Emerging contaminants in danish groundwater, geus rapport 2005/49

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Geological Survey of Denmark and Greenland, GEUSØster Voldgade 10, DK-1350 Copenhagen, DenmarkPhone: +45 3814 2000. Fax: +45 3814 2050 E-mail: [email protected]: www.geus.dk Danmarks og Grønlands Geologiske Undersøgelse, 2005 Emerging groundwater contaminants 1. Abstract
Danish groundwater is the source for almost all drinking water production in Denmark.
Groundwater monitoring is thus important in order to ensure the custumer with cleandrinking water. During the last decades the numbers of analysis has keept increasing –reflecting an increased knowledge and concern over important contaminants. Howeversome analysis has also been removed from the analysis program often reflecting that thecontaminant only very infrequently has been detected. Finally, the expences connectedwith the total number of contaminants being analysed should be constantly minimised. The present report can be seen as an attemt to review scientific litterature and other rele-vant sources to get a list of likely contaminants of Danish groundwater – not presentlybeeing monitored. Danish autorities has working groups concluding which contaminants toinclude on the list of analysed contaminants. Such "emerging contaminants" can bebroadly defined as any synthetic or naturally occurring chemical or any microorganism thatis not commonly monitored in the environment but has the potential to enter the environ-ment and cause known or suspected adverse ecological and (or) human health effects. Insome cases, release of emerging chemical or microbial contaminants to the environmenthas likely occurred for a long time, but may not have been recognized until new detectionmethods were developed. In other cases, synthesis of new chemicals or changes in useand disposal of existing chemicals can create new sources of emerging contaminants. The report points out that some pesticides and degradation products could be consideredto be included in the Danish monitoring system. Four degradation products from triazineherbicides that have not been analysed in the Danish monitoring system have been foundin US groundwater. Further metabolites from the herbicides bromoxynil and ioxynil havebeen found to be persistant in Danish soils, and might be mobile in soil.
Estrogens originating from livestock manure has been shown to leach trough Danish frac-tured soil at concentration many times the effect level of estrogen on fish. This estrogensource relating to specialised livestock production is not – like its human ancestor –passed through a sevage plant with efficient estrogen degrading microbial communities.
A Danish study on presence of fecale indicator bacteria in private wells shows that 25% ofall wells has high concenrations of these fecale indicator bacteria. Patogenic microorgan-isms has not been monitored for in Danish groundwater, but field trials in Ireland havedemonstrated significant leaching of patogenic bacteria following deposition of live stockmanure om farmland. Other animal breeded patogens, like cryptosporium or giardia, arefrequently found outside Denmark in drinkingwater based on surface water. This group ofpatogens is frequently present in livestock manure but has not been monitored for in Den-mark with the exception of pinpoint analysis to validate methods.
Pharmaceuticals are present in large amounts in most livestock manure but their degrada-tion and movement in soils is not well described. 8 different pharmaceuticals have beenidentified as the most likely contaminants originating from manure. Among different humanrelated pharmaceuticals 3 compounds are identified.
Emerging groundwater contaminants Finally several other industrial compounds like antibacterial compounds and syntheticmusk products have been detected in surface water, but no measurements have beenattempted in groundwatersamples. In the future the use of genetically modified plants that produce compounds like pharma-ceuticals or Bt toxin should be considered in relation to groundwater contamination. Pres-ently no such production has been started and the compounds are thus not risk assessed.
Emerging groundwater contaminants 2. Introduction to emerging contaminants
Optimization of efforts spend in monitoring of drinking water quality calls for constantlyconsidering the compounds and microorganisms being analyzed. The present GEUS re-port is seen as a review of recent scientific literature and searches in foreign governmentaldatabases and homepages to possibly point at maybe important areas not currently beingconsidered in the Danish priority list. The report will first give a brief overview in chapter 3 of sources to get knowledge of whichcompounds and microorganisms that today are being analyzed. The following chapters 4 -10 deals with the various areas of potential interest. Finally, chapter 11 gives a shortlist ofwhat we are considering as "emerging contaminants" in Danish drinking water.
2.1 Definition and background
Groundwater is the major source of drinking water in Denmark, with more than 90% of theproduced drinking water based on groundwater. The groundwater quality is high anddrinking water in Denmark is generally only given a very mild treatment in the water pro-duction plants. This treatment includes aeration and passage through a sand filter, but nofurther filtration or chemical safeguarding is used. Denmark is a land heavily impacted bypesticide use. Degradation product from 2 groups of soil applied herbicides is particularresponsible for more than 40% of those water production wells that have been closed(GEUS grundvandsovervågning). The chemical compounds being analyzed for today represent a small fraction of thechemicals that occur in the environment. The same is true with microorganisms – or ratherthe analysis is in the best case following indicator microorgansims, but are not specificallytowards the interesting pathogens.
The two areas, chemical compounds and microorganisms, contain emerging contami-nants. The definition of emerging is however imprecise in that an emerging contaminantcould be 1) contaminants which recently is being introduced in the environment and consequently not beforehand could have been a threat to the environment 2) contaminants which have not been possible to analyze – at least not in a robust and cost-effective way This report can not be considered a fully covering listing of what we need to analyze in thefuture, but rather be a listing of likely ideas which should be considered further by theDanish EPA. Its likely relevant to repeat the structured survey of litterature and monitoring-programs to search for emerging contaminants with regular intervals – every second orthird year.
Emerging groundwater contaminants 3. Current status of Danish groundwater contami-
nants
The Danish groundwatermonitoring program is providing a yearly report of the concentra-tions of groundwater polutants. The monitoring program can be reached via the followingURL: http://www.geus.dk/publications/grundvandsovervaagning/grundvandsovervaagning.htmThe detailed report is in Danish but a short Englism summary is given. From this summarythe following main conclusions regarding inorganic trace elements and organic micropol-lutant including pesticides and their degradation products is given: Maximum Admissible Concentration (MAC) of many inorganic trace elements has beenexceeded in all elements of the groundwater monitoring programme. From 1998-2003, theMACs have been exceeded in 32% of screens in the monitoring areas. In agricultural wa-tershed catchment areas, where young and shallow groundwater is surveyed in areas withintensive agriculture, results are conspicuous with many high nickel, zinc, lead and arsenicvalues. Within groundwater monitoring areas and in water abstraction wells, arsenic inparticular was found in high values. In major water works with effective sand filters, inor-ganic trace elements will partly precipitate and will not necessarily have a negative effecton drinking water quality. However, in smaller water supplies without water treatment facili-ties, they may form a water quality problem.
Organic micro pollutants have been found in 92% of well screens in groundwater moni-
toring areas from 1993-2003. By excluding anionic detergents (due to a non-specific
method of analysis), organic micro pollutants are detected at least once in 63% of well
screens. The percentage for agricultural watershed catchment areas is 56 and approxi-
mately 20% for water abstraction wells (also without anionic detergents). However, the
concentration of these compounds is below the MAC for drinking water in most groundwa-
ter abstraction wells, as well as in most well screens in groundwater monitoring areas.
The percentage of well screens with pesticides and/or their metabolites in groundwater
monitoring areas was approximately 27 in 2001, 2002 and 2003. The percentage of well
screens with concentrations above the MAC for drinking water (0,1 µg/l) was about 8.5 in
both 2001 and 2002, but increased to about 10% in 2003. Pesticides or their metabolites
were detected in more than 40% of well screens sampled from 1998 until 2003, and the
share above MAC was about 15%.
The metabolite 2,6-dichlorbenzamide (BAM), a degradation product of chlorthioamide anddichlobenil, and triazins and their metabolites, notably deethylisopropylatrazine, are themost commonly detected compounds. The detection of deethylisopropylatrazine has in-creased to 9% of wells sampled. This metabolite was detected in more than 30% of moni-toring at shallow depth below agricultural watershed catchment areas. The metabolite wasdetected in about 3% of analysed water supply wells. Only about 200 water supply wellswere analysed for this metabolite, and it is anticipated that detection will increase as analy-ses are performed on an increasing number of water supply wells. Groundwater abstraction wells are still severely affected by pesticides or metabolites. Dur-ing the period from 1998-2003, the percentage of detections was approximately 26; 6%exceeded MAC. During the same period, the annual percentage of wells with concentra-tions exceeding MAC, declined from 10 to 5%. In 2003, pesticides or their metaboliteswere detected in about 27% of the wells.
The most commonly detected compounds in water abstraction wells are BAM, atrazine andtriazine-metabolites as well as mechlorprop and dichlorprop. From 1998-2003, pesticidesor their metabolites have been detected in more than 50% of sampled shallow (0-20 mbgs)groundwater abstraction wells. Like in groundwater monitoring areas, occurrences de-crease with increasing depth.
The metabolite BAM often appears in combination with other pesticides and metabolites inshallow aquifers, and can, accordingly, be used as an indicator for other pesticides, forexample in small private dug or drilled wells, as these often abstract shallow groundwater.
In the Novana program: http://www.dmu.dk/Overv%C3%A5gning/NOVANA/ Detailed listing of number of contaminants measured within defined groups, the used time-span between repeated analysis, and the storage and data analysis can be found (also inDanish).
Emerging groundwater contaminants 4. Metals
Metals constitute limited group of compounds which may be a threat to the groundwaterresource. In water the metals will be at ionic forms as halo- oxo- or hydroxylated com-pounds. It is not all forms that constitute a threat to the groundwater, as some species areless toxic than other species. Also the solubility and the sorption of the individual speciesare different, parameters both affecting the leaching of the compounds towards thegroundwater. Routine measurements of groundwater corporate all forms of the individualmetals in one analysis and do not distinguish between the different metallic species. Withinthe last decades focus has been on the heavy metals due to their negative effects on hu-mans and the environment. For lead and mercury plans for reduction in their use has beeninitiated and therefore increased findings in groundwater is not expected. In the DanishGroundwater Monitoring Programme (GRUMO) several metals are as a routine measured,but only nickel, arsenic, aluminium, and zinc are found in concentrations above the limitsset for drinking water to a larger extend (table 1; GEUS 2004). Arsenic is found naturallyespecially in reduced aquifers and if the water recovery from such aquifers is increasede.g. due to pollution of the upper oxidised groundwater, then increased problems with ar-senic may be expected. Similar to arsenic the concentration of nickel will depend on the Table 1: Analysis of metals in the Danish Groundwater Monitoring Programme (GRUMO)in the period 1998-2003 (GEUS, 2004).
Limit concentration for Wells having more than one sample above the limit% 1Limit concentration/recommended concentration pattern of water recovery. In anaerobic aquifers nickel may be bound as sulphuric nickel.
Increased water recovery, however, will lower the water table and the reduced sedimentsmay be aerobic. At the aerobic conditions the free nickel will be released and be a threat tothe groundwater resource. Aluminium is also found in groundwater, probably due to thegeneral acidifying of the environment. At lower pH chalk and eventually clay minerals willdissolute and aluminium will be released to the water. Zinc is also found, but at present thesource is not known.
Recently the Danish EPA published a report about the fate and effect of 11 metals in theenvironment. The metals were so called 'second rank' elements with regard to use patternand consumption in Denmark. The elements were antimony, beryllium, bismuth, boron,gallium, indium, lithium, molybdenum, palladium, platinum, and vanadium (Kjølholt et al.,2002). Either of the metals is estimated to be a threat to the groundwater resource.
A web of science based search of the international literature reports no metals not alreadymeasured as emerging contaminants.
Emerging groundwater contaminants 5. Pesticides and their persistent degradation
products
Brüsch and Felding, 2000, compared pesticides found in Danish and foreign ground waterin a state of the art project. This project was based on reviewed literature, so-called greyliterature, on down loading databases from web sites and on direct contact with institutionsresponsible for ground water monitoring. The juxtaposition of more than 50 databases andchemical ground water data from monitoring programs were compare with approximate550 pesticides and metabolites, where the parent pesticides were used in Denmark in theperiod 1956 – 1998. To identify new upcoming pesticides the most relevant web sites usedby Brüsch and Felding, 2000, were revisited, and the data collected were compared withthe results from the state of the art project.
Denmark , national moni- Denmark, all analytical pro- 4,3 Deethyldeisopropyl- 2,5 Deisopropylatrazine 4,3 Deethylatrazine 9,5 Ethylenthiurea(ETU) Table 2. The 10 most frequently found pesticides and metabolites in ground water in USA,Europe and Denmark. Avg. frequency – A low number indicate, that the substance hasbeen found most frequently in the monitoring programs used as background material. Atop 10 list for the individual programme has been calculated. Summing up al top 10's anddividing by the number of programs give an average frequency. E.g. 2,6-dichlorbenzamidehas a value "1" in the column "Denmark, al analytic programs" indicating that 2,6-dichlorbenzamid was detected most frequently in al the programs. From Brüsch and Feld-ing,, 2002.
Information about more than 550 pesticides and their metabolites used in Denmark from1956 to 1998 has been collected, Brüsch and Felding, 2000, and the results from Europeand USA have been processed in a database (8). Approximately 300 pesticides and me-tabolites have been analysed in water samples from ground water and 140 have beenfound. A minor number of substances are only reported as "found" (9) and no information about number of analyses or circumstances were reported. In monitoring programs whereonly few parameters are analysed it is normal to find all compounds, while it is common tofind only some of the analysed parameters in large programs. But a trend is: Increasingnumber of parameters in the analytic program ® increasing number of parameters will befound. Obvious other limiting factors also could be detection limits, well type, analyticmethods, area use (agricultural, urban, roads or railways) and monitoring purpose.
The results have been used to improve the national Danish analytic ground water monitor-ing program. Results from the Danish pesticide leaching assessment programme havealso contributed to update of the national monitoring programme, for example frequentfindings in high concentrations of the metabolites desamino-diketo-metribuzin and diketo-metribuzin. These substances are now incorporated in the new ground water monitoringprogramme (NOVANA) and probably these two metabolites will be found frequently ingroundwater under areas where metribuzin has been used in agriculture. Metribuzin hasalso been found frequently in surface water in USA, draining agricultural areas, Martin,Crawford and Larson, 2004.
In table 2 pesticides and metabolites detected in monitoring programs in the US, Europeand in Denmark are compared. Only frequently analysed pesticides have been included:Pesticides analysed more than 100 times in monitoring programs, pesticides analysedmore than 200 times in larger compiled programs and pesticides analysed in more than 2-3 programs.
From table 2 it can be seen, that the metabolite BAM (2,6-dichlorbenzamide) is found fre-quently in Denmark, while atrazine and metabolites are detected most frequently in Europeand in the US. BAM has often been found in urbane areas and not in young ground watersamples from agricultural areas. In Europe bentazone, simazine, diuron, isoproturon andtwo phenoxy acids have also been frequently detected. Ethylen-thiourea (ETU) has beenfound in Denmark, but it should be noticed that the detection's originated from ground wa-ter sampled in selected wells. Also – it has been found that BAM may be a good indicatorfor contamination as other contaminants are often together with other compounds.
A recent study made at GEUS has demonstrated that possible persistent transformationproducts can be formed from bromoxynil and ioxynil (Nielsen et al 2005). This finding ishighly relevant in relation to the search for possible emerging contaminants in Danishgroundwater. Irrespective that bromoxynil and ioxynil not has been used for total weedcontrol in uncropped areas as dichlorobenil, the structure and degradation pathways arevery similar to the well known dichlorobenil degradation product BAM, that has been foundin 19% of 5000 samples of Danish groundwater.
Kolpin and Martin, 2003, have summarised preliminary Results from Cycle I of the NationalWater Quality Assessment Program, Pesticides in ground water and Pesticides in SurfaceWater of the United States. The data has been subdivided in ground water and surfacewater from areas with agricultural land use, mixed land use (major aquifer surveys), unde-veloped land use and urban land use. The ground water findings show only few pesticidesand metabolites not measured in Denmark. Dieldrin has been found in 1% of 1438 wellsunder agricultural areas, in 8,5% of 2717 wells in major reservoirs and in 5.1% of 823 wellsin urban areas. Dieldrin has also been found in surface water. Dieldrin has not been moni Emerging groundwater contaminants tored frequently in Denmark and dieldrin has been used from 1956 to 1988 in rather smallamounts. Occurrence of Pesticides in Shallow Ground Water of the United States, Kolpin,Barbash, and Gilliom, 1998, also show findings of dieldrin in ground water. It is possiblethat findings of dieldrin in Denmark could occur in wells situated near urban areas. U.S.
Geological Survey, 1999, has show that dieldrin persists in shallow urban ground waterand that the presence of dieldrin in ground-water several years after being banned indicatedieldrins persistence in soils and ground water and its potential to be a problem in somewells. The data from Kolpin and Martin, 2003, include app. 80 pesticides and metabolitesand there is no other findings of "new" substances.
Sulfonylurea, Sulfonamide, Imidazolinone, and Other Pesticides, U.S. Geological Survey,2004, have been monitored in streams and in ground water. At least one SU, SA, or IMIherbicide was detected in 6 of 8 reservoir samples and flumetsulam, imazethapyr, andimazaquin were each detected in 5 samples. At least one SU, SA, or IMI herbicide wasdetected in 5 of 25 ground-water samples. Imazethapyr was detected most frequently fol-lowed by flumetsulam and imazaquin. These pesticides have not been sold in Denmark butsimilar low doses pesticides are used in increasing amount and it can not be exclude thatsome similar pesticides can be found i Danish ground water.
Barbash et al, 1999, have evaluated Distribution of Major Herbicides in Ground Water ofthe United States and reported findings of several triazine metabolites. Most are also ana-lysed in different Danish monitoring programmes but didealkyl-atrazine, deethyl-hydroxy-atrazin, deisopropyl-hydroxy-atrazin and didealkyl-hydroxy-atrazin are not analysed inDanish ground water and the metabolites are not included in the danish monitoring system.
Al the substances have been analysed and found in ground water in US, as well as themore common metabolites like deethyl-atrazine, deisopropyl-atraxine which have beenfound both in Denmark and in USA. The metabolites deethyl-atrazine and deisopropyl-atrazine are included in the Danish monitoring system. The hydroxy metabolites have a better sorption in relation to clay and other minerals com-pared with the other triazine metabolites, but some investigations show a rather large de-tection frequency. Barbash et al, 1999, also mention that a large number of metabolitesfrom alachlor have been found, but the total consumption of alachlor in Denmark havebeen small and therefore it would be unlikely to find alachlor metabolites on a countrywidebasis.
Organochlorine and organophosphate pesticides occurrence and distribution in surfaceand ground water of the United States have been investigated, by Scribner, et al 2003 andHopkins et al, 2004. The organophosphorus pesticides studied are azinphos-methyl, chlor-pyrifos, diazinon, disulfoton, ethoprop, ethyl-parathion (parathion), fonofos, malathion,methyl-parathion, phorate, and terbufos. Azinphos-methyl, chlorpyrifos, diazinon, ethyl-parathion (parathion) and malathion have been sold in Denmark. Diazinon was found in1,2% of the analysed ground water samples, while the others were found less frequently.
Malathion, parathion and diazinon have been sold in rather large amounts in Denmark,while the other substances are sold only in small amounts. It can probably be expected tofind these substances locally in Danish ground water.
Terbuthylazine and deethylterbuthylazine have been found frequently in drinking waterfrom small private water supplies, Brüsch et al, 2004. It should be expected that an in-creasing number of findings will occur in deeper ground water reservoirs in the future. Itshould be noted however that both terbuthylazine and desethylterbuthylazine are includedin the monitoring system.
A summary from Umweltbundesamt, Abteilung Wasser, 2004 , include 38 pesticides andsummarise also reports from water companies in Germany. There is no indication of thenumber of analysed water samples, and the summary includes water samples from drink-ing water extracted from surface water and samples from monitoring stations in surfacewater.
Emerging groundwater contaminants 6. Hormones and steroids
6.1 Introduction to compounds
Within the last decade there has been an increasing interest in possible groundwater con-tamination with compounds that can cause hormone effect in human and biota. Obviously,this group of compounds includes the natural hormones such as the endogenous mam-malian estrogen and testosterone. For example, the steroid compounds are a family ofsubstances sharing a similar chemical structure and the steroid hormone testosterone is anexample of a natural compound from this group. Also, various drugs have steroid effect. Asdemonstrated by several toxicological studies many manmade chemicals may cause hor-mone or hormone-disrupting effects. One mechanism suggested to cause the effects isbinding of compounds to endogenous steroid receptors thereby causing either activation orblocking of the receptors Heberer,T. (2002c), Evans,N.P. et al. (2004), Singleton,D.W. andKhan,S.A. (2003), Machala,M. and Vondracek,J. (1998). The result is various effects onendocrine functions and for that reason the compounds of this group are called endocrinedisrupting compounds (EDCs). A list of 118 compounds that may have hormone disruptingeffects has been published by EU (available at http://www.mst.dk/kemi/01110400.htm) andreviews on compounds and fate studies has been published (Sonnenschein,C. andSoto,A.M. (1998),Sumpter,J.P. (1998),Ying,G.G. et al. (2002).
Examples of manmade compounds are the synthetic estrogen diethylstilbestrol and sev-eral chemical substances used in industry as bisphenol-A Ben-Jonathan, N. and Stein-metz,R. (1998) and nonylphenol White,R. et al. (1994). Also, organo-metal compoundssuch as tributyltin (TBT) has been shown to cause imposex in marine gastropodsBryan,G.W. et al. (1986),Bright,D.A. et al. (1990). Thus, several of the compounds dis-cussed in this chapter are also considered in other contexts elsewhere in this report. In thepresent chapter the focus is on the aspect of endocrine-disrupting effects in relation topossible emerging groundwater contaminants. The natural estrogens include 17b-estradiol (estradiol), 16a-hydroxy-17b-estradiol (estriol),and estrone. In general, natural estrogens are more readily biodegraded than syntheticestrogens such as 17a-ethynylestradiol (ethynylestradiol).
In the literature several classical studies has been published describing hormone effects inthe environment Colborn,T. (1995), Guillette,L.J., Jr. et al. (1995), Sumpter,J.P. and Job-ling,S. (1995), Toppari,J. et al. (1996), Aherne,G.W. and Briggs,R. (1989). The compoundsmay be present in the environment in very low levels. However, the concentrations neededto cause effects is also relatively low as compared to the levels generally accessed in clas-sical environmental toxicology studies Welshons, W.V. et al. (2003). Since the early start ofthe research within this area a major concern has been, and remains to be, the combinedeffect that may result when two or more weak environmental estrogens are present simul taneously. Thus, a 1000 times increase in response has been demonstrated by combiningtwo weak estrogens Arnold, S.F. et al. (1996).
Several studies have investigated the possible leaching and transformation of EDCs fol-lowing application of sludge to soil. One way of introducing the compounds to the soil andpossibly the groundwater is the use of sludge as a fertiliser on agricultural land. SeveralDanish and international studies have investigated the aspect of EDCs in sludge treat-ments plants and use of sludge on agricultural areas Fauser, P. et al. (2001), Christiansen,L.B. et al. (2004b), Davis, G.A. et al. (1992), Vikelsoe, J. et al. (2002). Fate and transport studies of of testosterone and beta-estradiol has been publishedCasey, F.X.M. et al. (2003), Casey, F.X.M. et al. (2004). Also, an EU-Project has beenestablished on the subject "Assessment of Technologies for the Removal of Pharmaceuti-cals and Personal Care Products in Sewage and Drinking Water Facilities to Improve theIndirect Potable Water Reuse – Poseidon (www.eu-poseidon.com). Within this forum anumber of fate and leaching studies has been presented, but the actual data available fromthe studies are not included in the publications – or presented with only limited details onexperimental conditions.
The relevance of the compounds within this group of contaminants is highly dependent onuse and source aspects. For example, some compounds in sewage may not be consideredas a possible contaminant as the content is removed by degradation in sewage treatmentplants. However, if such compounds were introduced into the environment by some othermeans – such as widespread use of soakaways (soil infiltration) – they may cause con-cern. The emission of natural estrogens from farm animals (cattle, pigs, chicken, etc.) ispotentially a major source of estrogen pollution in the environment. The major componentsare E1, E2, 17b-estradiol (E2-17b) and their conjugates. After storage in the manure-tank,estrogens excreted from stabled animals may be released to the soil environment whenmanure is used for fertilisation of soil. Most fate–studies have dealt with unconjugated estrogens of high biological activity andlow aqueous solubility. However, swine excrete 17-b-estradiol and estrone mostly as sul-fate- or glucuronide conjugates of low biological activity and high solubility (Hanselman et.
al. Environ. Sci. Tech.; 37:5471-5478; 2003). Transport of conjugates and their environ-mental transformation into biologically active compounds have been virtually non-investigated.
Recently a Danish study (Personal communication Mette Lægdsmand) applied pig-slurrywith a natural content of estrogens to intact soil monoliths (60 cm diameter and 100 cmlong) by direct injection. Concentrations of estrogens in the effluent leached from themonoliths were up to 10 times the effect-concentrations of aquatic wildlife. Most of theleached estrogens were present as estrone. Leaching of estrogens continued when outflowresumed after a dry summer period with no outflow. These results indicate (i) that estro-gens can be transported to one meter depth under certain conditions and (ii) that degrada Emerging groundwater contaminants tion of estrogens in soils when applied with slurry by direct injection was retarded com-pared to aerobic degradation of estrogens under laboratory conditions.
Overall, the data available for risk evaluation is focused on sludge treatment plants andfate studies in topsoil and surface water biotopes. Thus, in relation to groundwater riskassessment very few data are available considering sorption, degradation and transforma-tion. The lack of scientific knowledge is thus related to the processes and fate of thesecompounds in deeper soil layers. Only a few studies have focused on compounds withhormone effects in groundwater, such as Rie, M.T. et al. (2000). A prerequisite for the re-search is methods that can identify and quantify the compounds at concentrations that canbe expected in groundwater. Also, the analytical method must be sensitive enough toreach the levels relevant for the toxicology effect levels of the ECDs. A overview of tox-icity identification and evaluation procedures used for the effect-based analysis ofendocrine disrupting compounds has been published recently Petrovic, M. et al.
(2004). To provide an indication of relevant concentrations to be measured the effect levelin fish can be considered. Thus, it has been demonstrated that low nanograms per litterlevels of estrogens cause estrogenic responses (vitellogenin production in male fish,Panter, G.H. et al. (2000)). Such analytical methods are only just starting to be publishedTernes, T.A. et al. (1999 & 2002), Fine, D.D. et al. (2003), Richardson, S.D. (2004), Pet-rovic, M. et al. (2002). Consequently case studies and monitoring results on groundwaterare very limited. 6.2 Compounds of primary interest
In a recent report Christiansen, L.B. et al. (2004a) the research on numerous compoundswith endocrine effect is reviewed. It is concluded that in relation to surface waters andfeminisation of fish the most important compounds seems to be are 17ß-estradiol andestron as well as the synthetic estrofem ethinylestradiol. Considering possible endocrineeffect the synthetic compounds such as alkylphenol and bisphenol seems less likely can-didates. In relation to natural hormones and EDCs the sources of the contaminants arewastewater discharges as well as sewage manure. Thus, EDC contamination of surfacewater likely relates to manure used on farming areas, sewage and sewage plants whereassources to groundwater contamination may be manure usede on farming areas, sewageused as fertiliser or pollution originating from leaking sewage systems. Consequently, theconclusion is likely to be relevant for groundwater as well. Also, as discussed elsewhere inthe present report, several industrial products may be relevant as emerging groundwatercontaminants for other reasons than EDC effects. Considering endocrine-disrupting effectsin relation to groundwater contamination a basic understanding on sorption, transport anddegradation needs to be established. In particular, this is relevant for the prime candidatecompounds 17ß-estradiol, estrofem ethinylestradiol.
7. Natural organic matter and toxins
Toxins are produced naturally by many plants, fungi and soil bacteria and if they are mobileand toxic to human health they may potentially be a threat to the groundwater resource. Thenumber of toxins produced in nature is extremely high, but in general the compounds aredegradable and only produced in small amounts and therefore not a threat to the ground-water resource. Examples are toxins produced by poisonous fungi and many soil bacteriae.g. Clostridium tetani the bacterium causing tetanus. Only in very specific cases with adense population of toxin producing organisms toxic compounds may leach to the ground-water. Resent research in Denmark has focused on ptaquilosides which are found inbrackens and is shown to be toxic to humans (Rasmussen, 2003). Ptaquilosides has beenmeasured in concentrations from 4 to 6 µg/l in samples from two shallow Danish aquiferssituated below bracken stands. In Sweden concentrations up to 45 µg/l has been meas-ured also in shallow groundwater (Rasmussen, 2003). Most agricultural crops do not produce toxic compounds but there are exceptions. Potatoplants produce e.g. solanin, which is toxic and potentially may leach to the groundwater.
Recently a joint project involving The Royal Veterinary and Agricultural University andGEUS has been initiated focusing on the fate of solanin in soil and groundwater. Within the last decade, new crops genetically modified to produce toxic compounds withe.g. herbicidal or insecticidal effects have been invented. Such genetically modified organ-isms may limit the use of pesticides, but the compounds released by these plants mayleach to the groundwater and therefore pose a threat to the drinking water and humanhealth. Knowledge about compounds released from GMO, including their fate and humantoxicity are meagre at present, but needed to make more complex risk assessments ofmodern agricultural practise.
Emerging groundwater contaminants 8. Pharmaceuticals and antibiotics
This group of compounds contains very differentiated compounds. A number of sources tothese compounds has been described Kummerer, K. (2001), Halling-Sorensen, B. et al.
(1998). In relation to groundwater the sources to these contaminants are livestock manureand sludge that is spread on arable land. Also, the compounds may be introduced fromleaking sewage systems etc. Many of the compounds are water soluble, only slightly ab-sorbing to top soil, and may be rather stable in the soil and groundwater environment(Heberer, T. (2002c), Heberer, T. (2002b), Stuer-Lauridsen, F. et al. (2000) and referencesherein). Thus, it is very likely that some emerging groundwater contaminants may be con-cealed within this class of compounds. The problem is the lack of monitoring results de-scribing occurrences and time trends of contamination in relation to soil and groundwater.
At present, the Danish national groundwater monitoring program does not include pharma-ceuticals or antibiotics. Further, ecotoxicological data are available for less than 1% ofpharmaceuticals in the open peer-reviewed literature and ecotoxicological databasesECETOX (EU) and ECOTOX (US) Sanderson,H. et al. (2004), and much of the basis usedfor toxicological evaluation is based on modelling by tools such as QSAR programs. Manyof the QSAR models is targeted on describing compound effects on biota, particularlyaquatic biota, and very few tools can describe the transport, sorption and degradation inrelated to groundwater contamination as the basic data for the models has not been estab-lished.
In general, the literature available on fate of these compounds is related to processes insludge and sewage treatment plants. A number of German publications describe the pres-ence of pharmaceuticals in groundwater, and the source to these findings are suspected tobe impact of municipal or industrial waste water Sacher, F. et al. (2001). However, in gen-eral, knowledge on more widespread contamination is limited. Within recent years an efforthas been made by USGS to address the problem of possible emerging contaminantswithin this group. From the USGS National Reconnaissance Studies it is found that somecompounds are frequently detected in the aquatic environment. Among these are steroids,drugs, disinfectants, antibiotics and fragrances. One of the prerequisites for this study hasbeen the development of analytical procedures that allows for detection and quantificationof the compounds of interest. Thus, a large effort has been made by the USGS in recentyear, and the outcome has been methods for a large number of possible emerging con-taminants. However, it should be emphasised that not all compounds used in US are rele-vant to Danish conditions due to differences in use and treatment approaches. Considering toxicology a model study has demonstrated a negligible human risk connectedto the environmental exposure for the substances 17a-ethinylestradiol, phenoxymethyl-penicillin and cyclophosphamide Christensen,F.M. (1998). In this context it should be men-tioned that in relation to other (non-mammalian) eco-organisms the pharmacodynamic effects might potentially play a major role Seiler,J.P. (2002). Thus, the ongoing debate onhow to establish ecotoxicology assays is highly relevant for the compounds of this class.
Reviews on the occurrences and fate of pharmaceutical substances in the environmenthas been published Sanderson,H. et al. (2004), Halling-Sorensen, B. et al. (1998),Daughton, C.G. and Ternes, T.A. (1999), Kolpin, D.W. et al. (2002), Heberer, T. (2002a),Richardson, M.L. and Bowron, J.M. (1985), Zuccato, E. et al. (2000), Jorgensen, S.E. andHalling-Sorensen, B. (2000). An environmental risk assessment has been made for the 25most used pharmaceuticals in the primary health sector in Denmark Stuer-Lauridsen,F. etal. (2000). The PEC/PNEC ratio exceeded one for ibuprofen, acetylsalicylic acid, andparacetamol. A similar evaluation of the 25 most used pharmaceuticals in UK has beenpublished recently Jones, O.A.H. et al. (2002). Based on exceedings of aquatic PEC/PNECratios the drugs Paracetamol, Amoxycillin, Oxytetracycline and Mefenamic acid were iden-tified as priority compounds. A recent Danish report has investigated the content of envi-ronmental contaminants in liquid manure, including veterinary drugs. From this study anumber of eight possible antibiotic contaminants can be identified: sulfadiazine, sulfadi-midine, sulfatroxazole, sulfadoxine, sulfamethoxazole, tiamulin, trimethoprime and tylosin,and the compounds in Schwærter,R.C. and Grant,R. (2003). In addition to searching theexisting literature an examination of the use of drugs in Denmark may help identifying pos-sible emerging contaminants. Considering the Danish use of human antibiotics the follow-ing candidates can be identified based on a calculation of use: Antibakteria drugs for systemic use Beta-lactamase sensitive penicillins Penicillines, broad spectrum Makrolides, lincosamides, streptogramines Sulfonamide and trimethoprim Beta-lactamase resistant penicillines Nitrofurane derivatives Sulfonamider (short time effective) Trimethoprim and derivatives Emerging groundwater contaminants A calculation has been published previously Halling-Sorensen,B. et al. (1998), and a sum-mary of recent use can be calculated using the ongoing statistics published by the DanishMedicines Agency (number of doses used in 2000-2003, primary sector as published bythe Danish Medicines Agency, Considering candidate compounds erythromycin, sulfamethoxazole, fluoxetine, carbamaz-epine, ibuprofen, diclofenac and triclosan is included in the US surface water screeningprogram. Considering veterinary drugs a few publications on Danish and international research areavailable Nielsen, S.N. et al. (2004), Boxall, A.B.A. et al. (2003a), Boxall, A.B.A. et al.
(2003b), Tolls, J. (2001), Gavalchin, J. and Katz, S.E. (2004), az-Cruz, M.S. et al. (2003),Hirsch, R. et al. (1999), Jjemba, P.K. (2002). Household products often have content of antibiotics as for example trichlosan. The major-ity of data is related to sludge and wastewater treatment plants Bester,K. (2003), Singer, H.
et al. (2004), Paxeus, N. (1996). So, in general for pharmaceuticals as well as antibiotics,only limited data are available considering sorption, degradation and transport in relation togroundwater reservoirs.
8.2 Possible emerging contaminants within pharmaceuticals
and antibiotics
It must be emphasised that frequent use does not equal high groundwater contaminationrisk. Evidently, aspects of concentrations, degradation, effect levels, mixtures and leachingcharacteristics must be taken into consideration. However, as data for such assessment ofgroundwater contamination potential is not available it may be relevant to search for possi-ble emerging candidates within the drugs that are frequently used, as exemplified above.
Also, formation of metabolites is highly relevant for this group of compounds as manydrugs are designed to be degraded before the pharmacodynamic effects are achieved. Inrelation to possible leaching such metabolites may differ significantly from the appliedcompounds. As very few groundwater related data exists the search for emerging contami-nants within this group must be based upon use and source evaluation. Thus, from theliterature survey and data on use a set of initial primary candidates can be identified: aminoglycosides, ibuprofen, paracetamol, penicillines, sulfadiazine, sulfadimidine, sulfa-doxine, sulfamethoxazole, sulfatroxazole, tetracyclines, tiamulin, trichlosan, trimethoprime,and tylosine A literature search on "web of science" using the terms (water* or soil*) in combination withone or several of these compounds demonstrated that the majority of publications are ad-dressing the analytical aspects such as LC-MS method development as exemplified byHamscher,G. et al. (2002) and Lindsey,M.E. et al. (2001). A relatively large number of pub-lications were related to tetracycline Jacobsen, A.M. et al. (2004), Lindsey, M.E. et al.
(2001), Hamscher, G. et al. (2002), Lindsey, M.E. et al. (2001), Hamscher,G. et al. (2001),Chee-Sanford, J.C. et al. (2001), Hamscher, G. et al. (2000), Rabolle, M. and Spliid, N.H.
(2000) Also degradation and sorption studies has been made on these compounds, forexample on tylosine Ingerslev and Halling-Sorensen (2001), Rabolle, M. and Spliid, N.H.
(2000) Jacobsen, A.M. et al. (2004). A model for degradation of trichlosan has been madeZhang, H.C. and Huang, C.H. (2003). However, in general, the data in the existing litera-ture are few and a probably insufficient for modelling studies and evaluation of fate andrisk .
Emerging groundwater contaminants Microbial contamination of waterbodies is a major concern for all waterworks and the useof chlorination is common practice in many countries. The use of chlorination is problem-atic due to taste and the fact that some microorganisms is resistant to the chlorination; thusmany countries including Denmark resist to the use of chemical safeguiding the drinkingwater. Further the use of chlorination can at certain occations lead to the formation of chlo-rinated orgnic compounds with unknwn health effects.
Concerns for microbial contamination is in this review limited to the potential contaminationof groundwater bodies with pathogenic microorganisms in the open land. Thus contamina-tion of fresh water streams and lakes following surface runoff are not taken into account.
The major sources for microbial pathogens to enter the soil and subsequently the ground-water environment is in three areas: 1) the use of life stock manure as fertilizer in agricul-ture; 2) the use of wastewater sludge on farmland; 3) the septic sewage systems in theopen land. The general problem reviewing these areas is the lack of systematic and repre-sentative methods that allows the measurement of pathogens in the groundwater. In thefollowing three sections the current knowledge of microbial contamination of groundwaterdue to the above mentioned three sources will be addressed. The three major groups ofmicroorganisms (bacteria, virus and protozoa) will be adressed and the section will be fol-lowed by an discussion of the available methodologies.
9.1 Bacterial contaminants.
In the city of Walkerton (Ontario, Canada) in May 2000, 2300 people where medicaltreated (7 died) due to contamination of the water system with two bacteria, Eschericia coli0157:H7 and Campylobacter jejuni. The bacterial contamination originated from life stockmanure. The bacteria were most likely transported to the aquifer by infiltration water al-though direct entry of surface runoff into the groundwater well could not be ruled out (Uncand Goss 2004). Bacterial contaminants entering a groundwater aquifer through infiltrationafter "current best manure management practices" has lead to an unexpected high risk inconnections with the safe use of groundwater as drinking water source (Unc and Goss,2004). In an older work (Goss et al., 1998) it was found that the proportion of groundwaterwells with contamination of faecal bacteria were higher in areas where manure was spreadcompared to areas where only mineral fertilizers were used. In other cases drinking waterassociated outbreaks of Eschericia coli O157 has been reported and related to cattle fae-ces but not demonstrated if the contamination of the water body was done through badlymaintained wells or through soils (Dev et al. 1991; Swerdlow et al. 1992).
A Danish study (Brüsch et al. 2004) found colifom bacteria and termotolerant coliformbacteria in respective 26% and 15% of 621 individual wells. The source of the contamina-tion could not be disclosed since most of the investigated well (also the ones having no coliform bacterial contamination) is placed within the close distance to a septic sewagesystem. Further all wells were situated in agricultural areas and no registration have beendone whether the area are impacted by manure or not.
The heterotrophic plate count (HPC) is the traditional method to enumerate the totale countof microorganisms in drinking water (Allen et al 2004). The HPC technique enumerates aculturable fraction of the bacterial community including potential pathogens but also un-problematic soil and groundwater associated bacteria would be enumerated using thetechnique. The HPC counts can therefore not be linked to any apparent health associatedeffect and no WHO or EPA guidelines exist for these counts (Allen et al 2004). Howeversome countries, including Denmark, have established mandatory limits for HPC (Allen etal. 2004), and in the Danish survey mentioned above heterotrophic plate counts (Platecount agar at 37°C, limit 20 CFU per 100ml) was exceeded in 200 of the wells (32%). In astudy of 10 small waterworks in Quebec in Canada the total coliforms was between 2 and41 cfu per 100 ml with HPC counts of between 100 and 2200 cfu per ml. The proportionbetween total coliform bacteria and HPC was anything but constant varying between 0,005% and 0,12 % (Coulibaly and Rodriguez, 2004).
The survival of bacterial pathogens (Eschericia coli O157, Salmonella, Campylobacter andListeria) where investigated in dairy slurries and old fashion heating manure heaps (Nich-olson et al 2005). In the heating heaps the strains died out in between 2 and 8 days whilein the dairy slurry the pathogens survived up to six months (Nicholson et al 2005). Thesurvival after application to soils was further studied after land mixing into arable land top-soil or surface applying on grassland. In both cases the bacterial numbers were found todecrease markedly within one month, but the fraction of leached pathogens were not de-termined (Nicholson et al. 2005). Transport of Eschericia coli O157 from cattle slurry ap-plied through drained plots were found to highly depended on rainfall and between 0.2%and 10% of the applied Eschericia coli O157 were found to leach to the drains (Ogden et al2001). In a later study Vinten et al. (2002) also found leaching of Eschericia coli O157 todrains after application in dairy slurry, the first drain flow event contained between 1x103and 1x104 CFU ml-1 which is regarded a high concentartion. No studies have been dealingwith the subsurface transport and survival of pathogens. However Artz and Kilham (2002)found that Eschericia coli O157 was heavily predated in most well waters.
The genus Salmonella is a well known bacterial pathogen that can create human infectionhas in a recent field trial been found to survive for only short time in soil (Gessel et al.
2004). However some discrepancy exist since Salmonella sp. has previous been reportedto survive well in soil (for review see Mandsley et al. 1995). Like it has been recorded formany bacteria the method of detection might be a case when looking at Salmonella sp. insoil, since an active but non culturable state of Salmonella sp. has been described (Marshet al. 1998).
9.2 Virus contamination
A recent review of human enteric viruses in the environment Rzezutka and Cook (2004)includes only studies of survival of enteric viruses seeded into groundwater samples. The Emerging groundwater contaminants survival of poliovirus and echovirus were high at 5°C since no decrease could be observedin the 8 weeks experiment. The related survival in soil has been addressed in several pa-pers including a paper showing survival of coxsackievirus B3 added to municipal sludgeand duck into Danish soils placed in lysimeters (Damgaard-Larsen et al. 1977). This papershowed some decline of the virus over the time of the experiment but it was not possible todetect any viruses in the leaching water.
Detection of human virus has hitherto been dependend on difficult and timeconsumingmethod, if reliable methods at all have been available. Due to the recent establishment ofmethods to RT-PCR amplify viral RNA directly from environmental samples the quantifica-tion of human virus in the soil and water environment is now within reach. However themethods still need validation. The use of bacteriophage is common in the investigation of survival and transport of vi-ruses in the environment (Harvey and Ryan, 2004). From these studies it can be concludedthat the bacteriophage PRD1 is transported through many soil matrices measured in me-ters per hour (McKay et al 1999, Paul et al. 2002). If these data for bacteriophage transportcan be used directly as indicators for virus transport has not yet been proved.
9.3 Protozoan contamination
The protozoan parasite Cryptosporidium sp. is widely recognized as a pathogen of domes-ticated livestock and believed a wide spread threat to public health (Fayer, 2004). In a re-view by Carey at al (2004) mentioning a particular large outbreak of acute watery diarrheain Milwaukee, USA that affected 400.000 residents, highlights the public health significanceof Cryptosporidium sp. The review paper by Carey et al. (2004) quotes 263 references invarious fields of biology, persistence and detection of Cryptosporium sp. The oocyst is veryresistance to a long list of environmental stresses, and surface runoff is well understood(Davies et al. 2004). However, information on transport of Cryptosporium sp. through soil togroundwater after application to agricultural fields is non-existing. In a technical report for American Water Works Association Hancock et al 1998 (cited inFayer et al. 2004) claims that 9,5-22% of U.S. groundwater samples tested positive forCryptosporidium. The UK drinking water inspectorate introduced Cryptosporidium legisla-tion during 1999 not allowing more than one oocyst of Cryptosporidium sp. in 10 liters ofwater (Pearce et al. 2002). Cryptosporidium sp. is the most well described protozoan water contaminant but also Giar-dia lamblia is important waterborne protozoan parasite (Thurston et al. 2001).
Giardia lamblia is 0,6-0,8 µm large and a quite hardly organisms that has been shown tosurvive for weeks in cold waters. We have not been able to retrieve peer reviewed infor-mation on transport of Giardia lamblia to groundwater but numerous US websites mentionthe possibility of groundwater contamination (for examplehttp://www.des.state.nh.us/factsheets/ws/ws-4-4.htm).
9.4 The present technique and future developments.
Variants of the heterotrophic plate count / colony count in combination with enumeration oftotal coliforms and Eschericia coil is the traditional method to enumerate microorganisms indrinking water (Allen et al 2004). These techniques enumerate a culturable fraction of thebacterial community including both potential pathogens but also unproblematic soil andgroundwater associated bacteria. The proportion between total coliform bacteria and HPCwas anything but constant varying between 0,005 % and 0,12 % (Coulibaly and Rodriguez2004). The total coliforms is maybe a better estimate but again an enumeration of coli-forms is not a proof of problematic bacteria in the sample, neither is the lack of coliforms inthe water sample proof of an unproblematic sample.
The nucleic acid based techniques are today developed for the detection of several majorpathogens in water samples (Carey et al 2004; and Fey et al 2004), and the emergingtechnologies within automated gene analysis also indicates that prices per sample will de-crease in the years to come. Emerging groundwater contaminants 10. Industrial and household wastewater products
A increasing number of compounds originating from industry and household have beendetected in natural waters including ground and surface waters. Large scale reconnais-sance study have for example been initiated by U.S. Geological Survey (USGS) to monitorpharmaceuticals, hormones, antibiotics, and personal care products in natural waters ofthe United States (e.g. http://toxics.usgs.gov/bib/bib-emerging.html). These actions haverevealled a broad spectra of chemicals originating from wastewater (Kolpin et al. 2002).
Similar detections have been reported in other national monitoring studies (e.g. Petrovic etal. 2004). A summary of the most detected compounds and groups included in the moni-toring research in presented in table 3.
Detergents and metabolites p-NonylphenolNonylphenol monoethoxylate Nonylphenol diethoxylate Octylphenol monoethoxylate Octylphenol diethoxylate Personal care products Musk productsAcetophenone (fragrance)Triclosan and methyl-triclosan (metabo-lite) Nicotine and cotonine (metabolite)Fluorinated organic compounds (FOCs)Caffeine Table 3. Industrial and household wastewater products detected In various monitoring pro-grams involving surface and groundwater serving as drinking water (Barnes et al. 2004a,2004b, Lee et al. 2004).
Groundwater aquifers may be susceptible to industrial and household wastewater when forexample being located down gradient of a landfill or following bank infiltrations from ex-posed surface waters receiving effluent from wastewater treatment plants. Recent researchhave shown that a broad range of compounds from wastewaters can be transported togroundwater ressources (e.g. Barnes et al. 2004b, Scheytt et al. 2004, Wick et al. 2004).
USGS have studied the occurence of organic wastewater contaminants in 72 groundwater samples and detected compounds in 67 sites (93%) (Barnes et al. 2004b). Commonlymixtures of contaminants were detected and based on their primary groups of plasticizers,detergents and their metabolites, personal care products, flame retardants and variousother compounds were detected. Several plasticizers have been detected in natural waters. In all reportsdi(ethylhexyl)phthalate is measured as the dominant phthalate ester. This is likely relatedto its high production (Petrovic et al. 2004). Plasticizers was among the most frequentlydetected group in US groundwater monitoring by USGS (Barnes et al. 2004b). 10.2 Detergents and their persistent metabolites
Programs addressing the occurence, distribution and impact of alkylphenol ethoxylatesand their metabolites in natural systems have shown that the highest concentrations werefound in industrial areas. This pattern was likely attributed to discharge of industrial waste-water (Petrovic et al. 2004). This group of compounds have however also been detected inagricultural areas where sewage sludge is used as fertilizer (Petrovic et al. 2002). Due torestrictions on industrial usage of detergents it appears that the concentraions have de-clined within recent years in Scandinavian countries, Netherland, Switzerland, Germanyand the UK (Giger et al. 2002). 10.3 Flame retardants
Brominated flame retardants are chemical additives in plastics, electronic equitement, andin different consumer items that have been added to reduce potential risk of fire. Flameretardants, mainly the polybrominated diphenyl ethers, have been widely detected in theenvironment and they commonly occur in wastewater. This group includes a broad rangeof different compounds that may give rise to many different metabolites when introducedinto various environments (Fisk et al. 2003). There is however no convincing evidence forthe complete degradation of these compounds, and commonly the end-product is unknown(Fisk et al. 2003). Several different polybrominated diphenyl ethers have been detected insurface and groundwater near facilities for synthesis (Ronen and Abeliovich 2000). Otherflame retardants detected includes tri(2-chloroethyl)phosphate andtri(dichlorisopropyl)phosphate (Table 3). However as for the rest of the industrial andhousehold wastewater measured in groundwater the route and their further fate is un-known. 10.4 Personal care products
Compounds used in personal care products, such as cosmetics, food supplements, sun-screens, fragrances and the like, have been found in different natural waters (Daughton Emerging groundwater contaminants and Jones-Lepp. 2001). Synthetic musk products such as polycyclic musk, musk xyleneand musk ketone amino metabolites have been measured in waters including groundwa-ter. Highest concentrations was not supricingly measured near sewage treatment plants(Petrovic et al. 2004). The antibacterial compound triclosan, used in a variety of differentconsumer products, have along with its main metabolite triclosan-methyl been detected inseveral examination of surface waters. It howevere remains unknown if this compound iscapable of reaching deeper groundwater ressources.
10.5 Fluorinated organic compounds (FOCs)
In recent years Fluorinated organic compounds (FOCs) has gained much attention aspossible emerging contaminants Schultz,M.M. et al. (2003). Examples of these compoundsare perfluorooctane sulfonate (PFOS), perfluoro-octannate (PFOA), and perfluorooctanesulfonylamide (PFOSA). They are widely used in the manufacture of plastic, electronics,textile, and construction material in the apparel, leather, and upholstery industries. FOCshave been found in blood and environmental samples throughout the world , and recentpostnatal studies on developmental and reproductive indices have questioned the former findingsof low toxicological risk Lau,C. et al. (2004),Lau,C. et al. (2003) and concern for endocrinedisrupter effects has been published Austin,M.E. et al. (2003). Studies of biochemical degradation of perfluorooctanesulfonate (PFOS) and perfluorooc-tanoic acid (PFOA) has been published, and Perfluorooctane sulfonate was found to bequite mobile Meesters,R.J.W. and Schroder,H.F. (2004). In the US perfluorooctanesulfonateand other perfluorinated surfactants has been found in groundwater samples. In conclusion,emerging contaminants may be found within this group of compounds 11. Discussion of emerging contaminants in Dan-
ish groundwater
In Denmark the protection of the groundwater resurce is of high priority, due to environ-mental as well as ressource considerations. Thus, in most other countries intensive use ofsurface water calls for concern over certain types of contaminants linked to the openfreshwater environment. For instance compounds present in sun lotion is an increasingproblem in warmer areas, where surface waters is used for leasure such as swimming,may be of lower priority in relation to Danish drinkingwater quality aspects. However, theseaspects can not be totally ignored as surface waters is also used for drinking water inDenmark, although to a much smaler extent than groundwater, where more than 98% ofthe drinkingwater originate from groundwater reservoires. Such considerations are relevantto compounds as well as microorganisms escaping from municipal wastewater treatmentsfacilities or substances that are subject to surface runoff. In general, the most intensively monitored and analysed group of compounds is the pesti-cides. This is likely due to the simple but rigid detection threshold: 0.1ug per litre. Only fewpesticides and metabolites found in ground water in Europe or in USA have not been in-cluded in the Danish monitoring system. However due to their persistence and mobility it isrecomended that the following pesticides and degradation products are included in thenational monitoring programme: Didealkyl-atrazine, deethyl-hydroxy-atrazin, deisopropyl-hydroxy-atrazin, didealkyl-hydroxy-atrazin, dieldrin and possible persistent transformationproducts from bromoxynil and ioxynil. For some of these compounds more knowledge onthe fate in soil and groundwater is needed for designing a propper monitoring strategy.
Hormones relevant to the aquatic environment originating from wastewater treatment facili-ties have recently been concluded to be of minor importance. This may be related to thehigh activity within the estrogen degrading microbial communities. However, sources togroundwater contamination may be manure used on farming areas, sewage used as fertil-iser or pollution originating from leaking sewage systems and perculation of domesticwastewater. It has recently been shown that estrogens leach through structured agriculturalsoils in concentrations 10 times higher than the known effect concentration on aquatic or-ganisms. Considering endocrine-disrupting effects in relation to groundwater contaminationa basic understanding on sorption, transport and degradation needs to be established. Inparticular, this is relevant for the prime candidate compounds 17ß-estradiol, estrofemethinylestradiol.
Microorganisms being pathogenic to humans are a great concern in all drinking water pro-duction plants using surface water as source. However both a recent GEUS report andinternational literature point to the fact that groundwater exposure should be considered.
Pathogenic bacteria have been quantified in high numbers in drains below agricultural soilstreated with manure, and it is known that transport time of virus in soil is fast making car-ryover from sewage sludge and septic tanks a likely risk. However, for all classes of patho-gens (virus, bacteria and protozoa) a need for accurate and meaningful detection andquantification methods is evident. This should likely be based on combinations of cultural Emerging groundwater contaminants organisms and DNA/RNA quantification using PCR based detection. Also here a basicunderstanding of sorption, transport and survival of microorganism in soils needs to beestablished to quantify and direct an optimal monitoring strategy.
Within pharmaceuticals several likely groundwater contaminants can be identified. An envi-ronmental risk assessment has been made for the 25 most used pharmaceuticals in theprimary health sector in Denmark by Stuer-Lauridsen,F. et al. (2000). The PEC/PNEC ratioexceeded one for ibuprofen, acetylsalicylic acid, and paracetamol. A recent Danish reporthas investigated the content of environmental contaminants in liquid manure, includingveterinary drugs. From this study a number of eight possible antibiotic contaminants can beidentified: sulfadiazine, sulfadimidine, sulfatroxazole, sulfadoxine, sulfamethoxazole, tia-mulin, trimethoprime and tylosin. Also, within the monitoring program a screening project isbeing been planed aiming at a clarification of the potential groundwater contamination riskrelated to several pharmaceutical compounds. Aiming for an overall screening of the invi-ronment several other matrices such as wastewater, sediment and sludge is also intendedfor inclusion in the project being planned. Synthetic musk products such as polycyclic musk, musk xylene and musk ketone aminometabolites have been measured in freshwaters systems including groundwater. Furtherthe antibacterial compound triclosan, used in a variety of consumer products, have alongwith its main metabolite triclosan-methyl been detected in several examinations of surfacewaters. However, it remains unknown if this compound is capable of leaching to deepergroundwater resources.
The compounds and microorganisms highlighted in the present report are likely contami-nants of large groundwater resources. Many other compounds has been considered in-cluding plant toxins, metals and several other classes of industrial chemicals – withoutfinding them to be of particular concern. With the exception of the mentioned degradationproducts from pesticides it would be needed to establish recommended maximum concen-trations. Also, in many instances analytical methods and monitoring startegies needs to beestablished for clarification of the potential risk to the groundwater ressource – and identi-fication of the actual emerging contaminants.
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