UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

April 25, 2007

CERTIFIED MAIL

Subject:	Amendment to the Inorganic Sulfites RED

Dear Registrant:

 

The Reregistration Eligibility Decision (RED) document for inorganic
sulfites was signed on July 11, 2006.  On September 21, 2006, the Agency
received additional data regarding the rate of absorption of sulfur
dioxide into the fruit and packaging material during treatment of grapes
for black widow spider.  As a result of this information, the Agency has
published this amendment to the inorganic sulfites RED.  This amendment
also includes a table summarizing the label changes required by the RED.
 Initially, the Agency expected sulfur dioxide concentrations following
black widow spider treatment to be too high for buffer zones to be a
feasible option to address bystander exposure concerns.  However,
considering the additional absorption data, the Agency is currently able
to establish practical buffer zones as an option to using scrubbers to
reduce sulfur dioxide release concentrations.  To access the documents
supporting this amended decision please refer to docket number
OPP-2006-0335 on the electronic docket web site at
http://www.epa.gov/edocket/.  The Agency has determined that products
containing inorganic sulfites are eligible for reregistration provided
the requirements, as outlined in this document and in the RED, are
implemented.

	The inorganic sulfites RED currently states that “When treating
grapes for Botrytis cinerea (bunch rot/gray mold) or black widow spider
in a warehouse fumigation chamber, do not release treated air into the
atmosphere containing concentrations of sulfur dioxide in excess of 30
ppm (as determined by a Sensidyne or Kitagawa syringe sampler, or a
Draeger handpump).”  This addendum requires that fumigators establish
buffer zones during the aeration phase of sulfur dioxide grape
fumigation in warehouse fumigation chambers, unless the 30 ppm release
limit can be achieved.  EPA has prepared this guidance to assist
fumigators in determining the appropriate buffer size.  The buffer zones
in the tables below are based on the sulfur dioxide release
concentration, the release flowrate during aeration, and the volume of
the treatment chamber.  The release flowrate is defined as the rate at
which the treated air is forced from the treatment chamber during the
aeration phase of a fumigation.  Established buffer zones must be
maintained from the time aeration begins until the concentration being
exhausted from the enclosure is less than 30 ppm.  Only persons
supervising or performing fumigation activities are permitted within the
buffer zones.  All workers associated with the fumigation process must
follow the product label requirements at all times.  All monitoring
results and application dates must be kept on-site and be made readily
available to local/state/federal enforcement personnel and workers, and
be provided upon request to any interested party in the community. 
Limited transit (e.g., use of roads) for brief durations within the
buffer zone may occur if unavoidable.

The Agency modeled potential bystander exposure to sulfur dioxide using
PERFUM2.  The PERFUM2 model provides two types of results that include
the maximum buffer distance and the whole field buffer distance.  Each
is reported as a distribution of distances.  The whole field distance
outputs represent the entire range of potential exposures, whereas
maximum buffer distance outputs represent a subset of the highest daily
exposure levels that were calculated.  The Agency considered both the
toxicity of sulfur dioxide (listed as GRAS [with limitations], no
evidence of reproductive or developmental toxicity, and reversible
adverse effects such as dizziness, chest pains, itching, and teary eyes)
and the relatively low likelihood of exposure (black widow spider
treatments on grapes occur at facilities that are predominantly located
in rural areas that are sparsely populated) in determining that the 95th
percentile, whole field buffer distance outputs from the PERFUM2 model
correlate to a reasonable certainty of no harm.  The following tables
define the buffer zones required when the 30 ppm or less release limit
is not feasible:

Buffer Zones (in Feet) Required During Aeration with SO2 concentrations
in Excess of 30 ppm

	The following tables indicate the required aeration buffer zone size
(in feet).  Aeration buffer zone size is determined by using the
treatment chamber volume, the initial release SO2 concentration expected
during aeration, and by the flowrate of the treated air during aeration.
 Only persons supervising or performing fumigation activities are
permitted within the buffer zones.  An aeration buffer zone must be
established and maintained until the sulfur dioxide concentration being
exhausted is less than 30 ppm.  The buffer zone must be measured from
below the center point of the stack at ground level.  If multiple stacks
are used to exhaust treated air, measure from each stack and use the
largest resulting buffer zone.

	Table 1.

Treatment Chamber Volumes up to 9,500 ft3

Application Rate

(ppm)	Initial Release Air SO2 Concentration        (ppm)	Treated Air
Release Flowrate (in ft3/minute)



Greater than 6,000 up to  10,000 ft3/min	Greater than 10,000 up to
14,000 ft3/min	Greater than 14,000 up to 17,000 ft3/min	Greater than
17,000 ft3/min

!0,000	>2500 up to 3000	328	296	246	214

	> 2000 up to 2500	296	246	214	164

	>1500 up to 2000	246	214	164	132

	> 1000 up to 1500	197	164	115	82

	30 up to 1000	132	99	66	33



	Table 2.

                                    Treatment Chamber Volumes between
9,500 and 15,000 ft3

Application Rate

(ppm)	Initial Release Air SO2 Concentration        (ppm)	Treated Air
Release Flowrate (in ft3/minute)



Greater than 6,000 up to  10,000 ft3/min	Greater than 10,000 up to
14,000 ft3/min	Greater than 14,000 up to 17,000 ft3/min	Greater than
17,000 ft3/min

!0,000	>2500 up to 3000	443	410	361	328

	> 2000 up to 2500	394	361	312	279

	>1500 up  to 2000	328	296	263	230

	> 1000 up to 1500	279	230	197	148

	30 up to 1000	197	164	132	82



	If you have any questions on the inorganic sulfites RED or any
information in this amendment, please contact the Chemical Review
Manager, Mark Perry at 703-308-8024.

						Sincerely,

						Peter Caulkins

						Acting Director

						Special Review and Reregistration Division

Attachment

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