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Phosphine Gas - Registration of ECO2FUME 6/01


June 29, 2001


CERTIFIED MAIL
RETURN RECEIPT REQUESTED


Mr. Alan C. Katz
Agent for Cytec Industries, Inc.
Katz Associates
16090 Simon Kenton Road
Haymarket, VA 20169-2109


Dear Mr. Katz:

Re: Registration of One New Pesticide Product, ECO2FUME Fumigant Gas (EPA Reg. No. 68387-7), Which Contains the New Active Ingredient Phosphine Gas

    The New York State Department of Environmental Conservation (the Department) has reviewed your application, received March 14, 2000, and additional information, received July 10, 2000, September 5, 2000 and September 29, 2000, to register one new pesticide product, ECO2FUME Fumigant Gas (EPA Reg. No. 68387-7) in New York State. The product contains the new active ingredient phosphine gas. The application was deemed complete for purposes of review February 2, 2001 and a registration decision is due by July 2, 2001.

    ECO2FUME Fumigant Gas (EPA Reg. No. 68387-7) is labeled for control of certain insects in the following non-food commodities: animal hide; processed or unprocessed cotton, wool and other natural fibers or cloth; clothing, feathers, furs, human hair, rubberized hair, vulcanized hair, mohair, leather products; tobacco; wood, cut trees, wood chips and wood and bamboo products; paper and paper products; non-food flour; dunage; non-food starch; dried plants and flowers. Such dedicated lots may be fumigated in transport vehicles (truck trailers, railcars, and containers) prior to shipment.

    The Department received, on September 5, 2000, a revised label for ECO2FUME Fumigant Gas (EPA Reg. No. 68387-7). The new label added various food commodities such as: raw agricultural commodities, processed foods, and animal feed and feed ingredients.

    The Department has reviewed the information supplied to date in support of the pesticide product registration application for ECO2FUME Fumigant Gas (EPA Reg. No. 68387-7).

    The New York State Department of Health (DOH) has reviewed the information submitted to date in support of the application for registration of ECO2FUME Fumigant Gas (EPA Reg. No. 68387-7).

    The DOH stated that phosphine is a highly toxic respiratory poison and consequently, the United States Environmental Protection Agency (USEPA) classified ECO2FUME Fumigant Gas in Toxicity Category I (Danger - Poison with skull and crossbones). Because acute inhalation toxicity is the route of concern, acute toxicity studies for the oral and dermal routes of exposure were waived by the USEPA with the label requirement that personal protective equipment include the wearing of safety glasses. Because the USEPA based the assessment for acute toxicity of formulated products for phosphine fumigation on exposure to the active ingredient phosphine gas, no acute toxicity studies for the ECO2FUME product were required.

    In a 13-week rat inhalation study, administration of phosphine gas at the highest level tested, 3 parts per million (ppm) which is equivalent to 4 milligrams per cubic meter (mg/m3), did not result in any observable adverse effects. By contrast, inhalation exposure to 10 ppm (14 mg/m3) for four weeks was lethal to 80 percent of female rats, indicating a steep concentration-response curve. A chronic inhalation study in rats at concentrations up to 3 ppm did not report any adverse effects.

    In an inhalation rat developmental toxicity study, phosphine did not cause maternal or developmental toxicity at levels up to 5 ppm (7 mg/m3). At 7.5 ppm (11 mg/m3), a high incidence of maternal deaths occurred and this group had to be removed from the study. The maternal and developmental no-observed-effect level (NOEL) for phosphine was 5 ppm (7mg/m3) and the lowest-observed-effect level (LOEL), based on maternal deaths was 7.5 ppm (11 mg/m3). The requirement for a multi-generation reproduction toxicity study was waived by the USEPA since phosphine is used as a fumigant and the USEPA "does not routinely require the standard toxicological database for a food use chemical for fumigants" (Federal Register 64: pages 30939-30949, June 9, 1999).

    The USEPA's Office of Pesticide Programs (OPP) established a reference dose (RfD) of 0.0113 milligrams per kilogram body weight per day (mg/kg/day) for phosphine based on the NOEL of 3 ppm (4 mg/m3) converted to 1.3 mg/kg/day from the chronic inhalation study in rats and the uncertainty factor of 100. This RfD has not yet been adopted by the USEPA's Integrated Risk Information System (IRIS) which lists the RfD for this chemical as 0.0003 mg/kg/day based on a NOEL (0.026 mg/kg/day, the only dose tested) from a two-year rat feeding study and an uncertainty factor of 100. The OPP, however, has indicated that phosphine in the diet is difficult to measure because of volatilization and "therefore, the actual dosages in this study are unknown"(Federal Register 64: pages 30939-30949, June 9, 1999). IRIS lists the reference concentration for chronic inhalation exposure (RfC) to be 2 x 10-4 ppm (3 x 10-4 mg/m3) based on a NOEL of 1.0 ppm (adjusted to 0.25 mg/m3 to account for non-continuous exposures during the study) from a mouse subchronic inhalation study and an uncertainty factor of 1000.

    Phosphine did not cause oncogenic effects in either the rat chronic feeding or chronic inhalation studies. Genotoxicity studies have equivocal results overall, with some being negative and others positive. The USEPA classifies phosphine as a group D (not classifiable as to human carcinogenicity) carcinogen.

    The USEPA established tolerances for residues of phosphine in or on a large number of food commodities at either 0.01 ppm or 0.1 ppm, depending on the commodity type. The USEPA estimated that chronic dietary exposure to these residues would be 2 percent of the RfD of 0.0113 mg/kg/day for the U.S. population, 9 percent for non-nursing infants (less than one year old) and 4 percent for children (one to six years old). This chronic exposure analysis is based on the assumption that 100 percent of crops are treated and that all food consumed by an individual would contain phosphine residues at 0.006 ppm, which is the highest limit of detection reported in tolerance petitions. The USEPA does not expect measurable phosphine residues at the point of consumption based on numerous residue studies. This is because phosphine is very volatile and food commodities are aerated for a period of time after treatment and are cooked, shelled, washed or otherwise prepared before consumption.

    The USEPA conducted a risk assessment for inhalation exposure of workers to phosphine gas based on the labeled use of aluminum and magnesium phosphide fumigant products. No occupational risk assessment was conducted for the ECO2FUME product. For workers using National Institute of Occupational Safety and Health (NIOSH) approved respirators, margins of exposure (MOEs) were estimated to be adequate for 90 percent of all exposure scenarios involving daily exposure durations of 1 to 8 hours. The short, intermediate and long-term NOELs for inhalation exposure to phosphine gas were 7, 4 and 4 mg/m3, respectively. These NOELs used for estimating MOEs from inhalation exposure to phosphine were a rat developmental (short-term), a 13-week and a 2-year inhalation study, respectively. Although the USEPA's exposure risk assessment did not specify the estimated MOE values, it generally considers MOEs of 100-fold or greater to provide adequate protection for workers. In this USEPA risk assessment, the estimated exposures to workers were based on using phosphine gas-generating pellets. By contrast, workers using the ECO2FUME product should be subject to less exposure to phosphine gas since fumigation is accomplished by applicators working outside of the enclosed area to be fumigated (the gas is released into the structure by tubing, and not by placing pellets throughout the structure). Similarly, ECO2FUME use does not require that workers handle fresh, spent or partially-spent pellets as do the other phosphine-producing fumigant products. According to the USEPA Reregistration Eligibility Decision (RED) document for aluminum and magnesium phosphide (1998), additional studies are required to further evaluate exposures of workers and residential bystanders near treatment locations.

    There are no chemical specific Federal or State drinking water/groundwater standards for phosphine gas. Because phosphine is an inorganic compound, a New York State general drinking water standard of either 5 micrograms per liter for a "principal organic contaminant" or 50 micrograms per liter for an "unspecified organic contaminant" (10 NYCRR Part 5, Public Water Systems) is not applicable.

    Phosphine is a highly toxic respiratory poison and the USEPA registered the ECO2FUME product as a Restricted Use Pesticide to be sold and used only by certified applicators or by persons trained in accordance with this product's label and application manual. Personal protective equipment (gloves, safety glasses, safety shoes and NIOSH-approved respirator) are required for the application of the ECO2FUME product. To further minimize exposure to phosphine gas, the product is designed to be used outside of the enclosed area to be fumigated, where the gas is released into the structure by tubing rather than by placing phosphine gas-generating pellets throughout the structure. This application technique is expected to reduce worker risks and allows for better regulation of fumigant used. This product will not be used by the general public, but those residing near treatment sites could be exposed to phosphine fumigant emissions. However, phosphine fumigants are already registered in the State, and the use of the ECO2FUME product instead of these products is not likely to result in greater exposure of the public. In addition, the very high volatility of phosphine results in rapid dissipation after treatment which considerably limits exposure to this chemical from foods or other items that have been fumigated with the ECO2FUME product or other phosphine fumigants. Given the above, the DOH does not object to the registration of ECO2FUME Fumigant Gas in New York State as a Restricted Use Pesticide when used in accordance with its label and application manual.

    Therefore, the Department hereby accepts for registration, as a Restricted Use Pesticide, ECO2FUME Fumigant Gas (EPA Reg. No. 68387-7).

    According to the New York State Department of Environmental Conservation Regulations 6 NYCRR 326.3 (a): "It shall be unlawful for any person to distribute, sell, offer for sale, purchase for the purpose of resale, or possess for the purpose of resale, any restricted pesticide unless said person shall have applied for, and been issued a commercial permit."

    Furthermore, the product may only be purchased and used by certified applicators in New York State.

    Please contact the Pesticide Certification Section, at (518) 402-8753, if you require information concerning commercial permits or pesticide applicator certification.

    Enclosed are your New York State stamped "ACCEPTED" label and a copy of the Certificate of Registration.

    If you have any questions, please contact me, at (518) 402-8768.


Sincerely,


Maureen P. Serafini
Director
Bureau of Pesticides Management


Enclosures

cc: w/enc. - N. Kim/D. Luttinger - NYS Dept. of Health
R. Zimmerman/ R. Mungari - NYS Dept. of Ag. & Markets
G. Good/W. Smith - Cornell University, PMEP