We've all seen those color-coded air-quality charts on the news—warnings about smog, ozone, and pollen. Now it may be time to add a new alert to the list: illegal drugs. Researchers have found that regions with greater cocaine and marijuana use have higher levels of these drugs in the surrounding atmosphere.
A few studies since the mid-1990s have shown that illicit drugs make their way into the atmosphere. In 2007, for example, analytical chemist Angelo Cecinato and colleagues at the Institute of Atmospheric Pollution Research in Rome, detected small amounts of cocaine in the air of Rome and the city of Taranto on the coast of southern Italy. "We considered it a curiosity," Cecinato says.
But further research revealed that atmospheric concentrations of certain drugs were higher wherever drug use was presumed to be more prevalent—leading Cecinato and co-workers to wonder if they had found a better way to estimate the extent of drug abuse in a given area. Currently, authorities must rely on indirect information, such as communitywide surveys or questionnaires and police records. These methods can be time-consuming and expensive, Cecinato explains. Measuring the amount of drugs in the air, his group suspected, might be accurate, fast, and cheap.
To find out, Cecinato and colleagues analyzed the air in 20 spots in eight regions of Italy in winter and 39 sites in 14 regions in summer. The investigators collected air samples, extracted the contaminants, and analyzed the results, checking for cocaine and cannabinoids (the active ingredients in marijuana). To rule out false positives caused by other compounds, the team also tested for common pollutants including hydrocarbons, ozone, and nitric oxide.
Relationships were evaluated with the so-called Pearson regression coefficient (represented by the symbol R2), which shows how strongly two factors correlate when plotted on a graph. An R2 of 1 means the two essentially coincide. When the researchers compared their results against records of drug-related criminal activity, they found that airborne concentrations of cocaine correlated with the amount of drugs seized by police; R2 values were 0.54 for cocaine seizures and 0.73 for the total amount of illicit substances.
Average concentrations of cocaine also correlated strongly with users' requests for detoxification treatment (R2 exceeding 0.94), the team reports in today's issue of Science of the Total Environment.
The data also showed possible associations between air levels of cocaine and some types of crime, such as robbery. Statistical relationships between cocaine levels and some cancers, and between cannabinoid levels and mental disorders, also turned up. But Cecinato cautions that it's not clear what—if anything—those correlations mean. The study could be a starting point for future research, he says.
Epidemiologist Wilson Compton of the National Institute on Drug Abuse, Bethesda, Maryland, calls the work innovative. "We're always looking for more accurate ways to gauge the amount of drug use in communities," he says, adding that better information could lead to improved treatment, education, and policing.
Regarding the possible health risks to non-users, Compton said "I wouldn't sound any alarm bells based on this one study. But the researchers did find this link, and it's worth further exploration. Second-hand cigarette smoke wasn't considered a health threat either, until comparatively recently."