Science in Society Archive

Illicit Drugs in Drinking Water

Regulators are denying the risks of widespread contamination of our drinking water with illicit drugs. Prof Joe Cummins

Licit and illicit drugs

Until the mid-2000s, the emerging study of pharmaceuticals in the environment inexplicably excluded illicit drugs. Illicit drugs are a structurally diverse group of chemicals used in enormous quantities worldwide that are very likely to affect humans and other non-target organisms; and just like pharmaceuticals, can enter the environment via many pathways. It had been known for decades that illicit drugs and their breakdown products are excreted in urine, faeces, hair, and sweat; but this was ignored until 1999 when the United Nations included illicit drugs in its scope of concern.

However, the United Nations drug control conventions still do not recognize a distinction between licit and illicit drugs; they describe only use to be licit or illicit. The term ‘illicit drugs’ designates drugs that are under international control (and may or may not have licit medical purposes), but are produced, trafficked and/or consumed illicitly [1].

The first published indication that illicit drugs might be pervasive contaminants of our environment was a 1987 FBI study showing that cocaine was present on money in general circulation. Later surveys found illicit drugs in sewage wastewaters, surface waters, air, sewage sludge, and drinking water. The illicit drugs commonly encountered in the urban environment include codeine, morphine, methadone, amphetamine, methamphetamine, cocaine, tetrahydrocannabino (THC) and the primary metabolites of methadone. Although widely detected in clinical and forensic drug screens, the occurrence of heroin (diacetylmorphine) in the environment is limited primarily to banknotes, because of its propensity to hydrolyse in water.

Illicit drugs in the environment

Illicit drugs and their metabolites in the environment and their potential impact on the ecosystem is a growing concern. Cocaine, morphine, amphetamine, and MDMA have potent pharmacological activities and their presence as complex mixtures in water may well have adverse effects on aquatic organisms and human health. However, there is no regulation over the presence of these pollutants in treated wastewater, surface water, drinking water, or the atmosphere.

The concentrations (in ng/L) of illicit drugs in wastewaters and surface waters from around the world are compiled in two categories: cocainics, opioids, and cannabinoids; and amphetamine and ecstasy group compounds. The range spans three to four orders of magnitude (see Table 1) [2].

Table 1   Illicit Drugs in Water

 Wastewater ng/LSurface water ng/L
Cocainics, opioids, & cannabinoids18.8 - 7 5007.5 - 3 4250.1 - 316
Amphetamine & ecstasy group2.2 - 15 3801.0 - 10 9550.4 – 309

Extensive reviews from around the world reveal widespread pollution of water by illicit drugs. The data provide information on drug abuse that cannot be obtained from conventional epidemiology. Even more importantly, they highlight the need for remediation in order to restore the quality of urban drinking water [3].

Illicit drug consumption and sewage epidemiology

Drug consumption by wastewater analysis was carried out in Paris. Cocaine and its metabolite, amphetamine, MDMA (ecstasy) and buprenomorphine were compared in the areas around four water treatment plants. Drug consumption differed in the four areas, being most prevalent during weekends. The estimated illicit drug-taking in Paris were lower than in other countries such as Spain and Italy [4].  In Australia, wastewater analysis showed that in one year (from 2009 to 2010), the use of MDMA declined fifty fold with a rise in methamphetamine use [5].  Similar sewage epidemiology in the state of Oregon, USA, showed that cocaine use was mainly in urban settings and low or absent in rural areas [6].  MDMA was used in less than half of the communities, mainly in urban settings; while methamphetamine was used in all communities, whether urban and rural [6].

Three unnamed Canadian cities were studied for the use of cocaine, amphetamine, methamphetamine and MDMA.  The highest methamphetamine use was in the largest of the cities, while ecstasy and cocaine use was lowest in the smallest city [7]. The Canadian study violated a prime directive of science reporting by failing to identify the cities and wastewater plants studied; consequently, the experiments could never be repeated independently.

A study of surface waters from the Tagus River flowing through the province of Toledo (downstream of Madrid metropolitan area) and drinking waters in two nearby cities detected 12 out of 22 drugs of abuse at concentrations ranging from 1.14 to 40.9 ng/L [8]. Even as these relatively low concentrations, effects on wildlife or human health cannot be disregarded, especially in vulnerable populations

Cleansing drinking water polluted with illicit drugs

Drinking water polluted with illicit drugs has been deemed acceptable by government agencies including the World Health Organization, the European Union, the US Environment Protection Agency in clear violation of the precautionary principle with regard to public health and safety.

A photo-Fenton process has been shown to be remarkably effective in degrading the illicit drugs [8], and involves treating water with ferrous iron and hydrogen peroxide in the presence of ultraviolet light.

A recent review includes removal of illicit drug pollutants by conventional treatment technologies as well as advanced treatments such as membrane bioreactors [9]. Membrane bioreactor (MBR) technology is considered the most promising development in microbiological wastewater treatment. Several studies clearly outlined its strong potential for reducing ecological risks associated with illicit drugs as well as other polar micro pollutants.  Bank filtration is a type of filtration that purifies water by passing the water through the banks of a river or lake. It is then extracted by wells located some distance away from the water body. Bank filtration does not guarantee the complete removal of all potential illicit drug residues present in the water.  It can be regarded as a useful tool for the pre-treatment of raw water (wastewater, surface water and reclaimed water), which then requires further purification to produce drinking water.

Aptamers are a new class of single-stranded DNA/RNA molecules selected from synthetic nucleic acid libraries for molecular recognition [10] (see Aptamers for Biosensing, Diagnosis, Drug Delivery and Therapy, SiS 56). A novel aptamer column for removing trace drug pollutants in drinking water was developed. Cocaine and diclofenac (an anti-inflammatory drug) were chosen as model molecules to test the aptamer column. The removal of the illicit drug was as high as 88-95% [11].

Moral and ethical issues in sewage epidemiology

 A 2012 report from Australia deals with some legal ramifications in the use of site-specific wastewater analysis of illicit drug use in prisons and or sites such as nightclubs or music festivals [12].  The article from a law journal concludes that producing anonymous, non-identifiable data is essential for a number of reasons, including that the studies concern illegal activities, namely drug possession and trafficking. It states that for prison studies, it is important that publications do not name the facilities at which the research was conducted. Aside from alleviating concerns over negative media exposure, it is deemed important to protect the anonymity of participating prisons to avoid stigmatizing inmates, their families and prison staff. 

I disagree. The outlook of lawyers conflicts with the foundation of science that research results should be reported fully and truthfully. Publications in science journals should require that large anonymous samples such as those used in sewage epidemiology should report the time and place of sample collection and analysis. It is, further, a matter of public health, especially for those who are forced to suffer the consequences of water pollution, without their knowledge or consent. 

To Conclude

The growing pollution of surface and drinking water with illicit drugs and their by-products is a matter of concern. Like pharmaceutical drug pollution, the levels observed are sufficient to affect aquatic organism but claimed to be of no major concern for humans according to regulatory authorities. Precaution demands that the public be alerted to the growing threat to drinking water. The locations where drinking water is polluted with illicit drugs should not be withheld from the population affected.

Article first published 03/12/12


  1. Daughton C. Illicit Drugs: Contaminants in the Environment and Utility in Forensic Epidemiology 67-110 in D.M. Whitacre (ed.), Reviews of Environmental Contamination and Toxicology, Reviews of Environmental Contamination and Toxicology 210, DOI 10.1007/978-1-4419-7615-4_3, C  Springer Science+Business Media, LLC 2011
  2. Pal R, Megharaj M, Kirkbride KP, Naidu R. Illicit drugs and the environment - A review. Science of the Total Environment 2012 Jun 21. [Epub ahead of print]
  3. Huerta-Fontela M,Teresa Galceran M,Ventura F. Illicit Drugs in the Urban Water Cycle chapter 3 ,51-71 in D. Fatta-Kassinos et al. (eds.), Xenobiotics in the Urban Water Cycle: Mass Flows, Environmental Processes, Mitigation and Treatment Strategies, Environmental Pollution. Vol. 16,DOI 10.1007/978-90-481-3509-7_3, © Springer Science + Business Media B.V. 2010
  4. Karolak S, Nefau T, Bailly E, Solgadi A, Levi Y. Estimation of illicit drugs consumption by wastewater analysis in Paris area (France). Forensic Science International 2010, 200, 153-60
  5. Chen C, Kostakis C, Harpas P, Felgate PD, Irvine RJ, White JM. Marked decline in 3,4-methylenedioxymethamphetamine (MDMA) based on wastewater analysis. Journal of Studies on Alcohol and Drugs 2011, 72, 737-40.
  6. Banta-Green CJ, Field JA, Chiaia AC, Sudakin DL, Power L, de Montigny L. The spatial epidemiology of cocaine, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) use: a demonstration using a population measure of community drug load derived from municipal wastewater. Addiction 2009,104, 1874-80
  7. Metcalfe C, Tindale K, Li H, Rodayan A, Yargeau V. Illicit drugs in Canadian municipal wastewater and estimates of community drug use. Environmental Pollution 2010, 158, 3179-85
  8. Valcárcel Y, Martínez F, González-Alonso S, Segura Y, Catalá M, Molina R, Montero-Rubio JC, Mastroianni N, López de Alda M, Postigo C, Barceló D. Drugs of abuse in surface and tap waters of the Tagus River basin: heterogeneous photo-Fenton process is effective in their degradation. Environment International 2012, 41, 35-43
  9. Petrovic M, de Alda MJ, Diaz-Cruz S, Postigo C, Radjenovic J, Gros M, Barcelo D. Fate and removal of pharmaceuticals and illicit drugs in conventional and membrane bioreactor wastewater treatment plants and by riverbank filtration. Philos Transact A Math Phys Eng Sci 2009, 367, 3979-4003.
  10. Ho MW. Aptamers for Biosensing, Diagnosis, Drug Delivery & Therapy. Science in Society 56 ,14, 2012.
  11. Hu X, Mu L, Zhou Q, Wen J, Pawliszyn J. ssDNA aptamer-based column for simultaneous removal of nanogram per liter level of illicit and analgesic pharmaceuticals in drinking water. Environmental Science Technology 2011, 45, 4890-5
  12. Prichard, JP and Ort, C and Bruno, RB and Gartner, C and Kirkbride, P and Hall, W and Yin Lai, F and Carter, S and Thai, P and Mueller, J and Salinas, A, Developing a Method for Site-Specific Wastewater Analysis: Implications for Prisons and Other Agencies with an Interest in Illicit Drug Use, Journal of Law and Information Science, 20, (2) pp. 15-27. ISSN 0729-1485 (2010).

Got something to say about this page? Comment

Comment on this article

Comments may be published. All comments are moderated. Name and email details are required.

Email address:
Your comments:
Anti spam question:
How many legs on a tripod?

There are 6 comments on this article so far. Add your comment above.

joe cummins Comment left 7th December 2012 05:05:05
Thank you Pete Brenton for the interesting question. The transgenic insecticidal protein (Cry1Ab) produced in GM maize has been found in streams and waterways in maize producing areas of USA and Canada. The protein has also been found in the blood of humans consuming the GM maize and drinking water polluted with the protein. Unfortunately regulators have ignored such toxins in setting regulations for drinking water pollution. Furthermore the biological drugs (mainly human gene products produced using GM microbes) have begun to make up a large part of prescription medicine in many countries . The widely used transgenic proteins such as vaccines, monoclonal antibodies, and therapeutic proteins are employed in humans and in veterinary practice. Probiotic bacteria have begun to be modified with human genes and the strategy to prevent them from entering the environment is far from failsafe. I personally take a daily injection of a biological drug used to treat type 2 diabetes and know other individuals whose diseases are treated with biological drugs. The point here is that many of these very potent drugs may be entering the water supply without any effort to monitor or regulate their presence. The pharmaceutical industry may be exerting influence on government bureaucrats to discourage public questioning of the potential pollution and its impact on people. It may be reminiscent of cigarette smoking and asbestos impact on human health which was suppressed for years by influential corporations.

Andy Smith Comment left 4th December 2012 06:06:29
Is it better to do the research that demonstrates there is a problem, even though you are not at liberty to disclose locations, or to find that you are not allowed access to sites, or given the funding to do the work? Sometimes science must walk hand in hand with politics to get the job done. Science costs money, someone has to pay for it and if they set boudaries then either you don't do the science, get someone else to pay or accept them. Even though the specific locations aren't disclosed, we now know there is a problem and political pressure can be applied to take these studies further. Isn't this the right result for society?

sandy Comment left 4th December 2012 06:06:07
Does reverse osmosis remove these chemicals?

joe cummins Comment left 4th December 2012 19:07:10
In reply to Andy Smith the foundation of science has always been that experimental results must be reported fully and truthfully. In my experience bureaucrats tend to be timid and retentive of information that implicates any aspect of human health or welfare. It seems to me that the editors of scientific journals should have required that the locations of all polluted sites should have been identified and published along with the scientific report. The failure to report the locations where polluted drinking water was found withheld information that would allow people with allergies or other health concerns to seek alternative sources of drinking water. Most people would likely demand that the information about illegal drugs in their drinking water be made available to them . Those such as athletes, airline pilots, police officers and others subject to random drug tests could be unjustly implicated by their drinking water.

joe cummins Comment left 4th December 2012 19:07:05
In reply to Sandy: Yes reverse osmosis does remove those chemicals.

Pete Brenton Comment left 5th December 2012 19:07:45
Is there any regulation over the presence of GMOs in drinking water?