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.
Combination of Causes of Drug Abuse. While genetic, environmental and psychiatric causes of drug abuse are possible, it is likely that a combination of risk factors is truly the cause of drug abuse. If a person has a genetic predisposition to drug abuse, that likely indicates one of the parents abuses 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.