6
Emerging Chemical Drinking Water Contaminants

Walter Giger

The fate of contaminants in the aquatic environment is strongly influenced by their biodegradability and physico-chemical properties. The latter can be illustrated by a matrix showing polarity and volatility as coordinates (see Figure 6-1). Most of the aquatic pollutants, which have been studied up to now, are situated in the lower part of the polarity-volatility diagram. With regard to the potential of entering drinking water resources, the highly polar and hydrophilic contaminants in the upper right quadrangle of the polarity-volatility diagram are of elevated importance because of their high mobility in water. These contaminants, must be determined by liquid chromatography if not derivatized to make them amenable to gas chromatography. Currently, a breakthrough is occurring for analytical methods based on directly coupled liquid chromatography and mass spectrometry (LC/MS). It can be inferred that LC/MS will greatly enlarge the number of hydrophilic contaminants that can be determined at trace concentrations in wastewaters, ambient waters, and drinking waters.

This paper reviews current knowledge on the environmental occurrence of hydrophilic organic contaminants, including herbicide degradates, pharmaceuticals, and various high production volume chemicals.

Herbicide Degradates

Numerous studies have been and are being conducted to determine the occurrence and environmental fate of herbicides, which are extensively applied to control weeds. Only few studies have considered degradates of these herbicides (e.g., Lerch et al, 1997; Muller et al., 1997). Herbicide degradates were prevalent in about 75 percent of 88 municipal wells studied in aquifers across Iowa (Kalkhoff et al., 1998; Kolpin et al., 1998). The sulfonic and oxanilic metabolites of acetoclor, alachlor, and metolachlor were determined along with their parent compounds. Altogether, 13 herbicides and 17 herbicide degradates were determined (Kolpin et al., 1998). With the exception of atrazine, the frequencies of detection in groundwater for a given herbicide increased multifold when its degradates were also considered.



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--> 6 Emerging Chemical Drinking Water Contaminants Walter Giger The fate of contaminants in the aquatic environment is strongly influenced by their biodegradability and physico-chemical properties. The latter can be illustrated by a matrix showing polarity and volatility as coordinates (see Figure 6-1). Most of the aquatic pollutants, which have been studied up to now, are situated in the lower part of the polarity-volatility diagram. With regard to the potential of entering drinking water resources, the highly polar and hydrophilic contaminants in the upper right quadrangle of the polarity-volatility diagram are of elevated importance because of their high mobility in water. These contaminants, must be determined by liquid chromatography if not derivatized to make them amenable to gas chromatography. Currently, a breakthrough is occurring for analytical methods based on directly coupled liquid chromatography and mass spectrometry (LC/MS). It can be inferred that LC/MS will greatly enlarge the number of hydrophilic contaminants that can be determined at trace concentrations in wastewaters, ambient waters, and drinking waters. This paper reviews current knowledge on the environmental occurrence of hydrophilic organic contaminants, including herbicide degradates, pharmaceuticals, and various high production volume chemicals. Herbicide Degradates Numerous studies have been and are being conducted to determine the occurrence and environmental fate of herbicides, which are extensively applied to control weeds. Only few studies have considered degradates of these herbicides (e.g., Lerch et al, 1997; Muller et al., 1997). Herbicide degradates were prevalent in about 75 percent of 88 municipal wells studied in aquifers across Iowa (Kalkhoff et al., 1998; Kolpin et al., 1998). The sulfonic and oxanilic metabolites of acetoclor, alachlor, and metolachlor were determined along with their parent compounds. Altogether, 13 herbicides and 17 herbicide degradates were determined (Kolpin et al., 1998). With the exception of atrazine, the frequencies of detection in groundwater for a given herbicide increased multifold when its degradates were also considered.

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--> Figure 6-1 Polarity-volatility diagram for chemical contaminants. Furthermore, a majority of the measured concentration for a given herbicide was in the form of its degradates, even for a relatively persistent compound such as atrazine. The degradates comprised 60 to over 99 percent of a herbicide's measured concentration. It was shown that potentially stable and persistent degradates are being formed in the environment before complete herbicide mineralization occurs. Kolpin and coworkers (1998) concluded that any investigation of herbicides such as their occurrence and effects on the environment and human health would be missing a significant piece of the puzzle if data on herbicide degradates are not also obtained. It can be extrapolated that for other pesticides similar observations will be made regarding the environmental occurrence of more polar metabolites. Pharmaceuticals In several European countries research activities have been accelerated that are aimed at enlarging our knowledge of environmental occurrences of pharmaceutical chemicals. Good overviews are given by Stun and Heberer (1997) and Ternes (1998a,b) as well as for a public audience by Raloff (1998).

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--> One important route to follow is the collection of information on the types and amounts of pharmaceuticals used for human care and veterinary applications. Such a survey has been published by Halling-Sørensen et al. (1998) for the situation in Denmark. From a principal perspective, most drugs have a relatively high risk of causing residual levels in the environment because these chemicals are, to a large extent, excreted in urine or feces and are consequently contained in municipal wastewaters. For some chemicals their use as veterinary drugs is an important contamination source (Montforts, 1998). In 1992, clofibric acid the active metabolite of the drugs clofibrate, etofibrate, and etofyllin—was found for the first time as a contaminant in groundwater at considerable concentrations. This discovery occurred during screening analyses for phenoxyalkanoic herbicides in the Berlin area (Stan and Linkerhäger, 1992). In more recent studies it has been reported that a series of drugs and drag metabolites were found at concentrations up to the microgram per liter level in groundwater samples taken from a drinking water treatment plant (see Table 6-1; Heberer and Stan, 1997; Stan and Heberer, 1997; Heberer et al., 1997, 1998). These contaminants leach from the neighboring sewage-contaminated surface waters by bank filtration through the subsoil into the groundwater of the waterworks. In the same investigation N-(phenylsulfonyl)-sarcosine was measured, which is considered to be a metabolite of a corrosion inhibitor. Similarily, Buser and coworkers (1998a,b) came across the detection of clofibric acid as a trace contaminant in waters of the North Sea and in Swiss lakes (Table 6-2). The relatively higher residual concentrations of clofibric acid in the North Sea indicate that this contaminant is more persistent than mecoprop. The antirheumatic drug diclofenac was detected in rivers and lakes in Switzerland TABLE 6-1 Concentrations of Pharmaceutical Contaminants and of N(Phenylsulfonyl)-Sarcosine in 17 Groundwater Wells of a Drinking Water Treatment Plant and in Bank Filtrates of the Rhine River Contaminant Pharmaceutical Compound Class Concentration Range (ng/L)     Groundwater Clofibric acid Metabolite of lipid regulator 70-7,300 Diclofenac Antirheumatic N.D. - 3 80 Fenofibrate Lipid regulator N.D. - 45 Ibuprofen Antireumatic N.D. - 200 Phenazone Analgesic <10 - 1,250 Propyphenazone Analgesic N.D. - 1,465 Clofibric acid derivative Metabolite of clofibric acid, tofibrate, and etofyllin 50- 2,900 N-methylphenmacetin Metabolite of phenacetin <5 - 470 N-(phenylsulfonyl)-sarcosine Metabolite of a corrosion inhibitor 165 - 1,440     Bank Filtrate Carbamazepin Antiepileptic 130 (50th percentile)     360 (90th percentile)   SOURCES: Adapted from Heberer et al. (1997) and Sacher et al. (1998).

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--> TABLE 6-2 Clofibric Acid, Mecoprop, and Diclofenac in Swiss Ambient Waters and in the North Sea   Compound Concentration (ng/L) Location Clofibric acid Mecoprop North Sea 0.5 - 7 0.6 - 11 Lakes <1 - 9 <1 - 45   Diclofenac   Rivers <1 - 370   Lakes <1- 12     SOURCE: Adapted from Buser et al., 1998a, 1998b. (Table 6-2, Buser et al., 1998b). Based on the lake data and on the results of laboratory experiments it can be deduced that photodegradation is the predominant process affecting the environmental fate of diclofenac. The occurrence of 32 drug residues belonging to different medicinal classes such as antiphlogistics, lipid regulators, psychiatric drugs, antiepileptic drugs, betablockers, and beta(2)-sympathomimetics as well as five metabolites has been investigated in German municipal sewage treatment plant (STP) discharges and river and stream waters (Ternes, 1995a). Owing to incomplete removal of drug residues during passage through an STP, more than 80 percent of the selected drugs were detectable in at least one municipal STP effluent with concentration levels up to 6.3 µg/L (carbamazepine), thus resulting in contamination of the receiving waters. Twenty different drugs and four corresponding metabolites were measured in river and stream waters. Mainly acidic drugs such as the lipid regulators bezafibrate, and gemfibrozil; the antiphlogistics diclofenac, ibuprofen, indometacine, naproxen, and phenazone; and the metabolites clofibric acid, fenofibric acid, and salicylic acid as well as neutral or weak basic drugs such as the betablockers metoprolol, propranolol, and the antiepileptic drug carbamazepine were found to be ubiquitously present in rivers and streams, mostly in the nanogram per liter range. However, maximum concentrations were determined up to 3.1 µg/L and median values as high as 0.35 µg/L (both for bezafibrate). The drugs detected in the environment were predominantly applied in human medicine. It can therefore be assumed that the load of municipal STP effluents in surface water highly influences the contamination. Table 6-3 gives an overview on the concentrations found in surface waters (Ternes, 1998b). The relatively high environmental persistence of many pharmaceutical chemicals is documented by their widespread occurrence in ambient waters. Commonly applied wastewater treatment is obviously not

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--> TABLE 6-3 Ranges of Concentrations Found in German Surface Waters Median (>0.050 µg/L) Median (0.050-0.01 µg/L) Median < LODa; 90th Percentile > LOD; 90th percentile < LOD Maximum < LOD Lipid regulators     Zytostatica Bezafibrate     Cyclophosphamid Ifosfamid Metabolites       Clofibric acid Fenofibric acid Salicylic acid       Gentisic acid   Antiphlogistics       Diclofenac Ibuprofen Naproxen Indometacin Phenazon Ketoprofen Dimethylaminophenazon Antiepileptic Betablockers     Carbamazepin (Rhine River. Cmax =<1 µg/L, 50th-percentile = 290 µg/L) Metoprolol Propranolol Bisoprolol Carazolol Betaxolol       Bronchospasmolytics Salbutamol Fenoterol a Limit of detection. SOURCE: Adapted from Ternes (1998b) based on data from Ternes (1998a) and Sacher et al. (1998). sufficient for the complete removal of these residues. There is a certain probability that metabolites formed by conjugation (e.g., glucoronates and sulfates) can be cleaved during wastewater treatment, and thus the parent chemicals are being discharged to the receiving surface waters. The antiepileptic drug carbamazepin was detected in several German rivers and at elevated concentrations in the Rhine River (Sacher et al., 1998). It was inferred from these data that industrial wastewaters from companies manufacturing this pharmaceutical might add to its lead in the Rhine River. These authors also report on preliminary results of investigations assessing the behavior of carbamazepin during bank filtration and water treatment processes. Analogous studies in Brazil showed the sporadic presence of pharmaceuticals in rivers at concentrations below 10 ng/L, indicating a lower environmental contamination in this country (Stumpf et al., 1998).

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--> Antibiotics Hirsch et al. (1998a,b) have determined 18 antibiocidal chemicals, among them betalactams, makrolides, and tertracyclines as well as chloramphenicol, sulfamethaxol, and trimethroprim. Erythromycin was shown to occur only as a metabolite after water cleavage. Among the five antibiotics detectable in treated sewage effluents and in surface waters, erythromycin-water was most abundant with a median value of 2.5 µg/L and a maximum concentration of 6.0 µg/L. Roxitromycin, clarithromycin, sulfamethaxol, and trimethoprim occurred at concentrations below 1 µg/L. No tetracyclines or penicillins could be detected in five sewage treatment effluents and in 14 samples from surface waters. A large number of groundwaters were screened for possible occurrence of antibiocidal substances. Some of these samples were strongly contaminated by liquid manure as was evident from the high nitrate levels. In four samples trace levels of residual sulfonamides were detectable. Fluoroquinolone (FQ) antibiotics, inhibitors of the bacterial DNA unwinding enzyme gyrase, are important broad-spectrum antibiotics licensed for use in both humans and animals. Concentration of the prevalent FQ in human medicinal use, ciprofloxacin, was determined by reversed-phase high pressure liquid chromatography (HPLC) with fluorescence detection in hospital wastewaters and qualitatively confirmed by electrospray mass spectrometry (Alder et al., 1998; Hartmann et al., 1998). Concentrations ranged from 5 to 100 µg/L. Ciprofloxacin was found to be bioeliminated to 56 ±11 percent in 24 days using a modified OECD 302B in hospital wastewater. Bioavailability was unexpectedly high, as indicated by a bacterial genotoxicity assay (umuC test), which is highly sensitive for FQ antibiotics. Therefore, substantial amounts of bioavailable FQ antibiotics could be expected in wastewaters. The concentrations of ciprofloxacin in 24-hour composite samples in municipal wastewaters ranged from 0.2 to 0.4 µg/L in primary effluents and 0.1 µg/L in secondary effluents. Elimination of ciprofloxacin from the wastewater stream during aerobic treatment varied from 55 to 75 percent. High Production Volume Chemicals Among the high production volume chemicals (HPV), those with a high biopersistency and high polarity are potential drinking water contaminants. Table 6-4 gives a small collection of such chemical compound classes.

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--> Conclusion Based on the literature cited in this paper and related publications the following conclusions can be drawn: Introduction of directly coupled LC/MS techniques allows reliable and quantifiable determination of many polar hydrophilic water pollutants. Polar degradates of herbicides are increasingly important. Many pharmaceutical chemicals are detectable in the aquatic environment, antibiotics with an elevated level of concern. A large number of HPV chemicals should be investigated in more detail. TABLE 6-4 HPV Chemicals Either Documented as Drinking Water Contaminants or Having a Certain Potential Class of Chemical/Compound Organic complexing agents EDTA Surfactant metabolites Alkylphenols, alkylphenolpolyethoxylates, alkylphenolethoxcarboxylates Musk fragrances Benzenesulfonates naphthalenesulfonates Sulfonated naphthalene formaldehyde condensates Fuel additives Methyl tert-butyl ether (MTBE) Corrosion inhibitors (e.g. tolylbenzotriazoles) Haloacetic acids References Alder, A. C., E. Golet, A. Hartmann, S. Ibric, T. Koller, and R. M. Widmer. 1998. Occurrence of the antibiotic ciprofloxacin in wastewaters determined by solid-phase extraction and HPLC. Paper presented at the Society of Environmental Toxicology and Chemistry (SETAC) annual meeting. Buser, H. R., M.D. Müller, and N. Theobald. 1998a. Occurrence of the pharmaceutical drug clofibric acid and the herbicide mecoprop in various Swiss lakes and in the North Sea. Environmental Science and Technology 32(1):188-192. Buser, H. R., T. Poiger, and M. D. Müller. 1998b. Occurrence and face of the pharmaceutical drug diclofenac in surface waters: Rapid photodegradation in a lake. Environmental Science and Technology 32(22):3449-3456. Halling-Sorensen, B., S. Nors Niels, P. F. Lanzky, F. Ingerslev, H. C. Holten Lützhøft, and S. E. Jørgensen. 1998. Occurrence, fate and effects of pharmaceutical substance in the environment—A review. Chemosphere 36(2):357-393. Hartmann, A., A. C. Alder, T. Keller, and R. M. Widmer. 1998. Identification of fluoroquinolone antibiotics as the main source of umuC genotoxicity in native hospital wastewater. Environmental Toxicology and Chemistry 17(3):377-382.

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--> Heberer, T., U. Dünnbier, R. C., and H. J. Stan. 1997. Detection of drugs and drug metabolites in ground water samples of a drinking water treatment plant. Fresenius Environmental Bulletin 6:438-443. Heberer, T., K. Schmidt-Baumler, and H. J. Stan. 1998. Occurrence and distribution of organic contaminants in the aquatic system in Berlin. Part 1: Drug residues and other polar contaminants in Berlin surface and groundwater. Acta Hydrobiolgica et Hydrobiologica 26(5):272-278. Heberer, T., and H. J. Stan. 1997. Determination of clofibric acid and N(phenylsulfonyl)-sarcosine in sewage, river and drinking water. International Journal of Environmental Analytical Chemistry 67:113-124. Hirsch, R., T. A. Ternes, K. Haberer, and L. Kratz. 1998a. Occurrence of antibiotics in the aquatic environment. The Science of the Total Environment 225(1/2): 109-118. Hirsch, R., T. A. Ternes, K. Haberer, A. Mehlich, F. Ballwanz, and L. Kratz. 1998b. Determinations of antibiotics in different water compartments via liquid chromatography—electrospray tandem mass spectrometry. Journal of Chromatography A815:213-223. Kalkoff, S. J., D. W. Kolpin, E. M. Thurman, I. Ferrer, and D. Barcelo. 1998. Degradation of chloracetanilide herbicides: The prevalence of sulfonic and oxanilic acid metabolites in Iowa groundwaters and surface waters. Environmental Science and Technology 32:1738-1740. Kolpin, D. W., E. M. Thurman, and S. M. Linhart. 1998. The environmental occurrence of herbicides: The importance of degradates in ground water. Archives of Environmental Contamination and Toxicology 35:385-390. Lerch, R. N., P. E. Blanchard, and E. M. Thurman. 1997. Contribution of hydroxylated atrazine degradation products to the total atrazine load in midwestern streams. Environmental Science and Technology 32(1):4048. Monforts, M. H. M. M. 1998. The exposure assessment of veterinary medicinal products. The Science of the Total Environment 225(1/2):119-133. Muller, S.R., M. Merg, M. U. Ulrich, and R. S. Schwarzenbach. 1997. Atrazine and its primary metabolites in Swiss lakes: Input characteristics and long-term behavior in the water column. Environmental Science and Technology 31(7):2104-2113. Raloff, J. 1998. Drugged waters. Science News 153:187-189. Sacher, F., E. Lochow, D. Bethmann, and B. Heinz-Jürgen. 1998. Occurrence of drags in surface waters. Vom Wasser 90:233-243. Stan, H. J., and T. Heberer. 1997. Pharmaceuticals in the aquatic environment. Analusis 25(7):M20-M23. Stan, H. J. and M. Linkerhägner. 1992. Identifizierung von 2-(4-chlorphenoxy)-2-methylpropionsäure in grundwasser mittels kapillar-gaschromatographie mit atomemmissionsdetektion und massenspektrometrie (in German). Vom Wasser 79:75-88 Stumpf, M., T. A. Ternes, K. Haberer, S. V. Rodrigues, and W. Baumann. 1998. Polar drug residues in sewage and natural waters in the state of Rio de Janeiro, Brazil. The Science of the Total Environment 225(1/2):109-118. Ternes, T. A. 1998a. Occurrence of drugs in German sewage treatment plants and rivers. Water Research 32(11):3245-3260. Ternes, T. A. 1998b. Arzneimittelrueckstaende in Gewaessern und Klaeranlagen. Arzneimittel in Gewaessern-Risiko fuer Mensch, Tier und Umwelt? (in German), Wiesbaden, Germany.