目標：本研究在探討臺灣禁止多氯聯苯(PCBs)運作十二年後，多氯聯苯在主要河川魚體之生物累積(Bioaccumulation)情形。方法：本研究以臺灣西部基隆河、大漢溪、新店溪、淡水河本流、頭前溪、中港溪、朴子溪、二仁溪、高屏溪、東港溪等10條河川採得吳郭魚、大鱗鯔、烏魚、大眼海鰱、虱目魚、鯰魚、泰國鱧魚、北梭魚等八魚種，以解剖刀切取魚肉、魚皮、魚肝、魚卵、魚腸，經均質攪拌器分別攪拌均勻後，以氫氧化鈉鹼性溶液皂化處理，再以正己烷萃取，萃取液脫水濃縮後，經過酸性矽膠淨化管除去雜質，注入氣相層析儀，利用電子捕捉偵測器進行檢測分析，若測 出含有多氯聯苯時，再以氣相層析串聯式質譜儀確認之。結果：吳郭魚肌肉含PCBs平均濃度(wet wt)：基隆河17.7 ng/g、大漢溪19.1 ng/g(兩條河PCBs之檢出濃度呈上游＜中游＜下游之趨勢)、新店溪65.1 ng/g、淡水河本流13.2 ng/g、頭前溪38.5 ng/g、中港溪26.8 ng/g、朴子溪9.8 ng/g、二仁溪130.1 ng/g、高屏溪178.8 ng/g、東港溪26.1 ng/g。總平均濃度為67.6 ng/g(1.2-884.7 ng/g)。基隆河吳郭魚魚體不同部位生物累積之多氯聯苯平均濃度(wet wt)：肝207.8 ng/g＞腸140.0 ng/g＞卵113.0 ng/g＞魚皮37.1 ng/g＞肌肉17.7 ng/g。 PCBs各同屬物之檢出頻率及濃度 ：以六氯No.153、 No.138檢出率最高；檢出之平均濃度，以三氯的No.28最高，四氯的No.77、五氯的No.118次之。結論：河魚PCBs之生物累積檢測，可以作為PCBs環境污染之指標；臺灣淡水魚類多氯聯苯之生物累積，北、中部屬輕度污染，南部則為中、高度污染，尤其是二仁溪下游為最；但比較不同年代二仁溪魚體中的PCBs，發現二仁溪中的PCBs污染已趨緩和。魚體之各部位PCBs含量：肝＞腸＞卵＞皮＞肉。魚肉含PCBs，不論是平均濃度抑或個別樣品最高濃度，均符合我國食品衛生標準1ppm；魚內臟、卵及皮含PCBs濃度較魚肉高出甚多，食用時宜去除。

　　　　　Objective: This research was to study the levels of polychlorinated biphenyls (PCBs) in fish collected from major rivers in Taiwan after 12 years of prohibiting the use of PCBs. Method: We sampled Oreochromis sp, Liza macrolepsis, Mugil cephalus, Megalops cyprinoides, Chanos chanos, Channa sp., and Albula glossodonta in the following ten rivers: the Keelung River, the Ta Ham Chi, the Hsin Tien Stream, the Tanshui River, the Touchien Chi, the Chungkang Chi, the Potzu Chi, the Erhjen Chi,the Kaoping Chi, and the Tungkang Chi. We stabbed with a knife to collect the meat, skin, liver, eggs, and bowels of fish, which were homogenized and mixed with NaOH. The mixture was extracted with n-hexane and the solvent was evaporated to near dryness, then the mixture was cleanup through acidic silica gel column. Samples were analyzed by gas chromatography, which equipped with electron capture detector. If we found samples containing any PCB, then we would confirm it by GC/MS. Result: We found that the sample of meat of Or eochromis sp. containing PCBs (ng/g in wet wt) in the Keelung River was 17.7 ng/g, in the Ta Ham Chi was 19.1 ng/g, in the Hsin Tien Stream was 65.1 ng/g, in the Tanshui River was13.2 ng/g, in the Touchien Chi was 38.5 ng/g, in the Chungkang Chi was 26.8 ng/g, in the Potzu Chi was 9.8 ng/g, in the Erhjen Chi was 130.1 ng/g, in the Kaoping Chi was 178.8 ng/g, and in the Tungkang Chi was 26.1 ng/g. The average concentration was 67.6 ng/g(1.2-884.7 ng/g). In Keelung River, different parts of the fish containe d different PCBs level, it ranked as follows: livers (207.8 ng/g) > bowels (140.0 ng/g) > eggs (113.0 ng/g) > skin (37.1 ng/g ) > meat (17.7 ng/g). Among PCBs congeners detected, we found hexachoroide (No. 153, 138) was the highest in percentage, but in the concentration, we found Trichloroide (No.28) > Tetrachloroide (No.77) > Pentachloroide (No.118). Conclusion: The levels of polychlorinated biphenyls in river fish collected from northern and central Taiwan were low, while in southern Taiwan they were mi d to high. The PCBs concentration of fish meat was within ROC's food regulation standards (1 ppm), but the liver, bowels, eggs, and skin were considered polluted. So we believe fish meat is safe to ingest but not fish liver, bowels, eggs, and skin.