People have créated other mutagens that are now in the earth environment. Many industrial chemicals change genetic sequencing by changing the nucleotides of DNA. The first chemical mutagen discovered was mustard gas. Mustard gas was developed during World War as a way to kill the enemy. Since then, many chemicals have been created that cause mutations. Examples include insecticides and food preservatives. Many mutations caused by chemicals lead to different nds of cancer. These chemicals are often referred to as carcinogens. The number of these chemicals in the environment can affect the number of mutations in an organism. Many people are concerned that more chemical mutations may be a danger to humans