FLUORESCENT DYE TRACER TESTS : TOXICOLOGY AND REGULATIONS An overview Sofie de Voldera, Rudy Plouvierb, Jérémy Reboulb a – TRAQUA SA, Rue Godefroid 5/7, 5000 Namur, BELGIUM – contact@traqua.be b – Polytech Montpellier, Sciences et Technologies de l’Eau, Université de Montpellier, Place Eugène Bataillon CC 419, 34095 Montpellier Cedex 5, FRANCE
INTRODUCTION
COMMON FLUORESCENT TRACERS - TOXICOLOGY
The aim of this poster is to give an overview of the research on toxicological effects of common fluorescent tracers and regulations on fluorescent dye tracer tests in the EU. Resources and links can be accessed online through the QR code.
The relatively low cost, absence of the natural environment, and very low detection limits make fluorescent dye tracers a popular tool in hydrogeology. However, some fluorescent dyes should be used with caution or be avoided altogether.
Fluorescent dye tracer tests are commonly used in karst hydrogeology but need to be performed considering some precautions.
TRACER TEST “Tracer Test - a tracer (solute, suspended or floating matter, or heat) is artificially or naturally induced to evaluate the rate and direction of groundwater flow. Common tracers include salt, fluorescent dyes, and neutrally buoyant microspheres.” (Sharp, Jr., J. M. (2023). A glossary of hydrogeology. The Groundwater Project. https://doi.org/10.21083/978-1-77470-079-2). Tracer tests are usually performed to analyse flow pathways, residence times, recharge time, infiltration pathways, connectivity, or contaminant transport mechanisms. Both environmental (naturally present) and artificial (deliberately injected) tracers can be used. In general, environmental tracers are used in studies with a longer timescale (years), while artificial tracer tests are conducted over shorter timescales (weeks, months). Artificial tracers, and fluorescent dye tracers in particular, are mostly used in karst hydrogeology considering the faster flow rates.
TRACER
TOXICOLOGICAL ASSESSMENT
Uranine (fluorescein sodium)
Safe3
Eosin yellow
Safe3 / some concern1
Sulforhodamine B
Ecotoxicologically unsafe
Amidorhodamine G
Safe3 / some concern1
Rhodamine WT
Not recommended/ No risk at low concentrations2
Rhodamine B
Not recommended/ No risk at low concentrations2
Rhodamine 6G
Not recommended
Sodium naphthionate
Safe
Pyranine
Safe3
Tinopal CBS-X
Safe
Tinopal ABP Liquid
Safe
Table 1: Toxicological assessment based on genotoxic (salmonella and microsome test) and ecotoxic (daphnia and zebra fish) effects, after Behrens et al. (2001), supported or updated by more recent research by Field (2005)1, Skjolding et al. (2021)2, and Kieft et al. (2022)3. According to Carré et al. (2007) no tracer poses a risk for human health if the concentration is below 2mg/L (over 24h exposure). Field (2005) points out that use of an appropriate amount of tracer, through f.e. the EHTD method, minimises side effects such as coloured water or potential ecotoxicological effects. Gombert et al. (2017) didn’t find toxicological effects of the degradation byproducts (through chlorine or UV) for fluorescent tracers considered safe.
REGULATIONS The Water Framework Directive (WFD) has been in force in the European Union since 2000. It establishes a framework for a comprehensive EU water policy and is enforced by the competent national authorities (WFD CIRCA: "Implementing the Water Framework Directive and the Floods Directive“ link) in the EU Member States. The aim is to establish rules to halt the deterioration of EU water bodies and to achieve a “good ecological status” and a “good chemical status” for Europe's lakes, rivers and groundwater. Competent authorities and/or regulations Austria, Croatia (new tracer), Cyprus, Czech Republic, Finland, Germany (Bavaria), Hungary, Poland, Portugal, Romania, Slovakia, Slovenia (database), Spain, UK (Scotland, England, Wales, NI), Switzerland
Although not mentioned specifically, the directive is relevant in the context of tracer tests, since artificial substances are injected in natural water bodies. Fluorescent dye tracers should be chosen carefully, and injected in concentrations that have no demonstrated toxicological effects. Tracer tests can additionally be subjected to specific national or regional regulations. An overview of tracer tests regulations was already established by Wolkersdorfer and LeBlanc (2012). We aimed to update the regulatory situation regarding fluorescent dye tracer tests by contacting experts in the EU member States. As a general rule it is recommended to inform or inquire with the national or regional competent authority (link) and/or the organisation in the EU Member States responsible for groundwater monitoring programmes if a particular authorisation for tracer tests is required. A list of these organisations is available on the European Environment Agency website (link).
PERSPECTIVE
RESOURCES – TRACER TEST DESIGN
The future perspective is to elaborate and update this legislative research: ➢ What are the dye tracer regulations/requirements put in place in the EU Member States? ➢ What are the regulatory challenges to perform tracer tests? If you have additional information for your country on this topic, don’t hesitate to reach out or collaborate!
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RESOURCES - TOXICOLOGY
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• Behrens, H., Beims, U., Dieter, H., Dietze, G., Eikmann, T., Grummt, T., Hanisch, H., Henseling, H., Käß, W., Kerndorff, H., Leibundgut, C., Müller-Wegener, U., Rönnefahrt, I., Scharenberg, B., Schleyer, R., Schloz, W., & Tilkes, F. (2001). Toxicological and ecotoxicological assessment of water tracers. Hydrogeology Journal, 9(3), 321–325. https://doi.org/10.1007/s100400100126 Carré, J., Joyeux, M., & Montiel, A. (2007). Risques sanitaires associés aux traceurs fluorescents utilisés en hydrologie. Environnement Risques & Sante, 6(6), 443–452. https://doi.org/10.1684/ers.2007.0120 Field, M. S. (2005). Assessing Aquatic Ecotoxicological Risks Associated with Fluorescent Dyes Used for Water-Tracing Studies. Environmental & Engineering Geoscience, 11(4), 295–308. https://doi.org/10.2113/11.4.295 Gombert, P., Biaudet, H., de Sèze, R., Pandard, P., & Carré, J. (2017). Toxicity of fluorescent tracers and their degradation byproducts. International Journal of Speleology, 46: 23-31. https://digitalcommons.usf.edu/ijs/vol46/iss1/5/ Kieft, T. L., Byrd, E., & Veni, G. (2021). Toxicological study of Fluorescent Hydrologic Tracer dye effects on cave Bacteria. Ground Water, 60(3), 404–409. https://doi.org/10.1111/gwat.13160 Skjolding, L., Jørgensen, L., Dyhr, K., Köppl, C., McKnight, U., Bauer-Gottwein, P., Mayer, P., Bjerg, P., & Baun, A. (2021). Assessing the aquatic toxicity and environmental safety of tracer compounds Rhodamine B and Rhodamine WT. Water Research, 197, 117109. https://doi.org/10.1016/j.watres.2021.117109
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Wolkersdorfer, C., & LeBlanc, J. (2012). Regulations, legislation, and guidelines for artificial surface water and groundwater tracer tests in Canada. Water Quality Research Journal of Canada, 47(1), 42–55. https://doi.org/10.2166/wqrjc.2012.042 FOEN (n.d.). InfoTracer: Central coordination service for tracer tests. https://www.bafu.admin.ch/bafu/en/home/topics/water/state/infotracer--groundwater-tracer-tests.html www.PosterPresentations.com Groundwater monitoring in Europe. (n.d.). European Environment Agency. https://www.eea.europa.eu/publications/92-9167-032-4 RESEARCH POSTER PRESENTATION DESIGN © 2019
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Aley, T. & The Ozark Underground Laboratory. (2019). GROUNDWATER TRACING HANDBOOK. https://www.ozarkundergroundlab.com/assets/oul_groundwater_tracing_handbook-2019-revised.pdf Benischke, R. (2021). Review: Advances in the methodology and application of tracing in karst aquifers. Hydrogeology Journal, 29(1), 67–88. https://doi.org/10.1007/s10040-020-02278-9 BRGM & CETRAHE. (n.d.). Traçages artificiels en hydrogéologie : les bonnes pratiques - SIGES Centre-Val de Loire - ©2024. https://sigescen.brgm.fr/Tracages-artificiels-en-hydrogeologie-les-bonnes-pratiques.html Dörfliger, N., Ph. Crochet, R. Guerin, N. Jozja, B. Marsaud, P-H. Mondain, Ph. Muet, & V. Plagnes. (2010). Guide méthodologique. In BRGM (RP-58237-FR). https://infoterre.brgm.fr/rapports/RP-58237-FR.pdf Field, M. (2002a). Efficient hydrologic tracer-test design for tracer-mass estimation and sample-collection frequency, 1, method development. Environmental Geology, 42(7), 827–838. https://doi.org/10.1007/s00254-002-0591-2 Field, M. (2002b). Efficient hydrologic tracer-test design for tracer-mass estimation and sample-collection frequency. 2. Experimental results. Environmental Geology, 42(7), 839–850. https://doi.org/10.1007/s00254-002-0592-1 Field, M. S. (2003). A review of some tracer-test design equations for tracer-mass estimation and sample-collection frequency. Environmental Geology, 43(8), 867–881. https://doi.org/10.1007/s00254-002-0708-7 Goldscheider, N., & Drew, D. (Eds.). (2007). Methods in Karst Hydrogeology: IAH: International Contributions to Hydrogeology, 26 (1st ed.). CRC Press. https://doi.org/10.1201/9781482266023 Kresic, N. (2023). Hydrogeology 101 - Introduction to groundwater science and engineering. Blue Ridge Press LLC, PO Box 188, Warrenton, VA, USA. ISBN: 979-8-218-06984-1 Available from: https://www.un-igrac.org/sites/default/files/resources/files/Kresic_Hydrogeology_101_rev-1-Optimised.pdf Leibundgut, C., Maloszewski, P., & Külls, C. (2009). Tracers in Hydrology. https://doi.org/10.1002/9780470747148 OFEV (n.d.). Utilisation des traceurs artificiels en hydrogéologie. https://www.bafu.admin.ch/bafu/fr/home/themes/eaux/publications/publications-eaux/utilisation-traceurs-artificielshydrogeologie.html The Hydrology of Switzerland. (2005). In Berichte Des BWG, Serie Wasser – Rapports De L’OFEG, Série Eaux – Rapporti Dell’UFAEG, Serie Acque – Reports of the FOWG, Water Series: Vol. No. 7. Federal Office for Water and Geology. https://www.bafu.admin.ch/dam/bafu/en/dokumente/hydrologie/uw-umweltwissen/hydrologie_der_schweizausgewaehlteaspekteundresultate.pdf.download.pdf/the_hydrology_inswitzerlandselectedaspectsan dresults.pdf U.S. Environmental Protection Agency (EPA). (2003)Tracer-Test Planning Using the Efficient Hydrologic Tracer-Test Design (EHTD) Program. National Center for Environmental Assessment, Washington, DC; EPA/600/R-03/034. Available from: National Technical Information Service, VA; PB2003-103271. Van Wyk, Y., Dippenaar, M. A., & Ubomba-Jaswa, E. (2024). Enhancing hydrological analysis by incorporating environmental and artificial tracers of an altered vadose zone: A systematic review. Journal of African Earth Sciences, 105209. https://doi.org/10.1016/j.jafrearsci.2024.105209