P76P76P76P76P76P76P76P76P76P76P76P76第四单元阅读材料：Reading Material : Analytical Technique and MethodologyP76P76P76P76P76第八单元：空气污染物的来源和类型P76P76第八单元 Reading Material : Type and Sources of Air Pollutants [ II J 阅读材料：空气污染物的类型和来源（Ⅱ）What are PCBs? 什么是多氯联苯？There are 209 possible chlorinated biphenyls, ranging in physical characteristics. 大概有 209种氯化联苯，其物理性质不同。The mono-and dichloro biphenyls ( 27323-18-8), ( 25512-42-9) are colorless crystalline compounds that when burned in air give rise to soot and hydrogen chloride. 一氯联苯和二氯联苯（27323-18-8），（25512-42-9）是无色晶体的化合物，当它们在空气中燃烧会产生烟尘和氯化氢。The most important products are tri-chlorobiphenyls,tetrachlorobiphenyls, pentachlorobiphenyls and/ or hexachlorobiphenyls. 最重要的产品是三氯化联苯，四氯联苯，五氯联苯和/或六氯联苯。Chlorinated biphenyls are soluble in many organic solvents and in water only in the ppm range. 多氯联苯可溶于有机溶剂和仅在水的百万分之一 ppm（part per million）的范围内溶解。Although chemically stable (including to oxygen of the air) they can be hydrolyzed tooxybiphenyls under extreme conditions forming toxic polychlorodibenzofurans. 氯化联苯易溶于在许多有机溶剂和水只有在的范围内的可溶性。虽然化学稳定性（包括空气中的氧气）但是在一定条件下，多氯联苯可水解氧化成二氧化苯极端条件下形成的有毒的多氯代苯并二噁英。The PCB class of compounds received substantial attention and notoriety when in 1968, in Japan,accidental poisoning occurred by cooking rice in bran oil contaminated by PCBs. 在 1968 年，多氯联苯类化合物受到实质性的的关注和得到臭名，日本用受到多氯联苯污染的米糠油做饭的意外中毒事件。Over 1000 patients suffered from various morbid symptoms. 超过 1000 例患者出现各种病态症状。A similar poisoning occurred in Taiwan in 1979. Causative agents were considered...
