Answer:
Yes, Tetanus Toxoid does contain Thimerosal (mercury), in most vaccines.
For more info: http://www.vaccinesafety.edu/thi-table.htm
BUT, there are several tetanus vaccines that are free of mercury. Infanrix, Daptacel, ADACEL and Boostrix have no mercury in them.
Tripedia is manufactured with thimerosal that is gradually diluted out
of the final product. Some older ones still contain up to 25mcg/0.5ml
of mercury.