Sniffer Bees, Airborne Psychotropic Drugs

What’s an inexpensive and reliable way to detect volatile compounds such as explosives at parts-per-billion levels? Honeybees.

Yes, that’s right: Those black-and-yellow insects with the fuzzy torsos can do more than just seek out nectar. As part of the Stealthy Insect Sensor Project, researchers at Los Alamos National Laboratory (LANL) have trained bees to stick out their tongues when their antennae detect certain chemicals.

The scientists gently tape the bees into small holders and then simultaneously expose them to the vapor of a compound, such as TNT, and a cotton swab soaked in sugar water. A bee quickly learns to extend its tongue—technically, a tubular feeding tube called a proboscis—to get the sugar water.

Once trained, a trio of bees is placed in a box equipped with a video camera. Held near a car or person carrying the explosive they’ve been trained to detect, the bees will stick out their proboscises and get caught on camera.

Training can be completed in hours, making the bees much faster and less expensive to train than dogs. LANL has successfully demonstrated the “bees in a box” technology with explosives, narcotics, and the early-stage infection of grape crops with mildew.

A recent patent application for the technology, which is available for licensing, also describes a memory-enhancing cocktail that can be added to the sugar water to improve how long the bees retain their training. The cocktail compounds include caffeine, cyclic adenosine monophosphate, nitric oxide, and nicotine (U.S. patent application 20120264353).

Italian researchers have used more common analysis techniques—gas chromatography and mass spectrometry—to look for psychotropic substances in the air of eight Italian cities. Scientists commonly believe that airborne nicotine, caffeine, cocaine, and cannabinoids are at such low concentrations that they do not pose health risks, but studying the compounds could provide clues to drug abuse prevalence, says Angelo Cecinato, a scientist at the National Research Council of Italy’s Institute of Atmospheric Pollution Research, and colleagues (Environ. Pollut., DOI: 10.1016/j.envpol.2012.07.033).

Cecinato’s team looked to see what it could find in the air of Bologna, Florence, Milan, Naples, Palermo, Rome, Turin, and Verona. The researchers sampled the air over the course of a year, starting in May 2010. They found the highest concentrations of all four substances in Turin, which also has the most polluted air overall and a population density of more than 7,000 people per km². Palermo, in contrast, had the lowest amounts of airborne drugs and has the least polluted air overall with a population density roughly half that of Turin.

The data further revealed seasonal patterns for some of the compounds. Air concentrations of caffeine and cannabinoids noticeably peak in the winter months, while concentrations of nicotine and cocaine are more constant. A relatively high concentration of cannabinoids compared with other pollution in Bologna and Florence might reflect the high percentage of university students living in the cities, the researchers say.

The team also picked up variations in drug concentration for different areas of Rome, possibly indicating areas of high consumption. But relying on airborne drug concentrations as a robust measure of use, the authors say, requires better understanding of sources, phase partitioning, reactivity, and transport.