Lately, many readers have been asking me my thoughts on the recent report by Nanyang Technological University (NTU) on the nano-particle sized Zinc Oxide that may cause cancer.
I first heard the news about a sunscreen and cosmetic ingredient that may cause cancer from the Chinese radio station while on my way home from work early last week. The Chinese station didn’t mention the name of the ingredient. Upon reaching home, I was actually shocked and disappointed to realize that it is the popular and potent sunscreen ingredient Zinc Oxide. And it is the nano-particle sized Zinc Oxide with very small particles that can absorb into the skin cells and may cause cancer as it has claimed.
Zinc oxide, one of the 17 FDA approved active sunscreen ingredients, is an excellent broad spectrum UV reflector that protects the harmful UVA and UVB rays. Other than Titanium Dioxide, Zinc oxide is considered the safest and most effective physical sunscreen ingredient available.
When used as an ingredient in sunscreen, Zinc Oxide, a mineral powder, is claimed to sit on the skin’s surface scattering and absorbing ultraviolet rays without being absorbed into the skin. It is non-irritating and non-allergenic, therefore it is claimed to be very suitable for sensitive skin.
As compared to the normal Zinc Oxide powder that gives an opaque white cast, the nano-particles Zinc Oxide appears transparent when applied to the skin. Because of its small particles, the nano size Zinc Oxide does not scatter light and therefore does not appear white. It is found to have superior UV blocking properties compared to its normal size particles. Therefore it is commonly used in sunscreen creams and lotions to protect against sunburn and other damage to the skin caused by ultraviolet light.
Many controversial researches have shown that these nano-sized particles Zinc Oxide may cause potential health risks. They are claimed to enter healthy human cells like the blood or the lungs and damage DNA. However, there are also reports show that particles of Zinc Oxide greater than 30nm, when applied to the skin, do not get absorbed into the body, do not enter the bloodstream, and are not a threat to human health.
Although there has been concern that they might be absorbed into the skin, comprehensive reviews of the medical literature have not uncovered any risk.
Here’s an interesting link on a study that zinc from sunscreen is absorbed through the skin : http://www.abc.net.au/pm/content/2010/s2830477.htm
Despite all the hoo-ha being made by NTU, there’s nothing to be proud of in them anyway. The chemists from Nanyang Technological University (NTU) are not the first to uncover the safety issue over nano-particle sized Zinc Oxide. Many studies have been reported by scientists from various part of the world regards to this matter, way before the recent study done by NTU. So what’s the big deal NTU and why triggers the alarm now?
Anyway, NTU researchers have reassured the public that there is no cause for alarm, as the research is still in its preliminary stage. Cheh!!
This study was for the purpose of triggering further in-depth research into the safer use of nanomaterials and the team is working with regulatory bodies such as the Health Sciences Authority (HSA) to define a safe scope of use.
Although nano-particles Zinc Oxide in powders can be a health risk when inhaled, fortunately this is not a concern when the powder is dispersed in a cream base sunscreen. So does that mean the mineral makeup powder foundation with Zinc Oxide is at risk?
Ironically, there are also studies showing that chemical sunscreen ingredients, which are molecular in size and hence significantly smaller than nano-particles, are absorbed into the blood. And therefore the use of nano sized mineral sunscreens over chemical sunscreens is recommended actually. Confused? Me too!
So one more piece of bad news on Zinc Oxide I have found online. Zinc oxide can also be photo-reactive which means that when it is exposed to UV light it can generate free radicals that can damage living cells. To combat free radicals, consuming food or applying products with antioxidants is the best option.
One other thing that puzzled me is : isn’t the Zinc Oxide a mineral ingredient and not a chemical ingredient as what NTU has claimed?
Well after some googling, I found out that ordinary white powdered zinc oxide can actually be produced in the laboratory by electrolyzing a solution of sodium bicarbonate with a zinc anode. Zinc hydroxide and hydrogen gas are produced. The zinc hydroxide upon heating decomposes to zinc oxide. But I’m not too sure if it is the same Zinc Oxide used in cosmetics though.
I have tried searching for the sunscreen products that use nano-particles Zinc Oxide but in vain. I wouldn’t be able to tell if the products are formulated with nano-particles or normal size Zinc Oxide.
Well to be safe, I will refrain from using any sunscreen products that contain Zinc Oxide for the meantime. I guess there are other safer and effective sunscreen ingredients out in the market such as Mexoryl SX, a synthetic sunscreen agent developed and patented by L’Oreal. Sweat!