A commercial driver's license (CDL) is a driver's license required in the United States to operate any type of vehicle. 1  weighing 26,001 pounds or greater, or any combination of vehicles weighing 26,001 pounds or greater when towing a trailer weighing more than 10,000 pounds.
The cause of drug abuse is not fully known but likely include genetic predisposition, co-occurring conditions and environmental circumstances. Drug use and experimentation is common in pre-adolescents and adolescents, but only a small percentage of those users will go on to abuse drugs.hile many people use drugs, only a small percentage abuse drugs, but it has been noted drug abuse often runs in families, suggesting genetics is one of the causes of drug abuse.
Substance abuse, also known as drug abuse and substance use disorder, is a patterned use of a drug in which the user consumes the substance in amounts or with methods which are harmful to themselves or others, and is a form of substance-related disorder.hen an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped.