防晒霜难防晒.docx

防晒霜难防晒
Unless sun lovers continually reapply sunscreen〔2〕， agents〔3〕 in the sunscreen itself ca11〕 could potentially do more harm than good.
Unprotected skin exposed〔12〕 to UV radiation generates〔13〕 harmful compounds〔14〕 called reactive oxygen species〔15〕 or ROS. These molecules can react with cells， membranes〔16〕 and DNA， causing skin damage and signs of aging.










Hanson's research team found that three UV filters widely used in sunscreens generate ROS when skin is exposed to UV radiation. Only a few UV-filters are capable of blocking UV-A， the wavelengths〔17〕 that penetrate deeply into the skin.
"For now， the best advice is to use sunscreens and reapply them often — the Skin Cancer Foundation recommends every two hours， and especially after sweating or swimming， which can wash away sunscreen — to reduce the amount of UV radiation from getting through to filters that have penetrated the skin，" said Christopher Bardeen， an assistant professor of chemistry at UCR. "This， in turn， would reduce ROS generation."
探究人员称，除非日光浴爱好者不断地反复涂抹防晒霜，否那么防晒霜的成分本身会攻击皮肤，使身体更简单受紫外线辐射的影响。
加州大学河滨分校的科学家已经发觉防晒霜中能阻挡紫外线辐射的分子时间一长就会渗透到皮肤里，使体表更简单受紫外线攻击。
加州大学河滨分校化学系探究员克里。汉森说防晒霜在正确运用的状况下能精彩地完成爱护我们不被晒黑的工作。
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