I Have A Patient With A History Of Peripheral Neuropathy

I have a patient with a history of peripheral neuropathy of the lower extremities. He has had extensive neurological testing finding sensory and muscular weakness. However, no nerve impingement has been found. Vascular testing has been negative. His occupational history is significant having worked in the printing industry since the 60's with leaded ink and using gasoline(leaded) as a cleaning solvent. Patient is 71 y/o male, symptoms have been progressive over the past 5+ years.
Is there a blood test available? And is there a chelation therapy?