Fig. 1

Aging dose (AD)₅₀ demonstrates the acceleration of age-related phenotypes by the representative pollutant nano-silica in adult hermaphrodite C. elegans. a Populations of adult C. elegans were exposed to 0 (blue), 20 (gray) or 1250 (black) μg/mL silica nanoparticles (nano-silica). The locomotion phenotype of swimming was measured over the entire life span of the worms. Adult age is given in days (x-axis) and plotted against the number of worms showing the phenotype (y-axis). The effect of the pollutant was estimated using two representative concentrations (20 and 1250 μg/mL). Only 1250 μg/mL is effective and thus an aging dose (AD)₅₀ that represents the concentration in which 50% of the worms already show a specific age-related defect, while the other half still exhibit the normal phenotype. Notably, exposure to 1250 μg/mL nano-silica accelerates the cessation of swimming in 50% of the worms by 10 days, e.g., from 15-day-old worms to 5-day-old worms (dotted lines). Values represent mean ± SD from three independent experiments with n = 121–162 worms per condition per experiment. b Schematic: the aging dose (AD)₅₀ indicates any concentration of a pollutant that accelerates aging of a young worm concerning an age-related phenotype. c Representative for certain other pollutants nano-silica accelerates organismal aging that manifests in biochemical, morphological and neurobehavioral phenotypes. Life span-resolved analyses reveal that hallmarks of aging (black arrows) occur prematurely (light gray arrows), as early as on day 2, in wild-type C. elegans exposed to silica nanoparticles [10, 14, 15] (Additional file 1: Table S1)