5. Dangerously Reactive Material
危险的反应性物品

These materials may produce a poisonous gas or explode if the container is heated, pressurized or dropped. Reactive materials must not be mixed with other chemicals, even water. An example is a chemical called benzoyl peroxide which may explode when dry.

如果盛装这些物品的容器被加热、受压或抛掷时，这些物品会产生有毒气体或发生爆炸。反应性物品不能与其它化学品甚至水混合。比如，过氧化苯(甲)酰这种化学品在干燥时就会爆炸。

6. Poisonous and infectious Material, Causing Immediate and Serious Toxic Effects
有毒及传染性物质，可导致即刻和严重中毒现象

These materials may cause serious health problems including death within a short time after a person is exposed to them. When using such materials, make sure to wash your hands before you eat, smoke or drink. An example would be a substance such as cyanide which can cause immediate death.

当人体接触这些物品后，短时间内人体会出现严重的健康问题甚至死亡。因此，在使用过这类物品后，在饮食、吸烟之前要将手洗净。比如，氢化钾就是一种有毒物质，会致人立即死亡。

7. Poisonous and infectious Material, Causing Other Toxic Effects
有毒及传染性物质，可导致其它中毒现象

These are materials which cause harmful effects days, months or years after a person is exposed to them. Materials which can cause cancer are included in this group. An example would be asbestos fibers which when breathed may not cause a health problem until 15 or 20 years later.

接触这些物品会使人受到伤害，受害时间可从数日、数月到数年不定。这类物品包括一些致癌物质。比如，石棉纤维就是其中一类，它如果被人体呼吸，会在15年或者20年以后导致人体健康问题。

8. Poisonous and infectious Material, Biohazardous and Infectious Material
有毒及传染性的物质，有害生物及传染性物质

The materials in this group include living organisms or the poisons they produce that may cause serious disease. An example is the virus that causes hepatitis B.

这类物质包括动物器官及其产生的有毒物质，会导致严重的疾病。比如，病毒会导致B肝。

Understanding what these symbols mean will allow you to quickly identify the hazard and then to protect yourself against it.

了解上述这些标记的意义将帮助你迅速辨别有害物品并保护你自己不受伤害。