Dartmouth University wrote in 2001:

In a recent article in the journal NeuroToxicology, a research team led by Roger D. Masters, Dartmouth College Research Professor and Nelson A. Rockefeller Professor of Government Emeritus, reports evidence that public drinking water treated with sodium silicofluoride or fluosilicic acid, known as silicofluorides (SiFs), is linked to higher uptake of lead in children.

Sodium fluoride, first added to public drinking water in 1945, is now used in less than 10% of fluoridation systems nationwide, according to the Center for Disease Control’s (CDC) 1992 Fluoridation Census. Instead, SiF’s are now used to treat drinking water delivered to 140 million people. While sodium fluoride was tested on animals and approved for human consumption, the same cannot be said for SiFs.

Masters and his collaborator Myron J. Coplan, a consulting chemical engineer, formerly Vice President of Albany International Corporation, led the team that has now studied the blood lead levels in over 400,000 children in three different samples. In each case, they found a significant link between SiF-treated water and elevated blood lead levels.

“We should stop using silicofluorides in our public water supply until we know what they do,” said Masters. Officials at the Environmental Protection Agency have told Masters and Coplan that the EPA has no information on health effects of chronic ingestion of SiF-treated water.

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Also requiring further examination is German research that shows SiFs inhibit cholinesterase, an enzyme that plays an important role in regulating neurotransmitters.

“If SiFs are cholinesterase inhibitors, this means that SiFs have effects like the chemical agents linked to Gulf War Syndrome, chronic fatigue syndrome and other puzzling conditions that plague millions of Americans,” said Masters. “We need a better understanding of how SiFs behave chemically and physiologically.”