A pilot study in Mexico is showing promising results for measuring the frequency and type of drugs being used across the country by measuring metabolites in wastewater.
Researchers from Mexico’s National Institute of Public Health (Instituto Nacional de Salud Pública — INSP) took samples of metabolites — leftover traces of drugs that end up in human waste — across 13 cities, especially in the sewage systems of addiction treatment centers, prisons and high schools.
While marijuana and methamphetamine were frequently used across the country, cocaine was by far the most commonly found drug. Traces were collected in over 90 percent of samples.
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The highest concentration of all drugs was found in the northern states of Sinaloa and Tamaulipas. Across all samples, Sinaloa had an average of 628 nanograms per liter (ng/l) of cocaine, followed by Tamaulipas with 412 ng/l, which were two to three times the averages found in any other state.
Sinaloa led the use of methamphetamine by a wide margin, with 2,308 ng/l, with Sonora in second place at 480 ng/l, followed by Tamaulipas with 388 ng/l.
There was far less disparity in the use of marijuana-related products, with the highest concentrations of metabolites found in Chihuahua (287 ng/l), Quintana Roo (246 ng/l), and State of Mexico (224 ng/l).
The research was published in August of 2019, but the data collection took place in November and December of 2015.
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The results of the report are mostly in line with what could be expected when looking at Mexico’s illegal drug trafficking routes.
The highest values for cocaine, and high concentrations of methamphetamine and marijuana, were found in the cities of Nuevo Laredo, Culiacán and Torreón. All of these are important border cities or transit points along drug trafficking routes from Central America to the United States.
Culiacán is the capital of Sinaloa, the home state of the Sinaloa Cartel. It has been the backdrop for intense clashes between gangs and security forces, the most recent of which was an astonishing outbreak of violence on October 17 following the brief detention of Ovidio Guzmán López, the son of Joaquin Guzmán Loera, alias “El Chapo.”
Nuevo Laredo, along the US-Mexico border, has for years been a battleground for conflicts between the Gulf Cartel and Zetas over drug trafficking and human smuggling. The third city on the list, Torreón, also has a violent past as different cartels have fought over its strategic location.
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The high prevalence of marijuana traces in samples from cities in Sonora state is not surprising either. The state borders Arizona and New Mexico, and is a major drug trafficking hub mostly controlled by Los Salazar, a violent cell of the Sinaloa Cartel.
Another finding of the article was the high prevalence of all types of drugs in prisons, which is certainly linked to the constant flow of drugs seen in many prisons under the control of criminal groups.
Another interesting detail was the absence of heroin traces found in Mexican sewage. The researchers indicate that this possibly had to do with difficulties tracing heroin, which requires more refined techniques. This seems likely, since the absence of heroin does not match with the huge increase in heroin use in Mexico in 2014, the year before the samples were collected.
Wastewater analysis is proving to be an increasingly accurate method to understand the prevalence of drug use. While this INSP study is limited in scope, its results are useful to draw conclusions about drug use in critical areas, such as schools and prisons. The technique has been more widely applied in other regions, such as in Europe and Australia.