Dietborne Toxicity of Tebuconazole to a Benthic Crustacean, Heterocypris incongruens and Its Relative Contribution to the Overall Effects under Food–Water Equilibrium Partitioning

Tebuconazole (TEB), a widely used and persistent pesticide,
has
garnered attention due to its frequent detection in sediments worldwide.
This widespread occurrence has raised concerns about potential dietborne
toxicity to benthic crustaceans, as they may ingest contaminated particles
in their habitat. While bioaccumulation studies indicate the importance
of TEB ingestion for benthic crustaceans, limited data exist on direct
dietborne toxicity testing. This study investigated the diet-related
toxicity of TEB by subjecting a benthic ostracod, Heterocypris
incongruens, to a 6 day toxicity test under dietary
and combined exposures. Subsequently, the importance of dietary exposure
for TEB toxicity was uncovered, followed by quantification of relative
dietborne toxicity contributions using a modified concentration-additive
model. Results revealed that the dietary route was more toxicologically
significant than the aqueous route in equilibrium. The dietborne lethal
concentration (LC50) for TEB on H. incongruens was 200 (170–250) mg/kg, with an 80% relative dietborne toxicity
contribution. To gain comprehensive insights into dietborne significance,
toxicity data were collected from previous studies involving different
pollutants to calculate relative contributions. Finally, the correlation
between dietborne toxicity and the partitioning coefficient was analyzed
to understand the pollutant behavior and its toxic impact when ingested
through the diet.