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地球上最致命的5种毒素

Top 5 Deadliest Substances on Earth

有个像是来自詹姆斯邦德系列电影的故事
It’s a story straight out of a Bond film.
为BBC工作的保加利亚记者乔治马科夫是共产主义的叛徒
On September 7th, 1978, Bulgarian journalist Georgi Markov, a communist defector working for the BBC,
1978年9月7日 当他右腿感到轻微的刺痛时 他正走在伦敦的滑铁卢大桥上
was walking across the Waterloo Bridge in London, when he felt a slight sting in his right thigh.
他回头看时发现一个男人正从地上捡一把雨伞
He looked behind him and saw a man picking an umbrella up off the ground.
当天晚上 他就开始发烧
By that evening he had developed a fever.
四天后他就去世了
Four days later he was dead.
死亡原因是——中毒
The cause of death: poisoning.
马科夫被一把伞操控的火丸暗杀 火丸含有世界上最强大的天然毒素
Markov had been assassinated using an umbrella rigged to fire a pellet laced with one of the most powerful natural toxins in the world:
蓖麻毒素
Ricin.
蓖麻毒素是在动物之外发现的最致命的自然物质之一
Ricin is one of the deadliest natural substances that is not found in an animal.
它是在蓖麻植物的种子中发现的
It’s found in the beans of the castor plant.
500微克的这种物质就足以杀死一个人 那仅仅是曲别针万分之五的质量
Just 500 micrograms of this stuff, that’s 5/10 000 of what a paperclip weighs, is enough to kill a man.
尽管它如此强大 蓖麻毒素距离地球上最毒的自然物质仍差之千里
And as potent as it is, ricin isn’t even close to being the most poisonous natural substance on Earth.
细菌 植物和真菌上到处都潜伏着毒素
There are poisons that lurk in bacteria, plants, and fungi all over the place,
它们也不仅出现在奇异的热带地区或是19世纪70年代的伦敦
and they’re not just found in exotic, tropical locales or, like, 1970s’ London.
这些物质很有可能到处都是 事实上 它们的存在是有好处的
They’re pretty much everywhere, and the fact is, they’re there for good reasons.
但使其毒性如此巨大的化学成分是什么?
But what is it about their chemical makeup that makes them so poisonous?
它们的毒素是怎样以致命的效果攻击人体的?
How do their toxins attack the human body with such deadly efficiency?
以及为什么我的大腿突然间感到刺痛?
And why does my thigh suddenly feel all tingly?
那是一把雨伞吗!?
Is that an umbrella!!?
[音乐播放中]
[Music playing]
列举出自然界中最致命的毒素不仅很恐怖 还是几乎不可能的
Not only is it morbid to list the most deadly toxins in nature, it’s also nearly impossible.
很多植物 真菌和细菌在被食用 吸入或混入血液时是能够杀死人的
There are a lot of plants, fungi and bacteria out there capable of killing you if eaten, inhaled, or injected.
而且也有很多因素使准确界定某种物质毒性如何变得困难
And there are also a lot of variables to make it hard to quantify exactly how poisonous something is.
从受害者的年龄到其体内的抗体都可以反映出一种物质毒性如何
Everything from the age of the victim to the antibodies in your system can effect how potent a substance is.
然而 事无绝对
There is however, one exception.
没有人质疑人类已知的最致命的毒素属于天然有毒物质 或者说没有人质疑它是由微小的肉毒梭状芽孢杆菌产生的
No-one disputes that the most lethal toxic substance known to man natural or otherwise is produced by the tiny bacterium Clostridium botulinum.
你可能因为它造成的疾病——肉毒中毒 而知晓它
You probably know it by the disease it causes, botulism.
肉毒杆菌毒素究竟有多致命呢?
Just how deadly is the botulinum toxin?
专家用来衡量毒素杀伤力的一个方法被称为“半致命剂量”
One way experts use to measure the lethality of a poison is a method called the “Lethal dose 50%”,
即能够杀死一半测试者的剂量
Which is the dose required to kill half the members of a tested population.
显而易见的是人们无法在人类身上测试 毒理学家常称此数量为“半致死剂量”
Since, for obvious reasons, you can’t run these tests on humans, toxicologists usually gets this number, often called the LD50,
通过使用一种极其不幸的生物:
by using an endlessly unfortunate creature:
实验室的老鼠
The laboratory mouse.
半数致死量=毒素质量(毫克)/体重(千克)
LD50 is measured in a ratio of milligrams of toxin to kilograms of bodyweight,
对于肉毒杆菌毒素 半数致死量为一毫微克(十亿分之一克)每千克
and in the case of the botulinum toxin it’s about one nanogram, a billionth of a gram, per kilogram.
那意味着一粒沙子大小的肉毒杆菌晶体足以杀死9600个人
That means that a crystal of botulinum the size of a grain of sand, would be enough to kill 9,600 people.
实际上肉毒杆菌十分常见 它们产出的孢子遍布世界上的土壤和水中
The bacteria are actually really common and the spores they produce are found in soil and water all over the world.
问题源于 孢子发育为活细胞时 会产出七种不同的毒素
The problem starts when they germinate into active cells, at which point they begin to produce seven different toxins,
其中的四种对人类来说是致命的
four of which are deadly to humans.
C肉毒杆菌在低氧环境中繁殖 美国每年十到三十起中毒案例被报道
C. botulinum thrives in low-oxygen environments, and the ten to thirty cases reported each year in the U.S.
通常是由不恰当食用罐头食品造成 因为装罐时需要抽出氧气以保存食品
are usually the result of eating improperly canned food, since canning removes oxygen from food to preserve it.
但是如果没有正确加热罐头食品 那些孢子会在德州辣酱罐头里徘徊并安家立业
But if the food isn’t heated properly the spores can stick around and set up shop in that can of Texas chili.
肉毒杆菌的孢子也存在于蜂蜜中 如果你吃下它们 它们能够在你身体里找到一个超棒的无氧角落存活
Botulinum spores can also be found in honey, and if you eat them they can find a nice oxygen free nook of your body to hang out in.
儿童和成人都能够在其发育之前抵御孢子 但婴儿不行
Kids and adults can ward off these spores before they germinate, but infants cannot,
这就是为什么12个月以下的婴儿不能食用蜂蜜
which is why babies under 12 months old should never eat honey.
孢子之所以有毒是因为它们会将神经毒素作为废物排出
The spores are poisonous because they secrete a neurotoxin as a waste product.
它能够阻碍控制肌肉收缩的神经递质——乙酰胆碱的释放
It works by blocking the release of a neurotransmitter called acetylcholine, which controls muscle contractions.
这十分有效地使受害者的每一块肌肉变得无力
This effectively makes every muscle in the victim’s body go limp.
如果几天之内不注射抗毒素血清 受害者将窒息身亡
Within several days without antitoxin the victim will asphyxiate from the inability to breathe.
当然 多亏了科学和那些可怜的实验室老鼠 是有这种抗毒素血清
But yes, thanks to science, and all those poor lab mice, there is an antitoxin.
但是 托马修·奥菲拉的福 细菌会进化到向其宿主释放剧毒的原因究竟是什么?
But why in the name of Mathieu Orfila would a bacterium evolve to fart the deadliest poison on earth into its host?
答案仍是一个谜团
The answer remains a mystery.
有理论认为毒素目标不是宿主 而是“竞争细菌”
One theory is that the toxins are not aimed at the host, but rather at competitor bacteria.
它们创造出一个良性细菌不能存活的环境 使恶性细菌有机会传播
They create conditions where benign bacteria cannot survive, giving the evil bacteria a chance to spread.
在这种情况下 宿主人类常因此患病
The host, in this case a human, is often just in the way of this process.
与肉毒杆菌相比 食用氰化物就像吃橡皮泥一样
So compared to the botulinum toxins, cyanide is like eating play dough.
逗你的
Well, not really.
千万不要误食氰化物!
Do not eat cyanide!
那不仅会使你毁容 氰化物还是世界上生效最快的毒药
Not only will it kill your face, it’s also one of the most rapidly acting poisons in the world.
它存在于香烟烟雾和燃烧的塑料中 还存在于大量天然食品中 如扁桃仁与杏和苹果的种子中
It’s found in cigarette smoke, burning plastics, also a surprising number of natural foods including almonds and the seeds of apricots and apples.
氰化钠的半数致死量通常是每千克体重6.4毫克
The LD50 of sodium cyanide, a common form, is 6.4 mg per kg of bodyweight,
致命性比肉毒杆菌低了超过六百万倍
or over 6 million times less deadly than botulinum.
但据说从古罗马暴君尼禄到阿加莎·克里斯蒂 氰化钠都是流行且有效的治死工具
But that said, it’s been a popular and effective tool of death for everyone from Emperor Nero to Agatha Christie.
氰化物中氰键是碳氮三键
Cyanide is a carbon atom triple bonded to a nitrogen atom.
使它成为如此有力的杀手的是它能结合你细胞内线粒体中的蛋白质 而蛋白质是能够使细胞运转的微小发电站
What makes it such a fast killer is that it binds to proteins in your cell’s mitochondria, the tiny power plants that keep your cells going,
氰化物通过抑制细胞呼吸 基本上使人体在细胞水平窒息
and keeps them from using oxygen, basically asphyxiating the body at a cellular level.
一些水果和坚果的确含有氰化物
It is true that some fruits and nuts contain cyanide.
比方说苹果的种子 它含有一种化学物质可以在氰化物和消化酶接触时释放它
Apple seeds for instance contain a chemical that releases cyanide when it comes into contact with digestive enzymes.
这是一个阻止生物消化掉所有种子的好方法 并且留下的毒素将不足以杀死它们 或者我们
This is a good way to deter critters from digesting up all your seeds if you’re a fruit, but there’s not enough poison to kill them, or us.
但我猜我不会想要吃掉满满一碗苹果种子
Though I guess I wouldn’t make a point of like eating a bowl of apple seeds.
好消息是如果你碰巧氰化物中毒 维他命B12可以帮助你(解毒)
The good news is that if you happen to suffer from cyanide poisoning, there’s always vitamin B12.
你在商店里买到的B12实际上含有氰化物作为其华丽复杂的分子结构的一部分
The B12 that you get at the store actually contains cyanide as part of its gloriously complex molecular structure,
所以高剂量的维他命B12摄入可以逐个吸收你“中毒线粒体”中的氰化物
so high doses of a precursor to the vitamin can literally pull the cyanide off of your poisoned mitochondria,
然后你只需要排除B12形式的毒素
and then you just pee out the poison in the form of B12.
现在继续讨论我们的保加利亚朋友
Now, back to our Bulgarian friend.
杀死马科夫的蓖麻植物原产于非洲东部
Well the castor plant that killed him is next on our list. It’s native to East Africa,
但它生长在更加温暖的很多地方 像是美国西南部
but grows pretty much anywhere it’s warm, including the southwestern United States.
它产生的蓖麻毒素是其种子里的一种蛋白质
The toxin it produces, ricin, is a protein found in the castor bean,
但毒素本身源于种子磨制成油后剩下的糊状物
but the poison itself is made from the mash that’s left over after grinding the beans into oil.
在加热油时蓖麻毒素蛋白变性或失活 使其无害
When the oil is heated the ricin protein denatures or changes shape, which renders it harmless.
所以广泛用作泻药的油中不含毒素
So the toxin doesn’t end up in the oil itself, which is used widely as a laxative.
或许以前是这样 现在没有那么广泛了
Or used to be. Not so much anymore.
因为恶心
Cause gross.
但一旦被吸入 摄取或注射 未经处理的蓖麻毒素随时可能被身体细胞吸收
But when inhaled, ingested, or injected, untreated ricin is readily absorbed by the body’s cells.
一旦进入细胞 它会使核糖体灭活 核糖体能够制造细胞生长增殖所需的蛋白质
Once inside it inactivates the ribosomes, which manufacture proteins that your cells need to survive and reproduce,
一旦蛋白质链停止 生命也将终结
and once the protein train stops, life stops.
仅仅是一个蓖麻毒素分子每分钟就能够抑制1500个核糖体活动 因为它会杀死细胞
Just a single ricin molecule is capable of inactivating 1,500 ribosomes per minute as it kills the cell.
几小时内你将感受到毒素效果 但蓖麻毒素通常是慢性毒药 1-3天才能造成死亡
You may feel the effects within a few hours, but ricin is generally a slow acting poison, taking 1-3 days to cause death.
因此数年来它流行于想要开脱罪名的刺杀者中
Hence its popularity with assassins over the years who want to distance themselves from their crime.
发现于马科夫腿部的微小铂插头含有两个钻入的槽口 每个都能容纳1/5毫克的毒素
The tiny platinum plug found in Markov’s leg had two tiny channels drilled into it, each able to hold about 1/5 of a milligram of the poison.
但已足够杀死马科夫或者其余任何人
But that was more than enough to kill Markov or any other human.
蓖麻毒素的毒性可根据其进入身体的方式而改变
And the toxicity of ricin can change depending on how it enters the body.
口服时它的半数致死量是每千克体重 20毫克
Taken orally its LD50 is about 20 milligrams per kilogram of bodyweight,
大约需要8颗蓖麻种子来提取它
about 8 castor beans worth of the poison,
但当像马科夫一样注入体内时 半数致死量仅为每千克小小的
一毫克
but if it’s injected, like the way Markov got it, it’s just 1 tiny microgram per kilogram.
可悲的是 蓖麻毒素的解毒剂仍处于初期发展中 但由于蓖麻毒素致死需要数日
Antidotes to ricin, sad to say, are still in the early stages of development, but because ricin takes several days to kill,
人类正在研究能够阻止它进入体内其他细胞的核糖体的化合物
compounds are being investigated that can block it from reaching ribosomes in new cells in the body.
奇怪的是人们也在癌症治疗方面研究 蓖麻毒素
And strangely enough ricin is also being investigated as a possible cancer treatment,
因为它能够触发细胞中蛋白质的细胞凋亡机制
because of its ability to trigger that protein-stopping self destruct mechanism in cells,
当然包括癌细胞
including, of course, cancer cells.
如果你曾见过马钱子碱树 当然它确实存在
Now, if you ever come across a strychnine tree, and yes there is such a thing,
我建议大家尽可能远离它
my advice is to stay as far away as possible.
它源自印度和东南亚 它的树皮含有一种叫做二甲马钱子碱的毒素
It’s native to India and Southeast Asia, and its bark contains a poison called brucine,
但真正的致命性源于这种树绿色到橘色的圆形果实
but the real lethality comes from the trees round green-to-orange fruit
它的果实含有生物碱士的宁
which contains the alkaloid strychnine.
在这两种可怜的生物 鸽子和老鼠身上做的实验可确定 口服时士的宁的
半数致死量在每千克体重3-14毫克之间
Tests on both sad pigeons and sad rats have pegged the LD50 for strychnine at between 3 and 14 milligram per kilograms when taken orally,
致命程度与蓖麻毒素相似
which puts it in a similar category of lethalness as ricin.
但威胁在于一种能够影响控制肌肉收缩的脊髓神经的神经毒素
But the threat here is a neurotoxin that affects the nerves in the spinal cord that control muscle contraction.
本质上它阻碍控制神经信号的化学物质进入肌肉
Essentially it blocks the chemicals that control nerve signals to muscle.
通过阻塞那种化学物质 士的宁使人体肌肉持续收缩
By blocking that chemical, strychnine puts your muscles in a state of constant stimulation,
造成癫痫直到筋疲力尽甚至呼吸衰竭 这一切仅发生在30分钟内
causing seizures until the point of exhaustion and respiratory failure, in as little as 30 minutes.
这听起来可不像是一个舒适的死亡方式
This does not sound like a pleasant way to die.
最后 一个完整的天然毒素花名册一定不会少了真菌
Finally, no roster of natural poisons would be complete without a visit to the kingdom fungi,
因为尽管上千种真菌中只有少数有毒
because although few of its thousands of species are poisonous, some of the ones that are
其中的一些含有的毒素的剧毒程度堪比肉毒中毒 它叫做鹅膏毒素
contain toxins that would give botulism a run for its money, called amatoxins.
其中两种最危险的蕈类含有的毒素叫做 鹅膏蕈碱
The two most dangerous of these mushrooms contain the most lethal poison of its kind, called amanitin,
它们也有不那么神秘的名字 叫做死亡帽子和破坏天使
and they have the not so cryptic names of Death Cap and Destroying Angel.
口服时蕈类含有的鹅膏蕈碱的半数致死量为每千克体重0.1-0.2毫克
The oral LD50 of amanitin containing mushrooms is between 0.1 and 0.2 milligrams per kilogram.
所以我们说它的毒性至少是士的宁的30倍
So we’re talking at least 30 times deadlier than strychnine.
鹅膏毒素本质上是氨基酸环
Amatoxins are essentially rings of amino acids that interfere with enzymes that,
干扰酶同样是负责细胞内生命必须的蛋白质的生产
again are responsible for the production of lifegiving proteins in your cells,
但这种情况下它们的专能目标是 肝脏和肾脏细胞
but here they specifically target your liver and kidney cells.
它们如此危险的部分原因是摄入毒素后6-24小时才出现症状
Part of the reason they’re so dangerous is that symptoms are delayed for 6 to 24 hours after ingestion
所以受害者肝肾不适时仅仅知道身体出问题了
so victims only know there’s something wrong when their liver and kidneys begin to fail,
造成的呕吐腹泻常在急诊室被误诊为流感
causing vomiting and diarrhea, which is often mistaken in emergency rooms as the flu,
另一个原因是中毒常常是致命的
another reason the poisoning is often fatal.
美国大多数这类死亡案例都是由于亚洲移民错识蕈类
Most of these deaths in the U.S. are from the misidentification of mushrooms by immigrants from Asia,
亚洲不存在这些特殊的真菌种类 而且它们拥有看起来可以食用的外表
where these particular species of fungi don’t exist and instead have quite edible lookalikes.
在及早发现的情况下 大剂量的水飞蓟提取物可以阻止最严重的伤害
In cases that are caught early enough, massive doses of milk thistle extract can stop the worst of the damage –
提取物中含有能阻塞肝脏细胞吸收毒素的化合物
the extract contains chemicals that block the uptake of the toxin in liver cells.
但在最坏的情况下 受害者只能通过肝脏移植获救
But in the worst cases the victim can only be saved by a liver transplant.
我差不多说完了 既然我是一个对一切事情偏执狂热的家伙 从奇怪的男人和雨伞
Now I should probably stop, now that I’m just completely paranoid about everything from strange men with umbrellas,
到世界上所有外表美丽的蕈类
to all of the formerly beautiful mushrooms in the world.
好消息是 科学家和实验室老鼠正致力于发展这些最毒的天然毒性物质的抗毒素
The good news is that scientists, and lab mice, have been working hard developing anti-toxins to these most poisonous natural substances,
所以即使遭遇其中之一 我们也许不会因此丧命
so that if we do come across one of them, we might not die.
而且少数情况下 这些剧毒物质将会在某一天拯救我们
例如 针对癌细胞
And in a very few cases these terribly toxic substances may even be used to save us one day, by targeting cancer cells.
感谢您观看这期 科学秀 如果您有任何问题 意见或建议
So, thank you for watching this episode of SciShow. If you have any questions, comments or suggestions,
请通过脸书和推特联系我们 当然也可以通过下方的评论
we’re on Facebook and Twitter, and of course down in the comments below.
如果您想和我们一起变得越来越聪明 欢迎点击“youtube.com/scishow”订阅我们
And if you want to keep getting smarter with us here at SciShow, you can go to youtube.com/scishow, and subscribe.
砰!
Bam!
[音乐播放中]
[Theme music]

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视频概述

由马科夫遇刺引发的对剧毒物质的思考,蓖麻毒素、肉毒杆菌毒素、氰化物、士的宁、鹅膏毒素你都了解吗?

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