Even though most of us are aware of toxicology primarily from crime shows on TV, toxicologists actually do most of their work in other fields. Many are employed by drug companies, others by chemical companies. Many work for the government, making sure the public is being kept safe from environmental poisons in the water, soil, and air, as well as unhealthy substances in our food and drugs. These issues often have to do with quantity; questions about how much of some substance should be considered dangerous, whether in the air or in a soft drink, may be left to toxicologists. But occasionally a toxicology task may be more exciting: for instance, discovering that what looked like an ordinary heart attack was actually brought on by a hypodermic injection of a paralyzing muscle relaxant.