AN ASSESSMENT OF THE POTENTIAL ADVERSE PROPERTIES OF FLUORESCENT TRACER DYES USED FOR GROUNDWATER TRACING

The potential ecotoxicity of fluorescent dyes used in tracing, and the ir possible effects on human health, were evaluated by reviewing avail able toxicological information for 12 dyes fluorescein, Lissamine Flav ine FF, Rhodamine WT, Rhodamine B, Sulpho Rhodamine G, Sulpho Rhodamin e B, eosin, pyranine, Phorwite BBH Pure, Tinopal 5BM GX, Tinopal CBS-X , and Diphenyl Brilliant Flavine 7GFF - and a dye-intermediate, amino G acid. This evaluation used available toxicological information, test data on analogous substances, and mathematical expressions for biolog ical activity. Based on set criteria for human health and acute ecotox icity, the evaluation indicated that these tracers have low to moderat e levels of concern. The use of these tracers for the study of groundw ater flow is appropriate if consideration is given to the overall huma n health and environmental effects. Their use in the environment requi res tracer concentrations not exceeding 1-2 mg 1(-1) persisting for a period in excess of 24 h in the groundwater at the point of groundwate r withdrawal or discharge. A simple calculated potential dose was used in a comparison of the estimated acute toxicity of Rhodamine WT in ra ts to the known acute oral toxic dose in humans for several known acut ely toxic chemicals. This comparison showed that none of the fluoresce nt dyes evaluated would present an acutely toxic threat at or substant ially above the recommended 2 mg 1(-1) concentration.