專欄作者
你身邊的化學殺手
紀思道 2012年09月01日
一項最新研究表明，我們身邊的一些常見化工製品對我們可能比先前預想的更有害。它們對我們的危害好像會一代一代遺傳下去，不僅危及我們自己，還會危及我們的子孫後代。
然而，大化工企業仿照一代人以前的大煙草公司的套路， 迄今為止已經阻止了對這些內分泌干擾物的所有嚴肅監管。把它們稱作內分泌干擾物是因為它們會導致人體內分泌系統中的荷爾蒙分泌紊亂。
Damon Winter/The New York Times
紀思道(Nicholas D. Kristof)
最常見，也是最讓人警惕的，是雙酚A，它另一個更廣為人知的名字是BPA。未能對這種化學物質進行監管意味着我們隨時都會接觸到它。從塑料到罐頭食品再到自動取款機收據，我們能在每樣東西里發現BPA。90%以上的美國人尿液中含有BPA。
甚至在這項表明BPA可能會影響數代人的最新研究之前，已有研究將它同乳腺癌、糖尿病以及兒童的多動症、攻擊性和抑鬱症聯繫在一起。
讀到關於化學安全的報紙專欄可能會讓人有些吃驚，因為它不是總統競選涉及的問題，甚至都沒被堅定地置於國家議事日程上。化學安全也不是我們在新聞媒體上有很多報道的那一類事物。
然而，越來越多的證據表明，這些化學物質是一種嚴重威脅，而聯邦政府卻一直未能保護美國人免受這種威脅。我們面臨的挑戰是，這些化學製品涉及複雜的
科學和極大的不確定性，此外，化工企業——像在它們之前的煙草企業那樣——用金錢作為獎勵，鼓勵政客們採納騎牆觀望的態度。因此，什麼事情也沒發生。
然而，儘管截至目前整個化工行業有能力阻止在全國範圍內對BPA進行廣泛的限制，關於BPA跨代影響的新發現可能會最終削弱大化工企業的遊說努力。
有一個好的跡象是：7月末，參議院的一個委員會首次通過了《安全化學品法案》(Safe Chemicals Act)。這一具有里程碑意義的法案是由新澤西州民主党參議員弗蘭克·勞滕伯格(Frank Lautenberg)發起的，將開始對化學製品的安全進行監管。
在六年中，內分泌干擾物跨代影響的證據一直都在增加，但這些證據通常都是在劑量比較高的情況下得到的，人類通常不會接觸到那麼高的劑量。
現在，同行評鑒期刊《內分泌學》(Endocrinology)已經發表了一項測量低劑量BPA的影響的研究。該研究是對化工業的重大打擊。
將懷孕的老鼠暴露在BPA環境中，其中BPA的劑量和人類通常接觸到的劑量類似。那些母鼠產下的後代沒有控制組的老鼠那麼活躍（使用的度量是常被用來評價人類孤獨症的某一方面），在接下來的三代老鼠身上也有各種明顯影響。
BPA 好像會影響動物處理包括後葉催產素和後葉加壓素在內的荷爾蒙的方式，這些荷爾蒙會影響人的信任感和溫暖感。儘管老鼠不是人，但研究老鼠的行為是評估新葯或衡量化學製品的影響的標準方法。
“很嚇人，”弗吉尼亞大學(University of Virginia)博士後研究員、該報告的第一作者詹妮弗·T·沃斯藤霍姆(
Jennifer T. Wolstenholme)表示。她說，研究人員發現，被暴露在BPA環境中的老鼠和它們的後代的行為可能類似於人類的自閉症譜系障礙或注意力缺乏症。
報告合著者、 弗吉尼亞大學醫學院(University of Virginia Medical
School)生物化學和分子遺傳學教授埃米莉·里茲曼(Emilie
Rissman)指出，BPA不會導致DNA發生突變。相反，這種影響是“表觀遺傳”——最近生物學領域的流行概念之一——也就是說那些變化是通過影響基
因的激活和關閉方式而非DNA來進行遺傳的。
實際上，這有點像獲得性遺傳進化論——由19世紀科學家讓-巴蒂斯特·拉馬克(Jean-Baptiste Lamarck)提出的理論。他在高中科學課上的被嘲諷為查爾斯·達爾文(Charles Darwin)的陪襯，但在表觀遺傳學中，拉馬克名流千古。
“低劑量條件下的這些實驗結果加劇了人們對內分泌干擾物的擔憂，”環境衛生科學 組織(Environmental Health
Sciences)的首席科學家約翰·彼得森·邁爾斯(John Peterson Myers)說。“它會比阻止一代人接觸有害物質更難。”
美國國立衛生研究院(National Institutes of Health)的女發言人羅賓·馬奇卡爾(Robin Mackar)表示，研究院對此很關心，預計會使內分泌干擾物的跨代影響成為研究基金的重點對象。
像很多美國人一樣，對於來自內分泌干擾物等化學製品的危險，我過去常常持懷疑態度。畢竟它們無所不在，而且，還有什麼比罐頭食品更安全呢？我原來以為，反對意見來自那些傾向於陰謀論的環保勒德派們。
然而，幾年前，我開始看同行評鑒期刊上的文章，隨後發現，對內分泌干擾物的抗議明顯是由毒理學家、內分泌學家、泌尿科醫生和兒科醫生發起的。這些人都是很嚴肅的科學家，但政客或記者卻聽不進去他們的話。
我希望這些最新研究能讓這個問題上升到國家層面。哪怕我們面臨的威脅是來自像罐頭湯和自動取款機收據這樣的普通東西而非伊朗的核武器，它們也需要得到解決。
翻譯：陳亦亭
Experts worry that the evidence that BPA damages young ovaries is consistent and growing.
BPA worries scientists for a number of reasons, but evidence is gathering for one concern in particular: infertility.
WELL.BLOGS.NYTIMES.COM|由 DEBORAH BLUM 上傳
2008
BPA ProductsIs Connected to Health Problems in Monkeys
酚甲烷原文為
Bisphenol A（縮寫為BPA），中文譯作
雙酚A 、
二酚基丙烷、
2,2雙對酚甲烷或
酚甲烷， 一種已知的
內分泌干擾素或
環境荷爾蒙。
中國大陸塑料業多稱Bisphenol A為雙酚A，
台灣多稱之為酚甲烷。
對環境生物和人類的影響
酚甲烷為一種
內分泌干擾素，會影響
生殖系統。在清潔
聚氯乙烯、
環氧樹脂和
聚碳酸酯纖維時，若使用
氧化鈉、
氫氧化鈉(
苛性鈉/
哥士的)和其它
鹼清潔劑，會釋出酚甲烷。
有關酚甲烷對人類的影響，目前說法不一：
工業界資助的研究結果傾向於聲稱沒有發現重大影響；
政府資助的研究傾向於發現有重大影響。
歐洲及
日本學者已密切注視它對
人類生殖力的影響。
[編輯] 參看
Chemical in Plastic Is Connected to Health Problems in Monkeys
Washington Post Staff Writer
Thursday, September 4, 2008; Page A02
Researchers at the Yale School of Medicine have linked a chemical found in everyday plastics to problems with brain function and mood disorders in monkeys -- the first time the chemical has been connected to health problems in primates.
The study is the latest in an accumulation of research that has raises concerns about bisphenol A, or BPA, a compound that gives a shatterproof quality to polycarbonate plastic and has been found to leach from plastic into food and water.
The
Yale study comes as federal toxicologists yesterday reaffirmed an earlier draft report finding that there is "some concern" that bisphenol A can cause developmental problems in the brain and hormonal systems of infants and children.
"There remains considerable uncertainty whether the changes seen in the animal studies are directly applicable to humans, and whether they would result in clear adverse health effects," John R. Bucher, associate director of the National Toxicology Program, said in a statement. "But we have concluded that the possibility that BPA may affect human development cannot be dismissed."
In a study published in the
Proceedings of the National Academy of Sciences, the Yale team exposed monkeys to levels of bisphenol A deemed safe for humans by the
Environmental Protection Agency and found that the chemical interfered with brain cell connections vital to memory, learning and mood.
"Our findings suggest that exposure to low-dose BPA may have widespread effects on brain structure and function," the authors wrote. In contrast to earlier research on rodents, the Yale researchers studied monkeys to better approximate the way BPA might affect humans.
"Our goal was to more closely mimic the slow and continuous conditions under which humans would normally be exposed to BPA," said study author Csaba Leranth, a Yale professor of obstetrics, gynecology and reproductive sciences and of neurobiology.
BPA, in commercial use since the 1950s, is found in a wide variety of everyday items, including sports bottles, baby bottles, food containers and compact discs. One recent federal study estimated that the chemical is found in the urine of 93 percent of the population.
The
American Chemistry Council, a trade group, maintained yesterday that "there is no direct evidence that exposure to bisphenol A adversely affects human reproduction or development."
The National Toxicology Program, part of the
National Institutes of Health, has no power to regulate BPA, but its findings are used by other federal agencies such as the
Food and Drug Administration and the EPA, which set safe exposure limits for chemicals.
The FDA plays a critical regulatory role because it regulates the compound's use in plastic food containers, bottles, tableware and the plastic linings of canned foods.
The agency last month issued a draft report that declared BPA safe for use in food packaging and bottles, based largely on the strength of two studies, both funded by industry.
"Unfortunately the regulatory agency charged with protecting the public health continues to rely on industry-based research to arrive at its conclusions, rather than examining the totality of scientific evidence,"
Rep. John D. Dingell (D-Mich.), chairman of the
House Energy and Commerce Committee, said in a statement yesterday. His committee is investigating the FDA's handling of BPA.
U.S. manufacturers make about 7 billion pounds of BPA annually. A ban would affect thousands of businesses and perhaps billions of dollars in profit for its largest manufacturers.
Canada has said it intends to ban the use of BPA in baby bottles, and state and federal lawmakers have proposed a variety of BPA bans.
Sen. Charles E. Schumer (D-N.Y.) is sponsoring a bill to prohibit BPA from children's products, while
Rep. Edward J. Markey (D-Mass.) wants to bar it from all food and drink packaging.
"The FDA's assurances of BPA's safety are out of step with mounting scientific evidence to the contrary," Markey said yesterday. "For the sake of the health of every man, woman and child in America, we should ban BPA in food and beverage containers, especially because there are alternatives already available."
Several major retailers, including
Wal-Mart and Toys R Us, have pledged to drop BPA products next year while some makers of baby bottles and sports bottles have switched to BPA-free plastic.
