Long-term effects of nanoscaled titanium dioxide on the cladoceran Daphnia magna over six generations

Abstract We investigated the impact of nanoscaled titanium dioxide (nTiO 2 ) on Daphnia magna populations in a multi-generational study over six generations (F0–F5). Each generation was exposed for 21 days to nTiO 2 (AEROXIDE ® TiO 2 P25, primary particle size 21 nm) while mortality, individual growth, reproduction and population growth rates (PGR) were assessed as endpoints. The size distribution of nTiO 2 in the single test media was analysed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). nTiO 2 concentrations were measured using ICP-MS. Mortality and individual growth of D. magna were significantly affected with increasing exposure duration and concentration. Daphnids demonstrated decreasing reproduction over generations in all treatment groups (1.19–6 mg/L) but not in the control. At concentration levels of 1.78 mg/L chronic exposure resulted in a population collapse after five generations. This study indicates that multi-generational studies are suitable for evaluating long-term effects of nanoparticles since they reflect potential effects more accurately than single generation tests.