The identified chemical space is the subspace of measured chemical space, where those structures are fully characterized (e.g. measured via GC/LC-HRMS and available as analytical standard). This subspace is extremely small when compared to the size of the exposome chemical space. A recent meta analysis showed that all NTA studies in the past 5 years have resulted in around 1200 unique new structures while every year around 800 new structures are introduced into the market. Considering the number of potential transformation products of these chemicals, the speed of NTA studies are far too low to be able to catch up with the rate of expansion of the exposome chemical space.