Thimerosal has been largely removed from pediatric vaccines in recent years in what health officials have described as a precautionary measure. (This has been accomplished as drug makers have voluntarily switched from multi-dose vials of vaccine, which require a chemical preservative like thimerosal, to single-dose containers.)
In September, Gov. Arnold Schwarzenegger signed legislation prohibiting vaccines with more than trace amounts of thimerosal from being given to babies and pregnant women. Iowa has a similar ban.
For their part, Merck and other vaccine makers, along with many government health officials and scientists, say there is no credible evidence of harm from the amounts of mercury once widely present in kids' shots. They cite a report in May by a committee of the national Institute of Medicine concluding that the evidence "favors rejection of a causal relationship" between vaccines and autism.
The seven-page Merck memo was provided to The Times by James A. Moody, a Washington lawyer who works with parent groups on vaccine safety issues. He said he obtained it from a whistle-blower whom he would not name.
The memo provides the "first hard evidence that the companies knew -- or at least Merck knew -- that the children were getting significantly more mercury" than the generally accepted dose, the lawyer said.
He also provided a copy to attorneys for Vera Easter, a Texas woman who blames thimerosal for the condition of her 7-year-old son, Jordan, who is autistic and mentally retarded. The Easter lawsuit is pending in U.S. District Court for the Eastern District of Texas. The defendants include Merck; rival vaccine makers GlaxoSmithKline, Aventis Pasteur Inc. and Wyeth; and thimerosal developer Eli Lilly & Co.
Easter's lawyer, Andy Waters, described the memo as "incredibly damning and incredibly significant." After receiving it in the fall, he confronted Merck lawyers about why he hadn't seen it earlier.
In a letter to Waters in October, Merck attorneys said they had in fact made available 32 boxes of records, but that the copying service hired by the plaintiffs for some reason had failed to copy several of the boxes -- including the one with the Hilleman memo.
"The memo," said company spokeswoman Mary Elizabeth Blake, "was produced voluntarily by Merck in the ordinary course of discovery proceedings."
