Including ecotoxic impacts on warm-blooded predators in life cycle impact assessment

In current life cycle impact assessment, the focus of ecotoxicity is on cold-blooded species. We developed a method to calculate characterization factors (CFs) for the impact assessment of chemical emissions on warm-blooded predators in freshwater food chains. The method was applied to 329 organic chemicals. The CF for these predators was defined as a multiplication of the fate factor (FF), exposure factor (XF), bioaccumulation factor (BF), and effect factor (EF). Fate factors and XFs were calculated with the model USES-LCA 2.0. Bioaccumulation factors were calculated with the model OMEGA, for chemical uptake via freshwater, food, and air. Effect factors were calculated based on experimental, median lethal doses (LD50). The concentration buildup (CB) of the chemicals (i.e., FF, XF, and BF over the 3 routes of exposure) showed a range of 7 to 9 orders of magnitude, depending on the emission compartment. Effect factors displayed a range of 7 orders of magnitude. Characterization factors ranged 9 orders of magnitude. After emissions to freshwater, the relative contribution of the uptake routes to CB were 1% (90% confidence interval [CI]: 0%-2%) for uptake from air, 43% (11%-50%) for uptake from water, and 56% (50%-87%) for uptake from food. After an emission to agricultural soil, the contribution was 11% (0%-80%) for uptake from air, 39% (5%-50%) for uptake from water, and 50% (11%-83%) for uptake from food. Uptake from air was mainly relevant for emissions to air (on average 42%, 90% CI: 5%-98%). Characterization factors for cold-blooded species were typically 4 orders of magnitude higher than CFs for warm-blooded predators. The correlation between both types of CFs was low, which means that a high relative impact on cold-blooded species does not necessarily indicate a high relative impact on warm-blooded predators. Depending on the weighing method to be considered, the inclusion of impacts on warm-blooded predators can change the relative ranking of toxic chemicals in a life cycle assessment.