All DOT drug tests screen for which of the following substances?

In the context of DOT drug testing, the primary substances that are screened include certain drugs identified as having a potential for abuse, which is a safety concern in transportation industries. Marijuana is one of the key substances included in these screenings due to its legal status varying across states and its implications for fitness for duty in safety-sensitive positions.

The DOT's drug testing protocols follow specific guidelines that require testing for a panel of drugs, which includes marijuana among other substances like cocaine, opiates, amphetamines, and phencyclidine (PCP). These substances are included because they have known effects that could impair a driver's ability to operate a vehicle safely.

While alcohol may also be part of the overall testing process in terms of fitness for duty, it is typically evaluated through separate alcohol testing measures rather than the standard drug test. Nicotine is not part of the DOT drug testing panel, nor are barbiturates, which means they do not fall under the set substances that the DOT screens for in drug tests. This distinction highlights the specific focus on ensuring that individuals in safety-sensitive positions do not engage in the use of substances that could compromise their performance or safety on the job.