From discovery.com: Biblical Text-Writing May Have Poisoned Monks.
Medieval bones from six different Danish cemeteries reveal that monks who wrote Biblical texts and other religious materials may have been exposed to toxic mercury, which was used to formulate just one of their ink colors: red.
The study, which will be published in the August issue of the Journal of Archaeological Science, also describes a previously undocumented disease, called FOS, which was like leprosy and caused skull lesions. Additionally, the researchers found that mercury-containing medicine had been administered to 79 percent of the interred individuals with leprosy and 35 percent with syphilis.
Since the monks, who were buried in the cloister walk of the Cistercian Abbey at Øm, did not have these diseases but contained mercury in their bones, scientists believe the monks were either contaminated while preparing and administering medicines, or while writing the artistic letters of incunabula, or pre-1500 A.D. books.[continue]