Statistical analysis of a large set of semi-quantitative GC-MS screening data to evaluate and prioritize organic contaminants in surface and drinking water of the Netherlands.

Due to anthropogenic activities in the catchments, surface waters are contaminated with a large variety of chemical compounds. Drinking water companies in the Netherlands use surface water from the rivers Rhine, and Meuse, Lake IJssel and water from a reclaimed land area as sources for the production of drinking water. Samples from the abstraction points and the produced drinking waters were investigated using chemical screening with gas chromatography coupled to mass spectrometry to detect an as wide as possible range of organic contaminants, generating enormous data sets. This study aimed to evaluate and interpret five and a half years of screening data to get insight in the variety of known and new less polar compounds in surface and drinking waters, and to investigate if there were spatial patterns in the detection of compounds. Compounds from a wide variety of applications were detected. The vast majority of detected compounds was found only in a few samples. Certain compounds, however, e.g. organophosphate flame retardants, were detected with prevalences up to 100% per location. Most compounds were detected in samples from the rivers Rhine and Meuse, less in those from Lake IJssel and the reclaimed land area and only few in drinking water. Principal component and Hierarchical Cluster Analyses helped to detect patterns in the presence of contaminants on particular locations and to prioritize compounds for further investigation of their emission sources, and -in case of unknown compounds - their identification.

Impact of anionic ion exchange resins on NOM fractions: Effect on N-DBPs and C-DBPs precursors.

The formation potential of carbonaceous and nitrogenous disinfection by-products (C-DBPs, N-DBPs) after ion exchange treatment (IEX) of three different water types in multiple consecutive loading cycles was investigated. Liquid chromatography with organic carbon detector (LC-OCD) was employed to gauge the impact of IEX on different natural organic matter (NOM) fractions and data obtained were used to correlate these changes to DBPs Formation Potential (FP) under chlorination. Humic (-like) substances fractions of NOM were mainly targeted by ion exchange resins (40-67% removal), whereas hydrophilic, non-ionic fractions such as neutrals and building blocks were poorly removed during the treatment (12-33% removal). Application of ion exchange resins removed 13-20% of total carbonaceous DBPs FP and 3-50% of total nitrogenous DBPs FP. Effect of the inorganic nitrogen (i.e., Nitrate) presence on N-DBPs FP was insignificant while the presence of dissolved organic nitrogen (DON) was found to be a key parameter affecting the formation of N-DBPs. DON especially the portion affiliated with humic substances fraction, was reduced effectively (∼77%) as a result of IEX treatment.

Human health risk assessment of the mixture of pharmaceuticals in Dutch drinking water and its sources based on frequent monitoring data.

The presence of pharmaceuticals in drinking water is a topic of concern. Previous risk assessments indicate that their low concentrations are very unlikely to pose risks to human health, however often conclusions had to be based on small datasets and mixture effects were not included. The objectives of this study were to a) investigate if pharmaceuticals in surface and polder water penetrate in drinking water, b) assess the lifelong exposure of consumers to pharmaceuticals via drinking water and c) assess the possible individual and mixture health risks associated with this exposure. To fulfill these aims, a 2-year set of 4-weekly monitoring data of pharmaceuticals was used from three drinking water production plants. The 42 pharmaceuticals that were monitored were selected according to their consumption volume, earlier detection, toxicity and representation of the most relevant therapeutic classes. Lifelong exposures were calculated from concentrations and compared with therapeutic doses. Health risks were assessed by benchmarking concentrations with provisional guideline values. Combined risks of mixtures of pharmaceuticals were estimated using the concept of Concentration Addition. The lifelong exposure to pharmaceuticals via drinking water was calculated to be extremely low, i.e. a few mg, in total corresponding to <10% of the dose a patient is administered on one day. The risk of adverse health effects appeared to be negligibly low. Application of Concentration Addition confirmed this for the mixture of pharmaceuticals simultaneously present. The investigated treatment plants appeared to reduce the (already negligible) risk up to 80%. The large available monitoring dataset enabled the performance of a realistic risk assessment. It showed that working with maximum instead of average concentrations may overestimate the risk considerably.

A multicomponent snapshot of pharmaceuticals and pesticides in the river Meuse basin.

The river Meuse serves as a drinking-water source for more than 6 million people in France, Belgium, and The Netherlands. Pharmaceuticals and pesticides, both designed to be biologically active, are important classes of contaminants present in this river. The variation in the presence of pharmaceuticals in time and space in the Dutch part of the Meuse was studied using a multicomponent analytical method for pharmaceuticals combined with univariate and multivariate statistical analyses of the results. Trends and variation in time in the presence of pharmaceuticals were investigated in a dead-end side stream of the Meuse that serves as an intake point for the production of drinking water, and 93% of the selected compounds were detected. Highest concentrations were found for the antidiabetic metformin. Furthermore, a spatial snapshot of the presence of pharmaceuticals and pesticides was made along the river Meuse. Principal component analysis was successfully applied to reveal that wastewater-treatment plant effluent and water composition at the Belgian border were the main factors determining which compounds are found at different locations. The Dutch part of the river basin appeared responsible for approximately one-half of the loads of pharmaceuticals and pesticides discharged by the Meuse into the North Sea. The present study showed that multicomponent monitoring in combination with principal component analysis is a powerful tool to provide insight into contamination patterns in surface waters.