Eli Lilly researchers reported in 1931 that animals seemed to
tolerate high doses of thimerosal. However, many of those animals died
of evident mercury poisoning just days after the study ended. Also
noteworthy is the fact that in early animal toxicity studies and many
later research efforts, researchers did not assess socialization
behaviors or perform cognition tests. In other words, they did not
consider the possibility of mercury-induced brain damage. During this same time period, the Eli Lilly researchers reported on the first injections of thimerosal into humans.