Interregional Research Project No. 4 (IR-4)

Pesticide Petition #4E8236
	EPA has received a pesticide petition (4E8236) from Interregional Research Project No. 4 (IR-4), Rutgers, the State University of New Jersey, 500 College Road East, Suite 201W, Princeton, NJ 08540 requesting, pursuant to section 408(d) of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 180.245 by 1) establishing tolerances for residues of the fungicide streptomycin in or on grapefruit; grapefruit, dried pulp; fruit, pome, group 11-10; 2) moving the existing tolerances for streptomycin on celery, pepper, and tomato from paragraph (a)(2), and potato from paragraph (a)(3) to the table in (a)(1); 3) modifying the existing tolerance for tomato from 0.25 ppm  to 0.5 ppm; 4) removing  the existing time limited tolerances for grapefruit and grapefruit, dried pulp in paragraph (b) upon establishment of the permanent tolerances for grapefruit and grapefruit, dried pulp; 5) removing the existing tolerance for fruit, pome, group 11 upon establishment of the tolerance for fruit, pome, group 11-10; and 6) modifying the tolerance expression and creating a single paragraph and table under 180.245 (a) to read as follows: 
(a) General. Tolerances are established for residues of the fungicide streptomycin, including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels specified below is to be determined by measuring only streptomycin (O-2-Deoxy-2-(methylamino)-a-L-glucopyranosyl-(1-2)-O-5-deoxy-3-C-formyl-a-L-lyxofuranosyl-(1-4)-N,N'-bis(aminoiminomethyl)-D-streptamine) in or on the commodity.

EPA has determined that the petition contains data or information regarding the elements set forth in section 408 (d) (2) of FFDCA; however, EPA has not fully evaluated the sufficiency of the submitted data at this time or whether the data supports granting of the petition. Additional data may be needed before EPA rules on the petition.

A. Residue Chemistry

	1. Plant metabolism. The Agency has determined, and stated in the EPA Streptomycin Pesticide Fact Sheet (September, 1988) that plant (and animal) metabolism data were not needed for the following reasons:
   * Metabolism of streptomycin in mammals has already been traced in connection with its use in humans;
   * Residues are non-detectable (<0.5 ppm) in or on crops when treated according to label use rates and directions;
   * Large amounts of toxicological data exist;
   * Most crops are treated at or before transplanting (celery, peppers, potatoes, tomatoes) and pome fruits are treated foliarly but with a 30-day PHI for pears and a 50-day PHI for apples and crabapples;
   * Potential daily exposure to streptomycin as a pesticide is <0.01% of the daily clinical dosage (1-4 grams/day).

      	2. Analytical method. Grapefruit and tomato samples were analyzed for streptomycin using a laboratory working method based on USDA Food Safety and Inspection Service SOP No: CLG-AMG1.02, "Confirmation of Aminoglycosides by HPLC-MS/MS".  Modifications were made to improve the performance of the method for the various crop fractions.
      Briefly, residues were extracted by homogenizing and shaking with phosphate buffer.  (The grapefruit (citrus) oil did not require homogenization).  The tomato paste did not require shaking).  After filtration (RAC and juice) or centrifugation (oil and dried pulp, and tomato fractions), the extracts were subjected to C8 SPE cleanup.  The pH of the eluate from the C8 column was adjusted and loaded onto a CBX SPE column for further purification.  The analyte was eluted from the column with acidic methanol solution.  The methanolic extracts were then evaporated and reconstituted in water.  The reconstituted residues were analyzed by ion-pair reversed-phase liquid chromatography with detection by MS/MS spectrometry.  
      Based on recoveries of grapefruit fraction samples fortified at the LLMV, the limit of detection (LOD) and limit of quantitation (LOQ) were calculated as 0.0038 ppm and 0.011 ppm, respectively, for RAC, as 0.0045 ppm and 0.013 ppm, respectively, for oil, as 0.0044 ppm and 0.013 ppm, respectively for juice, and as 0.0037 ppm and 0.011 ppm, respectively, for dried pulp.  For tomato fractions, the limit of detection (LOD) and limit of quantitation (LOQ) were calculated as 0.0020 ppm and 0.0061 ppm, respectively, for RAC, as 0.0047 ppm and 0.014 ppm, respectively, for puree, and as 0.0042 ppm and 0.012 ppm respectively for paste. 
      Treated grapefruit samples were analyzed within 13 days of extraction (one dried pulp extract was analyzed after 25 days).  Treated tomato samples were analyzed within 10 days of extraction.  Analytical sets typically consisted of calibration standards, unfortified controls, fortified controls, and treated samples.  The analytical standard solutions were stored refrigerated (approximately -0.2 to 11 C).  


      	3. Magnitude of residues. 
      Tomato: Nineteen tomato trials were conducted during the 2009 growing season.  Three different types of tomatoes were grown for this study, processing varieties (field), fresh market varieties (field and greenhouse), and < 1-inch varieties (field and greenhouse).  Processing varieties were grown in six field trials covering the states of NY, CA (three locations), NM and AZ; fresh market varieties were grown in seven field trials covering the states of WI, FL, CA (four locations) and NM and two greenhouse trials in the states of CA and FL; and < 1-inch varieties were grown in two field trials in the states of NC and CA and two greenhouse trials in the states of MD and CO.  The number of trials and their locations are in accordance with OPPTS Guideline 860.1500 for the EPA regions represented by the trials.  
      In each trial, the test substance was applied four times as a foliar spray to runoff (or near runoff) at concentrations of approximately 203.73 ppm at up to 125 GPA per application.  The delivery rate varied based on the size of the plants at the time of application (ranging from 65.08 to 137.10 GPA); delivery rates of up to 125 GPA + 10% were considered within the protocol limits.  
      All tank mixes included an adjuvant, except for the first application in one of the CA locations (fresh market, field), where it was omitted due to an oversight.  The applications were made 6 to 8 days apart and timed so that marketable tomatoes could be collected 1 day after the final application.  Additional samples were collected for decline determination from two separate CA sites, one fresh market, field and one fresh market, greenhouse at approximately 3, 7, 14, and 21 days.  In addition, bulk samples were collected from the NY site for processing into puree and paste. 
      The maximum storage interval for treated tomato samples in this study was 332 days for tomato raw agricultural commodity (RAC), 394 days for puree, and 401 days for paste.  Storage stability testing was performed after 336 days (RAC), 415 days (puree), and 436 days (puree) of storage.  Results demonstrated stability. 
      The nature of the residues of streptomycin is adequately understood and an acceptable analytical method is available for enforcement purposes.  The lowest level of method validation (LLMV) was 0.01 ppm.
      The results from the trials show that the maximum residues following four applications at concentrations of approximately 203.73 ppm at up to 125 GPA (+ 10%) and a pre-harvest interval (PHI) of 1 day were 0.413 ppm.  Residues declined over time.  Residues of streptomycin did not concentrate in the processed fractions of puree and paste.  These results (i.e., residues less than 0.5 ppm) are consistent with the points noted in the Metabolism discussion under Number 1 above.
      
      Grapefruit: Eight field trials were conducted in Florida (EPA region 3), Texas (region 6), and California (region 10) during the 2008 growing season.  The number of field trials and their locations are in accordance with OPPTS Guideline 860.1500. 
      The product used in this study, Firewall 17WP, contains 22.4% of streptomycin sulfate, which is equivalent to 17% of streptomycin.  Calculations of the application rates in this study were based on the amount of the application of 2 lbs of Firewall 17WP. Streptomycin sulfate (22.4%) was used to calculate the rate of active ingredient in the protocol.   The amount of active ingredient, as expressed on the label, should be based on the streptomycin (17%) content.  This was documented with a deviation. 
      In each trial, the test substance was applied in two foliar applications of approximately 2.0 lbs product per acre, for a total of approximately 4.0 lbs product per acre.  In one FL trial, the test substance was applied to an additional plot at 5X the application rate to provide grapefruit for processing into oil, juice, and dried pulp.  In this additional plot, two applications of approximately 10.0 lbs product per acre each were made, for a total of approximately 20.0 lbs product per acre.  Crop oil was included in each tank mix except those used for the first application in two FL locations.  All applications were made at 20- to 22-day intervals and timed so that marketable grapefruit could be collected approximately 60 days after the final application.  Additional samples for decline determination were collected from a TX location at 0, 7, 14, 20, and 41 days.  
      Sample analysis for residues of streptomycin was conducted by the Food and Environmental Toxicology Laboratory, Gainesville, FL.  The maximum storage interval for field-treated samples in this study was 356 days for grapefruit raw agricultural commodity (RAC), 471 days for oil (approximately 15 months), 453 days for juice, and 640 days (approximately 21 months) for dried pulp.  Storage stability testing was performed after 327 days (RAC), 474 and 502 days (oil), 481 days (juice), and 720 days (dried pulp) of storage.  With the exception of oil, results demonstrated stability.  At 474 days, oil samples yielded recoveries of approximately 25 to 40%; when analyzed at 502 days, recoveries were approximately 30%. 
      The nature of the residues of streptomycin is adequately understood and an acceptable analytical method is available for enforcement purposes.  The lowest level of method validation (LLMV) was 0.01 ppm for RAC, oil, and juice, and 0.02 ppm for dried pulp. 
      The results from the trials show that streptomycin residues ranged from < 0.01 to 0.0855 ppm in 60-day RAC samples following a total application of approximately 4.0 lbs product per acre.  Residues declined over time, from a maximum of 0.136 ppm at 0 days to a maximum of 0.0479 ppm at 57 days.  For the processed fractions generated from grapefruit treated at 5X, residues were 0.698 ppm in dried pulp and < 0.01 ppm in both oil and juice. A comparison of the residues in the RAC with those in each processed fraction resulted in concentrated residues in pulp by a factor of 4.2X and reduced residues in oil and juice by a factor of 0.06X each. 

B. Toxicological Profile EPA has noted in the Streptomycin Pesticide Fact sheet (Fact Sheet Number 186, September, 1988) that streptomycin has been used since the late 1940's to treat bacterial infections in humans.  As a result of the uses as a human drug, there is an extensive body of toxicological data available on streptomycin.  Thus, all toxicological data requirements have been waived.  Further, it was noted in the Streptomycin TRED, June, 2006 (EPA 738-R-06-012) that EPA has evaluated the aggregate risks from the supported registered uses and has determined that there is a reasonable certainty that no harm to any population subgroup will result from exposure to streptomycin.  In regard to the cumulative risk of streptomycin, EPA stated the following in the Streptomycin TRED; Unlike other pesticides for which EPA has followed a cumulative risk approach based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as to streptomycin and any other substances, and streptomycin does not appear to produce a toxic metabolite that is also produced by other substances. Therefore, EPA has not assumed that streptomycin has a common mechanism of toxicity with other substances. 

The following is relevant available toxicological information on streptomycin.


      1. Acute toxicity.  The acute toxicity of the FireWall 17 WP formulation of streptomycin sulfate is summarized in the following table:
         
         
         
         
         
         
         
                             Route of application
                                    Animal
                       FireWall 17 WP formulated product
Oral LD 50
Rat
>5,000 mg/kg
Dermal LD 50
Rat
>5,000 mg/kg
Inhalation LC 50
Rat
>2.09 mg/L air  -  4 hours
Skin irritation
Rabbit
Slightly irritating
Eye irritation
Rabbit
Mildly irritating
Skin sensitization
Guinea pig
No evidence of sensitization observed
         
         
         
         
         
         
         
         

      2. Genotoxicty. Streptomycin sulfate exhibited negative to weakly positive results in a series of genetic toxicity tests to determine its potential to interact with DNA or damage chromosomes-indicating that it is unlikely to cause cancer.
   3.          Reproductive and developmental toxicity. The European Agency for the Evaluation of Medicinal Products, Veterinary Medicines and Information Technology (EMEA/MRL/728/00-Final, April, 2000) stated the following relative to potential reproductive effects: Panels of literature reviews and field data about the effects of streptomycin (and dihydrostreptomycin) on reproduction of farm animals were provided.  No adverse effects on reproduction have been reported.  Streptomycin (and dihydrostreptomycin) did not affect the sperm quality, the fertility and the reproductive performances and induced no toxic effects on the development of offsprings.  From this study it was possible to conclude that the consumption of residues of streptomycin (and dihydrostreptomycin) in food derived from animals treated in accordance with good practice in the use of veterinary drugs presents essentially no risk to peri and post natal human health.  
         
         In a teratology study rabbits were dosed at 5 and 10 mg/kg/day.  No teratogenic effects were noted in this developmental study at the highest dose which was considered the NOAEL.

   4.          Subchronic toxicity. A three month feeding study in cats was conducted at doses ranging from 25-250 mg/kg/day via intramuscular injections, which is greater than the dose when used as a drug in humans or animals.  Another group of cats received oral doses of 40 mg/kg/day.  Cats which were injected lost the righting reflex, but cats which were dosed orally did not.  Gross pathology and histopathology were unremarkable.  The NOAEL was 40 mg/kg/day.  In a 3-month feeding study in guinea pigs at 40 mg/kg/day it was noted there was no hearing loss.  No other remarkable findings were noted.

      5. Chronic toxicity. In a 2-year feeding study rats were dosed at 0, 1, 5 and 10 mg/kg/day.  The only adverse effect noted was reduced body weight gain in male rats at 10 mg/kg/day.  An increase in treatment-related tumors was not reported.  The NOAEL for this study was 5 mg/kg/day.  No evidence of carcinogenicity was found in a literature search of toxicity in animals or humans.

      6. Animal metabolism.  The Agency has determined, and stated in the EPA Streptomycin Pesticide Fact Sheet (September, 1988) that animal metabolism data were not needed because metabolism of streptomycin in mammals has already been traced in connection with its use in humans.

      7. Metabolite toxicology. Streptomycin sulfate dissociates in water to streptomycin, but otherwise undergoes minimal metabolism in the environment, as well as in crops, animals and humans.  The nature of the residue in plants and animals is adequately understood; the residue of concern is streptomycin for plant and livestock commodities and water.  Due to the wide use of streptomycin as a human drug, and to the low residue levels expected in/on raw agricultural commodities (RACs), no metabolism data have been required.

      8. Endocrine disruption. No specific information available.  No cited evidence in existing toxicological studies. 

C. Aggregate Exposure

	1. Dietary exposure. 

        i. Food and ii. Drinking water. EPA did a dietary and drinking water assessment using the Dietary Exposure Evaluation Model (DEEM-FCID[TM]), Version 2.03 (DP No. D310391, 1/9/06).  The drinking water component was based on EPA's evaluation of potential surface and ground water residues modeled with FIRST (surface water) and SCI-GROW (ground water) for aerial application to apples.  The chronic estimated drinking water concentrations in surface and ground waters were 0.0514 ppm and 0.0012 ppm, respectively.  The dietary assessment for the proposed new uses on grapefruit and tomatoes used the (higher) surface water concentration in water from treatment of apples in the DEEM model.  The acute drinking water concentration was not considered as streptomycin has no acute toxicological endpoint for risk assessment.  

         No residues (LOQ=0.01 ppm) were found in juice or oil in crop residue trials.  IR-4 evaluated grapefruit and tomato residues with the NAFTA Maximum Residue Level (MRL) Excel spreadsheet and has proposed the NAFTA MRLs (grapefruit: 0.15 ppm and Tomatoes: 0.50 ppm) as tolerances.  Dietary and drinking water exposure and risk assessments were done with DEEM-FCID Version 3.16 03-08-d based on the NHANES 2003-2008 food consumption survey.  The commodities grapefruit and grapefruit juice were added to the residue file in the latest EPA chronic dietary assessment (DP No. D310391, 1/9/06) with the high FIRST surface water concentration with the following additional inputs: 0.15 ppm in grapefruit, 0.005 ppm (50% LOQ) in grapefruit juice, 0.50 ppm in tomatoes, default processing factors (except for grapefruit juice and the assumption that 100% of crop treated.  It should be noted that EPA has determined that animal products are not of concern and need not be quantitatively evaluated.  While citrus pulp may be a minor component of cattle feed, it is not included in the Maximum Reasonable Balanced Diet and should not be of concern.  It should be noted that the cited residue file contained estimates of percent crop treated for apples and pears of 10% and 25%, respectively.  However, the text noted PCTs of 20% and 30% respectively.  For this dietary risk assessment the conservative (20 and 30%) estimates were used.

         As previously noted, acute exposure is not of concern.  The EPA chronic toxicity endpoint of 5.0 mg/kg BW and uncertainty factor of 100 were used (reference dose, RfD, 0.05 mg/kg BW). 

         Aggregated dietary and drinking water exposures were greatest in non-nursing infants, occupying 10.6 % of the chronic RfD with a margin of exposure of 945.  Based on this screening level assessment of adding grapefruit uses and increasing tomato tolerances, the EPA should have no concerns about excess risk.

   2.     Non-dietary exposure. EPA noted the following in the "Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk Management Decision (TRED) for Streptomycin"; EPA 738-R-06-012; June, 2006, with regard to residential risk: "At this time, products containing streptomycin are registered for residential use on home garden orchards (apples and pears), and ornamentals (pyracantha, chrysanthemums, dieffenbachia, philodendron and roses).  Dermal and inhalation exposure to residential handlers can occur when they mix, load, or apply streptomycin for use in a sprayer.
         
         Oral absorption of chemicals related to streptomycin is less than 1% because of the charged nature of the molecules.  Because the skin has a protective barrier role in comparison to the lining of the gastrointestinal tract, dermal absorption is expected to be much less than that by the oral route.  Although a dermal exposure study is not available for streptomycin, dermal absorption at environmental concentrations is expected to be so minimal that toxicity by the dermal route is not of concern.  Therefore, quantification of risk following dermal exposure is not required at this time.
         A chronic inhalation exposure assessment was conducted for homeowner application to fruit trees and shrubs using a low pressure handwand.  The resulting margin of exposure (MOE) is 75,000.  MOEs (calculated as NOAEL / dose) greater than 100, do not exceed EPA's level of concern; because the MOE for this use is greater than 100, risk from residential inhalation exposure does not exceed EPA's level of concern.  The inhalation exposure assessment is considered a reasonable worst-case scenario for homeowners because streptomycin is poorly absorbed by the oral and dermal routes; therefore, a postapplication dermal and oral exposure assessment was not conducted."
         
         The proposed new uses on grapefruit and tomatoes have no impact on the EPA's previous assessments of residential exposures and findings of no concern. 

D. Cumulative Effects 

	EPA has stated the following in the Streptomycin TRED (EPA 738-R-06-012, June, 2006): Unlike other pesticides for which EPA has followed a cumulative risk approach based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as to streptomycin and any other substances, and streptomycin does not appear to produce a toxic metabolite that is also produced by other substances. Therefore, EPA has not assumed that streptomycin has a common mechanism of toxicity with other substances. 


E. Safety Determination

	1. U.S. population. In the Streptomycin TRED, EPA aggregated residential inhalation exposure and chronic dietary exposure.  The same procedure has been used for this safety determination.  Accordingly, the sum of chronic dietary exposure for the U.S. population (0.002300 mg/kg/day) plus residential (garden) exposure (0.000067 mg/kg/day) are a total of 0.002367 mg/kg/day (MOE 2,112).  When compared to a human therapeutic dose of 15 mg/kg/day, the above noted dietary (plus residential) exposures would have minimal impact and cause no harm.

	2. Infants and children. Aggregate residential inhalation exposure (0.000067 mg/kg/day) plus non-nursing infants (0.005292 mg/kg/day) totaling 0.005359 mg/kg/day is well below the human therapeutic dose of 15 mg/kg/day, again demonstrating the dietary (plus residential) exposures would have minimal impact and cause no harm.

F. International Tolerances

	No available information.




