Hirzy was principal author in 2013 of a paper titled “Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride,” published in Environmental Science and Policy 29 (2013) 81-86. dx.doi.org/10.1016/j.envsci.2013.01.007, which required a correction that is discussed below. The correction is in Environmental Science and Policy 38 (2014) 282-284. dx.doi.org/10.1016/j.envsci.2013.11.002.

The basic error in the first paper arose from not considering the lifetime costs of the two chemicals along with the life time cancer cases in the exposed population caused by the arsenic in HFSA, and was corrected in the second paper most simply by using annual costs of both the cancer cases and the chemicals.

The second paper goes on to show that on an annual basis the number of excess cancer cases associated with the arsenic levels in HFSA reported by the CDC’s National Fluoridation Engineer is about 26, with a total cost advantage for HFSA of $6.2 million. This means avoiding each of those 26 cancer cases would cost society $240,000.

The paper also shows that arsenic at the level permitted by the NSF/ANSI Standard 60 (380 mg/kg HFSA) would result in about 59 excess cancer cases annually, and use of pharmaceutical NaF instead would save society over $100 million annually.

And the break even level of cancer cases and HFSA arsenic level would be reached at a significantly lower NSF/NASI Standard of 180 mg As/kg HFSA.

Further, it has been shown that blood-lead levels in children exposed to HFSA containing water are higher than those not so exposed. So social costs associated with the higher children’s blood-lead levels need to be considered along with lung and bladder cancer cases associated with use of HFSA.

The second paper notes that if all 118 million people now exposed to HFSA would prefer to continue having fluoridated drinking water – at a rate of 2 liters/day, municipal governments could supply such water with 0.5 mg F added via pharmaceutical NaF, at a nation-wide cost of about $600,000.

The phosphate industry, however, would have to find a way to dispose of ~250,000 tons of waste HFSA other that selling it to municipal water authorities and having cities then send 98% of that purchased material flowing back into the environment via waste water treatment plants.