It emits low-energy, beta particles which are a type of electron that can't penetrate skin.

它会放射出低能量的β粒子——一种无法穿透皮肤的电子。

As for their penetrating power, beta particles are typically stopped by a few millimeters of aluminum.

至于它们的穿透力，β 粒子通常会被几毫米的铝挡住。

The second type of decay that can occur is beta decay, when an unstable nucleus emits a beta particle, which is just an electron.

第二种可能发生的衰变是 β 衰变，当不稳定的原子核发射出 β 粒子时，它只是一个电子。

There's some evidence that once inside the body, beta particles might even be better at causing cancer than the higher-energy gamma rays that come from things like radium.

有证据表明，一旦进入体内，β粒子甚至可能比来自镭等物质的高能量γ射线更容易致癌。