Is radiation dangerous? - Matt Anticole

譯者: Charlize Hung 審譯者: Max Chern

When we hear the word radiation,

聽到輻射這個詞的時候

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

很容易聯想到大爆炸的畫面 跟可怕的基因突變

but that's not the full story.

其實不全然是那一回事

Radiation also applies to rainbows

因為彩虹 和醫生檢查用的 X 光也算輻射

and a doctor examining an x-ray.

So what is radiation really,

那輻射到底是什麼

and how much should we worry about its effects?

對其影響我們又該多憂心呢？

The answer begins with understanding that the word radiation

答案要先從瞭解「輻射」這個詞開始

describes two very different scientific phenomena:

是描述兩種截然不同的科學現象

electromagnetic radiation

那就是電磁輻射

and nuclear radiation.

和核輻射

Electromagnetic radiation is pure energy

「電磁輻射」是純能量

consisting of interacting electrical and magnetic waves

由電波與磁波通過空間 相互作用振盪所構成

oscillating through space.

As these waves oscillate faster,

隨著電磁波振盪速度變快

they scale up in energy.

能量隨之變大

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

光譜低頻端有無線電波

infrared,

and visible light.

紅外線

和可見光

At the higher end are ultraviolet,

高頻端則有紫外線

X-ray,

X 射線

and gamma rays.

和伽瑪射線

Modern society is shaped by sending and detecting electromagnetic radiation.

現代社會是藉由 發送和檢測電磁輻射成形的

We might download an email to our phone via radio waves

我們能透過無線電波 把郵件下載到手機

to open an image of an X-ray print,

來開啟 X 光片的影像

which we can see because our screen emits visible light.

影像之所以可見 是因為螢幕發射出可見光

Nuclear radiation, on the other hand,

另外一種就是「核輻射」

originates in the atomic nucleus,

它來自原子核，核中的質子 因為都帶正電荷而相斥

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

A phenomenon known as the strong nuclear force

一種現象稱為「強核力」

struggles to overcome this repulsion

會努力克服質子相斥

and keep the nucleus intact.

同時維持原子核的穩定

However, some combinations of protons and neutrons,

然而，某些質子與中子的組合

known as isotopes,

也就是「同位素」

remain unstable,

依然不穩定

or radioactive.

亦即具有放射性

They will randomly eject matter and/or energy,

會隨機放射物質 和／或 能量 ─ 稱為「核輻射」 ─

known as nuclear radiation,

to achieve greater stability.

以使自己達到較大穩定度

Nuclear radiation comes from natural sources, like radon,

核輻射來自大自然，例如氡

a gas which seeps up from the ground.

是一種由地下向上滲出的氣體

We also refine naturally occurring radioactive ores

我們還精煉天然的放射性礦石

to fuel nuclear power plants.

提供燃料給核電廠

Even bananas contain trace amounts of a radioactive potassium isotope.

甚至連香蕉裡都含有 微量的鉀放射性同位素

So if we live in a world of radiation,

因此，我們要是生活在輻射世界裡

how can we escape its dangerous effects?

該怎麼避免其危險與影響呢？

To start, not all radiation is hazardous.

首先，非所有輻射都具危害

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

當輻射撞擊出原子中的電子時 才會有危險

a process that can damage DNA.

這過程會對 DNA 造成傷害

This is known as ionizing radiation

這種輻射就叫「游離輻射」

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

因為原子失去或得到電子 就稱為離子

All nuclear radiation is ionizing,

所有核輻射都是游離輻射

while only the highest energy electromagnetic radiation is.

而電磁輻射只有最高能量的 才是游離輻射

That includes gamma rays,

包括 γ 射線

X-rays,

X 射線

and the high-energy end of ultraviolet.

和高能量端的紫外線

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

這就是為何照 X 光要做額外防護措施

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

醫生會遮住不需檢查的身體部位

and why beach-goers use sunscreen.

以及為何沙灘客要擦防曬油

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

相較之下 行動電話和微波爐放射低頻光譜

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

所以使用上沒有游離輻射的危險

The biggest health risk occurs when lots of ionizing radiation

對健康造成最大威脅 是大量游離輻射

hits us in a short time period,

在短時間內擊中人體時

also known as an acute exposure.

也稱為「急性曝露」

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

急性曝露把人體 自己修復能力破壞殆盡

This can trigger cancers,

會誘發癌症

cellular dysfunction,

細胞功能障礙

and potentially even death.

甚至可能死亡

Fortunately, acute exposures are rare,

所幸，急性曝露相當罕見

but we are exposed daily to lower levels of ionizing radiation

但是我們每天都曝露在 低劑量游離輻射下 ─

from both natural and man-made sources.

來自自然界和人造物品

Scientists have a harder time quantifying these risks.

科學家很難將這些風險量化

Your body often repairs damage from small amounts ionizing radiation,

人體經常要修復 由少量游離輻射造成的損害

and if it can't,

若修復不了

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

損害結果可能十年或更久 都不會顯現出來

One way scientists compare ionizing radiation exposure

科學家用來 計算游離輻射曝露量的方法

is a unit called the sievert.

是稱為「西弗」的單位

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

急性曝露在一西弗下 可能在數小時內出現噁心症狀

and four sieverts could be fatal.

四西弗可能會致命

However, our normal daily exposures are far lower.

然而，我們日常曝露量低得多

The average person receives 6.2 millisieverts of radiation

一般人每年從各種來源 接觸的輻射量是 6.2 毫西弗

from all sources annually,

around a third due to radon.

約三分之一是來自氡

At only five microsieverts each,

以每次照射只有 5 微西弗計

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

必須要超過 1200 次的口腔 X 光照射

to rack up your annual dosage.

才能達到一年的劑量

And remember that banana?

還記得香蕉嗎？

If you could absorb all the banana's radiation,

人體若能將香蕉的輻射劑量完全吸收

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

則必須一天吃 170 根香蕉 才能達到整年劑量

We live in a world of radiation.

我們雖生活在充滿輻射的世界

However, much of that radiation is non-ionizing.

然而，大部分輻射都是 非游離輻射

For the remainder that is ionizing,

就其餘是游離輻射而言

our exposures are usually low,

我們的曝露量通常很低

and choices like getting your home tested for radon

有些選擇 像檢測家中氡氣

and wearing sunscreen

外出擦防曬

can help reduce the associated health risks.

都能幫助減少危害健康的風險

Marie Curie, one of the early radiation pioneers,

早期輻射先驅之一 瑪麗·居禮（居禮夫人）

summed up the challenge as follows:

對挑戰作了以下結論：

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

「生活中沒什麼可怕的事，只有需要被瞭解的事。

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

現應當多一些瞭解，才能少一分擔心受怕。」

翻譯：Charlize Hung