Developmental Defects in Embryos and Larvae of Zebrafish Exposed to Arsenic and Fluoride Both Individually and in Combination.

Toxicity assessment in embryos and larvae is equally important as in their adult forms in the field of toxicological research. Most of the investigations in this field are conducted on normal embryos where toxicants are imposed after the release of mature fertilized eggs. In this investigation, we have observed the effects of arsenic (As, As₂O₃ 50 ppb) and fluoride (F, NaF 15 ppm), either individually or in combination, on larval zebrafish after exposing their parents for 60 days. A higher mortality rate, delayed hatching, and structural deformities, including yolk sac edema, hook malformation, and spiral malformation, were evident. Biochemical oxidative stress parameters, like the level of MDA and activity of catalase, increased, whereas the level of GSH decreased after treatments. Most importantly, the toxic effects were found to be the most severe after F exposure and were minimum after co-exposure to As and F, indicating an antagonistic effect.