Sunscreen會致癌嗎？

我們塗防曬霜, 是為了減少皺紋，老年斑，和防皮膚癌。

sunscreen 本身會致癌嗎？可能會，也可能不會。但有毒性。

防曬即防UV曬。UV輻射線含有UVA，UVB和UVC。經過地球的臭氧層ozone layer後，UVC和大部分UVB被濾過。達到地麵時，是95%UVA， 5%UVB，0%UVC。所以，UVB 會被厚雲和窗玻璃過濾掉，但UVA可以穿透, 大陰天和開車時車內都是有UVA的，但基本上沒有了UVB。

UVA is a silent killer, it causes all types of cancer and aging spots and wrinkles. UVA 的穿透力強，破壞深層細胞（the Dermis layer), 而UVB隻到表層 epidermis layer（見圖，來自網絡） UVB causes sunburn, discolor on skin and some types of cancer. But，remember, UVB is the one that makes Vit D。

 

如果每天上班是在室內，我從來不用含SPF的 lotion. 因2小時後無效，反而吸入可能的毒性化學成份。若是周末去戶外玩，應該用Sunscreen。選擇最安全可靠的zinc oxide防曬霜。這是一層physical barrier，像是給皮膚穿了件薄衣，擋住了UVA和UVB，它不會被吸收到血液造成傷害。戴帽子和圍頭巾是絕對好的，可以達到SPF50的效果。coconut oil and shea butter 也是安全的，但是防曬效果差很多，比沒有好。如果是去雪地，海灘，海水，UV比正常高出至少2倍（reflector)，一定每2小時要塗一次UVA/UVB sunscreen。

在保證有10多分鍾曬太陽得到VitaminD後，戴帽子和圍頭巾，使用zinc oxide防曬霜是我的建議。對了，車窗上我也帖上阻斷UVA的FILM，amazon有的。

以下來自網絡。

new U.S. FDA data reveals chemicals in sunscreens are absorbed into the human body at levels high enough to raise concerns about potentially toxic effects.

Most sunscreens on the shelf use chemicals such as oxybenzone, avobenzone and octocrylene to block harmful rays.  However,  the chemicals, oxybenzone in particular, might disrupt normal hormone patterns in people。These molecules are chemical rings, essentially, and they absorb light。 Chemical rings are also the fundamental basis for a lot of hormones, and chemical rings tend to enter cells。Oxybenzone has been found in human breast milk, amniotic fluid, urine and blood, the FDA researchers said.

A few studies have suggested that parabens act like estrogen in the body, which can speed up the growth of breast cancer tumours。

 

A small number of studies have shown that retinyl palmitate can cause minor changes to cells when they are treated with UVA radiation。