Neither one of these seems to penetrate the skin, and sunscreens based on these ingredients appear to be safe as well as effective.

这两种物质都不会穿透皮肤，基于这两种成分的防晒霜效果好，还安全。

youdao

The variation from pink to brown not only helps to prevent sunburn but also allows appropriate amounts of sunlight to penetrate the skin to create the vitamin D3 from its inactive precursors.

从粉色到棕色的变化不仅帮助防止了晒伤，而且还让合适数量的阳光穿透皮肤从而把未激活的前体变成维生素d3。

youdao

They have successfully inoculated mice against flu using scores of tiny needles that might be referred to as “hyperdermic”, because they do not fully penetrate the skin.

他们成功地用大量的小针头为老鼠做抗流感的预防注射——可以认为是“皮内注射”，因为他们没有完全穿透皮肤。

youdao

The recording electrodes can be carried by a skull cap, and nothing has to penetrate the skin.

ECONOMIST: Bionics (I)

It is unclear whether the antioxidants in grapeseed oil penetrate the skin sufficiently to benefit the skin, dermatologists say.

WSJ: An Oil's Promises, From Cooking to Cosmetics

And so -- but apparently the ones that are being tested right now by all the big laboratories, they only can be used for skin cancer or places where the light can penetrate fairly close to the surface.

WHITEHOUSE: Backyard Discussion on Women and the Economy