Toxicological Assessment of Phthalate Plasticizers in Hydra vulgaris: Acute Toxicity, Genotoxicity, Developmental and...

Phthalates pose significant risks to aquatic ecosystems, though their effects on nontarget organisms have been reported, with little information on Hydra. This study evaluated the developmental, cytotoxic and behavioural toxicity of four phthalates, dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) at concentrations ranging between 1 and 100 mg/L in Hydra vulgaris over 96 h. DBP induced acute toxicity and lethality with a 48 h LC₅₀ of 5.3 mg/L. No mortality was observed for DEP, DMP and DEHP at this range of concentrations; however, DEP induced severe morphological changes and affected locomotion and tentacle movements of hydra at 100 mg/L. DBP caused distinct developmental effects, with disrupted regeneration and decreased reproductive output at the respective 1/10th and 1/2nd LC₅₀ concentrations of 0.53 and 2.7 mg/L. Behavioural endpoints such as foraging responses and locomotor activity were impaired at 0.53 mg/L. Furthermore, cytotoxicity, with 53% DNA damage and an increased rate of apoptosis, was observed. This study reveals that DBP was highly toxic to hydra compared to the other three phthalates. The order of toxicity was found to be DBP > DEP > DMP > DEHP.