Dr. Slott says that fluorosilicic acid does not leach lead.
He cites a study by Urbansky. Read it here: http://www.epa.gov/nrmrl/wswrd/cr/pubs/rrbansky_schockawwa_ac2000.PDF.
Professor Sauerheber, response to Dr. Slott is this:
The claim by Slott that fluorosilicic acid materials cannot leach lead from lead based plumbing is based on a paper he references by Urbansky.
That paper describes chemical calculations that attempt to discredit the studies of Masters and Coplan, but the calculations merely determine the concentrations of lead and silicate and fluoride that would need to exist in order to cause lead complexes or precipitates to form. This of course is interesting but please understand that lead complexes are not necessary to form in order for flurosilicic acid materials to leach lead.
Fluorosilicic acid breaks down and one of the breakdown products is silicic acid, which is an intact acid molecule at the typical pH of drinking water.
Lead based plumbing typically has lead salts on surfaces that dissolve in the presence of acids. Some strong acids do not dissolve lead well.
Silicic acid, although a weak acid, dissolves lead. It has a high dissociation constant, meaning that it takes a great amount of alkalinizer to neutralize it. The amount of alkalizer which neutralizes fluorosilicic acid is not sufficient to neutralize silicic acid.
So silicic acid at neutral pH will displace lead from most of these salts, including lead bisulfate, lead biphosphate, and lead bicarbonate. The products are lead ion and silicate ions.
Of course added flurosilicic acid levels are not high enough to produce lead silicate precipitates, but so what? The point is that silicic acid can dissolve lead form lead salts and this is the most plausible mechanism that explains the detailed studies of Masters and Coplan indicating increase in lead ion levels in water and in blood of consumers after fluorosilicic acid treatment.
Richard Sauerheber, Ph.D. Chemistry
Urbansky was wrong. That is clear. Read more about the FACT that lead concentrations, both lead concentrations in water and in blood – whatever the mechanism – is higher when water is fluoridated with fluorosilicic acid. See: www.fluoride-class-action.com/lead.
The fluoridationists lose on this argument, so they have to take the backup position that the increase in lead caused by fluorosilicic acid is not enough to worry about. In Everett 10% of homes have up to around 50 ppb lead in first draw water. When Tacoma stopped fluoridating because of a water shortage, lead levels dropped almost in half. They went back up when fluoridation was restarted. See http://www.fluoride-class-action.com/tacoma.
You have to stop ignoring the science which would show fluoridation as harmful to health.
You have to find your way out of the maze and quit blocking the exits with journal articles which do not address the right issue.
Dr. Sauerheber adds this:
The notion that it is impossible for silicic acid to dissolve lead ion from lead salts is what is actually naive. The Ka for silicic acid is so weak that the bulk product remains the intact acid even at pH 8-9. The myth held by most fluoridationists is that silicic acid is totally harmless, but none have disproven the Masters observations. Remember the peculiarities of lead include the fact that lead solid is even dissolved by the very weak acid acetic acid. Lead salts are far easier to ionize than lead solid by ionic exchange mechanisms. The height of silliness would be to proclaim that this is impossible. I can assure you that many things are possible that on someone else’s paper led him to believe it is not possible.