The Iowa Department of Transportation is working with the Iowa National Guard to try to curb drug use by truckers, reports the Associated Press.

Two ion scanners owned by the Guard are being used to check truckers' logbooks and other paperwork for traces of drugs. At a state weigh station on I-80 near Van Meter, 10% to 15% of the truckers' paperwork that was scanned tested positive for traces of drugs such as methamphetamine and marijuana. At a state scale on I-29 near Missouri Valley and Salix, the rate was about 20%. Only a small portion of the paperwork is tested.
When commercial trucks are searched for drugs based on probable cause, DOT officer Mark Rehberg estimates, one out of five turns up drugs or drug paraphernalia.
The number of truckers being arrested in Iowa for driving under the influence of drugs remains fairly small, but more police are being trained to recognize illegal drug use. Until recently, state truck enforcement officers had been making about two drug-related arrests per month. That has increased to about four per month since officers received training in January.