如果你吃了鈾怎么辦?

如果你吃了鈾怎么辦?

Scan the periodic table and you'll spot a lot of the same words you'd find on an FDA food label: potassium, iron, calcium. But look on the bottom row, and you'll see something you're more likely to associate with news about nuclear accords than a box of breakfast cereal: uranium. You can't help but wonder — what if you picked up a spoonful and started eating?

掃描周期表，你會(huì)發(fā)現(xiàn)很多和FDA食品標(biāo)簽上的相同的單詞：鉀，鐵，鈣。但看看最下面一排，你會(huì)發(fā)現(xiàn)，比起一盒早餐麥片，你更可能聯(lián)想到有關(guān)核協(xié)議的新聞：鈾。你不禁要問(wèn)——如果你拿起一勺開(kāi)始吃呢?

Let's back up and take a closer look at atomic number 92. Uranium is a dense, weakly radioactive metal that's naturally found in soil, rock and water. After mining uranium from the ground, experts manipulate its three isotopes to produce depleted and enriched variations; the former is less radioactive and used to make bullets and armor plating, while the latter is used in nuclear weapons and power plants.

我們回過(guò)頭來(lái)，仔細(xì)看看92號(hào)原子。鈾是一種致密的、弱放射性的金屬，天然存在于土壤、巖石和水中。在從地面開(kāi)采鈾之后，專家們操縱它的三種同位素產(chǎn)生貧化和濃縮的變化;前者放射性較低，用于制造子彈和裝甲板，而后者則用于核武器和核電站。

But you don't have to work in defense manufacturing or in a place equipped with cooling towers to be exposed to uranium. In fact, eating uranium is one of the most common means of exposure. Crops like potatoes and turnips are among the most uranium-rich foods in our diet, but they aren't the only ones: According to the Environmental Protection Agency, the average person eats 0.07 to 1.1 micrograms of uranium per day [source: EPA].

你不必在國(guó)防制造業(yè)工作，也不必在一個(gè)裝備有冷卻塔的地方接觸鈾。事實(shí)上，吃是最常見(jiàn)的接觸方式之一。土豆和蘿卜等作物是我們飲食中最富含鈾的食物之一，但它們并不是唯一的：根據(jù)環(huán)境保護(hù)署的數(shù)據(jù)，普通人每天攝入0.07至1.1微克鈾[來(lái)源：環(huán)保署]。

The good news is you don't have to abstain from root vegetables anytime soon. That daily uranium consumption isn't nearly enough to be harmful, especially since your body has a hard time absorbing uranium as it is [source: Keith et al]. Between 95 and 99 percent of the uranium you ingest is excreted in feces, and you urinate 70 percent of the rest within 24 hours [source: ATSDR]. A small amount of uranium will stay in your bones anywhere from months to years after ingestion, but eating uranium is much less toxic than inhaling it.

好消息是你不必在短期內(nèi)戒掉根類蔬菜。每天攝入的鈾還不足以造成危害，特別是因?yàn)槟愕纳眢w很難像現(xiàn)在這樣吸收鈾[來(lái)源：Keith等人]。你攝入的鈾有95%到99%在糞便中排出，其余70%在24小時(shí)內(nèi)排尿[來(lái)源：美國(guó)毒物與疾病登記署]。少量的鈾會(huì)在攝入后的幾個(gè)月到幾年內(nèi)留在你的骨頭里，但是吃鈾的毒性比吸入鈾的毒性小得多。

But what if, instead of being a trace element in the food on your plate, uranium is the main course? You might not be surprised to learn that eating large doses of a radioactive substance leads to an increased chance of developing a cancer. But long-term concerns about radiation exposure pale in comparison to the immediate effects of chemical toxicity. Uranium mainly targets the kidneys: Damage starts to appear after taking in 25 milligrams, while intakes of more than 50 milligrams can cause renal failure and death [source: Argonne National Laboratory]. Additionally, studies of rats that ingest uranium over long periods of time have shown changes in brain chemistry [source: ATSDR].

但如果鈾不是你盤(pán)子里食物中的微量元素，而是主菜呢?當(dāng)你得知吃大劑量的放射性物質(zhì)會(huì)增加患癌癥的幾率時(shí)，你可能不會(huì)感到驚訝。但與化學(xué)毒性的直接影響相比，長(zhǎng)期以來(lái)人們對(duì)輻射暴露的擔(dān)憂顯得蒼白無(wú)力。鈾主要以腎臟為目標(biāo)：攝入25毫克鈾后開(kāi)始出現(xiàn)損害，而攝入超過(guò)50毫克鈾會(huì)導(dǎo)致腎衰竭和死亡[來(lái)源：阿貢國(guó)家實(shí)驗(yàn)室]。此外，對(duì)長(zhǎng)期攝入鈾的大鼠的研究表明，它們的大腦化學(xué)成分發(fā)生了變化[來(lái)源：美國(guó)毒物與疾病登記署]。

Fortunately, while there's plenty of reason to believe uranium is lethal in high doses, there are no known human deaths from "oral exposure" to uranium [source: Keith et al]. Still, instead of eating the kind of yellowcake that's made with uranium ore, you're better off sticking with the kind of cake you top with chocolate frosting.

幸運(yùn)的是，雖然有足夠的理由相信高劑量的鈾是致命的，但目前還沒(méi)有人因“口服”鈾而死亡[來(lái)源：Keith等人]。不過(guò)，與其吃那種用鈾礦石做成的黃蛋糕，不如堅(jiān)持吃那種上面涂有巧克力糖霜的蛋糕。