'91 Memo Warned of Mercury in Shots

February 08, 2005|Myron Levin | Times Staff Writer

A memo from Merck & Co. shows that, nearly a decade before the first public disclosure, senior executives were concerned that infants were getting an elevated dose of mercury in vaccinations containing a widely used sterilizing agent.

The March 1991 memo, obtained by The Times, said that 6-month-old children who received their shots on schedule would get a mercury dose up to 87 times higher than guidelines for the maximum daily consumption of mercury from fish.

"When viewed in this way, the mercury load appears rather large," said the memo from Dr. Maurice R. Hilleman, an internationally renowned vaccinologist. It was written to the president of Merck's vaccine division.

The memo was prepared at a time when U.S. health authorities were aggressively expanding their immunization schedule by adding five new shots for children in their first six months. Many of these shots, as well as some previously included on the vaccine schedule, contained thimerosal, an antibacterial compound that is nearly 50% ethyl mercury, a neurotoxin.

Federal health officials disclosed for the first time in 1999 that many infants were being exposed to mercury above health guidelines through routine vaccinations. The announcement followed a review by the U.S. Food and Drug Administration that was described at the time as a first effort to assess the cumulative mercury dose.

But the Merck memo shows that at least one major manufacturer was aware of the concern much earlier.

"The key issue is whether thimerosal, in the amount given with the vaccine, does or does not constitute a safety hazard," the memo said. "However, perception of hazard may be equally important."

Merck officials would not discuss the contents of the memo, citing pending litigation.

Separately, the drug giant is trying to fend off a legal onslaught over Vioxx, the popular painkiller it introduced in 1999. The company, based in Whitehouse Station, N.J., faces hundreds of lawsuits claiming that the drug caused heart problems and that Merck concealed the risks. Merck, which in September pulled Vioxx off the market, has denied the allegations.

The legacy of thimerosal, meanwhile, also is causing problems for Merck and other drug companies.