Under UMB3B, we are characterizing the impact of radiation in combination with UV, under different environmental conditions, to assess the cumulative risk. This will allow us: 1) to evaluate prediction models for combined effects and cumulative risk assessment (CRA) of multiple stressors; 2) to apply these models to relevant stressors, exposure scenarios, effect endpoints and species to characterize the impact of multiple stressors; and 3) to assess and reduce uncertainties in CRA, relevant for RA4.

Effects of exposure to low dose rates and total doses of UVB and gamma radiation combined showed no developmental defects but showed an increase in differentially expressed genes and similar gene pathways connected, but different involved genes. UVB radiation alone in higher doses caused differences in the metabolism and oxidative stress. Higher total doses caused increased ROS in gamma, UVB and UVB and gamma radiation combined. The two types of radiation did not show significant additive mixed toxicity effects.