River running with drugs tells a different story

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  • Published: Sep 15, 2005
  • Author: Steve Down
  • Channels: Base Peak
thumbnail image: River running with drugs tells a different story

A novel way of estimating drug use in Italy ignores the conventional use of statistics and social trends and looks instead to the final destination of the consumed drugs. The analysis of cocaine residues in water treatment plants and a local river has led to surprising results, strongly contradicting official figures.

The use of recreational drugs is on the increase, say official figures, and cocaine is one of the main drugs being abused. In the US, the Office of National Drug Control Policy reported that 14.4% of the US population over the age of 12 had used cocaine at least once in their lifetime and 3.6% had used crack cocaine. Those figures correspond to a massive 33 million and 8 million people, respectively, and that is for the US alone. Young adults tend to be the main abusers.

Drug user statistics are derived from a variety of sources, including treatment centres, hospitals, criminal statistics and population surveys, so by their very nature, they involve a series of broad assumptions and extrapolations. At the moment, however, they are the best way to estimate drug consumption, even though different countries have different methods of calculation.

The UN Office on Drugs and Crime launched a Global Assessment Programme to collect reliable and internationally comparable drug abuse data, based on a set of core indicators. However, even this plan is based on many estimates and assumptions, so reliability is still open to question.

These uncertainties have convinced Italian researchers to trial a new way of assessing drug use, which was described in the open-access journal Environ. Health 2005, 4. Concentrating on cocaine, they noted that about half of every cocaine dose is excreted in urine as its principal metabolite benzoylecgonine (BE), with a small fraction excreted as unchanged drug. So, they reasoned that measuring the concentrations of BE and cocaine in the ultimate destinations of human waste, rivers, would allow them to extrapolate to the amount of drug being consumed.

Team leader Ettore Zuccato and colleagues from the Department of Environmental Health Sciences of the Mario Negri Institute for Pharmacological Research in Milan with co-researchers from the Department of Biotechnology and Molecular Sciences at the University of Insubria in Varese studied the River Po in northern Italy. They took samples each day for four different days and extracted cocaine and BE by solid-phase extraction. Their concentrations were measured by LC/MS/MS with electrospray ionisation, using multiple reaction monitoring for each analyte.

The amounts of BE and cocaine in the river seemed small, at 25 and 1.2 ng/L, respectively, but that is equivalent to about 4 kg of cocaine per day flowing down the river. Based on a typical cocaine dose, this figure translates to a massive 40,000 doses per day.

Using the Italian 2001 Census to calculate the number of people living in the catchment area for the river (5 million) the team estimated the daily usage rate of the population to be 7 doses for every 1000 people. Considering only those people aged 15-34 years old, who are most likely to be cocaine users, the daily rate becomes 27 doses per 1000 young people.

These figures were put into perspective by comparison with official estimates of cocaine usage in Italy, which equate to a mere 15,000 doses per month (about 500 per day) for the young adults. It seems that the authorities are vastly underestimating the degree of cocaine abuse in Italy.

The researchers argue that their figures are likely to be correct because the ratio of cocaine to BE is in the expected range, similar to that found in urine. If cocaine had been dumped in the river, the ratio would have become distorted. The cocaine load was also determined at 5 wastewater treatment plants (WWTPs) around Italy and the results were consistent with the river-based studies.

There is no reason why this technique could not be extended to other drugs of abuse, such as amphetamines and cannabis, provided that the drugs and/or their metabolites maintain stability in WWTPs and rivers. Heroin would be more difficult, because it is metabolised to morphine, which is used in its own right as a legal drug. The legitimate environmental burden of morphine would need to be estimated before heroin levels in waters could be determined confidently.

Similarly, this general survey method could be applied to other consumer chemicals that cause concern in the environment, such as cosmetics, personal care products and prescription medicines.

Canoeing on the River Po

Canoeing on the River Po - but don't drink the water

Image: courtesy Turin tourism

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