機場人體掃描儀的輻射有危險嗎?

機場人體掃描儀的輻射有危險嗎?

What do granite countertops, bananas and airports have in common?

花崗巖臺面、香蕉和機場有什么共同點?

They're all emitting low-level radiation — constantly. Yet, according to toxicologists, people aren't coming into their offices with concerns about their kitchen renovations. Instead, just one of these sources is a cause of disproportionate anxiety: the security scanners in airports.

共同點就是它們都在不斷地發(fā)出低水平的輻射。然而，根據(jù)毒理學(xué)家的說法，人們不會擔心廚房裝修，卻往往對另一件事非常擔憂：機場的安全掃描儀。

Patient concerns are often based on the warnings health care providers have issued regarding medical X-rays. The Food and Drug Administration cautions cautions patients to undergo X-ray imaging only when strictly necessary. But should people also be concerned about the security scanners at airports?

人們的擔憂通常是基于醫(yī)療保健提供者發(fā)布的關(guān)于醫(yī)用x射線的警告。美國食品藥品監(jiān)督管理局警告稱，只有在嚴格必要的時候，患者才需要接受x射線成像。但是人們也應(yīng)該擔心機場的安檢掃描儀嗎?

Luckily for health-conscious frequent fliers, there's no need to worry, said Dr. Lewis Nelson, professor and chair of emergency medicine at Rutgers New Jersey Medical School. Radiation is a general term for different kinds of moving electromagnetic energy: ionizing radiation (what X-ray machines emit) and nonionizing radiation (which includes radio and magnetic waves). The key difference between ionizing and non-ionizing radiation is the level of energy they transmit. Ionizing radiation has enough energy to knock electrons away from atoms, creating free radicals; these chemically reactive particles can damage DNA and increase people's risk of cancer.

新澤西州羅格斯醫(yī)學(xué)院(Rutgers New Jersey Medical School)急診醫(yī)學(xué)教授兼主席劉易斯·納爾遜(Lewis Nelson)博士說，對于注重健康的常旅客來說，幸運的是，他們沒有必要擔心。輻射是各種移動電磁能量的總稱:電離輻射(x射線機發(fā)射的)和非電離輻射(包括無線電波和電磁波)。電離輻射和非電離輻射之間的關(guān)鍵區(qū)別在于它們傳輸?shù)哪芰克健ｋ婋x輻射有足夠的能量使電子遠離原子，產(chǎn)生自由基;這些化學(xué)反應(yīng)性粒子會破壞DNA，增加人們患癌癥的風險。

But ionizing radiation has a real impact on our health only when received at high doses. And in airport X-ray machines, even though about half of the scanners emit ionizing radiation, the dose just isn't high enough to do bodily harm, Nelson said. (Roughly half of scanners use millimeter waves, a form of non-ionizing radiation.)

但是電離輻射只有在高劑量時才會對我們的健康產(chǎn)生真正的影響。尼爾森說，在機場的x光機中，盡管大約一半的掃描儀會發(fā)出電離輻射，但輻射劑量還不足以對人體造成傷害。(大約有一半的掃描儀使用毫米波，這是一種非電離輻射。)

"It's so tiny that it's inconsequential," he told Live Science.

他在接受《生活科學(xué)》(Live Science)采訪時表示:“它是如此之小，以至于可以忽略不計。”

While patients may be right to be concerned about the number of medical X-rays they receive, the amount of radiation delivered by an airport X-ray is tiny in comparison. A chest X-ray exposes patients to roughly 1,000 times the radiation of an airport scanner. The Health Physics Society estimates that airport X-ray scanners deliver 0.1 microsieverts of radiation per scan. In comparison, a typical chest X-ray delivers 100 microsieverts of radiation, according to a 2008 study published in the journal Radiology.

雖然人們對他們所接受的醫(yī)用x光的數(shù)量感到擔憂可能是對的，但相比之下，機場x光所釋放的輻射量是很小的。胸部x光片使病人暴露在機場掃描儀輻射的1000倍左右。健康物理學(xué)會(Health Physics Society)估計，機場的x射線掃描儀每次掃描的輻射量為0.1微西弗。相比之下，根據(jù)2008年發(fā)表在《放射學(xué)》(Radiology)雜志上的一項研究，典型的胸透會釋放100微西弗的輻射。

And travelers are exposed to far more radiation on the flight itself, Nelson said. Every minute on a plane delivers roughly the same dose of radiation as one airport X-ray scan.

尼爾森說，乘客在飛機上受到的輻射量要大得多。飛機上每分鐘的輻射劑量與機場一次x光掃描大致相同。

“It’s ironic that peoeple afraid of radiation exposure in screening don’t have any qualms about getting on the airplane,” Nelson said.

尼爾森說:“令人啼笑皆非的是，人們害怕在安檢中暴露在輻射下，卻對上飛機沒有任何顧慮。”

These scanners emit such a tiny amount of radiation that even if you flew every day for a year, you'd still receive only a fraction of the ionizingradiation you absorb from food, based on dose estimates from NASA.

根據(jù)美國國家航空航天局(NASA)的劑量估計，這些掃描儀發(fā)出的輻射量如此之小，即使一年中你每天都在飛行，也只會受到電離輻射的一小部分。

Most food contains small amounts of the radioactive molecules carbon-14 and potassium-40, according to NASA. In fact, many of the objects and substances we encounter daily emit radiation; the soil, cement sidewalks and buildings, and even the air we breathe are all slightly radioactive.

據(jù)美國宇航局稱，大多數(shù)食物含有少量的放射性分子碳-14和鉀-40。事實上，我們每天遇到的許多物體和物質(zhì)都會放射出輻射;土壤、水泥人行道和建筑物，甚至我們呼吸的空氣都有輕微的放射性。

Compared to all that radiation, an X-ray scanner emits an insignificant amount, Nelson said. That holds true even for people more vulnerable to radiation exposure, such as pregnant women and babies, who receive the same amount of background radiation daily as anyone else.

尼爾森說，與所有這些輻射相比，x射線掃描儀的輻射量微不足道。即使對更容易受到輻射的人來說也是如此，例如孕婦和嬰兒，他們每天接受的本底輻射量與其他人相同。

"The dose makes the poison," Nelson said, "Everything is toxic if you have enough of a dose. The corollary to that is everything's nontoxic if you have a low enough dose."

尼爾森說:“劑量會產(chǎn)生毒素，如果劑量足夠大，一切都是有毒的。由此得出的結(jié)論是，如果劑量足夠低，所有物質(zhì)都是無毒的。”

And in this case, Nelson added, airport X-rays definitively fall on the nontoxic side of the spectrum.

尼爾森補充說，在這種情況下，機場的x射線絕對屬于光譜的無毒范圍。