Comment Info: =================

General Comment:Re: Dockets EPA-HQ-OPP-2005-0174 and EPA-HQ-OPP-2003-0373

Dear Sirs:

Regarding the requested stay of tolerances for sulfuryl fluoride, I would like to make a few brief
comments. I regret that I have not had the time to give you a more complete review of the
proposed tolerances.

First, it was inappropriate to base the tolerances for sulfuryl fluoride on the existing MCLG/MCL of 4
ppm fluoride in drinking water. That is a standard intended for the protection of adult health and was
never designed for the protection of children's health. The appropriate standard, in principle, would
have been EPA's RfD (currently 0.06 mg/kg/d, based on an assumed NOAEL of 1 ppm fluoride in
drinking water; http://www.epa.gov/iris/subst/0053.htm).

Second, a National Research Council committee, of which I had the honor of being a member,
recently reported that an MCLG of 4 ppm fluoride in drinking water is not protective of human health.
So even if that standard were the appropriate one for use in deriving pesticide tolerances, the
current value is not protective of human health.

Third, it is my professional opinion that an RfD of 0.06 mg/kg/d is not protective of human health,
particularly not for some population subgroups. The NRC committee was not charged to evaluate
that standard, but the report contains considerable information which, if handled by EPA's ordinary
risk assessment procedures, would lead to a much lower value for the RfD.

Fourth, a considerable fraction of the US population, especially infants and children, already has
fluoride intakes exceeding 0.06 mg/kg/d, without consideration of a contribution from sulfuryl
fluoride residues. Information on fluoride intakes for average or typical conditions and for certain
population subgroups is contained in the NRC report and is relevant to the current context of setting
limits on an additional source of fluoride exposure.

Finally, EPA should take care to ensure that tolerances for specific foods are appropriate for the
amounts of those foods actually consumed by people who consume them. For example, many or
most people probably have a very low intake of powdered eggs, while some individuals could have
a regular intake of meal-sized amounts. The fluoride tolerance for a given food type must be
protective for an individual who regularly consumes that food type, not for an "average"
consumption rate based on many individuals with little or no consumption of that food type.

Sincerely yours,
Kathleen M. Thiessen, Ph.D.
Senior Scientist, SENES Oak Ridge, Inc., Center for Risk Analysis
Oak Ridge, Tennessee
kmt@senes.com