In vitro bioassays for monitoring drinking water quality of tap water, domestic filtration and bottled water.

BACKGROUND: Location-specific patterns of regulated and non-regulated disinfection byproducts (DBPs) were detected in tap water samples of the Barcelona Metropolitan Area. However, it remains unclear if the detected DBPs together with undetected DPBs and organic micropollutants can lead to mixture effects in drinking water. OBJECTIVE: To evaluate the neurotoxicity, oxidative stress response and cytotoxicity of 42 tap water samples, 6 treated with activated carbon filters, 5 with reverse osmosis and 9 bottled waters. To compare the measured effects of the extracts with the mixture effects predicted from the detected concentrations and the relative effect potencies of the detected DBPs using the mixture model of concentration addition. METHODS: Mixtures of organic chemicals in water samples were enriched by solid phase extraction and tested for cytotoxicity and neurite outgrowth inhibition in the neuronal cell line SH-SY5Y and for cytotoxicity and oxidative stress response in the AREc32 assay. RESULTS: Unenriched water did not trigger neurotoxicity or cytotoxicity. After up to 500-fold enrichment, few extracts showed cytotoxicity. Disinfected water showed low neurotoxicity at 20- to 300-fold enrichment and oxidative stress response at 8- to 140-fold enrichment. Non-regulated non-volatile DBPs, particularly (brominated) haloacetonitriles dominated the predicted mixture effects of the detected chemicals and predicted effects agreed with the measured effects. By hierarchical clustering we identified strong geographical patterns in the types of DPBs and their association with effects. Activated carbon filters did not show a consistent reduction of effects but domestic reverse osmosis filters decreased the effect to that of bottled water. IMPACT STATEMENT: Bioassays are an important complement to chemical analysis of disinfection by-products (DBPs) in drinking water. Comparison of the measured oxidative stress response and mixture effects predicted from the detected chemicals and their relative effect potencies allowed the identification of the forcing agents for the mixture effects, which differed by location but were mainly non-regulated DBPs. This study demonstrates the relevance of non-regulated DBPs from a toxicological perspective. In vitro bioassays, in particular reporter gene assays for oxidative stress response that integrate different reactive toxicity pathways including genotoxicity, may therefore serve as sum parameters for drinking water quality assessment.

Analysis of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and its brominated analogues in chlorine-treated water by gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS).

A simple, selective and sensitive method for the analysis of the strong mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and its brominated analogues (BMXs) in chlorine-treated water has been developed. The method is based on gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS), previous liquid-liquid extraction (LLE) of a smaller sample volume compared to other methods and on-line derivatization with a silylation reactive. GC-QqQ-MS/MS has been raised as an alternative easier to perform than gas chromatography coupled to high resolution mass spectrometry (GC-HRMS) for the analysis of MX and BMXs, and it allows to achieve low LODs (0.3 ng/L for MX and 0.4-0.9 ng/L for BMXs). This technique had not been previously described for the analysis of MX and BMXs. Quality parameters were calculated and real samples related to 3 drinking water treatment plants (DWTPs), tap water and both untreated and chlorinated groundwater were analyzed. Concentrations of 0.3-6.6 ng/L for MX and 1.0-7.3 ng/L for BMXs were detected. Results were discussed according to five of the main factors affecting MX and BMXs formation in chlorine-treated water (organic precursors, influence of bromide ions, evolution of MX and BMXs in the drinking water distribution system, groundwater chlorination and infiltration of water coming from chlorination processes in groundwater).

Concentrations of organochlorine pesticides and 2,4,6-trichloroanisole in cork bark.

Organochlorine pesticides are persistent lipophilic organic pollutants and tend to accumulate in growing plants. During growth, cork is in contact with the open air for long periods (9-12 years). Owing to the previous widespread use of organochlorine pesticides and their high persistence in the environment, there is a risk that residues of such pesticides may be present in cork. In this study, the concentrations of 14 organochlorine pesticides-all of which are indicators of environmental pollution-were analyzed in cork bark samples from three regions in Spain and one in Portugal. In addition, the concentrations of 2,4,6-trichlorophenol (TCP) and 2,4,6-trichloroanisole (TCA) were also analyzed. Our results show only very low concentrations of lindane, γ-HCH (<2.6 ng g(-1)) and its byproducts α-HCH (<3.5 ng g(-1)) and ß-HCH (<0.6 ng g(-1)). Among the DDT and its metabolites, only two were found: p,p'-DDT was found in a cork sample from Extremadura (0.1 ng g(-1)) and p,p'-DDE was present at a maximum concentration of 2.9 ng g(-1) in a cork sample from Castile-La Mancha. However, all concentrations were well below the legal limit established by Regulation (EC) No. 396/2005 (10 ng g(-1) in foodstuffs). We can conclude, therefore, that the cork samples we studied complied with food safety standards.

Analysis of pesticides and metabolites in Spanish surface waters by isotope dilution gas chromatography/mass spectrometry with previous automated solid-phase extraction Estimation of the uncertainty of the analytical results.

A method based on isotope dilution gas chromatography/mass spectrometry (GC/MS) with automated solid-phase extraction (SPE) is described for the analysis of 32 pesticides and metabolites in surface waters. This approach consist in the use of nine isotopically labelled representative pesticides as internal standards, which allows high accuracy (trueness and precision) and sensitivity for most analysed compounds, as it is required for isotope dilution-based methods. Uncertainties associated with pesticide determination in real samples were estimated using quality assurance/quality control (QA/QC) data. For most pesticides expanded uncertainty was below 40%, according to the commonly established requirements for analytical results. Ninety three Spanish surface waters collected in June-July and September-November 2004 were analysed. Concentration and occurrence of pesticides were evaluated. These parameters were higher in the summer than in the autumn period. In summer four pesticides were found in more than 50% of the analysed samples and four compounds were detected above the concentration level of 1 microg/l (atrazine, terbutylazine, 3,4-dichloroaniline and fenitrothion), while in autumn percentage of detection was below 50% for all pesticides and only one compound (terbutylazine) exceeded 1 microg/l.

Analysis of alkyl and 2-6-ringed polycyclic aromatic hydrocarbons by isotope dilution gas chromatography/mass spectrometry. Quality assurance and determination in Spanish river sediments.

An accurate, precise and sensitive method is described for the analysis of 29 polycyclic aromatic hydrocarbons (PAHs), including 19 2-6-ringed PAHs and 10 alkyl-PAHs. The method is based on an isotope dilution technique using gas chromatography/mass spectrometry (GC/MS) and available labeled PAHs as internal standards. Quality parameters were calculated with satisfactory results and 36 Spanish river sediments were analysed. Results were evaluated regarding to the sediment quality guidelines (SQGs) based on the effects range-low (ERL) and the effects range-median (ERM) values. Most analysed sediments showed a good quality, since only 7 of them exceeded ERL values, including one sample surpassing ERM values. PAH profiles were studied in order to identify PAH sources as mainly petrogenic or pyrogenic. Most samples showed petrogenic-type fingerprints, although 6 of the 11 sediments with the highest PAH concentrations (> 1000 ng/g) were classified as pyrogenic, including 4 of the 7 samples exceeding ERL values. Quality assurance was carried out by the triplicate analysis of one preanalysed river sediment without PAHs subsequently spiked at a medium (500 ng/g) and a low concentration level (10 ng/g) of each analyte. Main quality requirements for methods based on isotope dilution were accomplished. Method accuracy was 80-120% for most PAHs, method precision was <15% for all the analysed compounds and method detection limits (MDLs) were 1-3 ng/g.