Is radiation dangerous? - Matt Anticole

翻译人员: 维康 廖 校对人员: Rebecca Wang

When we hear the word radiation,

当我们听到辐射这个词，

it's tempting to picture huge explosions and frightening mutations,

我们会不禁想起大爆炸 和可怕的变异，

但那并不完整。

but that's not the full story.

Radiation also applies to rainbows

辐射同适用于彩虹

and a doctor examining an x-ray.

和医生检测用的X射线。

So what is radiation really,

那么辐射到底是什么，

and how much should we worry about its effects?

对于它的影响我们又应该担心多少呢？

The answer begins with understanding that the word radiation

答案从理解辐射这个

describes two very different scientific phenomena:

描述两种完全不同的科学现象开始：

electromagnetic radiation

电磁辐射

and nuclear radiation.

和核辐射。

Electromagnetic radiation is pure energy

电磁辐射是纯能量

consisting of interacting electrical and magnetic waves

由相互作用的电磁波

oscillating through space.

在空间中振动形成。

As these waves oscillate faster,

这些波振动越快，

they scale up in energy.

能量也就成比例增加。

At the lower end of the spectrum, there's radio,

在光谱的低频端的是无线电，

infrared,

and visible light.

红外线，

和可见光。

At the higher end are ultraviolet,

位于高频端的有紫外线，

X-ray,

X射线

and gamma rays.

和伽马射线。

Modern society is shaped by sending and detecting electromagnetic radiation.

发射和检测电磁辐射构成了现代社会。

We might download an email to our phone via radio waves

我们可以通过无线电波下载一封邮件到手机上

to open an image of an X-ray print,

以打开X射线印出的一张图，

which we can see because our screen emits visible light.

我们可以看见这些是由于屏幕发出可见光。

Nuclear radiation, on the other hand,

另一边呢，

originates in the atomic nucleus,

核辐射源于原子核，

where protons repel each other due to their mutually positive charges.

带有正电荷的质子正正相斥。

A phenomenon known as the strong nuclear force

一种叫做强核力的现象

struggles to overcome this repulsion

艰难地克服这种排斥

and keep the nucleus intact.

并保持原子核完整。

However, some combinations of protons and neutrons,

然而，一些质子和原子的组合，

known as isotopes,

同位素，

remain unstable,

依然不稳定，

or radioactive.

换句话说，有放射性。

They will randomly eject matter and/or energy,

它们会随机释放出物质和(或)能量，

known as nuclear radiation,

也就是核辐射，

to achieve greater stability.

来使自己更稳定。

Nuclear radiation comes from natural sources, like radon,

核辐射来源于自然物质，例如氡，

a gas which seeps up from the ground.

一种从地下渗出的气体。

We also refine naturally occurring radioactive ores

我们也提纯自然出现的放射性矿石

to fuel nuclear power plants.

来为核能工厂提供燃料。

Even bananas contain trace amounts of a radioactive potassium isotope.

即使是香蕉都含有微量钾的放射性同位素。

So if we live in a world of radiation,

因此如果我们住在充满辐射的世界，

how can we escape its dangerous effects?

我们怎么能躲开它的危害呢？

To start, not all radiation is hazardous.

首先，不是所有的辐射都有危险。

Radiation becomes risky when it rips atoms' electrons away upon impact,

当撞击将原子的电子分开时核辐射才有危险，

a process that can damage DNA.

这是一个可以损坏DNA的过程。

This is known as ionizing radiation

这个叫做电离辐射

because an atom that has lost or gained electrons is called an ion.

因为一个已经失去或得到电子的原子叫做离子。

All nuclear radiation is ionizing,

所有的核辐射都是电离，

while only the highest energy electromagnetic radiation is.

然而电磁辐射只有最高能量的才是。

That includes gamma rays,

那包括γ射线，

X-rays,

X射线，

and the high-energy end of ultraviolet.

和紫外线的高能末端。

That's why as an extra precaution during X-rays,

那就是为什么要在X射线时额外警惕，

doctors shield body parts they don't need to examine,

医生们把不需要检测的身体部分保护住，

and why beach-goers use sunscreen.

以及为什么常去海滩的人要用防晒霜。

In comparison, cell phones and microwaves operate at the lower end of the spectrum,

对比来看，手机和微波在光谱的低频端，

so there is no risk of ionizing radiation from their use.

因此使用它们没有电离辐射的危险。

The biggest health risk occurs when lots of ionizing radiation

最大的健康危害发生在大量的电离辐射

hits us in a short time period,

在短时间内击中我们时，

also known as an acute exposure.

或急性暴露。

Acute exposures overwhelm the body's natural ability to repair the damage.

急性暴露压垮人体自然修复损害的能力。

This can trigger cancers,

这可能引发癌症，

cellular dysfunction,

细胞功能紊乱，

and potentially even death.

甚至死亡。

Fortunately, acute exposures are rare,

幸运的是，急性暴露很少见，

but we are exposed daily to lower levels of ionizing radiation

但我们每天都暴露在较低级的电离辐射下

from both natural and man-made sources.

既来自于自然，也来自于人造物质。

Scientists have a harder time quantifying these risks.

科学家们很难给这些危害定量。

Your body often repairs damage from small amounts ionizing radiation,

你的身体经常修复小量电离辐射造成的损害。

and if it can't,

如果无法修复，

the results of damage may not manifest for a decade or more.

损害带来的结果十年或更久都不会显现。

One way scientists compare ionizing radiation exposure

科学家们区别电离辐射暴露的一个方法

is a unit called the sievert.

是一种叫西韦特的单位。

An acute exposure to one sievert will probably cause nausea within hours,

一西韦特的急性暴露下可能会造成几个小时的恶心，

and four sieverts could be fatal.

四西韦特可以致命。

However, our normal daily exposures are far lower.

不过，我们正常生活的暴露度要低好多。

The average person receives 6.2 millisieverts of radiation

平均每个人每年累计接收

from all sources annually,

6.2毫西韦特辐射

around a third due to radon.

大约三分之一是氡。

At only five microsieverts each,

口腔x光一次仅5微西韦特，

you'd need to get more than 1200 dental X-rays

你需要1200次以上的口腔X光

to rack up your annual dosage.

才抵得上每年的量。

And remember that banana?

还记得香蕉吗？

If you could absorb all the banana's radiation,

如果你把香蕉所有的辐射都吸收了，

you'd need around 170 a day to hit your annual dosage.

你每天吃大约170根香蕉才能达到你一年的量。

We live in a world of radiation.

我们住在一个充满辐射的世界。

However, much of that radiation is non-ionizing.

然而，大多的辐射是非电离的。

For the remainder that is ionizing,

余下那些电离的，

our exposures are usually low,

我们暴露度基本很低，

and choices like getting your home tested for radon

而且像检测你家的氡含量

and wearing sunscreen

和抹防晒霜这样的决策

can help reduce the associated health risks.

能够帮助减少相关的健康危害。

Marie Curie, one of the early radiation pioneers,

玛丽·居里， 早期的辐射研究先驱之一，

summed up the challenge as follows:

将挑战总结如下：

"Nothing in life is to be feared, it is only to be understood.

“世上无可畏惧， 只是有待理解。

Now is the time to understand more, so that we may fear less."

现应当理解更多， 我们才可越无惧。”