This article is somewhat disinformation, but it does spell out a timeline of such (1999 onward) for the use of a form of mercury in some childhood vaccines. Unfortunately, it does not go back to 1988, but I think there is enough circumstantial evidence to place the blame upon childhood vaccines: https://www.cdc.gov/vaccines/hcp/patient-ed/conversations/downloads/vacsafe-thimerosal-color-office.pdf