Guha et al. discuss that for a long time, assessment of lipid peroxidation in vivo was restricted to tissue measurements of alkanes, malondialdehyde, or hydroxynonenal levels, all of which have serious limitation in accurately assessing oxidative stress. Roberts and coworkers discovered a series of novel prostaglandins, now termed F2-isoprostanes, which are now considered the gold standard for assessment of oxidative injury in vivo. These prostaglandins are formed initially in situ by oxidation of arachidonic acid containing phospholipids, and then released by the action of phospholipase. These can be measured in plasma or urine samples by using gas chromatography mass spectrometry or ELISA.13-16 Recently, Dr. Vallyathan's group in West Virginia demonstrated that total antioxidant status, glutathione peroxidase, and isoprostane levels were increased in shipyard welders consistent with oxidative stress secondary to their occupational exposures.17