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).
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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 
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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. 
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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:
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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 

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
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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-FCIDTM), 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, 
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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
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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.