What is Classification Of Poisons?

Legal Definition
US Department of Transport puts poisons in two classes. (1) ClassA, which includes highly toxic chemicals, which are dangerous to life even in very small quantities as a gas or vapor in air, such as cyanogen, hydrocyanic acid, nitrogen peroxide, and phosgene. (2) ClassB includes chemicals other than those included in ClassA and still considered dangerous, but comparatively less poisonous.