Would an ideal government issue bans/regulations to prevent harmful activity?

At the turn of the 20th century it was common to use cyanide gas to fumigate buildings. Although it was well-known that cyanide gas was extremely poisonous and alternatives were available, its use continued and resulted in a number of accidental deaths due to the gas traveling through cracks in walls and even in plumbing. With the development of better toxocology practices, these deaths were more frequently recognized for what they were and at the end of summer in1825 the NYC government banned its use.

In a similar situation, tetraethyl lead (TEL) was banned after several men in a factory were killed while a couple dozen others when insane from the gas. The factory was adding the chemical to gasoline to render uncombusted gasoline in engines inert. Safety practices in factories being what they were at the time people really didn't know how to safely handle TEL. Moreover, the chief medical examiner of NYC at the time believed that having it as a gasoline additive presented a risk to the public if they came into contact with either gasoline with the additive or the byproducts of using it in the engines of their vehicles.

In these and other situations, it was recognized that the substance in question was extremely poisonous and could only be handled with the most extreme care -- care that was rarely demonstrated in the public.

The question is this: should the government step in and ban the substance from general use or should it simply stand by and wait for people to die and prosecute the users for manslaughter or is there another option?