Assessing lethal and sub-lethal effects of trichlorfon on different trophic levels

Area of Science:

• Environmental Toxicology
• Aquatic Ecotoxicology
• Veterinary Pharmacology

Background:

• Trichlorfon (TCF) is a widely used veterinary antiparasitic, raising environmental and human health concerns due to high concentrations.
• Assessing the ecotoxicity of TCF on non-target organisms across different trophic levels is crucial.

Purpose of the Study:

• To evaluate the acute toxicity of Trichlorfon (TCF) on aquatic organisms: zebrafish (Danio rerio), Daphnia magna, and algae.
• To investigate the potential of biomarkers (ChE, GST, LDH, CAT) in assessing sub-lethal TCF effects in zebrafish and daphnids.

Main Methods:

• Standardized OECD guidelines were followed for acute toxicity tests on zebrafish (early life stages and adults), Daphnia magna, and algae.
• Biomarker levels (ChE, GST, LDH, CAT) were measured in zebrafish and daphnids following TCF exposure.
• Teratogenic effects of TCF on zebrafish embryos were documented.

Main Results:

• Daphnia magna exhibited the highest sensitivity to TCF (48 h-LC50 = 0.29 μg/L), followed by zebrafish (96 h-LC50 = 25.4-28.8 mg/L) and algae.
• Cholinesterase (ChE) activity emerged as the most sensitive biomarker for detecting TCF effects across tested species.
• Trichlorfon induced teratogenic effects in zebrafish embryos, including yolk sac edema, spinal deformities, and pericardial edema.

Conclusions:

• Daphnia magna's sensitivity to TCF highlights potential ecosystem-wide impacts due to its role in aquatic food webs.
• Biomarkers, particularly ChE activity, are effective tools for monitoring TCF exposure and its sub-lethal effects.
• Further research is essential to monitor environmental TCF levels and assess long-term impacts of realistic concentrations.