ARTICLE pubs.acs.org/est
In Situ Calibration of a Passive Sampling Device for Selected Illicit Drugs and Their Metabolites in Wastewater, And Subsequent Year-Long Assessment of Community Drug Usage Christopher Harman,*,† Malcolm Reid,† and Kevin V. Thomas Oslo Centre for Interdisciplinary Environmental and Social Research (CIENS), Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, NO-0349, Oslo, Norway.
bS Supporting Information ABSTRACT: Polar organic chemical integrative samplers (POCIS) were calibrated in situ for selected illicit drugs and their metabolites at a sewage treatment works. Eleven out of 13 target compounds were detected and eight of those exhibited linear uptake kinetics with sampling rates between 0.035 and 0.150 L d1. Subsequently POCIS were deployed for 2 week periods over the course of a whole year, in order to examine trends in drug usage. Amphetamine and methamphetamine showed several similar peaks in concentration during the course of the year as did cocaine and two of its metabolites. Low levels of ecstasy were observed, with a prominent peak in May and a steady increase toward the end of the year. The antihistamine Cetirizine showed a clear increase in use during the summer months as expected and back calculation of the yearly dosage from POCIS accumulations yielded very similar results to that registered in the Norwegian prescription database. Estimations of cocaine usage using the parent compound averaged between 0.31 and 2.8 g d1 per 1000 inhabitants. POCIS is a cost-effective technique for the long-term monitoring of drug usage of a defined population and may overcome the difficulties of representative sampling associated with autosampling equipment.
’ INTRODUCTION Concern surrounding the use of illicit drugs in society continues to grow. Accurate information regarding trends in consumption is critical for both policy makers and enforcers. Recently a new methodology has emerged that involves the measurement of drug metabolites in wastewater to determine usage,1 so-called sewage epidemiology. Since the first reported measurements of illicit drugs in surfaces waters2,3 the technique has been applied to a variety of compounds including opiates, stimulants and cannabis.4,5 However, the ability of the automatic sampling equipment most often applied to adequately integrate short-term fluctuations in concentrations and or flow rates, has been questioned.6 Additionally the wider application of autosamplers, especially for long-term monitoring, is probably not feasible due the associated costs, and requirements of power and space.7 Passive sampling devices (PSDs) may address these issues, offering time integrated sampling that compensates for fluctuations in concentrations and lower detection limits compared to standard water sampling.8 Sampling occurs unattended, without the power requirements of autosamplers and their low cost means that they may be widely applied to long-term monitoring studies or for regulatory purposes. Out of the passive sampling devices currently available, the polar organic chemical integrative sampler (POCIS)9 has been successfully applied to the measurement of a wide range of polar organic contaminants including r 2011 American Chemical Society
pharmaceuticals8,1013 and illicit compounds.2,14,15 Despite some attempts to correlate POCIS sampling rates with some physicochemical property of grouped target compounds such as log Kow,11,16,17 an overall model is lacking. This means that uptake rates for “new” compounds must first be determined experimentally by calibration. As POCIS sampling rates are affected by environmental factors such as water flow rates and temperature9,12,18 then the accuracy of calibration sampling rates in subsequent environmental studies is dependent on similar exposure conditions. For hydrophobic passive samplers this issue has been overcome by the use of performance reference compounds (PRCs) the dissipation of which is equally affected by changes in deployment conditions.19 The application of the PRC approach to polar PSDs has proved to be problematic largely due to differences between isotropic uptake in hydrophobic samplers and the strong sorptive properties of receiving phases in polar samplers.20 However some progress has been made for correcting uptake of polar herbicides in POCIS using PRCs.17 One possible solution is the calibration of PSDs in situ at fixed locations.21 This is advantageous as exposure conditions and any matrix effects will be similar. Received: April 6, 2011 Accepted: May 27, 2011 Revised: May 23, 2011 Published: June 07, 2011 5676
dx.doi.org/10.1021/es201124j | Environ. Sci. Technol. 2011, 45, 5676–5682
Environmental Science & Technology
ARTICLE
Table 1. Sampling Rates (RS L d1) and Measured Water Concentrations (Cw ng L1) sampling rate (RS L d1)
Cw (ng L1) average
average cetirizine metoprol acida morphine
14 day
0.088
0.103
373 (157496)
0.035
0.003 0.044
3137 (9365165) 1304 (3782747)
0.025
6389 (26578640)
0.094
0.125
201 (74452)
hydroxy-cotininea amphetamine MDMAb
(range)
