Drugs in prison: Wastewater analysis is an indicator of usage levels and trends

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  • Published: Nov 29, 2010
  • Author: Steve Down
  • Channels: HPLC
thumbnail image: Drugs in prison: Wastewater analysis is an indicator of usage levels and trends

An indicator of regional use

There are the official statistics on illicit drug use and the unofficial ones. The former rely on data from treatment centres and hospitals, as well as criminal statistics and population surveys, so involve a series of broad assumptions and extrapolations. By their very nature, they calculate drug consumption over a past period, perhaps a few years ago, and do not relate to the present.

In 2005, a novel way of estimating drug use came to light, with the publication of a paper by Italian researchers who measured the levels of cocaine and its principal metabolite benzoylecgonine (BE) in the River Po. They estimated that 4 kg of cocaine passed down the river daily.

Knowing that about 50% of each dose is excreted as BE, and only a small proportion as unchanged cocaine, they equated the river level to 40,000 doses per day. This figure dwarfed the official estimates of cocaine use at 15,000 doses per month, indicating that the authorities were grossly underestimating cocaine use.

The difference between this work and the official statistics was that is provided almost real-time data on drug consumption from the catchment area of the river, bearing in mind the relatively short time covering drug taking, excretion and wastewater treatment. Since then, there have been numerous studies measuring drug levels in wastewater in the USA and Europe to estimate human consumption.

Now, a further study along the same lines has been reported by Spanish scientists who wished to evaluate drug use in a prison.

Prison drug use profiled by LC/MS analysis of sewage water analysis

Cristina Postigo, Miren Lopez de Alda and Damia Barcelo from the Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, and the Catalan Institute for Water Research (ICRA), Girona, collected samples of sewage water at the entrance to a wastewater treatment plant which processed exclusively the waste from a prison of about 3500 inmates. Samples were taken over several months, covering 10-day periods within a month and once a week for the remainder of the month to expose weekly trends and more long-term patterns.

Drugs in the wastewater were preconcentrated and spiked with a mixture of deuterated internal standards before LC/MS analysis on a reversed-phase end-capped C18 column. An acetonitrile-water gradient elution program was applied to separate the target analytes for analysis by electrospray ionisation in positive and negative ion modes. Quantitation and confirmatory analyses were carried out by selected reaction monitoring.

A total of 19 drugs and metabolites were targeted, covering cocaine and BE, cannabinoids, opioids, amphetamines, LSD and its metabolites, and benzodiazepines. The major drug excretion products were selected as drug consumption indicators and others were monitored to confirm use of those drugs. The measured concentrations were used to calculate drug use within the prison.

The data indicated that methadone, alprazolam, ephedrine, cannabis and cocaine were taken daily by the inmates, whereas heroin, ecstasy, amphetamine and methamphetamine use was more sporadic. Certain drug-taking trends were visible from the results.

For instance, methadone consumption was highest at the beginning of the week at 174 doses/day/1000 inmates (ddi) and declined to 121 ddi towards Sunday. The average consumption was in line with the amount of methadone prescribed by the prison medical staff for the treatment of heroin addiction. Methadone use fell to a minimum during September and maximised in December, possibly due to the approach of Christmas.

Heroin itself was detected by its metabolite 6-acetylmorphine and its consumption ranged from 27-120 ddi in an uneven pattern. However, heroin itself was found at notably high levels on one particular day, higher than the level of 6-acetylmorphine. On the same day, unusually high levels of methadone, alprazolam and LSD were also observed. The researchers interpreted these anomalies as the deliberate dumping of drugs in the sewage system, perhaps due to a prison inspection.

The same behaviour was observed on a different day several months later, when unusually large amounts of MDMA, amphetamine and methamphetamine were found and the same conclusion was drawn.

The average levels of the other detected drugs were 129 ddi (alprazolam), 46 ddi (ephedrine), 33 ddi (cannabis) and 3 ddi (cocaine). Their consumption patterns varied too, with highest daily use on Tuesday for alprazolam, cannabis and methadone, but Saturday for ephedrine and Sunday for cocaine.

The public perception of prisoner drug use is that they consume more than people in free society. However, figures reported by the same research team for drugs at two sewage treatment plants in Barcelona appear to refute that. Prison use is lower than public use for all drugs except ephedrine and cannabis.

Analysis of prison sewage water for drugs of abuse represents a rapid way to monitor drug use in almost-real time in prisons and other facilities with dedicated sewage treatment plants. The procedure could also be used to assess efforts by the prison staff to limit drug entry into the premises.

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.



Trends in illicit drug use within a large Spanish prison, estimated by analysing the sewage wastewater by LC/MS, suggest that some drugs are used daily whereas others are consumed sporadically

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