In the study DNA photo protection conveyed
by sunscreen by DeHaven, C., et al., (2014) skin models were used to
confirm that DNA damage is protected by sunscreens. DNA damage can
be measured by the development of sunburn cells (SBC) and
cyclopyrimidine dimers (CPDs). With UV exposure, the normal pairings and
structure of the DNA double helix can be disrupted. CPDs are the types of
lesions that result from that disruption. When solar UV energy damages the
nucleus and DNA, that cell is considered a sunburn cell. For this study, an
EpiDerm-FT™ full thickness human skin model was used. This model
contained normal human epidermal cells including keratinocytes and
fibroblasts. These tissues were prepared with one sample treated with
sunscreen of SPF30 and one not treated as a control and UV doses were
administered. The results showed that the application of sunscreen to the
skin model prior to exposure protected against SBCs. As for the CPDs, the
results showed that the sunscreen application also provided protection
against CPD formation. This study showed the effective protection of the
SPF 30 sunscreen at preventing the formation of sunburn cells and the
alteration of CPD formation to the human skin model.
•
DeHaven, C., Hayden, P. J., Armento, A., & Oldach, J. (2014). DNA photoprotection conveyed by sunscreen.
Journal Of Cosmetic Dermatology, 13(2), 99-102. doi:10.1111/jocd.12087
Evaluation of the Effectiveness of a Broad-Spectrum
Sunscreen in the Prevention of Chloasma in Pregnant
Women
Chloasma is a hyperpigmentation disorder that typically appears on the
forehead, cheeks and chin. This condition has both negative psychological
and emotional effects. This can affect up to 50-70% of pregnant women.
During the pregnancy, there is no treatment other than to use effective
sunscreen, because sun exposure increases the chloasma. Lakhdar, H. et al.,
(2016) reported research on the efficacy of broad spectrum sunscreen in the
prevention and treatment of chloasma in pregnant women. Two hundred
women of at least age 18 and less than three months pregnant were selected
for this study. Out of the 200, 185 completed the study. All gave written consent
to participate in the 12 month study. The participants applied the sunscreen
every two hours and avoided using any other products that could interfere
with the sunscreen. Three or four visits were made during the study. An inclusion
stage when the pregnancy was announced was the first meeting in which two
dermatologists noted 12 preexisting cases of chloasma. Next was an optional
three month visit, in which the effectiveness of the sunscreen was recorded as
excellent by both the participant and the dermatological evaluation. There
was next a visit at six months and lastly one at the final end of the pregnancy.
Tolerance to the sunscreen was assessed during the study and was rated as
good to excellent by 94% of the cases. As a result of the study, only five new
cases of chloasma were noted of the 185 participants. This was compared to
53% observed in the control group for chloasma formation. This study confirms
the efficacy of broad spectrum sunscreen in efforts to prevent and treat
chloasma in pregnant women.
•
Lakhdar, H., Zouhair, K., Khadir, K., Essari, A., Richard, A., Seit, S., & Rougier, A. (2007). Evaluation of the effectiveness
of a broad-spectrum sunscreen in the prevention of chloasma in pregnant women. Journal Of The European
Academy Of Dermatology & Venereology, 21(6), 738-742. doi:10.1111/j.1468-3083.2007.02185.x