"A new study by Arline Geronimus et al. found that low-income residents of Detroit, regardless of race, have significantly shorter telomeres than the national average. But the effects of race/ethnicity and income within this group were varied. Geronimus says that's because racial or ethnic identity interacts with environmental conditions in influencing health disparities. She says research must take into account "the extent to which [race/ethnicity] is validated, or discriminated against, or even understood within everyday life experience." " (thanks Amir)