飲用水中的 PFAS 從哪裡來，對健康有什麼影響？ 公衛專家告訴你

「永久性化學物質」PFAS 如何悄悄潛入我們的日常？從水源、管線到體內累積，這些看不見的環境足跡正牽動著全家人的健康。面對無所不在的微量暴露，我們該如何正視潛在威脅？公共衛生專家胡景堯教授帶您深入解析 PFAS 的污染途徑與健康風險，並教您透過科學的淨水防線，為居家飲水品質把關。

全氟及多氟烷基化合物（PFAS）是一大類具有高度穩定碳–氟鍵的人工合成物質，因耐熱、耐化學反應及部分具有界面活性，過去數十年間廣泛應用於半導體與電子製程、金屬加工、防水防油紡織、食品包裝及含氟消防泡沫等用途[1,2]。

許多 PFAS 在環境中極難自然降解，製程廢水、消防訓練廢水、都市污水、掩埋場滲出水等，都可能使 PFAS 進入河川、土壤與地下水，並隨地下水遷移，因此距離污染源較遠的取水井也可能受到影響[2–5]。

當受污染的地表水或地下水成為自來水水源時，傳統混凝、沉澱、砂濾與消毒流程通常無法穩定去除溶解態 PFAS，尤其部分短鏈 PFAS 更容易穿透既有處理單元[5,6]。若供水系統未設置粒狀活性碳、陰離子交換樹脂或高壓膜等專門處理單元，即使飲用水中的 PFAS 濃度偏低，長期持續攝入仍可能使 PFAS 在體內逐漸累積，進而提高血清中的 PFAS 濃度[10-12]。

除了水源污染，在特定條件下，配水系統完整性也可能成為污染物進入飲用水的途徑。當管線破裂、抽水或瞬間高流量造成壓力驟降時，可能形成短暫負壓，使周圍土壤孔隙水或地下水進入管線[8,9]。若這些外部水體恰受 PFAS 污染，理論上也可能將 PFAS 帶入配水系統。

不過，目前直接證實「管線破裂或負壓使 PFAS 進入飲用水」的研究仍不多，然而在鄰近 PFAS 污染場址或地下水位較高的區域，做好管線維護、壓力監測、破管後沖洗與水質追蹤，仍是降低潛在風險的重要預防措施[8,9]。

飲用水中的 PFAS 之所以受到環境衛生學界重視，主要是因為部分 PFAS 具有體內持久性。某些長鏈 PFAS 進入人體後會與血清蛋白結合，並分布於血液、肝臟與腎臟等部位；部分化合物在人體中的半衰期可達數年，因此長期低劑量攝入仍可能增加體內負荷[10–12]。

目前流行病學與毒理研究顯示，特定 PFAS 暴露與血脂上升、肝臟代謝變化、免疫反應降低，以及部分發育與生殖結果存在關聯，但不同 PFAS、不同健康終點的證據強度並不完全一致[10–15]。例如，兒童研究曾觀察到較高 PFAS 暴露與疫苗抗體反應降低之間的關聯；歐洲食品安全局也將免疫反應列為 PFAS 健康風險評估的重要依據[14,15]。

致癌性方面，國際癌症研究機構（IARC）將 PFOA 分類為「對人類具致癌性」（Group 1），PFOS 則列為「可能對人類具致癌性」（Group 2B）[16]。整體而言，飲用水中的 PFAS 風險較屬於長期、低劑量累積的慢性暴露問題，而不是典型的急性中毒。

目前可用於降低飲用水 PFAS 的技術包括粒狀活性碳（GAC）、離子交換樹脂，以及逆滲透等高壓膜處理[6,7]。其中，活性碳是研究較多、實務上也廣泛使用的方法之一。

GAC 主要利用多孔性碳材表面吸附 PFAS，一般而言，對 PFOA、PFOS 等較長鏈 PFAS 的去除效果較佳；部分短鏈 PFAS 則較容易提早穿透濾床[6,17–19]。實際效果也會受到碳材種類、水中天然有機物、流速、接觸時間與濾材使用時間等因素影響，因此不能只看到「含活性碳」就推定一定能有效降低 PFAS。

對家庭用戶而言，如果希望降低飲水中的 PFAS，應優先確認產品是否經獨立測試或認證，並明確標示可降低 PFOA、PFOS 或其他 PFAS。同時，濾材吸附容量有限，仍需依額定處理水量及製造商建議定期更換濾芯[21]。EPA 也提醒，不同家用濾水設備對各類 PFAS 的去除能力並不相同。

參考文獻

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