Ecotoxicological Assessment of DNA-Tagged Silica Particles for Environmental Tracing

Environmental tracers are chemical species that move with a fluid and allow us to understand its origin and material transport properties. DNA-based materials have been proposed and used for tracing due to their potential for multitracing with high specificity and sensitivity. For large-scale applications of this new material it is of interest to understand its impact on the environment. We therefore assessed the ecotoxicity of sub-micron silica particles with and without encapsulated DNA in the context of surface and underground tracing of natural waterflows using standard ecotoxicity assays according to ISO standards. Acute toxicity tests were performed with Daphnia magna (48 h), showing no effect on mobility at tracer concentrations below 300 ppm. Chronic ecotoxicological potential was tested with Raphidocelis subcapitata (green algae) (72 h) and Ceriodaphnia species (7 d) with no effect observed at realistic exposure scenario concentrations for both silica particles with and without encapsulated DNA. These results suggest that large-scale environmental tracing with DNA-tagged silica particles in the given exposure scenarios has a low impact on aquatic species with low trophic levels such as select algae and planktonic crustaceans.