From the WaPo, 12/19:
"'My understanding is that he is leaving show business to pursue a career as a thermometer.' -- Playwright David Memet to Variety after star Jeremy Piven abruptly left Broadway hit "Speed-the-Plow" because of his startlingly high mercury levels. His doctor told People the actor was eating too much sushi (twice a day!) and Chinese herbs."
(Please note, esteemed Tokyo bureau chief!)