Page 1 of 46 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES 19 JUN 2006 MEMORANDUM SUBJECT: Oxytetracycline: HED Chapter of the Tolerance Reregistration Eligibility Decision Document ( TRED) and Proposed New Uses on Apples. Revised After Phase 3 Public Comment Period. PC Codes: 006304, 006308, and 006321; DP Barcode: D330129; Case No. 0655.

Regulatory Action: Phase 3 Reregistration Action Risk Assessment Type: Single Chemical Aggregate FROM: William H. Donovan, Ph. D., Chemist Reregistration Branch 3 ( RRB3) Health Effects Division ( HED) ( 7509P)

AND Kimyata Morgan, Ph. D., Toxicologist RRB3/ HED ( 7509P)

THROUGH: Danette Drew, Branch Senior Scientist RRB3/ HED ( 7509P)

TO: Lance Wormell, CRM Reregistration Branch 2 Special Review and Registration Division ( 7508P) Page 2 of 46 Table of Contents 1.0 Executive Summary ........................................................................ Page 4 of 45 2.0 Ingredient Profile ............................................................................ Page 8 of 45 2.1 Summary of Supported Uses.................................................. Page 8 of 45 2.2 Structure and Nomenclature .................................................. Page 9 of 45 2.3 Physical and Chemical Properties.......................................... Page 10 of 45 3.0 Metabolism Assessment ................................................................. Page 11 of 45 3.1 Comparative Metabolic Profile.............................................. Page 11 of 45 3.2 Nature of the Residue in Foods............................................. Page 11 of 45 3.2.1 Description of Primary Crop Metabolism................... Page 11 of 45 3.2.2 Description of Livestock Metabolism........................ Page 11 of 45 3.2.3 Description of Rotational Crop Metabolism, including identification of major metabolites and specific routes of biotransformation               Page 12 of 45 3.3 Environmental Degradation .................................................. Page 12 of 45 3.4 Tabular Summary of Metabolites and Degradates ................. Page 12 of 45 3.5 Toxicity Profile of Major Metabolites and Degradates .......... Page 12 of 45 3.6 Summary of Residues for Tolerance Expression and Risk Assessment                  Page 12 of 45 3.6.1 Tabular Summary              . Page 12 of 45 3.6.2 Rationale for Exclusion of Metabolites and DegradatesPage 13 of 45 4.0 Hazard Characterization/ Assessment ........................................... Page 13 of 45 4.1 Hazard Characterization ....................................................... Page 13 of 45 4.1.1 Qualitative Assessment of Antimicrobial Resistance.. Page 17 of 45 4.2 FQPA Hazard Considerations .............................................. Page 24 of 45 4.2.1 Adequacy of the Toxicity Data Base.......................... Page 24 of 45 4.2.2 Evidence of Neurotoxicity......................................... Page 25 of 45 4.2.3 Developmental Toxicity Studies ................................ Page 25 of 45 4.2.4 Reproductive Toxicity Study..................................... Page 26 of 45 4.2.5 Additional Information from Literature Sources ........ Page 26 of 45 4.2.6 Pre and/ or Postnatal Toxicity ................................... Page 26 of 45 <IP_ADDRESS> Determination of Susceptibility...................... Page 26 of 45 <IP_ADDRESS> Degree of Concern Analysis and Residual Uncertainties for Pre and/ or Post natal Susceptibility............... Page 26 of 45 4.3 Recommendation for a Developmental Neurotoxicity Study.. Page 26 of 45 4.3.1 Evidence that supports requiring a Developmental Neurotoxicity study              Page 27 of 45 Page 3 of 46 4.3.2 Evidence that supports not requiring a Developmental Neurotoxicity study        Page 27 of 45 4.4 Hazard Identification and Toxicity Endpoint Selection.......... Page 27 of 45 4.4.1 Acute Reference Dose ( aRfD) ................................. Page 27 of 45 4.4.2 Chronic Reference Dose ( cRfD) ................................ Page 27 of 45 4.4.3 Recommendation for Aggregate Exposure Risk Assessments              . Page 28 of 45 4.4.4 Classification of Carcinogenic Potential..................... Page 29 of 45 4.5 Special FQPA Safety Factor ................................................. Page 29 of 45 4.6 Endocrine disruption............................................................. Page 30 of 45 5.0 Public Health Data......................................................................... Page 30 of 45 6.0 Exposure Characterization/ Assessment ........................................ Page 30 of 45 6.1 Dietary Exposure/ Risk Pathway............................................ Page 30 of 45 6.1.1 Residue Profile.......................................................... Page 31 of 45 6.1.2 Chronic Aggregate Dietary Exposure and Risk.......... Page 32 of 45 6.2 Water Exposure/ Risk Pathway.............................................. Page 34 of 45 6.3 Residential ( Non Occupational) Exposure/ Risk Pathway....... Page 35 of 45 6.3.1 Home Uses ............................................................... Page 35 of 45 6.3.2 Recreational Uses...................................................... Page 35 of 45 6.3.3 Other ( Spray Drift, etc.) ............................................ Page 35 of 45 7.0 Aggregate Risk Assessments and Risk Characterization............. Page 36 of 45 7.1 Acute Aggregate Risk........................................................... Page 36 of 45 7.2 Chronic Aggregate Risk........................................................ Page 36 of 45 8.0 Cumulative Risk Characterization/ Assessment ........................... Page 36 of 45 9.0 Data Needs and Label Requirements .......................................... Page 37 of 45 9.1 Toxicology........................................................................... Page 37 of 45 9.2 Residue Chemistry................................................................ Page 37 of 45 9.3 Occupational and Residential Exposure................................. Page 37 of 45 9.4 Recommended Data for Refining Qualitative Risk Assessment ................................................................... Page 37 of 45 10.0 References ...................................................................................... Page 38 of 45 11.0 APPENDICIES .............................................................................. Page 42 of 45 1.0 TOXICOLOGY DATA REQUIREMENTS ......................... Page 42 of 45 2.0 NON CRITICAL TOXICOLOGY STUDIES ...................... Page 43 of 45 3.0 TOLERANCE REASSESSMENT SUMMARY................... Page 45 of 45 Page 4 of 46 1.0 Executive Summary This assessment provides information to support the issuance of a risk management decision document known as a Tolerance Reregistration Eligibility Decision ( TRED) Document for oxytetracycline. EPA's pesticide reregistration process provides for the review of older pesticides ( those initially registered prior to November 1984) under the Federal Insecticide, Fungicide, and Rodenticide Act ( FIFRA) to ensure that they meet current scientific and regulatory standards. The process considers the human health and ecological effects of pesticides and incorporates a reassessment of tolerances ( pesticide residue limits in food) to ensure that they meet the safety standard established by the Food Quality Protection Act ( FQPA) of 1996.

Use Profile Oxytetracycline is a broad spectrum antibiotic produced from the actinomycete Streptomyces rimosus. Oxytetracycline is a human and animal antibiotic drug which, in various forms, is used primarily to control bacteria, fungi, and mycoplasma like organisms. In agriculture, oxytetracycline is used to help control fire blight of pears, peaches, and nectarines. Nufarm Americas, Inc., and IR 4 have submitted a tolerance petition ( PP# 7E4855) for use on apples. Oxytetracycline hydrochloride and oxytetracycline calcium are registered for use as bactericide/ fungicides to control bacterial diseases on nectarines, peaches and/ or pears. The current memo concerns oxytetracycline hydrochloride, oxytetracycline calcium, and oxytetracycline ( hereafter collectively referred to as " oxytetracycline").

Oxytetracycline is a FIFRA List A reregistration chemical. Under the Oxytetracycline Case No. 0655, manufacturing use products are registered under PC Codes 006308 ( oxytetracycline hydrochloride) and 006321 ( oxytetracycline calcium). There are currently no registered manufacturing use products under PC code 006304 ( oxytetracycline); however, the agency has required the registration of the oxytetracycline TGAI in the form of oxytetracycline dihydrate in connection with a number of oxytetracycline calcium end use product registrations.

Tolerances are currently established for the residues of oxytetracycline per se [ 40 CFR § 180.337], and are set at 0.35 ppm for peach and pear. As indicated in 40 CFR § 180.1( h), tolerances for peaches also cover nectarines. There are adequate field trial data available to support the establishment of a tolerance for residues of oxytetracycline per se in/ on apples at 0.35 ppm.

This preliminary risk assessment for oxytetracycline was based on the supported uses as outlined in the Use Closure Memo ( L. Wormell, 31 MAR 2005); in addition, a proposed new use on apples is also included.

Hazard Identification and Dose Response Assessment Oxytetracyclines include oxytetracycline, oxytetracycline calcium and hydroxyoxytetracycline monhydrochloride. The toxicity of all three oxytetracyclines would be expected to be similar and shall be considered equivalent in this hazard characterization. Historically, all the toxicological data requirements for oxytetracycline have been waived. The information available on the effects Page 5 of 46 of oxytetracycline in humans, supplemented with the data available on the toxicity of oxytetracycline in laboratory animals, is sufficient to evaluate the toxicity of oxytetracycline and related compounds. Based on the information available from these sources, the database is complete and there are no datagaps.

Animals In mice, oxytetracycline has a low acute toxicity, being a Category IV for oral toxicity ( LD50 > 7200 mg/ kg). Based on the extensive availability of human data from the drug use of oxytetracycline, the data requirements for the acute dermal, inhalation, primary eye irritation, and skin sensitization studies in animals have been waived.

A definitive target organ has not been identified. The most common effect in intermediate or long term oral exposures was a decrease in body weight and/ or body weight gain. Clinical signs noted were increased incidence of respiratory signs and rough hair coat and decreased maternal survival and percent of treated dams found pregnant. In a chronic toxicity study in dogs, a yellow discoloration of the thyroid was observed in all dosed animals at necropsy. No other changes in clinical signs, mortality, body weight, food consumption, macrosopy, or histopathology were reported in dogs.

In prenatal developmental toxicity studies, maternal toxicity was evident in rats as a dose related increase in mortality. A dose related decrease in fetal body weight was observed in rats. No maternal or developmental toxicity was observed in mice treated up to 2,100 mg/ kg/ day. No treatment related external, visceral, or skeletal abnormalities were found in either species. In a study citation that was reported by a Joint FAO/ WHO committee, oxytetracycline did not adversely affect reproductive parameters in rats over two generations.

There is no evidence of increased sensitivity in pups versus adults based on rat and mice developmental studies and the rat multi generation reproduction study. In prenatal developmental studies in both rats and mice treated with oxytetracycline, there was no toxicity identified in the pups at any dose tested. In the two generation study, there was no toxicity identified in pups at the highest dose tested ( 18 mg/ kg/ day). The degree of concern is low for pre and/ or postnatal toxicity resulting from exposure to oxytetracycline and the special FQPA safety factor can be reduced to 1X since there are no residual uncertainties for pre and/ or postnatal toxicity.

No evidence of neurotoxicity was observed in any study.

There is carcinogenic potential but no evidence of carcinogenicity was observed in rats. In F344/ N rats, histological examination showed a dose related increase in the incidence of benign phaeochromcytomas in the adrenal gland of male rats fed 2,500 mg/ kg/ day. In females an increase in the incidence of adenomas of the pituitary gland was found in the highest dose group ( 1,875 mg/ kg/ day). Mice fed up to 1,875 mg/ kg/ day exhibited no evidence of carcinogenicity. The bacterial reverse mutation test, chromosome aberration study, and sister chromatid exchange assays were all negative, with and without metabolic activation. The mouse lymphoma forward mutation assay revealed that oxytetracycline was mutagenic only with metabolic activation, however, the dose levels were close to toxic concentrations and the positive effect in the in vivo Page 6 of 46 micronucleus assay in mice was not dose related.

The microbiological effects of oxytetracycline were examined by studies examining the induction of drug resistant organisms in dogs. In a 6 week study in dogs, which received oxytetracycline, there was no increase in the level of resistant fecal coliforms at 2 ppm in the diet ( equivalent to 0 .05 mg/ kg/ day). Dogs receiving 10 ppm ( equivalent to 0.25 ppm) displayed an increase in a multiple antibiotic resistant population of enteric lactose fermenting organisms.

A relevant study on metabolism is available in the open literature. After oral administration of 47.6 mg 14C labeled hydroxyoxytetracycline monohydrochloride/ kg b. w. to mice, 72% of the applied dose was found in the large intestine after 2 hours; only 5% was absorbed, of which the major portion ( 3.6%) was excreted in the urine. In the liver 1.9% and 1.1% of the dose applied was recovered after 1 and 2 hours, respectively.

Mode of Action Tetracyclines exert their activity in bacteria by inhibiting protein synthesis. Inhibition occurs when oxytetracycline binds to the 30S ribosomes, preventing aninoacyl tRNA from reading the mRNA ribosome complex, thereby preventing polypeptide chain elongation. High concentrations of tetracyclines also impair protein synthesis in mammalian cells. However, the active transport system found in bacteria is absent in these cells and there are differences in sensitivity at the ribosomal level. These differences are likely to be important determinants in the selective action of tetracyclines. In humans, oxytetracycline is administered orally or intravenously to treat infectious diseases caused by a wide variety of microorganisms. The dose for adults range from 1000 to 2000 mg per day. The usual daily dose for children is 25 to 50 mg/ kg.

Qualitative Assessment of AntiMicrobial Resistance The overall risk of the development of antibiotic resistance to oxytetracycline in human health and the environment is medium. Following the recommendation of FDA's Guidance # 152, a medium concern for release and exposure and a highly important concern for consequence results in an overall risk assessment rank as medium.

Endpoints used in risk assessment are provided in Table 1.

Table 1. Endpoint Used for Oxytetracycline Risk Assessment Dietary NOAEL mg/ kg/ day RfD mg/ kg/ day PAD mg/ kg/ day chronic  all populations 0.05 0.0005 ( UF= 100; FQPA = 1) 0.0005 Exposure Assessment Page 7 of 46 An acute dietary and drinking water exposure analysis was not conducted because a toxic endpoint attributable to a single dose effect was not identified in the database. Analysis of chronic dietary and drinking water exposure pathways were included in the oxytetracycline risk assessment. Sources of dietary exposure include food from treated crops of apple, peach, nectarine, and pears; as well as from drinking water. The dietary exposure to oxytetracycline is expected to be low due to the long PHIs and the limited number of crop uses. Drinking water exposure may occur due to run off from the agricultural uses of oxytetracycline in orchards. Occupational exposures are not assessed for TREDs. Residential exposures were not assessed because no residential exposures are anticipated.

The use of oxytetracycline as a drug in food animals is regulated by the FDA according to 21 CFR 556.500. The FDA has established the following tolerances for the sum of residues of the tetracyclines including chlortetracycline, oxytetracycline, and tetracycline: 2 ppm in muscle ( meat) of cattle, swine, sheep, poultry, fish and lobsters; 6 ppm in liver, 12 ppm in fat and kidney, and 0.3 ppm in milk. HED notes that the drug uses of oxytetracycline in livestock and humans result in considerably higher exposure levels to oxytetracycline residues than the agricultural uses; the estimated percentage of antibiotics applied to plants compared to all other antibiotic use is < 0.5% ( McManus et al.). Wet apple pomace is a feedstuff of regulatory interest associated with apples, while peaches/ nectarines and pears have no livestock feedstuffs. Due to low oxytetracycline residue levels in apples, quantifiable residues of oxytetracycline in livestock commodities as a result of feeding wet apple pomace from treated apples are not expected. Therefore, based on the agricultural uses of oxytetracycline, HED finds there is no reasonable expectation that residues of concern will transfer to livestock tissues [ 40 CFR § 180.6( a)( 3)]. However, to account for the possibility of oxytetracycline residues in livestock commodities arising from drug and subtherapeutic dosing of animals, HED included the results of Food Safety and Inspection Service ( FSIS) livestock monitoring data from the years 2002 2004 in the dietary exposure analyses ( see section 6.1.2).

Risk Assessment and Risk Characterization Risk assessments were conducted for dietary and drinking water exposure pathways together as an aggregate assessment of risk from the combined food and drinking water pathways. A cumulative risk assessment considering risks from other pesticides or chemical compounds having a common mechanism of toxicity has not been conducted for this TRED. HED has not yet determined that any other chemical substances have a mechanism of toxicity in common with that of oxytetracycline.

Aggregate Exposures and Risks Since there is potential for concurrent exposure via food and water, the combined exposures are estimated for the aggregate assessment. To assess aggregate risk, drinking water model based EDWCs determined by EFED are included in the dietary exposure assessment along with Page 8 of 46 potential residue levels in foods.

HED conducted a partially refined chronic dietary exposure analyses using the Dietary Exposure Evaluation Model with the Food Commodity Intake Database ( DEEM FCID   ) . The chronic dietary analyses were conducted for the general U. S. population and all population subgroups.

Chronic aggregate risks are expressed as a percentage of the chronic Population Adjusted Dose ( cPAD). An aggregate risk of 100% of the PAD is the level of exposure that should not be exceeded, ( i. e., estimated risk less than 100% of PAD is not of concern). The PAD is the chronic reference dose ( cRfD) modified by the special FQPA Safety Factor. The special FQPA safety factor for sensitivity in infants and children for the chronic dietary assessment in this case is 1X. Based on these analyses, the aggregate ( food + water) chronic dietary risk from existing and proposed uses of oxytetracycline are below HED's level of concern for the general US population and all population subgroups. Oxytetracycline chronic aggregate exposure ( food + water) was estimated at 0.000160 mg/ kg/ day for the U. S. population ( 32% of the cPAD) and 0.000473 mg/ kg/ day ( 95% of the cPAD) for the most highly exposed population subgroup ( All Infants (< 1 year old)). These results indicate that chronic aggregate dietary exposure to oxytetracycline from food and drinking water is below HED's level of concern for all population subgroups.

2.0 Ingredient Profile Oxytetracycline is an antibiotic bactericide/ fungicide registered for use on pears, peaches, and nectarines. This TRED also includes a requested new use on apples.

2.1 Summary of Supported Uses Table 2.1. Overall Use Patterns for Oxytetracycline Oxytetracycline hydrochloride Page 9 of 46 Crop Max Single Rate ( Lbs/ ai/ A) Applications per Yr Maximum Seasonal Rate ( Lbs / A/ Yr) Retreatment Interval ( RTI, days) Preharvest Interval ( days)

Pear 0.1847 10 1.847 4 6 60 Peach, Nectarine 0.6926 9 6.233 7 21 Oxytetracycline calcium Crop Max Single Rate ( Lbs/ ai/ A) Applications per Yr Maximum Seasonal Rate ( Lbs / A/ Yr) RTI ( days) Preharvest Interval ( days)

Pear 0.3150 10 3.15 4 6 60 Peach, Nectarine 0.6926 9 6.233 7 21 Apple 0.255 6 1.53 3 6 60 2.2 Structure and Nomenclature TABLE 2.2. Oxytetracycline Nomenclature PC Code 006304 Chemical structure OH O OH O OH NH 2 O OH H N C H 3 CH 3 CH 3 O H H OH Common name Oxytetracycline Molecular Formula C22H24N2O9 Molecular Weight 496.47 IUPAC name ( 4S, 4aR, 5S, 5aR, 6S, 12aS) 4 dimethylamino 1,4,4a, 5,5a, 6,11,12a octahydro 3,5,6,10,12,12a hexahydroxy 6 methyl 1,11 dioxonaphthacene 2 carboxamide CAS name 4 Dimethylamino 3,5,6,10,12,12a hexahydroxy 6 methyl 1,11 dioxo 1,4,4a, 5,5a, 6,11,12a octahydro naphthacene 2 carboxylic acid amide CAS # 79 57 2 2.3 Physical and Chemical Properties Page 10 of 46 Oxytetracycline is a non volatile solid with low water solubility.

TABLE 2.3 Physicochemical Properties of Oxytetracycline hydrochloride and Oxytetracycline Calcium Parameter Value Reference Oxytetracycline hydrochloride ( PC Code 006308)

Melting point Decomposes above 180 ° C RED 12/ 29/ 92 pH 2.4 ( 1% aqueous solution) RED 12/ 29/ 92 Density, bulk density, or specific gravity 5.0 lbs/ ft3 1.98 g/ mL ( bulk density) RD D289846, 9/ 9/ 03, S. Malak D167892, 9/ 22/ 92, F. Toghrol Water solubility Freely soluble in water RD D289846, 9/ 9/ 03, S. Malak Solvent solubility Sparingly soluble in alcohol RD D289846, 9/ 9/ 03, S. Malak Vapor pressure N/ A; water soluble salt RD D289846, 9/ 9/ 03, S. Malak Dissociation constant, pK N/ A; water soluble salt RD D289846, 9/ 9/ 03, S. Malak Octanol/ water partition coefficient N/ A; water soluble salt RD D289846, 9/ 9/ 03, S. Malak UV/ visible absorption spectrum Not available Oxytetracycline calcium ( PC Code 006321)

Melting point Decomposes above 180 ° C RD D203326, 9/ 30/ 94, A. Smith pH 8.6 ( 1% aqueous solution) RED 12/ 29/ 92 Density, bulk density, or specific gravity Bulk density:

0.39 g/ cc free flowing 0.56 g/ cc compressed RD D203326, 9/ 30/ 94, A. Smith Water solubility g/ 100 mL at 23 ° C:

3.14 in pH 1.2 water 0.05 in pH 5 water 0.11 in pH 7 water 3.86 in pH 9 water RD D203326, 9/ 30/ 94, A. Smith Solvent solubility Not available Vapor pressure Not available Dissociation constant, pKa Not available Octanol/ water partition coefficient K = < 10 RD D203326, 9/ 30/ 94, A. Smith Page 11 of 46 TABLE 2.3 Physicochemical Properties of Oxytetracycline hydrochloride and Oxytetracycline Calcium Parameter Value Reference UV/ visible absorption spectrum Not available 3.0 Metabolism Assessment 3.1 Comparative Metabolic Profile Rat metabolism: No oxytetracycline rat metabolism data have been submitted.

Plant metabolism: No oxytetracycline plant metabolism data have been submitted.

Livestock metabolism: No oxytetracycline livestock metabolism data have been submitted.

Water degradates: No oxytetracycline water metabolism data have been submitted.

No guideline metabolism studies were submitted for rats, plants, or livestock due to a data waiver. The only available metabolism data for oxytetracycline involve human and mouse metabolism studies reported in the open literature.

3.2 Nature of the Residue in Foods 3.2.1. Description of Primary Crop Metabolism Due to the widespread use of oxytetracycline as a drug, and the low residue levels expected in or on tree fruit, no plant metabolism data are required ( see memo of W. J. Hazel dated 4/ 12/ 88; memo of W. B. Greer dated 4/ 19/ 88; and memo of R. B. Perfetti dated 10/ 13/ 92). The residue of concern is the parent compound, oxytetracycline per se, as specified in 40 CFR 180.337.

3.2.2 Description of Livestock Metabolism Due to the widespread use of oxytetracycline as a drug, and the low residue levels expected in or on tree fruit, no livestock metabolism data are required ( see memo of W. J. Hazel dated 4/ 12/ 88; memo of W. B. Greer dated 4/ 19/ 88; and memo of R. B. Perfetti dated 10/ 13/ 92). The residue of Page 12 of 46 concern is the parent compound, oxytetracycline per se, as specified in 40 CFR 180.337.

3.2.3 Description of Rotational Crop Metabolism, including identification of major metabolites and specific routes of biotransformation No rotational crop metabolism data are required since orchard crops are not rotated.

3.3 Environmental Degradation No environmental fate studies have been submitted for oxytetracycline. The studies were waived in the reregistration process ( USEPA, 1993) on the basis of limited use patterns and low estimated risks. Some fate and transport data for oxytetracycline were located from product chemistry studies and the open literature.

3.4 Tabular Summary of Metabolites and Degradates Not applicable since no metabolism data were submitted.

3.5 Toxicity Profile of Major Metabolites and Degradates Not applicable since no metabolism data were submitted.

3.6 Summary of Residues for Tolerance Expression and Risk Assessment 3.6.1 Tabular Summary Page 13 of 46 Table 3.6. Summary of Metabolites and Degradates to be included in the Risk Assessment and Tolerance Expression Matrix Residues included in Risk Assessment Residues included in Tolerance Expression Primary Crop oxytetracycline per se oxytetracycline per se Plants Rotational Crop Not Applicable  no crop rotation from orchard crops Not Applicable  no crop rotation from orchard crops Ruminant Not Applicable  no residues expected Not Applicable  no tolerances required Livestock Poultry Not Applicable  no residues expected Not Applicable  no tolerances required Drinking Water oxytetracycline per se Not Applicable 3.6.2 Rationale for Exclusion of Metabolites and Degradates The oxytetracycline risk assessment team has determined that the regulated residues in apple, peach, nectarine, and pear will include parent only for the purpose of tolerance enforcement and risk assessment. The basis for this decision is that due to the widespread use of oxytetracycline as a drug, and the low residue levels expected in or on tree fruit, plant and livestock metabolism studies were waived.

Wet apple pomace is a feedstuff of regulatory interest associated with apples, while peaches/ nectarines and pears have no livestock feedstuffs. However, quantifiable residues of oxytetracycline in livestock commodities as a result of feeding wet apple pomace from treated apples are not expected. Therefore, based on the agricultural uses of oxytetracycline, HED finds there is no reasonable expectation that residues of concern will transfer to livestock tissues [ 40 CFR § 180.6( a)( 3)].

4.0 Hazard Characterization/ Assessment 4.1 Hazard Characterization Oxytetracyclines include oxytetracycline, oxytetracycline calcium and hydroxyoxtetracycline monhydrochloride. The toxicity of all three oxytetracyclines would be expected to be similar and shall be considered equivalent in this hazard characterization. Oxytetracycline is a member of the Page 14 of 46 tetracycline family of antibiotics. It is a broad spectrum antibiotic produced by the actinomycete Streptomyces rimousus and became available for use in 1950. Its use as broad spectrum antibiotic is possible because of its activity against a wide range of disease causing bacteria. The chemical name of oxytetracycline is 2 napthacenecarboxamide, 4( dimethylamino) 1, 4, 4a, 5, 5a, 6, 11, 12a octahydro 3, 6, 10, 12, 12a pentahydroxy 6 methyl 1 11 dioxo. The information available on the effects of oxytetracycline, oxytetracycline calcium, and dihydroxy tetracycline monohydrochloride in laboratory animals is sufficient to evaluate the toxicity of oxytetracycline and related compounds.

Animal Data In mice, oxytetracycline has a low acute toxicity, being a Category IV for oral toxicity ( LD50 > 7200 mg/ kg). Historically, the data requirements for the acute dermal, inhalation, primary eye irritation, and skin sensitization studies in animals have been waived.

Oxytetracycline has low toxicity potential when administered by the oral route to animals. In the rat, the liver is a potential target organ at high dose levels ( > 1, 250 mg/ kg/ day). Long term administration of oxytetracycline to male and female rats at this dose led to fatty metamorphosis of the liver. No other signs of hepatic toxicity were observed in the 13 week oral toxicity study or the prenatal developmental study in rats. However, the available database did not demonstrate the potential for the liver to be the primary target organ in other animal species ( e. g. mice or dogs). Clinical signs in the rat included increased incidence of respiratory signs and rough hair coat and decreased maternal survival. The most common effect in intermediate or long term oral exposures was a decrease in body weight and/ or body weight gain. In a 13 week feeding study in mice, a decrease in body weight was observed at 7,500 mg/ kg/ day. In a 103 week feeding study in mice, a slight decrease in body weight ( 7 9%) was observed in males at 945 mg/ kg/ day. No adverse effects were seen in mice at 2,100 mg/ kg/ day in a mouse prenatal developmental study.

Toxicity in dogs was manifested as a shift from a predominantly drug susceptible population of enteric lactose fermenting organisms to a multiple antibiotic resistant population in intestinal flora isolated from fecal samples in a 44 week feeding study ( see section 4.4.2). In a chronic toxicity study in dogs, a yellow discoloration of the thyroid was observed in all dosed animals at necropsy. No other changes in clinical signs, mortality, body weight, food consumption, macrosopy, or histopathology were reported in either of the two chronic toxicity studies in dogs.

No evidence of neurotoxicity was observed in any study.

In developmental toxicity studies, maternal toxicity was evident in rats as a dose related increase in mortality. A dose related decrease in fetal body weight was observed in rats. The high incidence of maternal deaths and fetotoxicity noted at all dose levels tested did not allow for an establishment of a NOAEL ( LOAEL = 1200 mg/ kg/ day; LDT). No maternal or developmental toxicity was observed in mice treated up to 2,100 mg/ kg/ day. No treatment related external, Page 15 of 46 visceral, or skeletal abnormalities were found in either species. Historically, the requirement for a rabbit prenatal developmental toxicity study has been waived. Given the data available on the toxicity of oxytetracyclines in rats, mice and humans and the lack of reported adverse effects to children and infants, further studies will not provide additional information for risk assessment.

In a study citation that was reported by a Joint FAO/ WHO committee in 2000, reproductive parameters in rats such as litter size, litter and pup weight, and the number and percent of live or dead fetuses did not show significant differences in the first or second generations. Additionally, growth rate was not significantly affected. The NOAEL in this study was 18 mg/ kg/ day ( note that only 1 dose was tested). Historically, the data requirement for the 2 generation reproductive study was waived. A reproductive study is unlikely to result in a more sensitive endpoint than the one already being used for risk assessment.

Although benign tumors were observed in rats, HED has no carcinogenicity concerns for this chemical. In F344/ N rats, histological examination showed a dose related increase in the incidence of benign phaeochromcytomas in the adrenal gland of male rats fed 2,500 mg/ kg/ day. In females an increase in the incidence of adenomas of the pituitary gland was found in the highest dose group ( 1,875 mg/ kg/ day). Mice fed up to 1,875 mg/ kg/ day exhibited no evidence of carcinogenicity. The bacterial reverse mutation test, chromosome aberration study, and sister chromatid exchange assays were all negative, with and without metabolic activation. The mouse lymphoma forward mutation assay revealed that oxytetracycline was mutagenic only with metabolic activation, however, the dose levels were close to toxic concentrations and the positive effect in the in vivo micronucleus assay in mice was not dose related.

The microbiological effects of oxytetracycline were investigated by studies examining the induction of drug resistant organisms in dogs. In a 6 week study in dogs, there was no increase in the level of resistant fecal coliforms at 2 ppm in the diet ( equivalent to 0.05 mg/ kg/ day). Dogs receiving 10 ppm ( equivalent to 0.25 mg/ kg/ day) displayed an increase in a multiple antibioticresistant population of enteric lactose fermenting organisms.

There is a relevant study on mice in the open literature. After oral administration of 47.6 mg 14Clabeled hydroxyoxytetracycline monohydrochloride/ kg b. w. to mice, 72% of the applied dose was found in the large intestine after 2 hours; only 5% was absorbed, of which the major portion ( 3.6%) was excreted in the urine. In the liver 1.9% and 1.1% of the dose applied was recovered after 1 and 2 hours, respectively.

Mode of Action and Data from Therapeutic ( Non pesticidal) Uses Tetracyclines exert their activity in bacteria by inhibiting protein synthesis. Inhibition occurs when oxytetracycline binds to the 30S ribosomes, preventing aninoacyl tRNA from reading the mRNA ribosome complex, thereby preventing polypeptide chain elongation. High concentrations of tetracyclines also impair protein synthesis in mammalian cells. However, the active transport Page 16 of 46 system found in bacteria is absent in these cells and there are differences in sensitivity at the ribosomal level. These differences are likely to be important determinants in the selective action of tetracyclines. In additional to the available animals studies and reports, there is extensive data on the toxicity of oxytetracyclines in humans. In humans, oxytetracycline is administered orally and intravenously to treat infectious diseases caused by a wide variety of microorganisms such as chlamydia, rickettsial, mycoplasma pneumonia, spirochetes, gram negative bacteria ( Bartonella bacilliformis, Pasteurella pestis, Brucella sp.), and gram positive bacteria ( Streptococcus sp., Staphylococcus aureus, Neisseria gonorrhoeae). Both the oral and intravenous dose for adults ranges from 1 to 2 grams per day. The daily oral dose for children is 25 to 50 mg/ kg daily in two to four divided doses.

The antibiotic may cause gastrointestinal irritation, mostly after oral administration, in some but not in all individuals. Epigastric burning and distress, abdominal discomfort, nausea, vomiting and diarrhea may occur which may be lessened by administrating oxytetracycline with a meal and/ or at more frequent intervals and smaller doses. Intravenous administration may produce thrombophlebitis. Oxytetracycline appears to be one of the least hepatoxic among the tetracyclines. Most hepatic toxicity develops in humans receiving 2000 mg or more of drug per day parenterally. This effect may occur when large quantities are administered orally. Pregnant women appear to be susceptible to severe tetracycline induced hepatic damage. Children under 7 years of age may develop a brown discoloration of the teeth. Treatment of pregnant women may also produce discoloration of the teeth of infants. Oxytetracycline is deposited in the skeleton of fetuses and children which can produce depression of bone growth. However, this is readily reversible if the period of exposure to the drug is short. ( Hardman et al., 10th ed)

Additionally, various skin reactions such as morbiliform rashes, urticaria, and generalized dermatitis may occur following exposure to oxytetracyclines in humans, but they are rare. Angioedema and anaphylaxis may develop. Other effects such as burning sensation of the eyes, cheilosis, brown or black coating of the tongue, atrophic or hypertrophic glossitis, pruritus ani or vulvae or vaginitis, fever and eosinophilia may persist for weeks after cessation of therapy. Administration of oxytetracycline to undernourished adults results in weight loss, increased urinary but not fecal nitrogen excretion, negative nitrogen balance, and elevated serum nonprotein nitrogen concentrations. Administration of oxytetracycline may lead to development of superinfections by strains of bacteria or yeasts resistant to the agent ( see antimicrobial resistance section). ( Hardman et al., 10th ed)

Tetracyclines as a class are incompletely absorbed from the gastrointestinal tract. The percentage of an oral dose of oxytetracycline absorbed by the gastrointestinal tract is 60 to 80%. Most absorption takes place in the stomach and upper small intestine. Absorption of tetracyclines is impaired by chelation of divalent or trivalent cations. Therefore, the absorption of oxytetracycline is compromised by the concurrent ingestion of dairy products, aluminum hydroxide gels, calcium, magnesium, iron and zinc salts, and bismuth subsalicylates. Tetracyclines are widely distributed through the body and into tissues and secretions, particularly in the liver, kidney, bones and teeth. Tetracyclines are eliminated primarily by the kidney, although they are also concentrated in the Page 17 of 46 liver and excreted by way of the bile into the intestines. Renal clearance of tetracyclines is by glomerular filtration. From 10 35% of the dose of oxytetracycline is excreted in active form in the urine as the parent drug. ( Hardman et al., 10th ed)

4.1.1 Qualitative Assessment of Antimicrobial Resistance Bacterial resistance to oxytetracycline as a result of drug use has long been recognized. HED recognizes that pesticidal uses of oxytetracycline may contribute to antibiotic resistance of bacterial pathogens with potential adverse public health consequences. This section of the risk assessment is a qualitative assessment of the development of antibiotic resistance from pesticidal uses. This is a qualitative assessment because not enough data are available to quantitate development of resistance.

Oxytetracycline has two major agricultural uses. It is used to treat plant and animal disease and at subtherapeutic doses in animals to promote growth. Clinically, oxytetracycline is a second line of defense against a host of infections. The pesticidal use of oxytetracycline on plants is small compared to the animal and human usage; it has been estimated as < 0.5% of all antibiotic uses ( McManus et al.). The mechanisms of action of antimicrobials is based on effecting the pathogenic organism and not the host. The database for oxytetracycline demonstrates that it is indeed of low toxicological concern as most adverse effects seen following oral oxytetracycline treatment in animals are observed at very high dosages ( e. g, near or above 1000 mg/ kg/ day in animals). In humans, there are demonstrated toxicological concerns associated with the use of oxytetracycline, although the risk of adverse effects are low.

Of more recent concern are the documented cases of tetracycline resistance and a marked potential for multi drug resistance and the development of super infections that may result from this resistance. Resistance to antibiotics has reduced the clinical effectiveness of the tetracyclines over the past few decades. Microorganisms often display cross resistance across the tetracycline family of compounds, that is microorganisms that become resistant to one tetracycline frequently exhibit resistance to others. Of the microorganisms which cause human disease, bacteria have and continue to develop resistance to antibiotics in general, particularly to enterobacters, enterococci and pseudomonads. Specifically, most strains of gram positive bacteria which cause human diseases are resistant to tetracyclines. Many of the enterobacteriaceae ( aerobic gram negative bacilli) have also developed resistance to tetracyclines. However, there are other alternatives to treatment with oxytetracycline. These alternatives include but are not limited to ( usually first line agents) gentamicin, penicillins, and others.

Although oxytetracycline has been used in plant agriculture for over 30 years without any documented evidence of human health effects, it is imperative that its potential impact on human health and the environment be further assessed based on the potential for the development of antibiotic resistance. Page 18 of 46 Given that the development of antibiotic resistance could pose a major threat to human health, that increased application of antibiotics in the environment has the potential to impact the acquisition of human pathogen resistance to antibiotics and the general lack of substantial data, the HED has adopted a qualitative risk assessment process similar to that of the Food and Drug Administration's Center for Veterinary Medicine in evaluating animal drugs Guidance for Industry # 152 ( URL: http:// www. fda. gov/ cvm/ Documents/ fguide152. doc) As a part of the hazard assessment/ characterization of oxytetracycline, the risk assessment team will qualitatively consider the potential impact on human health that the pesticidal uses of oxytetracycline might pose focusing on the following assessments: 1) Release Assessment: the probability that resistant bacteria are present in the commodity as a consequence of pesticidal use, 2) Exposure Assessment: the probability for humans to ingest bacteria in question from a relevant food commodity, and 3) Consequence assessment: the probability that human exposure to resistant bacteria results in an adverse health consequence. Criteria 1 & 2 will be assigned either a high, medium or low classification and criteria 3 will be assigned as important, highly important or critically important classification. The overall risk estimate, which integrates the components of risk assessment into an overall conclusion, provides a qualitative indication of the potential to human health of the proposed use of this antimicrobial pesticide and is ranked as high, medium, or low. The qualitative assessment is outlined below:

Release Assessment The probability that tetracycline resistant bacteria are present in the commodity as a consequence of the pesticidal use of oxytetracycline use is of medium concern. Application of antibiotics by occupational handlers to commodities in the orchard is of concern not only because of resistance pressure, but because of its potential to affect microorganisms in the orchard, whether they are beneficial, innocuous, pathogenic or otherwise. Orchards are treated prophylactically with antibiotics in the early spring when trees are most susceptible to infection. It is believed that by harvest, these antibiotics have fully degraded into the environment. In the US, oxytetracycline has been used on pear and apple for control of E. amylovora and on peach and nectarine for control of X. arboricola. There have been reports of tetracycline resistant strains of E. amylovora in apple orchards, however, the extent of this resistance is unknown at present time ( McManus et al). What is known is that these resistance genes are carried on mobile genetic elements such as plasmids and transposons identical or similar to those described in tetracycline resistant bacteria of environmental, animal and human origins. Transmission of resistant genes on mobile elements makes them easier to transmit between bacterial species than chromosomally mediated resistance mechanisms. Genes coding for antibiotic resistance can be transferred between bacteria and it is possible for bacteria never exposed to the antibiotic to acquire resistance from those which have. Additionally, tetracyclines can select for multi drug efflux pumps in bacteria that are capable of conveying resistance to other classes of antimicrobials. Considering these factors, there is a moderate concern that resistant genes present in the commodity and orchards can be released into the environment based on oxytetracycline's pesticidal uses. The default of medium concern is justified based on the confirmed presence of resistant genes in the orchards and the residual uncertainty related to the extent of the resistance present. Since, to date, there are no reports available regarding the quantitative amounts of tetracycline resistant bacteria on the plant commodities, it is possible to further refine this assessment by consideration of monitoring data Page 19 of 46 for antimicrobial resistance among bacteria isolated from fruits that are commonly treated with antibiotic pesticides. We recommend that the registrants supply monitoring data for antimicrobial resistance to oxytetracycline in the orchards. In addition, when additional appropriate screening and/ or testing protocols have been developed, oxytetracycline may be subjected to further screening and/ or testing to better characterize effects related to the release of tetracycline resistant bacteria into the environment.

Exposure Assessment The probability of humans ingesting resistant bacteria in question from a relevant food commodity ( peaches, pears, apples, and/ or nectarines) is of medium concern. There is a possibility of the oxytetracycline resistant plant pathogens being ingested by humans and transferring that resistance to bacteria that are responsible for causing broad spectrum human infections. The default ranking as a medium risk for exposure is justified by the fact that there is a medium probability that resistant plant pathogens are ingested. Although there is a medium concern that humans will ingest resistant bacteria present on food commodities, it is possible to further refine the assessment if the pesticidal use is significantly much less than the human and animal therapeutic uses and animal non therapeutic uses ( e. g., as a growth promoter). Accurate information on oxytetracycline use on plants vs. its therapeutic human and animal uses and non therapeutic animal uses would give further insight to the scope of the exposure and assist HED scientists in refining the assessment in order to modify our default characterization. We recommend that the registrants supply usage data for oxytetracycline on fruit trees currently used in order to incorporate the level of oxytetracycline pesticidal uses verses human and animal agricultural uses into the risk assessment. In addition, when additional appropriate screening and/ or testing protocols have been developed, oxytetracycline may be subjected to further screening and/ or testing to better characterize effects related to exposure of tetracycline resistant bacteria to humans via its plant agricultural use.

Consequence Assessment The probability that human exposure to resistant bacteria results in an adverse health consequence is highly important. Naturally occurring host flora in the intestine are a potential reservoir of genes that may become resistant to oxytetracycline and which may confer that resistance to pathogenic bacteria. Since many of the tetracyclines are incompletely absorbed from the gastrointestinal tract, high concentrations are reached in the intestinal contents and enteric flora are markedly altered. After repeated exposures, it is possible for resistant strains of aerobic and anaerobic coliform microorganisms and gram positive spore forming bacteria to appear. This could increase the potential for two human health consequences of antimicrobial resistance, an increase in food borne illnesses and an increase in the number of treatment failures. Tetracyclines are utilized for treatment of a variety of diseases and infections. Tetracyclines are a first choice for the control of diseases caused by microorganisms other than bacteria including chlamydiae, rickettsiae, mycoplasmas, and spirochetes. It is important to note that the CDC has indicated that resistance to the tetracyclines by chlamydia, mycoplasmas, rickettsiae and spirochetes has not occurred in approximately 50 years of clinical use. Oxytetracyclines are also broad spectrum antibiotics that are used for treating a wide variety of bacterial infections including infections of Page 20 of 46 the lungs, urinary system, respiratory system, skin, and eyes. They are also used as a prophylactic treatment following surgery or injury. Broad spectrum antibiotics are used in a variety of clinical situations. They are often used empirically prior to identifying the causative bacteria for an infection. Moreover, they are used when drug resistant bacteria do not respond to narrow spectrum antibiotics or in the case of superinfections, where there are multiple types of bacteria causing illness. It should be noted, however, that although oxytetracyclines are broadspectrum antibiotics, they are primarily used as second line agents for the control of most diseases and infections caused by bacteria and there are other alternatives to treatment with oxytetracycline. There is already a moderate level of resistance to these antibiotics by bacteria. Gentamicin and penicillins are often the first line agents against bacteria. However, oxytetracycline has recently been used as a second line agent for bacteria which pose significant health threats such as anthrax. Given the far reaching use of oxytetracycline and its use as a second line of defense against potentially deleterious microorganisms, the classification of highlyimportant is justified. When additional appropriate screening and/ or testing protocols have been developed, oxytetracycline may be subjected to further screening and/ or testing to better characterize effects related to human exposure of tetracycline resistant bacteria to humans via its plant agricultural use.

Overall Risk Estimate The overall risk of the development of antibiotic resistance to oxytetracycline in human health and the environment is medium. Following the recommendation of FDA's Guidance # 152, a medium concern for release and exposure and a highly important concern for consequence results in an overall risk assessment rank as medium. Please note that the overall risk estimate can be impacted by submission of monitoring data and usage data. While there are no monitoring data available, the estimated percentage of antibiotics applied to plants compared to all other antibiotic use is < 0.5% ( McManus et al). Monitoring studies ( see data needs [ Section 9.4] for suggestions) and accurate information on the usage of oxytetracycline on plants would allow for refinements of default assumptions.

Table 4.1a Acute Toxicity Profile  Test Substance Guideline No. Study Type MRID( s) Results Toxicity Category 870.11 Acute oral [ mice] No MRID LD50 = 7,200 mg/ kg IV Page 21 of 46 Table 4.1b Subchronic, Chronic and Other Toxicity Profile Guideline No./ Study Type MRID No. ( year)/ Classification / Doses Results 870.3100 90 Day oral toxicity ( mice) No MRID National Toxicology Program ( NTP) study 0, 3100, 6300, 12500, 25000, or 50,000 ppm M & F: 0, 465, 945, 1875, 3750, 7500 mg/ kg/ d NOAEL = 3750 mg/ kg/ day LOAEL = 7500 mg/ kg/ day based on decreases in body weight.

870.3150 90 Day oral toxicity ( rats) No MRID National Toxicology Program ( NTP) study 0, 3100, 6300, 12500, 25000, or 50,000 ppm 0, 155, 315, 625, 1250, 2500 mg/ kg/ day NOAEL = 2500 mg/ kg/ day ( HDT)

LOAEL = not identified.

870.3700a Prenatal developmental in ( rats) 00932391 Oxytetracycline hydrochloride 0, 1200, 1350, or 1500 mg/ kg/ day Maternal NOAEL = not identified LOAEL   1200 mg/ kg/ day based on increased incidence of respiratory signs and rough hair coat and decreased body weight gain, mortality, and percent of treated dams found pregnant ( LDT).

Developmental NOAEL = not identified LOAEL   1200 mg/ kg/ day based on decreased fetal body weights ( LDT). Page 22 of 46 870.3700b Prenatal developmental in ( mice) 00132392 Oxytetracycline hydrochloride 0, 1325, 1670, and 2100 mg/ kg/ day Maternal NOAEL   2100 mg/ kg/ day ( HDT)

LOAEL = not identified.

Developmental NOAEL   2100 mg/ kg/ day ( HDT)

LOAEL = not identified.

870.3800 Reproduction and fertility effects ( rat) No MRID Oxytetracycline hydrochloride 0 or 360 ppm 0 or 18 mg/ kg/ day Parental/ Systemic NOAEL= 18 mg/ kg/ day LOAEL = not identified.

Reproductive NOAEL and LOAEL > 18 mg/ kg/ day. No effects at the highest dose tested.

Offspring NOAEL = 18 mg/ kg/ day LOAEL = not identified.

870.4100a Chronic toxicity ( rat: Osborne Mendel) No MRID 0, 1000 or 3000 ppm 0, 5, 50 or 150 mg/ kg/ day NOAEL = 150 mg/ kg/ day ( HDT)

LOAEL = not identified.

870.4100b Chronic toxicity ( rat: Sprague Dawley) No MRID 0, 100, or 1000 ppm 0, 5, or 50 mg/ kg/ day NOAEL = 50 mg/ kg/ day ( HDT)

LOAEL = not identified.

870.4100c Chronic toxicity ( dog) 00132394 0, 100, 3000, or 10000 ppm 0, 2.5, 75, or 250 mg/ kg/ day NOAEL = 250 mg/ kg/ day ( HDT)

LOAEL = not identified. Page 23 of 46 870.4100d Chronic toxicity ( dog) 00132395 0, 5000, 10000 ppm 0, 125, or 250 mg/ kg/ day NOAEL = 125 mg/ kg/ day ( HDT)

LOAEL = not identified.

870.4200 Carcinogenicity ( mice) 00159856 Oxytetracycline hydrochloride 0, 6300, 12500 ppm 0, 945, 1875 mg/ kg/ day NOAEL = 945 mg/ kg/ day LOAEL = 1875 mg/ kg/ day based on decreased body weight in male mice.

No evidence of carcinogenicity 870.4300 Combined chronic toxicity/ carcinogeni city ( rat) 00159856 Oxytetracycline hydrochloride 0, 25000, 50000 ppm 0, 1250, or 2500 mg/ kg/ day NOAEL = not identified.

LOAEL = 1250 mg/ kg/ day based on fatty metamorphosis of the liver.

No evidence of carcinogenicity Bacterial reverse mutation test 870.5100 No MRID NTP Study Oxytetracycline hydrochloride 0 1 µ g/ ml in DMSO Negative up to 1 µ g/ plate with or without metabolic activation.

Mouse Lymphoma forward mutation assay 870.5195 No MRID NTP Study Oxytetracycline hydrochloride 12.5 800 µ g/ ml Concentrations of 100 and 200 mg/ ml were mutagenic in L5178Y/ TK+/ mouse lymphoma cells, only with metabolic activation.

Chromosome aberration assay ( CHO cells)

870.5375 No MRID NTP Study Oxytetracycline hydrochloride 80 200 µ g/ ml 700 900 µ g/ ml Negative up to 900 µ g/ ml with or without metabolic activation Page 24 of 46 Sister chromatid exchange assay ( CHO cells)

870.5900 No MRID NTP Study Oxytetracycline hydrochloride 60, 70 and 80 µ g/ ml 400, 500 and 700 µ g/ ml Negative up to 700 µ g/ ml with or without metabolic activation.

870.6200a Acute neurotoxicity screening battery NA 870.6200b Subchronic neurotoxicity screening battery NA 870.6300 Developmental neurotoxicity NA 870.7485 Metabolism and pharmacokinetics ( species) Data requirement historically waived. However a study from open literature is available. Oral administration of 47.6 mg 14C labeled hydroxyoxytetracycline monohydrochloride/ kg b. w. to mice, 72% of the applied dose was found in the large intestine after 2 hours; only 5% was absorbed, of which the major portion ( 3.6%) was excreted in the urine. In the liver 1.9% and 1.1% of the dose applied was recovered after 1 and 2 hours, respectively.

Special studies:

Antimicrobial resistance ( dogs) 40840101 NTP Oxytetracycline 0, 2, or 10 ppm 0, 0.05 or 0.25 mg/ kg/ day NOAEL = 0.05 mg/ kg/ day LOAEL = 0.25 mg/ kg/ day based on a shift from a predominantly drug susceptible population of enteric lactose fermenting organisms to a multiple antibioticresistant population in intestinal flora.

4.2 FQPA Hazard Considerations 4.2.1 Adequacy of the Toxicity Data Base Historically, all the toxicological data requirements for oxytetracycline have been waived. The prenatal developmental and carcinogenicity studies in rats and mice were the only acceptable studies submitted to the agency. However, given the extensive literature and study reports Page 25 of 46 available on the oxytetracyclines, this risk assessment takes a weight of the evidence approach, considering the available data from a variety of sources, including studies submitted and reviewed by the agency, the National Toxicology Program, the WHO, the FDA, and open literature studies. The information available on the effects of oxytetracycline in laboratory animals is sufficient to evaluate the toxicity of oxytetracycline and related compounds. Based on the information available from these sources, the database is complete and there are no datagaps.

4.2.2 Evidence of Neurotoxicity Neurotoxicity studies have not been conducted with oxytetracycline. However, no evidence of neurotoxicity was observed in any study. No clinical signs indicative of toxicity were noted in subchronic and chronic studies in dogs, rats, or mice.

4.2.3 Developmental Toxicity Studies Rat Developmental Studies In a rat prenatal developmental study ( MRID 00932391), thirty six female Charles River CD ( COBS) rats were dosed by gavage during days 6 through 15 of gestation with 1,200, 1,350, or 1,500 mg/ kg/ day of oxytetracycline hydrochloride. Thirty seven control dams received corn oil during the same time period. There were dose related decreases in maternal survival and body weight gain, and increases in incidence of breathing difficulties and rough coat. In addition, there were significant dose related decreases in the percent of treated dams found pregnant. There was also a dose related decrease in fetal body weight. The high incidence of maternal deaths and the fetotoxicity noted at all dose levels tested did not allow for an establishment of a NOAEL. The LOAEL was 1,200 mg/ kg/ day ( lowest dose tested). The significant findings discussed in this study can be attributed to the excessive dose levels used, thereby overly stressing the treated dams.

In a mouse prenatal developmental study ( MRID 00132392), groups of 42 female CD 1 mice were dosed by gavage during days 6 through 15 of gestation with 0, 1,350, 1,670, or 2,100 mg/ kg/ day of oxytetracycline hydrochloride. No adverse effects were demonstrated. The NOAEL for maternal and developmental toxicity in this study was 2,100 mg/ kg/ day ( highest dose tested).

Rabbit Development Study Historically, the requirement for a rabbit prenatal developmental toxicity study has been waived. Given the data available on the toxicity of oxytetracycline in rats and mice and the lack of reported adverse effects to children and infants, further studies will not provide additional information for risk assessment. Page 26 of 46 4.2.4 Reproductive Toxicity Study Historically, the data requirement for the 2 generation reproductive study was waived. The cRfD derived from the resistance study in mature beagles will be protective for all effects. Data gathered from further studies will not provide additional information for risk assessment.

Although the data requirement was waived by the agency, a literature study conducted in 1954 and cited by the WHO is available. In a reproduction study, groups of female and 10 male Wistar rats were fed diets containing 0 or 360 ppm oxytetracycline hydrochloride beginning at weaning ( 23 days of age). Animals were first mated at 120 days of age. A second mating was performed one month after the weaning of the first litter. One male and one female of these second litters were mated and effects on reproduction and lactation were determined in the second generation. Growth rate was not significantly affected. Reproductive parameters such as litter size, litter and pup weight, and the number and percent of live or dead fetuses did not show significant differences in the first or second generations. Dosed pups of both generations gained significantly more weight from days 3 21 post partum compared to controls. The NOAEL in this study was 360 ppm oxytetracycline hydrochloride, equivalent to 18 mg/ kg/ day.

4.2.5 Additional Information from Literature Sources Extensive information is available from literature sources and have been cited where appropriate in the risk assessment.

4.2.6 Pre and/ or Postnatal Toxicity <IP_ADDRESS> Determination of Susceptibility No quantitative or qualitative evidence supports increased susceptibility of rat or mouse fetuses from in utero exposure to oxytetracycline in the developmental toxicity studies. Effects on offspring body weight were seen in the presence of systemic effects in the dam. The data requirement for the 2 generation reproduction study has been waived but a study available in literature demonstrates no quantitative or qualitative evidence of increased susceptibility in rats.

<IP_ADDRESS> Degree of Concern Analysis and Residual Uncertainties for Pre and/ or Post natal Susceptibility There is a low degree of concern and no residual uncertainties; therefore, the FQPA safety factor can be adjusted to 1X.

4.3 Recommendation for a Developmental Neurotoxicity Study Page 27 of 46 4.3.1 Evidence that supports requiring a Developmental Neurotoxicity study The available data on the toxicity of oxytetracycline do not support the recommendation for a developmental neurotoxicity study.

4.3.2 Evidence that supports not requiring for a Developmental Neurotoxicity study The available data on the toxicity of oxytetracycline do not support the recommendation for a developmental neurotoxicity study.

4.4 Hazard Identification and Toxicity Endpoint Selection 4.4.1 Acute Reference Dose ( aRfD)  Females age 13 49 and the General Population No appropriate endpoint for females age 13 49 or for the general population attributable to a single exposure.

4.4.2 Chronic Reference Dose ( cRfD)

Studies Selected: Microbiological effects in dogs.

MRID No.: 40840101( dog; NTP study)

Executive Summary: Study 1 Microbiological Effects in Dogs Mature beagles were fed a ground meal diet containing 0, 2, or 10 ppm of oxytetracycline for 44 days ( equivalent to 0, 0.05, or 0.25 mg/ kg/ day). Fecal samples from individual animals were collected during the experimental period and examined for resistant coliforms by a comparative plate counting technique. The 10 ppm ( 0.25 mg/ kg/ day) diet resulted in a shift from a predominantly drug susceptible population of enteric lactose fermenting organisms to a multiple antibiotic resistant population. A shift to resistance did not occur in the group fed 2 ppm ( 0.05 mg/ kg/ day).

Dose and Endpoint: The NOAEL of 0.05 mg/ kg/ day based on a shift from a predominantly drugsusceptible population of enteric lactose fermenting organisms to a multiple antibiotic resistant population at 0.25 mg/ kg/ day ( LOAEL) in mature beagle dogs. Page 28 of 46 Comments about Study/ Endpoint/ UF: The selection of the chronic endpoint was based on the microbiological study in dogs. The endpoint is conservative and protective for the entire toxicological database and was selected based on the qualitative classification of overall risk of resistance being medium. Other studies in the toxicological database demonstrated NOAELs near or above 1000 mg/ kg/ day with the exception of a cited 2 generation reproductive study which had a NOAEL of 18 mg/ kg/ day. Based on the data available, the UF for the dog study is 10X for intraspecies variations and 10X for interspecies extrapolation. The cRfD was selected using an animal resistance endpoint in mature beagle dogs. The risk assessment team acknowledges that this study is not a precise description of antibiotic resistance in animals or humans. It is, however, a good indicator of the selective pressure of antibiotic usage and recognizes the potential for resistance in future infections.

Chronic RfD = 0.05 mg/ kg/ day = 0.0005 mg/ kg/ day ( dog study)

100 4.4.3 Recommendation for Aggregate Exposure Risk Assessments As per 1996 FQPA, when there are potential residential exposures to the pesticide, aggregate risk assessment must consider exposures from three major sources: oral, dermal and inhalation exposures. The requirement of occupational or residential exposure monitoring data is not required by the agency therefore the dermal and inhalation routes were not considered in this risk assessment. The oral route of exposure is the only route of concern and is addressed in this risk assessment.

4.4.4 Classification of Carcinogenic Potential The RfD/ Peer Review Committee ( File R058617, dated 12/ 18/ 92) concluded that the doses tested in the rat and mice are adequate for carcinogenicity testing, and the data evaluation records for these two studies are adequate. The chemical was tested in rats up to 50,000 ppm ( 2500 mg/ kg/ day) and in mice up to 12,500 ppm ( 1875 mg/ kg/ day). On the basis of these two studies, the chemical was classified as a " Group D."

This classification is in agreement with the conclusion made by the National Toxicology Program's ( NTP) Peer Review Committee. In their report, the NTP Peer Review Committee concluded that " . . there was equivocal evidence of carcinogenicity for male F344/ N rats ( the high dose group) as indicated by increased incidences of pheochromocytomas of the adrenal gland [ with a statistically significant positive trend, not significant in pairwise comparison with concurrent controls, and was outside the historical control range]. There was equivocal evidence of carcinogenicity for females F 344/ N rats as indicated by increased incidences of adenomas of the pituitary gland [ to have a high background rate] in the high dose group". With respect to the Page 29 of 46 mouse study, the NTP report concluded that ".... there was no evidence of carcinogenicity for male or female B6C3F1 mice fed oxytetracycline hydrochloride for two years."

Given the equivocal nature of the carcinogenic response in the rat study at an extremely high dose level ( especially when the actual dietary exposure to man is taken into consideration), and the fact that mutagenicity data were somewhat inconclusive, the RED cRFD/ Peer Review Committee felt that the " D Group" classification is appropriate. It should be emphasized, however, that this classification is based on adequate studies in two animal species. Therefore, new carcinogenicity studies are not needed at this time. The Committee indicated that the carcinogenicity issue may be revisited if the exposure changes.

Table 4.4. Summary of Toxicological Doses and Endpoints for Chemical for Use in Human Risk Assessments Exposure Scenario Dose Used in Risk Assessment, UF Special FQPA SF* and Level of Concern for Risk Assessment Study and Toxicological Effects Acute Dietary ( females 13 49 and the general population) None selected No appropriate endpoint for females age 13 49 or for the general population attributable to a single exposure.

Chronic Dietary ( all populations) NOAEL = 0.05 mg/ kg/ day ( dogs)

UF = 100 cRfD = 0.0005 mg/ kg/ day FQPA SF = 1X cPAD =

chronic RfD FQPA SF = 0.0005 mg/ kg/ day Microbiological Study in Dogs LOAEL = 0.25 mg/ kg/ day based on a shift from a predominantly drugsusceptible population of enteric lactose fermenting organisms to a multiple antibiotic resistant population.

Cancer ( oral, dermal, inhalation) Classification: The Agency's Peer Review Committee has classified oxytetracycline as a " Group D" carcinogen (" Not Classifiable as to Human Carcinogenicity").

UF = uncertainty factor, FQPA SF = Special FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest observed adverse effect level, PAD = population adjusted dose ( a = acute, c = chronic) RFD = reference dose, MOE = margin of exposure, LOC = level of concern, NA = Not Applicable 4.5 Special FQPA Safety Factor Based on the hazard data, the risk assessment team recommended the special FQPA safety factor be reduced to 1x because there is a low degree of concern and no residual uncertainties with regard to pre and/ or postnatal toxicity. The oxytetracycline risk assessment team evaluated the quality of the exposure data; and, based on these data, recommended that the special FQPA safety factor be reduced to 1x. The recommendation is based on the following:

° The dietary food exposure assessment utilizes mean residue levels and percent crop treated Page 30 of 46 information for all relevant commodities, and monitoring data to estimate possible livestock residue levels. By using these refined assessments, chronic exposures are not likely to be underestimated.

° The dietary drinking water assessment ( Tier 1 estimates) yields values generated by modeling methods which are designed to provide conservative, health protective, high end estimates of water concentrations.

4.6 Endocrine disruption EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to determine whether certain substances ( including all pesticide active and other ingredients) " may have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or other such endocrine effects as the Administrator may designate." Following recommendations of its Endocrine Disruptor and Testing Advisory Committee ( EDSTAC), EPA determined that there was a scientific basis for including, as part of the program, the androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC's recommendation that the Program include evaluations of potential effects in wildlife. For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in wildlife may help determine whether a substance may have an effect in humans, FFDCA authority to require the wildlife evaluations. As the science develops and resources allow, screening of additional hormone systems may be added to the Endocrine Disruptor Screening Program ( EDSP). In the available toxicity studies on oxytetracycline, there was no estrogen, androgen, and/ or thyroid mediated toxicity.

When additional appropriate screening and/ or testing protocols being considered under the Agency's EDSP have been developed, oxytetracycline may be subjected to further screening and/ or testing to better characterize effects related to endocrine disruption.

5.0 Public Health Data Reference: Review of Oxytetracycline Incident Reports. Monica Hawkins. D315687. 22 AUG 2005.

There were almost no reports of ill effects from exposure to oxytetracycline in the available data bases.

6.0 Exposure Characterization/ Assessment 6.1 Dietary Exposure/ Risk Pathway Page 31 of 46 Reference: Oxytetracycline Reassessment Eligibility Decision ( TRED). Summary of Product Chemistry and Residue Data. William Donovan. D315689. 15 AUG 2005.

6.1.1 Residue Profile Due to the widespread use of oxytetracycline as a drug, and the low residue levels expected in or on tree fruit, no plant or livestock metabolism data are required ( see memo of W. J. Hazel dated 4/ 12/ 88; memo of W. B. Greer dated 4/ 19/ 88; and memo of R. B. Perfetti dated 10/ 13/ 92). Permanent tolerances are established for residues of oxytetracycline per se in/ on peaches, pears at 0.35 ppm [ 40 CFR § 180.337]. IR 4 has submitted a tolerance petition ( PP# 7E4855) proposing residues of oxytetracycline per se in/ on apples at 0.35 ppm. There are currently no tolerances for oxytetracycline residues in livestock commodities or for inadvertent residues in rotational crops.

As noted in the oxytetracycline Registration Standard ( 4/ 14/ 1988), the available microbiological assay method for the determination of oxytetracycline residues in or on tree fruit is inadequate for tolerance enforcement; however, this method was used for data collection purposes. The method is similar to Final Action Microbiological Methods I and II in the AOAC Official methods of Analysis ( 1984; 42.293 42.298). This method is nonspecific and insufficiently sensitive for quantitative determination of oxytetracycline because it does not distinguish oxytetracycline from other compounds that may alter the response of the bioassay test organism. The available data indicate that recoveries are generally low and markedly variable. In a 12/ 15/ 04 meeting of the HED Chemistry Science Advisory Council ( ChemSAC), the Council reaffirmed that the described method is not acceptable for tolerance enforcement purposes, and recommended that the registrant develop a validated enforcement method based on HPLC, similar to AOAC methods 995.09 and 995.04, which use HPLC to determine tetracycline levels in animal tissues and milk, respectively.

The use of oxytetracycline as a drug in food animals is regulated by the FDA according to 21 CFR 556.500. The FDA has established the following tolerances for the sum of residues of the tetracyclines including chlortetracycline, oxytetracycline, and tetracycline: 2 ppm in muscle ( meat) of cattle, swine, sheep, poultry, fish and lobsters; 6 ppm in liver, 12 ppm in fat and kidney, and 0.3 ppm in milk. HED notes that the drug uses of oxytetracycline in livestock result in considerably higher exposure levels to oxytetracycline residues than the agricultural uses; the estimated percentage of antibiotics applied to plants compared to all other antibiotic use is < 0.5% ( McManus et al.). Wet apple pomace is a feedstuff of regulatory interest associated with apples, while peaches/ nectarines and pears have no livestock feedstuffs. Due to low oxytetracycline residue levels in apples, quantifiable residues of oxytetracycline in livestock commodities as a result of feeding wet apple pomace from treated apples are not expected. Therefore, based on the agricultural uses of oxytetracycline, HED finds there is no reasonable expectation that residues of concern will transfer to livestock tissues [ 40 CFR § 180.6( a)( 3)]. However, to account for the possibility of oxytetracycline residues in livestock commodities arising from drug and sub Page 32 of 46 therapeutic dosing of animals, HED included the results of FSIS livestock monitoring data from the years 2002 2004 in the dietary exposure analyses ( see section 6.1.2).

Adequate field trial data are available to support the use of oxytetracycline in/ on peach and pear. An adequate number of field trials were conducted in the appropriate geographical regions using the appropriate formulation applied at the maximum use rate.

Crop field trials for apples were conducted from 0.5 to 11.6x the proposed seasonal rate of 1.53 lb ai/ A and from 49 to 61 days PHI as compared to the proposed PHI of 60 days. Residues were largely at the limit of quantitation ( LOQ) of 0.013 and 0.2 ppm up to 0.252 ppm. The mean apple residue level found at a 1x treatment rate was 0.033 ppm ( D298424, W. Cutchin, 03 JAN 2005). Considering the wide range of application rates, up to 11.6x the recommended rate, the general lack of detectable oxytetracycline residues, and the existence of the data on a similar crop ( pear), HED tentatively concludes that adequate field trial data are available to support the establishment of a tolerance for residues of oxytetracycline per se in/ on apples at 0.35 ppm, provided that an adequate analytical enforcement method is developed and submitted.

No data have been submitted for processed food uses of oxytetracycline, as no processed commodity data are required for peaches or pears. Apple processed commodities were produced from apples treated at 5 and 11.6x the proposed use rate. Residues were below LOQ on the apple RACs and apple processed commodities. As the maximum theoretical concentration factor for apple pomace is 14x, the processing studies indicate that concentration of oxytetracycline would not be expected in processed apple commodities. Tolerances are not required on apple processed commodities.

Data were not submitted for confined accumulation in rotational crops. The use sites will not involve rotated crops; therefore, data are not required for rotational crops.

6.1.2 Chronic Aggregate Dietary Exposure and Risk Reference: Oxytetracycline Chronic Dietary Exposure Assessments for the Tolerance Reregistration Eligibility Decision ( TRED). Revised After Phase 1 Error Only Corrections. DP Barcode: D315686, William Donovan, 06 FEB 2006.

Chronic aggregate risk assessments were conducted using the Dietary Exposure Evaluation Model  Food Consumption Intake Database ( DEEM FCID   , Version 2.0) model. This model uses food consumption data from the USDA's Continuing Surveys of Food Intakes by Individuals ( CSFII) from 1994 1996 and 1998. The analyses were performed to support the tolerance reregistration eligibility decision for oxytetracycline. Page 33 of 46 The chronic analysis used anticipated residue levels for apples, peaches ( and nectarines), and pears, percent crop treated information as supplied by BEAD together with default processing factors, and monitoring data from the Food Safety Inspection Service ( FSIS) collected during the years 2002 2004 to estimate residue levels in livestock commodities. Thus, the following average residue values were used for apples; peaches and pears; and livestock commodities: 0.033, 0.20, and 0.0058 ppm, respectively. Drinking water was incorporated directly in the dietary assessment using the highest relevant chronic estimated drinking water concentration ( EDWC) for surface water generated by the FIRST model: 4.6 ppb. Table 6.1.2a summarizes the results of the chronic dietary analyses.

Table 6.1.2a. Results of Chronic Dietary ( Food + Water) Exposure Analysis Using DEEM FCID DEEM FCID   Population Subgroup cPAD ( mg/ kg/ day) Exposure ( mg/ kg/ day) % cPAD General U. S. Population 0.0005 0.000160 32 All Infants (< 1 year old) 0.0005 0.000473 95 Children 1 2 years old 0.0005 0.000441 88 Children 3 5 years old 0.0005 0.000329 66 Children 6 12 years old 0.0005 0.000205 41 Youth 13 19 years old 0.0005 0.000121 24 Adults 20 49 years old 0.0005 0.000127 25 Adults 50+ years old 0.0005 0.000132 26 Females 13 49 years old 0.0005 0.000126 25 The resulting chronic aggregate dietary exposure estimates using the DEEM FCID model were less than 100% of the cPAD for the U. S. population and all population subgroups. Oxytetracycline chronic aggregate exposure ( food + water) was estimated at 0.000160 mg/ kg/ day for the U. S. population ( 32% of the cPAD) and 0.000473 mg/ kg/ day ( 95% of the cPAD) for the most highly exposed population subgroup ( All Infants (< 1 year old)). These results indicate that chronic aggregate dietary exposure to oxytetracycline from food and drinking water is below HED's level of concern for all population subgroups.

For comparison purposes, a second chronic dietary analysis was conducted to depict exposure levels resulting from food uses only. Table 6.1.2b summarizes the results of the food only analysis, which, when compared to the food + water results in Table 6.1.2a, shows the relative Page 34 of 46 contributions of water and food sources to the total exposure level to residues of oxytetracycline.

Table 6.1.2b. Results of Chronic Dietary ( Food Only) Exposure Analysis Using DEEM FCID DEEM FCID   Population Subgroup cPAD ( mg/ kg/ day) Exposure ( mg/ kg/ day) % cPAD General U. S. Population 0.0005 0.000063 13 All Infants (< 1 year old) 0.0005 0.000155 31 Children 1 2 years old 0.0005 0.000297 59 Children 3 5 years old 0.0005 0.000194 39 Children 6 12 years old 0.0005 0.000112 23 Youth 13 19 years old 0.0005 0.000051 10 Adults 20 49 years old 0.0005 0.000036 7.2 Adults 50+ years old 0.0005 0.000037 7.3 Females 13 49 years old 0.0005 0.000036 7.2 Based on these analyses, the food only chronic dietary risk from existing and proposed uses of oxytetracycline are below HED's level of concern for the general US population and all population subgroups. The highest food only chronic dietary exposure ( 0.000297 mg/ kg/ day) was found for Children 1 2 years old ( 59% cPAD), while that for the US population was 0.000063 mg/ kg/ day ( 13% cPAD). The results presented in Tables 6.1.2a and 6.1.2b clearly indicate that water consumption is a large contributor to chronic dietary exposure of oxytetracycline residues.

6.2 Water Exposure/ Risk Pathway Reference: Tier I Drinking Water Exposure Assessment of Oxytetracycline Supporting the Reassessment Under FQPA of Pear and Peach & Nectarine Use Patterns and the Assessment of the New Use Pattern, Apple. Greg Orrick, D315690, 04 AUG 2005.

Tier I Estimated Drinking Water Concentrations ( EDWCs) were calculated for oxytetracycline using the surface and ground water models FIRST V 1.0 and SCI GROW V 2.3, respectively. The highest resulting EDWC values reflecting the maximum use pattern for oxytetracycline ( on Page 35 of 46 peaches and nectarines) are presented in Table 6.2.

Table 6.2. Summary of Estimated Surface and Ground Water Concentrations for Oxytetracycline.

Oxytetracycline Exposure Duration Surface Water EDWC, ppb a Ground Water EDWC., ppb b Chronic 4.6 0.033 a From the Tier 1 FIRST model. Input parameters are based on the physical properties of oxytetracycline, and assuming 9 separate applications of oxytetracycline calcium to peaches and/ or nectarines at a rate of 0.642 lb ai/ A with a 7 day retreatment interval.

b From the SCI GROW model assuming 9 separate applications of oxytetracycline calcium to peaches and/ or nectarines at a rate of 0.642 lb ai/ A with a 7 day retreatment interval.

Because the highest EDWC value was obtained for surface water ( 4.6 ppb), this level was selected for use a point estimate in the aggregate dietary analysis of oxytetracycline.

6.3 Residential ( Non Occupational) Exposure/ Risk Pathway Oxytetracycline uses are being supported only for the following agricultural crops: apples, peach, pear, and nectarine. There are no anticipated exposures in or around homes or recreational areas.

6.3.1 Home Uses  Not applicable.

6.3.2 Recreational Uses  Not applicable.

6.3.3 Other ( Spray Drift, etc.)

Spray drift is always a potential source of exposure to residents nearby to spraying operations. This is particularly the case with aerial application, but, to a lesser extent, could also be a potential source of exposure from the ground application method employed for oxytetracycline. The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices. On a chemical by chemical basis, the Agency is now requiring interim mitigation measures for aerial applications that must be placed on product labels/ labeling. The Agency has completed its evaluation of the new data base submitted by the Spray Drift Task Force, a membership of U. S. pesticide registrants, and is developing a policy on how to appropriately apply the data and the AgDRIFT computer model to its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic methods. After the policy is in place, the Agency may Page 36 of 46 impose further refinements in spray drift management practices to reduce off target drift with specific products with significant risks associated with drift. Page 37 of 46 7.0 Aggregate Risk Assessments and Risk Characterization In accordance with the FQPA, HED must consider and aggregate ( add) pesticide exposures and risks from various sources including food, drinking water, and residential exposures. In an aggregate assessment, exposures from relevant sources are added together and compared to quantitative estimates of hazard ( e. g., a NOAEL or PAD), or the risks themselves can be aggregated. When aggregating exposures and risks from various sources, HED considers both the route and duration of exposure.

For most pesticide active ingredients, water monitoring data are considered inadequate to determine surface and ground water drinking water exposure estimates, so model calculations have been used to determine estimated drinking water concentrations ( EDWCs). FDA approved uses of oxytetracycline were included in the chronic aggregate risk assessment through the use of Food Safety Inspection Service ( FSIS) monitoring data of livestock commodities in the dietary analyses.

7.1 Acute Aggregate Risk An acute aggregate risk assessment was not conducted because no endpoint of concern attributable to a single dose was identified.

7.2 Chronic Aggregate Risk A chronic aggregate risk assessment was conducted for oxytetracycline, as presented in Section 6.1.2. In summary, chronic aggregate exposures to oxytetracycline in food and drinking water are not of concern from a risk perspective.

8.0 Cumulative Risk Characterization/ Assessment 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 oxytetracycline and any other substances, and oxytetracycline does not appear to produce a toxic metabolite produced by other substances. For the purposes of this tolerance action, therefore, EPA has not assumed that oxytetracycline has a common mechanism of toxicity with other substances. For information regarding EPA's efforts to determine which chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the policy statements released by EPA's Office of Pesticide Programs concerning common mechanism determinations and procedures for cumulating effects from substances found to have a common mechanism on EPA's website at http:// www. epa. gov/ pesticides/ cumulative/. Page 38 of 46 9.0 Data Needs and Label Requirements 9.1 Toxicology None 9.2 Residue Chemistry The registrant should submit a validated analytical enforcement method ( Guideline # 860.1340) for oxytetracycline. This should include an independent laboratory validation ( ILV), and an acceptable confirmatory method. Once these are received, BEAD/ ACL will be requested to conduct a petition method validation ( PMV) of the enforcement method. Note that the tolerance reassessment summary presented in Appendix 3.0 of this document is contingent upon successful Agency completion of PMV of the analytical enforcement method.

9.3 Occupational and Residential Exposure None 9.4 Recommended Data for Refining Qualitative Risk Assessment ( Note that submission of this data is recommended to further refine the qualitative assessment but is not required)

° Since oxytetracycline's potential contributions to antibiotic resistance are not fully understood, monitoring for antimicrobial resistance among bacteria isolated from fruits that are commonly treated with antibiotic pesticides is suggested ( possibly through the National Antimicrobial Resistance Monitoring System or by expanding a CDC pilot study of antibiotic resistance in orchards).

° Additional usage data specific to pesticidal use of oxytetracycline ( or tetracyclines) relative to human and animal therapeutic uses and animal non therapeutic use ( e. g., as a growth promoter). Page 39 of 46 10.0 References Regulatory Documents on Oxytetracycline:

Tier I Drinking Water Exposure Assessment of Oxytetracycline Supporting the Reassessment Under FQPA of Pear and Peach & Nectarine Use Patterns and the Assessment of the New Use Pattern, Apple. Greg Orrick, D315690. 04 AUG 2005.

Oxytetracycline Chronic Dietary Exposure Assessment for the Tolerance Reassessment Eligibility Decision ( TRED). Revised After Phase 1 Error Only Corrections. William Donovan. D315686. 06 FEB 2006.

Oxytetracycline Reassessment Eligibility Decision ( TRED). Summary of Product Chemistry and Residue Data. William Donovan. D315689. 15 AUG 2005.

Screening Level Usage Analysis ( SLUA) for Oxytetracycline. Alan Halvorson. 1/ 3/ 05.

Hydroxytetracycline Monohydrochloride and Oxytetracycline Calcium Reregistration Eligibility Document ( RED). 3/ 30/ 93.

Review of Oxytetracycline Incident Reports. Monica Hawkins. D315687. 22 AUG 2005.

Oxytetracycline. Section 3 Use on Apples. Summary of Analytical Chemistry and Residue Data. Petition Number 7E4855. William Cutchin. D298424. 03 JAN 2005.

Articles on Oxytetracycline from the Open Literature:

ABBITT, B., BERNDTSON, W. E. & SEIDEL, G. E. ( 1984). Effect dihydrostreptomycin or oxytetracycline on reproductive capacity of bulls. Am. J. Vet. Res., 45, 2242 2246.

ANDREWS, A. W., FORNWALD, J. A. & LIJINSKY, W. ( 1980). Nitrosation and mutagenicity of some amine drugs. Toxicol. Appl. Pharmacol., 52, 237 244. Page 40 of 46 BLACK, W. D. & GENTRY, R. D. ( 1984). The distribution of oxytetracycline in the tissues of swine following a single oral dose. Can. Vet. J., 25, 158 161.

BURROWS, G. E., BARTO, P. B. & MARTIN, B. ( 1987). Comparative pharmacokinetics of gentamicin, neomycin and oxytetracycline in newborn calves. J. Vet. Pharmacol. Therap., 10, 54 63.

CORPET, D. & LUMEAU, S. ( 1987). Effect of low levels of antimicrobials on drug resistant populations of intestinal bacteria in gnotobiotic mice. In Fedesa report: Rational view of antimicrobial residues. An assessment of human safety. Abstracts of a seminar held in Zurich, March 24.

DEICHMANN, W. B., BERNAL, E., ANDERSON, W. A. D., KEPLINGER, M., LANDEEN, K., MCDONALD, W., MAHON, R. & STEBBINS, R. ( 1964). The chronic oral toxicity of oxytetracycline HCl and tetracycline HCl in the rat, dog and pig. Ind. Med. Surg., 787 806.

EPA ( 1988). Guidance for the registration of pesticide product containing oxytetracycline, oxytetracycline hydrochloride and oxytetracycline calcium complex as the active ingredient. OMB control no. 2070 0057. Submitted to WHO by Pfizer Central Research, Groton, CT, USA.

GYRD HANSEN, N. ( 1980). The effect of tetracyclines on the rabbit heart. Zbl. Vet Med. A., 27, 288 237.

HARDMAN, J. G., LIMBIRD, L. E., GILMAN, A. G. ( 2001) Goodman and Gilman's the pharmacological basis of therapeutics. 10th ed. New York: McGraw Hill.

IMMELMAN, A. ( 1977). Blood levels of oxytetracycline in dogs after oral administration. J. South African Vet. Assoc., 48 ( 3), 183 186.

LEBEK, G. & EGGER, R. ( 1983). The effect of low levels of antibiotics on the selection of resistance in intestinal bacteria in vitro observations. Cited in Fedesa report: Rational view of antimicrobial residues. An assessment of human safety. Abstract of a seminar held in Zurich, March 24.

LEVY, J., ORNOY, A. & ATKIN, I. ( 1980). Influence of tetracycline on the calcification of epiphyseal rat cartilage. Transmission and scanning electron microscopic studies. Acta Anat., 106, 360 369.

LIKINS, R. C. & PAKIS, G. A. ( 1965). Fetal uptake of radiocalcium in tetracycline treated rats. Nature, 5004, 1394 1395.

MCMANUS, PS; STOCKWELL, VO; SUNDIN, GW; JONES, AL ( 2002) Antibiotic Use in Page 41 of 46 Plant Agriculture, Annu Rev Phytopathol, 40: 443 65 MEVIUS, D. J., VELLENGA, L., BREUKINK, H. J., NOUWS, J. F. M., VREE, T. B., & DRIESSENS, F. ( 1986a). Pharmacokinetics and renal clearance of oxytetracycline in piglets following intravenous and oral administration. The Vet. Quart., 8( 4) 274 284.

MEVIUS, D. J., Nouws, J. F. M., Breukink, H. J., Vree, T. B., Driessens, F.& Verkaik, R. ( 1986b). Comparative pharmacokinetics, bioavailability and renal clearance of five parenteral oxytetracycline  20% formulations in diary cows. The Vet. Quart., 8( 4) 285 294.

MORRISSEY, R. E., TYL, R. W., PRICE, C. J., LEDOUX, T. A., REEL., J. R., PASCHKE, L. L., MARR, M. C. & KIMMEL, C. A. ( 1986). The developmental toxicity of orally administered oxytetracycline in rats and mice. Fund. Appl. Toxicol., 7, 434 443.

NOUWS, J. F. M., VAN GINNIKEN, C. A. M. & ZIV, G. ( 1983). Age dependent pharmacokinetics of oxytetracycline in ruminants. J. Vet. Pharmacol. Therap., 6, 59 66.

NOUWS, J. F., VREE, T. B., TERMOND, E., LOHUIS, J., VAN LITH, P., BINKHORST, G. J. & BREUKINK, H. J. ( 1985). Pharmacokinetics and renal clearance of oxytetracycline after intravenous and intramuscular administration to diary cows. The Vet. Quart., 7( 4), 296 305.

NTP ( 1987). Toxicology and carcinogenesis studies of oxytetracycline hydrochloride in F344/ N rats and B6C3F1 mice. ( feed studies). National Toxicology Program, Technical reports series No. 315. Submitted to WHO by NTP, Research Triangle Park, NC, U. S. A.

PRASAD, S., JAYACHANDRAN, C. & SINGH, M. K. ( 1987). Pharmacokinetics of oxytetracycline in dairy cows. Ind. J. Anim. Sciences, 157( 2), 106 110.

ROLLINS, L. D., GAINES, S. A., POCURULL, D. W., & MESEAR, H. D. ( 1975). Animal model for determining the no effect level of an antimicrobial drug on drug resistance in the lactose fermenting enteric flora. Antimicrob. Agents Chemother., 7, 661 665.

SANDE, M. A. & MANDELL, G. L. ( 1985). Tetracyclines, Chloramphenicol, Erythromycin and miscellaneous antibacterial agents. In: Goodman and Gilman's, The Pharmacological Basis of Therapeutics. 7th edition, Macmillan Publishing Company, New York. 1170 1176.

SNELL, J. F., GARKUSCHA, R., & ALLEN, E. L. ( 1957). Radioactive Oxytetracycline II. Distribution in C 57 BL Mice ( preliminary experiments). Antibiot. Ann., 502 506.

SWEZEY, J. L., BALDWIN, B. B. & BROMEL, M. C. ( 1981). Environment and health. Effect of oxytetracycline as a turkey feed additive. Poultry Science, 60, 738 743.

SZUMIGOWSKA SZEAJBER, G. & JESKE, J. ( 1970). Influence of tetracycline base, tetracycline hydrochloride and oxytetracycline base on development of metatarsal bones in the rat fetus. Acta Polon. Pharm., 27( 1), 78 83. Page 42 of 46 TARARA, R. P., HANSEN, L. G. & SIMON, J. ( 1976). Effects of repeated administration of oxytetracycline on kidney, liver and liver mixed function oxidases in the rat. Toxicol. Appl. Pharmacol., 35, 321 331.

TAYLOR, H. W. & LIJINSKY, W. ( 1975). Tumor induction in rats by feeding aminopyrine or oxytetracycline with nitrite. Int. J. Cancer, 16, 211 215.

URAM, J. A., FRENCH C. E., BARRON, G. P., & SWIFT, R. W. ( 1954). The effect of high levels of terramycin or streptomycin on growth, reproduction and lactation of the rat. J. Nutr., 481 492.

XIA, W., GYRD HANSEN, N & NIELSEN, P. ( 1983). Comparison of pharmacokinetic parameters for oxytetracycline preparations in pigs. J. Vet Pharmacol. Therap., 113 120. Page 43 of 46 11.0 APPENDICIES 1.0 TOXICOLOGY DATA REQUIREMENTS The requirements ( 40 CFR 158.340) for food uses of oxytetracycline are listed in the table below. Use of the new guideline numbers does not imply that the new ( 1998) guideline protocols were used. The prenatal developmental and carcinogenicity studies in rodents are the only acceptable submitted studies in the oxytetracycline database. Historically, all database requirements were waived based on animal data that are available from various sources ( open literature, NTP, etc). Thus, the agency did not require any toxicity studies on the technical grade ingredient. This waiver is justified based on the current availability of animal data. Therefore, none of the studies are required but all of the study requirements are satisfied by the plethora of information available on oxytetracycline in animals. The data obtained from various sources are listed in Tables 4.1a and 4.1b.

Technical Test Required Satisfied 870.1100 Acute Oral Toxicity.......................................................... 870.1200 Acute Dermal Toxicity ..................................................... 870.1300 Acute Inhalation Toxicity................................................. 870.2400 Primary Eye Irritation....................................................... 870.2500 Primary Dermal Irritation................................................. 870.2600 Dermal Sensitization ........................................................ Yes Yes No No No No yes waived

870.3100 Oral Subchronic ( rodent) .................................................. 870.3150 Oral Subchronic ( nonrodent) ............................................ 870.3200 21 Day Dermal................................................................ 870.3250 90 Day Dermal................................................................ 870.3465 90 Day Inhalation............................................................. Yes Yes No No No waived waived

870.3700a Developmental Toxicity ( rodent)..................................... 870.3700b Developmental Toxicity ( nonrodent)............................... 870.3800 Reproduction .................................................................... Yes Yes Yes waived waived waived 870.4100a Chronic Toxicity ( rodent) ............................................... 870.4100b Chronic Toxicity ( nonrodent) ......................................... 870.4200a Oncogenicity ( rat)........................................................... 870.4200b Oncogenicity ( mouse) ..................................................... Yes Yes Yes Yes waived waived waived waived 870.5100 Mutagenicity  Gene Mutation  bacterial ......................... 870.5195 Mutagenicity  Gene Mutation  mammalian.................... 870.5375 Mutagenicity  Structural Chromosomal Aberrations........ 870.5900 Mutagenicity  Other Genotoxic Effects ........................... Yes Yes Yes Yes waived waived waived waived 870.6100a Acute Delayed Neurotox. ( hen) ....................................... 870.6100b 90 Day Neurotoxicity ( hen) ............................................ 870.6200a Acute Neurotox. Screening Battery ( rat) ......................... 870.6200b 90 Day Neuro. Screening Battery ( rat) ............................ 870.6300 Develop. Neuro................................................................ No No No No No          Page 44 of 46 Technical Test Required Satisfied 870.7485 General Metabolism ......................................................... 870.7600 Dermal Penetration........................................................... Yes No waived

Special Studies for Ocular Effects No

2.0 NON CRITICAL TOXICOLOGY STUDIES Subchronic Mouse Feeding Study In a range finding study groups of B6C3F1 mice ( 10/ sex/ group) were fed diets containing 0, 3100, 6300, 12500, 25000 or 50000 ppm OTC HCl for 13 weeks. These dose levels are approximately equal to an intake of 0, 465, 945, 1875, 3750, or 7500 mg/ kg/ day. No dose related effects were observed on mortality, food consumption, macroscopy and histology. Body weights were decreased from 3 to 15% at 25000 ppm and at 50000 ppm. OTC concentrations in bone were measurable fluorometrically in high dosed females ( NTP, 1987).

Subchronic Rat Feeding Study In a range finding study, groups of F344/ N rats ( 10/ sex/ group) were fed diets containing 0, 3100, 6300, 12500, 25000 or 50000 ppm OTC HCl for 13 weeks. These dose levels were approximately equal to intakes of 0, 1200, 1350 or 1500 mg/ kg/ day. No dose related effects were observed on mortality, food consumption, body weight or macroscopy. Minimal periacinar fatty metamorphosis in the liver of male rats was observed at all dose levels ( no dose relation, control values not given). Measurable OTC concentrations in bones were detected in both sexes and increased with the dose. The OTC concentration in bone was significantly increased in females from 12500 ppm and up and in males at 50000 ppm only ( NTP, 1987).

Chronic Rat Feeding Study Groups of Osborne Mendel male rats were fed diets containing 0 ( 180 rats), 100 ( 100 rats), 1000 ( 130 rats) or 3000 ppm ( 100 rats) OTC HCl for 24 months. Observations included clinical signs, mortality, food consumption, body weight, haematology, macroscopy, and histopathology. After 24 months the mortality rates were 43, 23, 23 and 13% for the control and experimental groups, respectively. Treated rats gained weight more rapidly than controls. Body weight and haematology were not affected. At macroscopy pale kidneys were observed in 4, 7, 16 and 16% in the control and treated groups, respectively. A slight to moderate brownish pigmentation of the thyroid gland was seen in treated rats, but it was not dose related. Tumour incidences were not enhanced. The NOAEL in this study was 3000 ppm ( highest dose tested), equivalent to 150 mg/ kg b. w. ( Diechmann et al., 1964). In a second study, groups of Sprague Dawley rats were fed diets containing 0, 100, or 1,000pm ( approximately 0, 5, or 50 mg/ kg/ day) hydroxytetracycline monohydrochlorate. Observations included clinical signs, mortality, body weight, food consumption, haematology, organ weights, macroscopy and histopathology. No dose related effects were observed. The NOAEL was 50 mg/ kg/ day, the highest dose tested. Page 45 of 46 Chronic Dog Feeding Studies Groups of mongrel dogs ( 2/ sex/ group) were fed diets containing 0, 5000 or 10000 ppm OTC HCl for 12 months. Observations included clinical signs, mortality, body weight, food consumption, haematology, organ weights, macroscopy and histopathology. No dose related effects were observed except for a degenerating germinal epithelium in the testicular tubules in high dosed male dogs. The NOAEL in this study was 5000 ppm in the diet, equivalent to 125 mg/ kg/ day.

In a second study, groups of 8 male dogs, four beagle dogs and four mongrel dogs per group, were fed diets containing 0, 1000, 3000 or 10000 ppm OTC HCl for 24 months. An interim sacrifice of 1 beagle and 1 mongrel dog/ group was performed after 12 months. Observations included clinical signs, mortality, body weight, food consumption, haematology, alkaline phosphatase ( ALP), bromosulphophthalein ( BSP) clearance, urea nitrogen determinations, organ weight macroscopy, histopathology and semen examination. Two dogs died after 12 and 24 months, respectively ( 1 because of filaria and 1 because of gastroenteritis). No dose related effects were observed. Atrophy of testes and epididymus occurred more frequently in control dogs than in treated ones. The NOAEL was 10000 ppm in the diet ( the highest dose tested), equivalent to 250 mg/ kg b. w. ( Deichmann et al., 1964).

Combined Chronic Toxicity/ Carcinogencity ( Rats) Groups of F344/ N rats ( 50/ sex/ group) were fed diets containing 0, 25000, or 50000 ppm OTCHCl ( purity 98.8%) for 103 weeks. Observations included clinical signs, mortality, body weight, food consumption, macroscopy and histopathology. Mean male body weights were 5 8% lower during the first year of the study at 50000 ppm. Histological examination showed a dose related increase in the incidence of benign phaeochromocytomas in the adrenal gland of male rats. In females an increase in the incidence of adenomas of the pituitary gland was found in the highest dose group ( see Tables 2 and 3, respectively) ( NTP, 1987).

Combined Chronic Toxicity/ Carcinogencity ( Mice) Groups of B6C3F1 mice ( 50/ sex/ group) were fed diets containing 0, 6300 or 12500 ppm OTCHCl ( purity 98.8%) for 103 weeks. Observations included clinical signs, mortality, body weight, food consumption, macroscopy and histopathology. Mean body weights of high dosed mice were 5 9% lower than those in the control group only after the first half year of the study. The tumour incidence was not significantly increased in either sex. The NOAEL in this study was 12500 ppm in the diet ( the highest dose tested), equal to 1372 mg/ kg b. w. ( NTP, 1987).

Metabolism ( Mice) After oral administration of 47.6 mg 14C labelled OTC HCl/ kg b. w. to mice, 72% of the applied dose was found in the large intestine after 2 hours; only 5% was absorbed, of which the major portion ( 3.6%) was excreted in the urine. In the liver 1.9% and 1.1% of the dose applied was recovered after 1 and 2 hours, respectively ( Snell et al., 1957). Page 46 of 46 3.0 TOLERANCE REASSESSMENT SUMMARY Tolerance Reassessments for Oxytetracycline The tolerances listed in 40 CFR § 180.337 are currently expressed in terms of oxytetracycline per se. The oxytetracycline risk assessment team has determined that the residues of concern for the tolerance expression consists of oxytetracycline per se. A summary of oxytetracycline tolerance reassessments is presented in Table A. 3.0.

Tolerances Listed Under 40 CFR § 180.337:

Contingent on submission of an adequate analytical enforcement method and successful Agency petition method validation ( PMV), residue data are available to reassess the established tolerances on peach and pear. The available residue data indicate that the established tolerances are appropriate and can be retained at their present levels ( see Table A. 3.0). Also, contingent on submission of an adequate analytical enforcement method and successful Agency PMV, residue data are available to support a tolerance for apple. The available residue data indicate that the proposed tolerance of 0.35 ppm is appropriate ( see Table A. 3.0.).

TABLE A. 3.0. Tolerance Reassessment Summary for Oxytetracycline.

Commodity Current Tolerance ( ppm) Tolerance Reassessment ( ppm) Comments Tolerances Listed in 40 CFR § 180.337 Peach 0.35 0.35 Contingent on an adequate enforcement method.

Pear 0.35 0.35 Contingent on an adequate enforcement method.

Tolerances To Be Proposed Under 40 CFR § 180.337 Apple N/ A 0.35 Contingent on an adequate enforcement method.