Toxicology is the science of adverse effects of chemical substances on living organisms.
Living organisms include the algae in the sea, animals and people, all flora and fauna. There are no safe substances, all chemicals can be poisonous and cause injury or death. This information is obtained from laboratory tests with cells, bacteria, animals and from accidents involving the substance. Large amounts of toxicological information are collected into data bases and data banks. To have an adverse effect a substance must be able to enter the system.