On the lifespan of Enchytraeus crypticus - impact of iron (nanomaterial and salt) on aging

Abstract

Iron oxide nanomaterials (Fe 3 O 4 NMs) have important biomedical and environmental applications, e.g. drug delivery, chemotherapy, magnetic resonance imaging contrast agents, etc. However, the environmental risks of such Fe 3 O 4 are not fully assessed, particularly for soil living invertebrates, which are among the ones in the first line of exposure. Research has showed that longer-term exposure time is required to assess hazards of NMs, not predicted when based on shorter time and are therefore recommended. Thus, in the present study the effects of Fe 3 O 4 NMs and FeCl 3 were assessed in the terrestrial environment, using the soil model species Enchytraeus crypticus (Oligochaeta), throughout its entire lifespan (202 days). Two animals’ density were used: 1 (D1) and 40 (D40) animals per replicate, in LUFA 2.2 soil. The endpoints were survival and reproduction monitored over-time, up to 202 days. Results showed that density clearly affected the toxicity response, with higher toxicity and lower lifespan in D1 compared to D40. Overall, FeCl 3 was more toxic than Fe 3 O 4 NM in terms of reproduction, however, adult animals can be at higher (long-term) risk when exposed to Fe 3 O 4 NM. Differences might be linked to slower Fe kinetics for the Fe 3 O 4 NMs, i.e., slower Fe dissolution and release of ions.