R D Masters1 and M Coplan2

Toxic metals like lead, manganese, copper and cadmium damage neurons and deregulate neurotransmitters like serotonin and dopamine, which are essential to normal impulse control and learning. Exposure and uptake of lead has been associated with industrial pollution, leaded paint, plumbing systems in old housing, lead residues in soil, diet, and demographic factors. Here, we report on an additional "risk co-factor" making lead and other toxic metals in the environment more dangerous to local residents: the use of silicofluorides as agents in water treatment.

The two chemicals in question - fluosilicic acid and sodium silicofluoride - are toxins that, despite claims to the contrary, under normal conditions of usage change water chemistry and do not dissociate completely. As a result, water treatment with silicofluorides apparently functions to increase the cellular uptake of lead. Data from lead screening of over 280,000 children in Massachusetts indicates that silicofluoride usage is associated with significant increases in average lead in children's blood as well as percentage of children with blood lead in excess of 10 g/dL. Consistent with the hypothesized effect of enhanced lead uptake, in communities with more old housing or lead in excess of 15 ppb in first draw water samples, and where silicofluorides are also in use, children are especially at risk of higher blood lead levels. Preliminary findings from county-level data in Georgia confirm that silicofluoride usage is associated with higher levels of lead in children's blood. In both Massachusetts and Georgia, moreover, behaviors associated with lead neurotoxicity are more frequent in communities using silicofluorides than in comparable localities that do not use these chemicals. Because there is no record of animal or human testing of silicofluoride treated water, further study of the effect of silicofluorides is needed to clarify the extent to which these chemicals are risk co-factors for lead uptake and the hazardous effects it produces.

1 Dartmough College, Hanover, New Hampshire. 2 Intellequity, Natick, Massachusetts, USA


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