The message has been clear in recent years – use sunscreen to avoid skin cancer. It seemed like common sense to follow this advice because of the thousands of people who die from skin cancer every year. The three main types of skin cancer are basal cell carcinoma, squamous cell carcinoma and malignant melanoma. Melanoma, the least common form is skin cancer, is also the most aggressive form of skin cancer and can become fatal very rapidly.
Because of widespread media campaigns by public health organizations and sunscreen companies, it became commonplace to use sunscreen products when in the sun, even for as little as 20 minutes. However in recent years some debate has arisen over how effective these sunscreen products are, and if the sunscreen products themselves present a cancer risk.
Questions on the effectiveness of Sunscreen
It has been suggested that sunscreens only protect against UVB protection and not the more dangerous UVA component of the spectrum. Because people who are wearing sunscreen believe they are safe in the sun, they are inclined to spend more time in it. Because of the additional time in the sun and lack of UVA protection, it has been suggested that individuals may be putting themselves at risk of developing melanoma.
Sunscreen may be in fact effective for protecting against the more common basal cell carcinoma, squamous cell carcinoma, but is not effective at preventing malignant melanoma. Some studies have actually demonstrated that melanoma rates have been higher in people who used sunscreen compared to those who don’t. However you have to consider whether this has been impacted by the actual period of time spent in the sun. Also the fact that fair skinned people (who are prone to skin cancer) are more likely to be in the sunscreen users category.
Other studies suggest that because the sunscreens are blocking UVB, they are preventing the body from adapting to the level of sunlight and allowing the UVA to penetrate unchecked. When exposed to the sun the body will create a photoprotectant called melanin to stop the sun deeply penetrating and damaging the skin – that is what call a “tan”. If melanin is not generated because the UVB is blocked, the UVA can bypass the sunscreen and enter the skin more easily because it has no low levels of melanin.
Keep in mind that melanoma is responsible for around 75% of all skin cancer deaths. A number of studies on mice have found that the use of sunscreen delays or prevents the more common forms of skin cancer, but does not reduce the risk of melanoma.
Sunscreen ingredients risks
It has also been suggested that the actual ingredients of some sunscreens is a cancer risk. Studies have suggested that when rubbed into the skin, 1% and 10% is absorbed into the body. This may be of concern when you consider the fact that some sunscreens have ingredients including octyl methoxycinnamate, benzophenone, oxybenzone,and octocrylene which are potentially carcinogenic.
Of those chemicals – benzophenone, oxybenzone,and octocrylene have been demonstrated to increase the number of reactive oxygen species and free radicals when exposed to UVA. That can damage DNA and lead to cancer.
Additionally, there have been toxicity studies at Missouri S&T by Dr. Yinfa Ma and Qingbo Yang which suggest the zinc oxide in sunscreens react with sunlight in a dangerous way. They found that the zinc oxide undergoes a chemical reaction that may release unstable molecules known as free radicals. The free radicals attempt to bond with other molecules and can damage DNA as well as increase the risk of cancer. However the researchers said that despite their findings, they would suggest continuing to wear sunscreen.
Other studies have also highlighted similar concerns. A study in 1999 demonstrated that there could be pathogenic cytotoxicity and carcinogenicity risks from micronized metals like titanium or zinc oxide found in sunscreens. That is the tiny particles of metal entering your body and potentially causing cancer.
Over time as the skin absorbs more of the metal and chemicals there could also be increased risk.
Vitamin D Deficiency
There is also a risk of vitamin D deficiency from the continual use of sunscreen. Studies have found that even in countries with sunny climates, like Australia, many people are vitamin D deficient. While hotly contested, some research indicates that vitamin D might play an important role in reducing cancer mortality rates.
What to do?
The best solution is to get the right amount of sun exposure and use sunscreens which avoid the worst chemicals mentioned earlier. You should continue to use sunscreen, but don’t assume that having a sunscreen on means you can stay in the sun for hours. If the warnings about UVA and melanoma are accurate, you need to limit sun exposure to a sensible amount. You should also use UV resistant clothing in conjunction with a good sunscreen if you intend on being in the sun for a long period. The best bet is to limit sun exposure to periods of 30 minutes and not during high UV times of the day.