Shark Fins Contain Toxic "One–Two Punch"
鱼翅的双重剧毒

Sharks can accumulate both methylmercury and a toxin called BMAA, which can have synergistic effects on human consumers. Christopher Intagliata reports.
在鲨鱼的体内，甲基汞和一种叫BMAA（β-甲氨基-L-丙氨酸）的毒素累积，两种毒素对人类消费者产生协同损害效应。克里斯托弗·因塔利亚塔报道。

撰文/播音：克里斯托弗·因塔利亚塔(Christopher Intagliata)
翻译：杨枭
审校：吴非

Living at the top of the food chain, sharks can accumulate dangerous levels of methylmercury. So much that pregnant women and children are advised not to eat shark at all. But sharks can accumulate another toxin too, called BMAA, which has been linked to the development of neurodegenerative disease. Which could be bad news for shark eaters.
因为位于食物链顶端，鲨鱼体内积累了高剂量的甲基汞，孕妇和儿童被建议不要食用。但是，鲨鱼体内还积累了另一种叫做BMAA的毒素，这种毒素会导致神经退行性疾病，这对鲨鱼肉消费者来说无疑是个噩耗。

"Mercury in combination with BMAA is a one-two punch." Deborah Mash, a professor of neurology at the University of Miami's Miller School of Medicine. "These are two synergistic toxins. So even if there are low levels of exposure from the mercury or the BMAA, when humans are exposed to both of these toxins, then they will have a synergistic effect on the nervous system."
 德博拉·马什是迈阿密大学米勒医学院的神经学教授，她表示：“汞和BMAA的结合无疑是个双重打击。这两种毒素具有互相促进的作用，即使人们接触低剂量的汞和BMAA，它们也会对神经系统产生协同的毒害影响。”

BMAA starts out in cyanobacteria, and travels up the food chain through crabs and shrimp and fish. And, as previous studies have shown, all the way to sharks. What Mash and her colleagues wanted to know was how widespread the problem was, and if the chemical often appeared alongside mercury. So they analyzed fin and muscle samples from 10 species of shark—55 individuals in all—from the Atlantic and Pacific Oceans. And they found BMAA and mercury in all 10 species. Suggesting that exposure to that "one-two punch" could be pretty common. The results are in the journal Toxins. [Neil Hammerschlag et al.,Cyanobacterial Neurotoxin BMAA and Mercury in Sharks]
BMAA从蓝藻进入食物链，之后通过虾、蟹和鱼向食物链上端攀爬直至进入鲨鱼体内。马什和她的同事想要了解这个现象的广泛性以及BMAA是否常与汞一同出现。为此，他们分析了鲨鱼的鱼翅和肌肉样本。这些鲨鱼来自从大西洋到太平洋的十个不同的物种，共55只。在全部10种鲨鱼体内，他们都发现了BMAA和汞，足以表明“双重打击”普遍存在。这项研究结果发表在了Toxins期刊上。

It's still not clear at this point what sort of risk this occasional exposure through food might have. Still, Mash isn't waiting.
尽管对于通过食物接触毒素产生的风险尚不明确，但马什决定立即采取行动。

"I myself would not want to be exposed to BMAA or methyl mercury in my diet by eating shark fin or shark meat or taking shark cartilage products. We already know that mercury is toxic to our health. And we already know that BMAA plus mercury is a very bad mix for the brain. So people need to be concerned, and I think that's not only for the benefit of us as consumers, but also to the poor sharks, who are threatened with extinction."
“我自己并不想因为食用鲨鱼肉或是软骨制品而接触BMAA或是甲基汞。我们已经知道汞对健康的危害，也已经知道BMAA加上汞对大脑的混合伤害。所以，我认为人们应该提高警惕，不仅仅为了消费者自身的利益，还要想想可怜的鲨鱼，它们正在面临物种灭绝的危险。”

Conservationists have argued for years that sharks should be spared. Maybe now that it's us who are threatened... people might finally start to leave them alone.
很多年来，环保主义者一直在主张我们应该放过鲨鱼。或许现今轮到我们被威胁了……或许人们终于可以真正地放过鲨鱼了。

原文链接：
https://www.scientificamerican.com/podcast/episode/shark-fins-contain-toxic-one-two-punch/

（题图来源：http://www.scientificamerican.com）