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Octyl methoxycinnamate is a chemical ingredient found in some brands of sunscreen and lip balm that blocks UV-B rays from the sun to protect the skin against harmful radiation. It is considered the most commonly used chemical for blocking UV-B rays. Controversy exists over whether or not octyl methoxycinnamate may harm humans who use products with the chemical in them. The chemical is termed octyl methoxycinnamate by the International Nomenclature of Cosmetic Ingredients (INCI), which provides names for certain chemicals and other ingredients used in soaps, cosmetics and related ingredients. It is referred to as octinoxate according to the United States Adopted Names (USAN), which provides individual names for pharmaceutical products sold in the United States.
The chemical is an organic compound formed from methoxycinnamic acid and 2-ethylhexanol. When mixed together, they form a clear liquid that does not dissolve in water. It can absorb UV-B rays from the sun but does not protect against UV-A rays. Both types of rays are dangerous to humans, and other ingredients may be included in sunblocks and lip balms to offer full protection.
Sunblock functions by absorbing certain wavelengths of light. The chemicals and ingredients in sunblocks are designed to absorb light at the specific wavelengths the sun emits. The thickness of the sunblock itself also forms a physical barrier to protect the skin as well as the chemical barrier provided from the ingredients. Different varieties of sunblock provide differing levels of protection. Thinner sunblocks may feel more comfortable to apply but may not protect the user as well as the stronger, typically thicker sunblocks.
Safety concerns over octyl methoxycinnamate arise from the possibility that the chemical may break down and absorb into the user's skin when it comes into contact with sunlight. Chemical reactions that occur then happen underneath the protective barrier a person's skin provides and may be absorbed into the body. This may lead to temporary problems such as skin irritation or long-term problems such as increasing the user's risk of developing cancer and causing the skin to age more quickly.
Though tests have been performed, no conclusive evidence has been found and it is uncertain what the exact effects of octyl methoxycinnamate are. More research is needed to determine whether or not the chemical poses a risk when used in products applied to the skin. Until then, users can try other methods to protect themselves against the sun and check the ingredients in the sunscreens and lip balms they use.
@indigomoth - For one thing, it's not an either or choice, as there are plenty of sunscreens that don't include this ingredient. And, for another, they haven't just given the chemical to rats and seen problems.
Actually, they have measured it in humans that after exposing skin to octyl methoxycinnamate and then to the sun there is an increase in free radicals in the skin. Free radicals are what cause skin cancer, and other kinds of cancer as well. Now, they don't know for sure what's actually happening, and how this affects people in the long term. And, yes, they don't know if you are more at risk using sunscreen with the ingredient, or not using sunscreen at all.
probably you're better off using it. But, since there are sunscreens which don't contain it, it's not a choice you need to make. Better to be safe than sorry and just go with a sunscreen that doesn't contain the controversial ingredient.
Personally, I think that the fuss over octyl methoxycinnamate is ridiculous. Generally, what seems to happen is they give a huge amount of the chemical to a lab animal and then make a fuss when this enormous amount no human is likely to be exposed to makes the animal sick.
On the other hand, it's been shown that use of sunscreen will absolutely decrease your risk of skin cancer.
So, you can forgo the sunscreen for some kind of perceived slight risk, and increase your chances of actually getting skin cancer, or you can just risk maybe having a slight increase of cancer risk from using octyl methoxycinnamate.
You really have to make sure that your sunblock is going to protect you from both UV-A and UV-B rays. Just protecting you from one is not enough.
UV-A is actually the kind that often isn't blocked by sunscreens and that's the one you need to check for. You might not even realize the sunscreen isn't blocking this kind of ray, because it doesn't burn your skin, but it still increases the chances of skin cancer if you are exposed to it.
Generally, if a sunscreen is recommended by a skin cancer organization, particularly a national one like the American Cancer Society, you can trust that it will block the sun properly.
But don't take it for granted, just because it says it blocks "UV rays" that it blocks both A and B.
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