If you are looking for clinical lab testing for mercury toxicity and/or oxidative stress, my lab of choice is Doctor's Data Inc in St. Charles, Illlinois...about an hour west of Chicago.
The tests I recommend are: Fecal Metals, Urnine Toxic Elements, DNA Oxidative Damage/Stress, Glutathione-Erythrocytes (Red Blood Cells), and Hepatic Detox Profile. These are all explained in their separate sections.