Drugs of abuse and tranquilizers in Dutch surface waters, drinking ...

RIVM Report 703719064Urban wastewaterOut of the total number of 37 compounds investigated, 18 compounds weredetected in STP influents and 25 compounds in STP effluent samples. Mostcompounds detected in the STP influent were also detected in the STP effluent,except for the cannabinoid THC-COOH and a metabolite of cocaine(Cocaethylene). Compounds from all chemical groups except the cannabinoidswere present in STP effluents: amphetamines, barbiturates, benzodiazepines,cocainics, opiates and others. Concentrations of drugs and metabolites weremostly lower in effluents than influents, suggesting degradation or sorption ofthese substances and metabolites in wastewater treatment plants.Concentrations in the Dutch STPs are mostly of the same order of magnitude asmonitoring data that were acquired during other studies in Spain, UK and Italy.Comparison with provisional drinking water limitsThe concentrations of the DOA detected in drinking water are far below thegeneral signal value of 1 µg/L, which is specified for organic compounds ofanthropogenic origin in the Dutch Drinking water act. For individual DOA, nostatutory drinking water standars are available. Therefore health basedprovisional drinking water limits were derived in this study, based on currentlyavailable toxicological knowledge. For the three barbiturates that are detected infinished drinking water, the provisional drinking water limit is about 1800 timeshigher than the actual concentrations detected. Based on this information,effects on public health are not expected. However, little is known about thepossible effects of combined exposure to multiple compounds at lowconcentrations. Long-term effects on organisms in the aquatic environment likerivers are also less clear.Loads of DOA through rivers and wastewater and origin of thecompoundsSubstantial fractions of the total load of drugs in the Rhine and Meuse riversenter the Netherlands from abroad. At Lobith, the load of oxazepam is highestand comparable to the loads of other broadly used pharmaceuticals, such asantibiotics. For some compounds loads seem to increase downstream, which isprobably caused by a contribution from STP effluents.For phenobarbital, a compound that is clearly difficult to remove duringtreatment, prescription use is probably an important source besides possible‘abuse’ of this so-called soft drug that is listed as a List II substance in the DutchOpium act. Prescription uses is also an important source for the benzodiazepinsoxazepam and temazepam which were among the top10 of most prescribedpharmaceuticals in the Netherlands in 2007 and 2008.Based on the measured concentrations for benzoylecgonine, cocaineconsumption could be estimated for eight Dutch towns. The results show avariable level of drug consumption which is within the range of cocaineconsumption for Belgian cities as estimated in other studies.RecommendationsAlthough there is no indication of human health risks with respect to thecompounds detected in finished drinking water, alertness is required. Ongoingresearch with respect to possible effects of combined exposure to multiplecompounds at low concentrations needs attention, as well as the development ofanalytical techniques to detect possible new emerging contaminants.Page 13 of 90