9. Substance Abuse
Substance abuse is the use of legal or illegal drugs in amounts or methods that are harmful to the user. Examples of drugs often abused are cocaine, heroin, nicotine, crystal meth, marijuana, and prescription painkillers. These drugs not only give the user a feeling of being high they can also cause cancers.
There are primary two ways substance abuse can cause, through the carcinogenic chemicals in the substances that are sniffed or injected in the blood. The second way is through the smoke that accompanies the means of partaking the substances. For instance, people who smoke marijuana often can develop lung cancer because of the smoke’s effect on the lungs.