PFAS 屬於一組人造化合物，被稱為 "永恒的化學品"，可以在環境和人體中無休止地存在，有時還會產生毒性影響。它們隨處可見，在藥店的收據上、防汙沙發上、消防泡沫中、水源裏，還有廚房裏。
近年來，PFAS 和另一種永久性化學物質 BPA 越來越成為研究人員和消費者關註的焦點。它們是什麽？有什麽影響？您能保護您的廚房免受它們的危害嗎？
01 什麽是 PFAS？
PFAS 是一個 "龐大的化學品家族"，環境工作群組高級科學家 Tasha Stoiber 說。有多大？似乎沒有人知道--估計有 15000 種不同的化合物，甚至更多。每種化合物都含有氟碳鍵，"這使它們具有防汙、防油、防水的獨特效能，"斯托伊伯說。
更重要的是 "幾乎每個人體內都含有這種物質，"Stoiber補充道。
美國疾病控制和預防中心的官方說法是，接觸 PFAS 對人體健康的影響 "尚不確定"，需要進行更多的研究。但該機構也承認，現有的動物實驗表明，這些化學物質 "可能會影響生殖、甲狀腺功能、免疫系統和肝臟"。
愛荷華州立大學聚合物與食品保護聯合會主任 Keith Vorst 說："你很難找到人說這不會對健康產生影響，"該聯合會為私營部門公司研究此類問題。"現在有足夠的醫學史料表明，這些化合物確實會引起一些相當嚴重的健康問題"。
02 PFAS 與 BPA 有何不同？
雙酚 A 來自一類完全不同的化學品，用於制造硬質聚碳酸酯塑膠。這種化學物質還存在於食品罐頭（包括汽水罐頭）的保護層以及牙科密封劑、塑膠玩具和其他產品中。
與 PFAS 一樣，美國疾病預防控制中心表示，雙酚 A 對健康的影響 "尚不清楚"，但它補充說，這種化學物質 "已被證明會影響實驗室動物的生殖系統"。
EWG的Stoiber說："它基本上是一種環境雌激素。"它會擾亂你體內的荷爾蒙，導致一些問題，比如乳癌風險增加、生育問題等等。
03 廚房裏哪裏有這些化學物質？
無處不在。不粘鍋往往最受關註，但各種食品容器都可能含有某種形式的 PFAS 或 BPA。
Birnbaum說：「塑膠是當今廚房的一個主要問題。」
"雖然消費者似乎已經註意到水瓶、嬰兒奶瓶和其他容器中使用的雙酚 A，但全氟辛烷磺酸更為隱蔽：它們經常出現在披薩盒和微波爐爆米花袋等容器中。"伯恩鮑姆說："我們知道，吃快餐較多的人體內的 PFAS 含量往往高於吃新鮮食物較多的人。"
這就是為什麽美國食品和藥物管理局在 2024 年 2 月宣布，各公司將自願逐步淘汰在食品包裝中使用 PFAS 的原因。
然而，PFAS 在環境中如此普遍，以至於無論包裝如何，在食物和水中都能找到它們。"自然資源保護委員會報告說："食物也可能透過其生長的土壤、水和空氣受到 PFAS 的汙染。這包括農產品，也包括魚類和貝類。"
04 如何保護自己？
"作為個人，這並不容易，"Birnbaum說。
從平底鍋開始。沃斯特說："你可以透過使用無塗層平底鍋、無防刺平底鍋來避免這種情況，"無塗層平底鍋指的是由玻璃、碳鋼和鑄鐵制成的炊具。但這並不容易--它們更難清洗，而且價格也更貴。"
食物準備方面的工作可能也會更多。斯托伊伯說："我們建議盡可能在家裏用完整的食材烹飪。如果必須使用不粘鍋，要註意不要讓食物過熱。"她說："如果你燒焦了食物--高溫烹飪--這時你可能會更多地接觸到鍋裏的化學物質或油煙。"
至於剩菜剩飯，最好不要把塑膠容器放在微波爐裏。Birnbaum 說："如果你用塑膠儲存，這並不可怕，但一定不要用塑膠加熱"。
標簽並不總能幫到你。專家們描述了一種被稱為 "遺憾替代 "的現象，即產品中的一種有害物質可能會被另一種同樣有害但不太為人所知的物質所替代。標榜產品 "不含雙酚 A（BPA）"的標簽可能含有雙酚 S，一種同樣引起關註的相關化學物質。同樣，貼有 "不含 PFAS "標簽的炊具可能仍然使用另一種 PFAS 。有疑問時，您可以檢視專家網站，如綠色科學政策研究所（Green Science Policy Institutes）的網站。
05 下一步該怎麽辦？
這些小竅門可能會有所幫助，但它們可能無法讓廚房完全不受汙染，因為這個世界上的化學物質實在是太多了。斯托伊伯說："不可能透過購物來擺脫汙染。"
但研究表明，微小的改變--少吃微波爐爆米花或外賣食品--可以降低人血液中可測量的 PFAS 含量。Stoiber補充說："很多行為確實會產生影響。"
既然存在這些問題，為什麽 PFAS 和 BPA 仍在使用呢？很簡單：它們很有用。Vorst說："它們的作用非常好。例如，沒有人希望漢堡包的油脂透過包裝紙滲漏到汽車座椅上，也沒有人想出更好的辦法來控制油脂。我認為我們還沒有找到一種替代化學材料，既具有成本效益，又具有這些材料的效能。"
目前，選擇主要取決於個人消費者。"如果我們決定真的需要它們，我們就必須提出這樣的問題：那麽，有安全的替代品嗎？伯恩鮑姆說。"如果有安全的替代品，我們就改用替代品"。
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
