*3.2. Study Characteristics*

Included studies used different animal models: C57BL/6J mice (n = 5) [44,45,47,50,51], Sprague-Dawley rats (n = 3) [36,37,43], C57BL/6 (n = 3) [35,39,40], Wistar rats (n = 2) [8,48], Drosophila Melanogaster (n = 2) [42,46], CD-1 mice (n = 1) [38], ICR mice (n = 1) [49], and *Bombyx mori* (n = 1) [41]. Sample size ranged from 8 [43] to 80 animals [38]. Dose exposure ranged from 2 mg/day/kg body weight of TiO2 NPs [36,37,42,45] to 1 g/day/kg body weight of TiO2 NPs [39] and exposure period ranged from 24 h [39] to 100 days [8]. The characteristics of each included study are detailed in Table 2.


**Table 2.** Characteristics of included animal studies (listed by animal type).


**Table 2.** *Cont.*





spp, species; TG, triglyceride; TLR4, toll-like receptor 4; TMA, trimethylamine. \* Age at the start of the study.
