Use of polyethylene beads in facial cleansers has been continuously questioned by scientific communities for they adversely affect aquatic organisms once these beads find their way into their habitats. This study specifically aims to determine Danio rerio mortality rate using lethal endpoints and to evaluate sublethal teratogenic effects in Danio rerio due to polyethylene microbead exposure. Danio rerio, a model organism for ecotoxicology, was subjected to the Fish Embryo Acute Toxicity Test. Embryos were exposed to polyethylene microbead suspensions (PE-MBS) of varying concentrations (i.e., 20 μg/L, 200 μg/L, 2000 μg/L). They were also exposed to 5% ethanol (positive control), reconstituted water (negative control), 0.01% Tween 80 (emulsifier control), and 1% DMSO (solvent control). Toxicological endpoints (i.e., egg coagulation, lack of somite formation, non-detachment of tail, and lack of heartbeat) were observed every 24 hours until the 96th hour exposure. Hatching was observed from 48 hpf while teratogenicity was observed at 144 hpf. Significant differences between means and variances were observed for all treatment groups in relation to the negative control. For all groups, 0.01% Tween 80, 1% DMSO and 20 μg/L PE-MBS did not significantly differ with the negative control due to negligible concentration but 5% ethanol and higher concentrations of PE-MBS did. This indicated that high concentrations of PE-MBS exposure may induce early hatching, mortality, increased malformation, and increased heart rate. Tukey Kramer post hoc Test substantiated that PE-MBS toxicity is dose dependent since embryotoxicity and teratogenicity increases at higher concentrations. LC50 obtained using probit analysis based on experimental data was 2455.096 μg/L, and was higher than the concentrations used in this study. Further studies should be conducted to know more about the adverse effects of polyethylene microbeads to the biota.Author SummaryMargaret De Guzman, MSc, Patricia Chua, and Franceska Sedano have all equally contributed to this work in conceptualization, formal analysis, funding acquisition, and investigation. All authors have also equally headed project administration, procurement of resources and writing.