Cocaine is one of the most frequently used drugs, and the smuggling of cocaine has become a big problem. A common way to get the drug through border controls is the so-called body-packing [1, 2]. These drug traffickers smuggle drugs, mainly cocaine or heroin, inside their bodies, usually by inserting a packet of drugs into the rectum or vagina or by swallowing them. This kind of smuggling is dangerous, and complications of intoxication [3, 4] and even death [5] have been reported.

However, there are many other ways to smuggle drugs—for instance, by hiding them inside luggage or cargo [6, 7]. Cocaine has been found concealed in various imaginative ways, as reports of cases of cocaine concealed in wax [8], baseball caps [9], wooden globes [10], beer cans [11], milk cans [12], or in cocaine-impregnated cloth [13] show. Methods to detect these hidden drugs at the border are important and must keep pace with the increasingly imaginative ideas of the smugglers [13–15].

Reported cases have shown the successful application of techniques such as fluoroscopy [6, 7], backscatter radiography [6, 7], conventional radiography [1, 2, 6, 7], CT [1, 2, 6, 7], and sonography [14] in detecting drug-filled foreign bodies inside humans, luggage, parcels, and cargo containers. But if a drug such as cocaine is dissolved in a liquid, it cannot be detected by these scanning methods (Fig. 1A, 1B). Several cases have shown that this kind of smuggling does exist, especially with cocaine [16]. To find a dissolved drug at the border, an immunologic test using a drug-test panel (e.g., RapidCHECK10 panel Multi Drug Professional Card, Craig Medical Distribution) must be performed. Such panels are the same as the clinical urine-stick tests and are based on the same principle as a pregnancy quick test. Thus, a control sample of the cargo must be opened to perform the test. Because it is not possible to open all boxes, and smugglers hide the drug-containing boxes between boxes containing legitimate goods, contaminated cargo can be overlooked. Investigators prefer not to arouse the smugglers' suspicion when checking the cargo.

At our institute, three bottles of red wine under went chemical analysis because they were suspected of containing dissolved cocaine. In the context of the Virtopsy project (www.virtopsy.com [University of Bern, Switzerland]), MDCT is available at our insti tute to perform postmortem radiology [17].

To determine whether dissolved cocaine is detectable with MDCT, we performed MDCT of these bottles. We noticed that significant mean density differences could be measured between the bottles with and the ones without cocaine. On the basis of this observation we developed a rapid method to detect cocaine solutions inside bottles without opening them. To test our new screening method, we performed simulated testing using cocaine-spiked wine bottles hidden between normal bottles of red wine.

This study was performed in collaboration with the Federal Customs Administration (FCA), Drugs Unit (Bern, Switzerland).

The method described in this article to detect dissolved cocaine in liquids seems to be an accurate technique, as the results of our simulated testing showed. The question that initiated the experiments was whether it is possible to perform a screening examination on liquids in bottles that are suspected of containing dissolved cocaine without opening the bottles. As the FCA Drugs Unit declares, this can be a useful screening method—for example, when a large shipment of bottles is suspected of containing cocaine. Usually the drug is hidden in a few bottles and most of the others are filled with uncontaminated liquid. Hiding the drugs in regular cargo makes it easier for drug smugglers to go undetected because they know that at the border only random samples are examined. Although opening some bottles of a large shipment and performing immunologic drug testing can miss single drug-contaminated bottles, our screening method can test all the bottles rapidly (scanning duration, 5–10 minutes; analysis possible in 10–30 minutes). Another benefit of the method is the noninvasive method of examination. Shipments can be controlled without opening bottles, thus allowing a suspicious delivery to be tracked without arousing the suspicion of the smugglers.

As the results show, the method is suitable for detecting cocaine as a dissolved substance in a liquid because cocaine shows X-ray attenuation. When a carton or a group of wine bottles contains the same wine, the bottles will have more or less the same mean attenuation on the cross-section images. The scan of our carton showed that the six uncontaminated bottles displayed a mean attenuation between –3.8 and 0.3 H. It is suspicious when the attenuation of some bottles differs much from the rest. To be absolutely certain, these bottles can be opened and tested using the immunologic method. The chance of detecting contaminated bottles is much higher than when arbitrarily chosen bottles are tested.

As our experiment shows, the method works better in detecting higher drug concentrations. Bottles containing 30 g or more of cocaine show significant differences, whereas the bottle with 10 g of cocaine is not as clearly suspicious, and the mean attenuation peak of 1.7 H was within the SD rate. However, we do not believe this poses a problem in daily practice because experience has shown that if cocaine is dissolved in a liquid, the concentration is higher—for example, 80 g—as in our described case.

Our study shows that it is not possible to give a critical mean attenuation value that makes a wine suspicious for containing dissolved substances. Although most commercially available wines show mean attenuation peaks between –18 and –10 H, some are beyond these values—for example, our tested dessert wine, which had a mean attenuation of 23.6 H, and the unfiltered Barbera, with a mean attenuation of –6 H. This fact shows that it is necessary to compare single bottles in one shipment with one another or to compare the bottles with a reference bottle that is sure to be free of the dissolved drug.

In our study we tested different kinds of wine with cocaine as a dissolved substance. Principally, the method can detect any dissolved substance in any liquid, because the dis solved substance leads to a change of X-ray attenuation in the liquid, which can be measured because of the altered mean attenuation peak. For example, we changed the X-ray attenuation of water from –3 to 14 H by dissolving sugar. With an increasing amount of the dissolved substance, an increasing mean attenuation peak will be reached. As the example of water and sugar shows, 30 g of sugar dissolved in water leads to a mean attenuation of 14 H, and 90 g of sugar produced a mean attenuation of 42 H.

The method we describe seems also to be applicable to other sorts of smuggling. As articles [10, 12, 16] show and as the Swiss FCA declares, cocaine and other drugs are also smuggled inside small sculptures and hollowed fruits or dissolved in other liquids and vessels. Using CT and measuring the mean opacity of the content, differences in hidden drugs can be detected without destroying the carrier. If the carrier is expensive, this aspect will be especially important because in cases of an incorrect suspicion the owner of the destroyed or opened object must be reimbursed.

To apply our method, collaboration between police or customs officials and a medical department is necessary. The scanning can be performed in every hospital that has a CT scanner, and forensic departments also use this radiologic tool.

If a forensic chemistry department must analyze a confiscated shipment that is suspected of containing dissolved cocaine or other drugs, the screening scan can be helpful to get a first overview to sort out suspicious vessels, so that the more expensive quantitative chemical analyses can be performed on selected items.

In conclusion, our study describes a rapid screening method for detecting dissolved substances having X-ray attenuation, such as sugar or cocaine, in liquids. Because of its noninvasive fashion and fast practicability, this method is suitable for the examination of large cargos or to confirm suspicions without changing the package.

Performed in collaboration with the Federal Customs Administration (FCA), Drugs Unit, Bern, Switzerland.

Financial support was provided by the Virtopsy Foundation, Bern, Switzerland.

Address correspondence to S. Grabherr ([email protected]).