根據多倫多大學最新研究表示，用在速食包裝以及爆米花包裝袋上的防油膩化學品，因污染食物而被吃下肚進入血液中。
這類化學品為「全氟烷化合物」(perFluoroalkyls)，是穩定的合成化學物質，可以防油、油脂和水，廣泛使用於地毯和衣物的表面保護處理、紙張護膜和紙板包裝上。
多倫多大學的環境化學家馬伯里(Scott Mabury)和狄昂(Jessica D'eon)2007年就曾發表研究指出，包裝材料是這些化學品出現在人類的血液中的來源。而他們的最新研究表示，全氟化物(perfluorinated chemicals)會從包材滲透到食品。
這次研究的含氟化學品是「氟烷基磷酸酯」(PAPs，polyfluoroalkyl phosphate esters)，這是由全氟羧酸(PFCAs，perfluorinated carboxylic acids)裂解而來的，PFCAs是用於食品包材的塗層。
「我們懷疑人體接觸PFCAs的來源，是攝取及代謝了PAPs。」多倫多大學化學系研究生狄昂(D'eon)指出，「PAPs是一種撥油劑，應用在速食包裝和微波爆米花袋與食物接觸的紙面上。」
他們最新的研究中，狄昂和馬伯里讓大鼠接觸PAPs，包括用口服或注射，同時監測3個星期，追踪血液中PAPs和PFCA的代謝產物濃度。並且。研究人員使用先前在人體血液內觀察到的PAP濃度，和在大鼠體內的PAP以及PFCA濃度，來計算人體接觸的全氟辛酸(PFOA，perflurooctanoic acid)濃度。
「在這個研究中，我們清楚地證明，現在使用PAPs應用在包材的實品接觸面的情況，確實會使人體接觸到PFCAs，包括PFOA。」馬伯里說。
根據美國聯邦有毒物質及疾病登記署(Agency for Toxic Substances，ATS)表示，血中高濃度PFOA與性荷爾蒙及膽固醇有關，暴露在PFOA也會造成老鼠和大鼠的幼鼠早夭或發育不良。
長期攝入PFOA的大鼠會長出腫瘤。然而，因為大鼠和人類之間的差異，科學家還沒有確定人類是否也會發生。
「我們發現PAP代謝產生PFOA的濃度很明顯，因此結論PAPs是人體接觸到PFOA以及其他PFCAs的主要來源。」馬伯里說。
這項研究8日發表在由美國國家環境衛生科學研究所所發行的《環境健康展望》期刊，是由加拿大自然科學暨工程委員會(Natural Sciences and Engineering Research Council of Canada, NSERC)出資支助。
馬伯里說，「我們無法分辨PAPs是不是人類接觸PFOA的唯一來源，但無庸置疑地，我們可以說PAPs是其中一個來源，並且研究證據顯示這是相當明顯的。」
研究人員得出結論，因為PFOA會長期留存在血液中，即使是長期接觸低濃度的PAP，一樣是明顯暴露在PFOA下。
多倫多大學的研究人員說，儘管人類直接接觸食品和灰塵中的PFCAs，但因為人體處理這些化學品的方式，「接觸PAP應該視為PFCA污染明顯的間接來源」。
有關於人體接觸PAPs的議題已逐漸引起管理當局關注，各國政府如加拿大、美國和歐洲都已表明，將展開對此化學物質廣泛而長期的監測計劃。
馬伯里一面展示他2007年的研究報告一面指出，管理當局先前曾提出3個假設，「該化學物質不會從包材釋出進入食品、不會進入人體、身體不會代謝。但是這3點全錯了！」
Chemicals used to keep grease from leaking through fast food wrappers and microwave popcorn bags are migrating into food, being ingested by people and showing up as contaminants in blood, according to new research at the University of Toronto.
The contaminants are perfluoroalkyls, stable, synthetic chemicals that repel oil, grease, and water. They are used in surface protection products such as carpet and clothing treatments and coating for paper and cardboard packaging.
Earlier research by University of Toronto environmental chemists Scott Mabury and Jessica D'eon, established in 2007 that the wrappers are a source of these chemicals in human blood. Their new study shows that perfluorinated chemicalscan migrate from wrappers into food.
The specific chemicals studied are polyfluoroalkyl phosphate esters, or PAPs, breakdown products of the perfluorinated carboxylic acids, or PFCAs, which are used in coating the food wrappers.
"We suspected that a major source of human PFCA exposure may be the consumption and metabolism of polyfluoroalkyl phosphate esters, or PAPs," said D'eon, a graduate student in the University of Toronto's Department of Chemistry.
"PAPs are applied as greaseproofing agents to paper food contact packaging such as fast food wrappers and microwave popcorn bags," she explained.
In their latest study, D'eon and Mabury exposed rats to PAPs either orally or by injection and monitored for a three-week period to track the concentrations of the PAPs and PFCA metabolites in their blood.
The researchers used the PAP concentrations previously observed in human blood together with the PAP and PFCA concentrations observed in the rats to calculate human exposure to the chemical perflurooctanoic acid, PFOA.
"In this study we clearly demonstrate that the current use of PAPs in food contact applications does result in human exposure to PFCAs, including PFOA," said Mabury, the lead researcher and a professor in the university's Department of Chemistry.
Elevated levels of PFOA in blood have been associated with changes in sex hormones and cholesterol, according to the U.S. Agency for Toxic Substances. Exposure to PFOA also has resulted in early death and delayed development in mice and rat pups, the agency says.
Rats that ingested PFOA for a long time developed tumors. However, based on differences between rats and humans, scientists have not determined for certain whether this could also occur in humans, the agency says.
"We found the concentrations of PFOA from PAP metabolism to be significant and concluded that the metabolism of PAPs could be a major source of human exposure to PFOA, as well as other PFCAs," said Mabury.
The study is published today in the journal "Environmental Health Perspectives," published by the U.S. National Institute of Environmental Health Sciences.Research was funded by the Natural Sciences and Engineering Research Council of Canada.
"We cannot tell whether PAPs are the sole source of human PFOA exposure or even the most important, but we can say unequivocally that PAPs are a source and the evidence from this study suggests this could be significant," Mabury said.
The researchers concluded that due to the long time that PFOA remains in human blood, even low-level PAP exposure could, over time, result in significant exposure to PFOA.
Although humans are exposed directly to PFCAs in food and dust, the University of Toronto researchers said that because of the way the human body processes these chemicals, "PAP exposure should be considered as a significant indirect source of human PFCA contamination."
Regulatory interest in human exposure to PAPs has been growing. Governments in Canada, the United States and Europe have signaled their intentions to begin extensive and longer-term monitoring programs for these chemicals.
Regulators have made three assumptions, said Mabury, releasing the results of his 2007 study. "That the chemicals wouldn't move off paper into food, they wouldn't become available to the body and the body wouldn't process them. They were wrong on all three counts."
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