PFAS 属于一组人造化合物，被称为 "永恒的化学品"，可以在环境和人体中无休止地存在，有时还会产生毒性影响。它们随处可见，在药店的收据上、防污沙发上、消防泡沫中、水源里，还有厨房里。
近年来，PFAS 和另一种永久性化学物质 BPA 越来越成为研究人员和消费者关注的焦点。它们是什么？有什么影响？您能保护您的厨房免受它们的危害吗？
01 什么是 PFAS？
PFAS 是一个 "庞大的化学品家族"，环境工作组高级科学家 Tasha Stoiber 说。有多大？似乎没有人知道--估计有 15000 种不同的化合物，甚至更多。每种化合物都含有氟碳键，"这使它们具有防污、防油、防水的独特性能，"斯托伊伯说。
更重要的是 "几乎每个人体内都含有这种物质，"Stoiber补充道。
美国疾病控制和预防中心的官方说法是，接触 PFAS 对人体健康的影响 "尚不确定"，需要进行更多的研究。但该机构也承认，现有的动物实验表明，这些化学物质 "可能会影响生殖、甲状腺功能、免疫系统和肝脏"。
爱荷华州立大学聚合物与食品保护联合会主任 Keith Vorst 说："你很难找到人说这不会对健康产生影响，"该联合会为私营部门公司研究此类问题。"现在有足够的医学史料表明，这些化合物确实会引起一些相当严重的健康问题"。
02 PFAS 与 BPA 有何不同？
双酚 A 来自一类完全不同的化学品，用于制造硬质聚碳酸酯塑料。这种化学物质还存在于食品罐头（包括汽水罐头）的保护层以及牙科密封剂、塑料玩具和其他产品中。
与 PFAS 一样，美国疾病预防控制中心表示，双酚 A 对健康的影响 "尚不清楚"，但它补充说，这种化学物质 "已被证明会影响实验室动物的生殖系统"。
EWG的Stoiber说："它基本上是一种环境雌激素。"它会扰乱你体内的荷尔蒙，导致一些问题，比如乳腺癌风险增加、生育问题等等。
03 厨房里哪里有这些化学物质？
无处不在。不粘锅往往最受关注，但各种食品容器都可能含有某种形式的 PFAS 或 BPA。
Birnbaum说：「塑料是当今厨房的一个主要问题。」
"虽然消费者似乎已经注意到水瓶、婴儿奶瓶和其他容器中使用的双酚 A，但全氟辛烷磺酸更为隐蔽：它们经常出现在披萨盒和微波炉爆米花袋等容器中。"伯恩鲍姆说："我们知道，吃快餐较多的人体内的 PFAS 含量往往高于吃新鲜食物较多的人。"
这就是为什么美国食品和药物管理局在 2024 年 2 月宣布，各公司将自愿逐步淘汰在食品包装中使用 PFAS 的原因。
然而，PFAS 在环境中如此普遍，以至于无论包装如何，在食物和水中都能找到它们。"自然资源保护委员会报告说："食物也可能通过其生长的土壤、水和空气受到 PFAS 的污染。这包括农产品，也包括鱼类和贝类。"
04 如何保护自己？
"作为个人，这并不容易，"Birnbaum说。
从平底锅开始。沃斯特说："你可以通过使用无涂层平底锅、无防刺平底锅来避免这种情况，"无涂层平底锅指的是由玻璃、碳钢和铸铁制成的炊具。但这并不容易--它们更难清洗，而且价格也更贵。"
食物准备方面的工作可能也会更多。斯托伊伯说："我们建议尽可能在家里用完整的食材烹饪。如果必须使用不粘锅，要注意不要让食物过热。"她说："如果你烧焦了食物--高温烹饪--这时你可能会更多地接触到锅里的化学物质或油烟。"
至于剩菜剩饭，最好不要把塑料容器放在微波炉里。Birnbaum 说："如果你用塑料储存，这并不可怕，但一定不要用塑料加热"。
标签并不总能帮到你。专家们描述了一种被称为 "遗憾替代 "的现象，即产品中的一种有害物质可能会被另一种同样有害但不太为人所知的物质所替代。标榜产品 "不含双酚 A（BPA）"的标签可能含有双酚 S，一种同样引起关注的相关化学物质。同样，贴有 "不含 PFAS "标签的炊具可能仍然使用另一种 PFAS 。有疑问时，您可以查看专家网站，如绿色科学政策研究所（Green Science Policy Institutes）的网站。
05 下一步该怎么办？
这些小窍门可能会有所帮助，但它们可能无法让厨房完全不受污染，因为这个世界上的化学物质实在是太多了。斯托伊伯说："不可能通过购物来摆脱污染。"
但研究表明，微小的改变--少吃微波炉爆米花或外卖食品--可以降低人血液中可测量的 PFAS 含量。Stoiber补充说："很多行为确实会产生影响。"
既然存在这些问题，为什么 PFAS 和 BPA 仍在使用呢？很简单：它们很有用。Vorst说："它们的作用非常好。例如，没有人希望汉堡包的油脂通过包装纸渗漏到汽车座椅上，也没有人想出更好的办法来控制油脂。我认为我们还没有找到一种替代化学材料，既具有成本效益，又具有这些材料的性能。"
目前，选择主要取决于个人消费者。"如果我们决定真的需要它们，我们就必须提出这样的问题：那么，有安全的替代品吗？伯恩鲍姆说。"如果有安全的替代品，我们就改用替代品"。
PFAS belong to the set of human-made compounds known as 「forever chemicals」 that can linger endlessly in the environment and human body, sometimes with toxic effects. They can be found everywhere—on the receipts from your drugstore, on your stain-resistant couch, in firefighting foams, in the water supply and, yes, in your kitchen.
("Forever chemicals" are more common in tap water than we thought.)
PFAS and another forever chemical, BPA, have increasingly been the focus of concern among researchers and consumers in recent years. What are they? What are the effects? And can you protect your kitchen against them?
What are PFAS?
PFAS are a 「huge family of chemicals,」 says Tasha Stoiber, senior scientist for the Environmental Working Group. How huge? Nobody seems to know—estimates range as high as 15,000 different compounds or more. Each contains a fluorine-carbon bond 「that gives them unique properties of being stain-resistant, grease-resistant, water-resistant,」 Stoiber says.
What’s more: 「Almost everyone has it in their bodies,」 Stoiber adds.
Officially, the U.S. Centers for Disease Control and Prevention says the human health effects of PFAS exposure are 「uncertain」 and require more research. But the agency also acknowledges that existing animal studies indicate the chemicals 「may affect reproduction, thyroid function, the immune system and injure the liver.」
「You'd be hard pressed to find somebody to say that this does not have a health impact,」 says Keith Vorst, director of the Polymer and Food Protection Consortium at Iowa State University, which researches such issues for private-sector companies. 「There's enough medical history now to say these compounds do cause some pretty serious health concerns.」
How are PFAS different from BPA?
Bisphenol-A comes from an entirely different class of chemicals, used to make hard polycarbonate plastics. The chemical is also found in protective linings of food cans—including soda cans—as well as dental sealants, plastic toys, and other products.
(This is what you need to know about the world's plastic pollution crisis.)
Like PFAS, the CDC says the health effects of BPA are 「unknown,」 though it adds that the chemical 「has been shown to affect the reproductive systems of laboratory animals.」
「It's basically an environmental estrogen,」 says EWG’s Stoiber. 「It can disrupt hormones in your body and lead to problems, things like increased risk of breast cancer, problems with fertility, things like that.」
Where can these chemicals be found in the kitchen?
Everywhere. The nonstick pans tend to draw the most attention, but a variety of food containers can contain some form of PFAS or BPA.
「Plastic is a major problem in kitchens today,」 Birnbaum says.
Although consumers seem to have caught on to BPA use in water bottles, baby bottles, and other containers, PFAS are more insidious: They can often be found in containers like pizza boxes and microwave popcorn bags. 「We know that people who eat more fast food tend to have higher levels of PFAS than people who eat more freshly prepared food,」 Birnbaum says.
That’s why the U.S. Food and Drug Administration announced in February 2024 that companies are voluntarily phasing out the use of PFAS in food packaging.
Still, PFAS are so pervasive in the environment that they’re often found in food and water, regardless of packaging. 「Food can also be contaminated with PFAS via the soil, water, and air where it’s grown,」 reports the Natural Resources Defense Council. That includes produce, but also fish and shellfish.
How can you protect yourself?
「The answer is: As an individual, it's not easy,」 says Birnbaum.
Start with the pans. 「You get away from that by going to non-coated pans, non-antistick pans,」 says Vorst—meaning cookware made of glass, carbon steel, and cast iron. But that’s not easy—they’re harder to clean 「and they're more expensive too,」 he says.
There might be more work on the food preparation side, as well. 「As much as you can, we recommend cooking at home with whole ingredients,」 Stoiber said. If you must use nonstick pans, be careful not to overheat the food. 「It may be if you burn your food—cook at high temperatures—that's when you might get more exposure of chemicals from the pan or the fumes,」 she says.
(Simple ways to make your laundry routine more eco-friendly.)
As for leftovers, it’s probably best to keep plastic containers out of the microwave. 「If you store in plastic, that's not terrible,」 Birnbaum says, 「but certainly don't heat in plastic.」
Labeling won’t always help you. The experts describe a phenomenon known as 「regrettable substitution」 in which one harmful substance in a product can be swapped out for another one that is also harmful but less known. A label that touts a product as 「BPA-free」 might instead contain bisphenol-s, a related chemical that has also raised concerns. Similarly, cookware containing a 「PFOA-free」 label might still use another form of PFAS. When in doubt, you can check expert websites like those run by the Green Science Policy Institute for help in making shopping decisions.
What next?
These tips can help, but they probably won’t produce a completely uncontaminated kitchen as the world is simply too saturated with forever chemicals. 「It is impossible to shop your way out of it,」 Stoiber says.
But studies show that small changes—eating less microwave popcorn or takeout food—can lower the measurable amounts of PFAS in a person’s blood. 「A lot of these behaviors do make a difference,」 Stoiber adds.
Given the concerns, why do PFAS and BPA remain in use? Simple: They’re useful. 「They are so good at what they do,」 Vorst said. Nobody wants hamburger grease leaking through the wrapper onto a car seat, for example, and nobody has come up with a better way to keep that grease contained. 「I don't think we have found an alternative chemistry that is as cost-effective and has the performance of these materials.」
For now, the choices are largely left to individual consumers. 「If we decide we really need them, we have to ask the question, well, is there a safe alternative?」 Birnbaum said. 「And if there's a safe alternative, we switch to the alternative.」
Credit: National Geographic；Date: 10 Mar 2024
