This study investigated the effects of Fe3O4 nanoparticles released from synthesized thiourea catalyst on the biological aspects of Chlorella vulgaris. Fe3O4 concentrations (0, 10, 100, 250, 500, 750, and 1000mg L-1) were used for the exposure tests. Biological parameters of C. vulgaris, including cell density, cell viability, and pigment content, were assessed. Bioconcentration and bioaccumulation factors were evaluated for contaminated microalgae. Non-carcinogenic risks were then assessed using target hazard quotient (THQ) for potential risks in human consumptions. Findings showed that C. vulgaris cell number increased from 0 to 500mg L-1 of Fe3O4 concentration. Chlorophyll a represented a time-dependent response, and greatest values were detected in 250 and 500mg L-1 Fe3O4 at 4.2 and 4mg/g, respectively. Chlorophyll b content showed a time-related manner in exposure to Fe3O4 with the highest values recorded at 250mg L-1 after 96h. Moreover, bioaccumulation displayed a dose-dependent response at 15,000µg/g dw in 1000mg L-1, whereas the lowest concentration was in the control group at 1700µg/g dw. The bioconcentration factor showed a concentration-relevant decrease in all iron treatments and 10mg L-1 of Fe3O4 represented the greatest BCF at 327.3611. Non-carcinogenic risks illustrated negligible hazard (THQ < 1) and the largest EDI and THQ were calculated in 1000mg L-1 at 7.4332E-07 (mg kg-1day-1) and 1.06189E-09, respectively. Together, iron is an essential trace element for biological purposes in aquatic systems, but in exceeding concentrations could impose toxicity effects to C. vulgaris populations.