Federal Food, Drug, and Cosmetic Act (FFDCA) Considerations for Muscodor albus Strain SA-13 and the Volatiles Produced on Rehydration

                    Docket ID Number: EPA-HQ-OPP-2014-0919
                            Date: November 8, 2016
                                       
Section 408(c)(2)(A)(i) of FFDCA allows the U.S. Environmental Protection Agency (EPA) to establish an exemption from the requirement for a tolerance (the legal limit for a pesticide chemical residue in or on a food) only if EPA determines that the exemption is "safe." Section 408(c)(2)(A)(ii) of FFDCA defines "safe" to mean that "there is a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical residue, including all anticipated dietary exposures and all other exposures for which there is reliable information." This includes exposure through drinking water and in residential settings but does not include occupational exposure. Pursuant to FFDCA section 408(c)(2)(B), in establishing or maintaining in effect an exemption from the requirement of a tolerance, EPA must take into account the factors set forth in FFDCA section 408(b)(2)(C), which require EPA to give special consideration to exposure of infants and children to the pesticide chemical residue in establishing a tolerance or tolerance exemption and to "ensure that there is a reasonable certainty that no harm will result to infants and children from aggregate exposure to the pesticide chemical residue . . . ." Additionally, FFDCA section 408(b)(2)(D) requires that EPA consider "available information concerning the cumulative effects of [a particular pesticide's] . . . residues and other substances that have a common mechanism of toxicity."
EPA performs a number of analyses to determine the risks from aggregate exposure to pesticide residues. First, EPA determines the toxicity of the pesticide. Second, EPA examines exposure to the pesticide through food, drinking water, and other exposures that occur as a result of pesticide use in residential settings.
I. Summary of Petitioned-for Tolerance Exemption and Revision to the Requested Tolerance Exemption
In the Federal Register of January 28, 2015 (80 FR 4527), EPA issued a notice pursuant to FFDCA section 408(d)(3), 21 U.S.C. 346a(d)(3), announcing the filing of a pesticide tolerance petition (PP 4F8271) by Marrone Bio Innovations, Inc. (MBI), 2121 Second Street, Suite B-107, Davis, CA 95618. The petition requested that 40 CFR part 180 be amended by establishing an exemption from the requirement of a tolerance for residues of sterile grain inoculated with Muscodor albus strain SA-13 in or on all food commodities. That document referenced a summary of the petition prepared by the petitioner MBI, which is available in Docket ID Number EPA-HQ-OPP-2014-0919 via http://www.regulations.gov. 
One modification has been made to the requested tolerance exemption. When MBI first submitted this petition in 2014, it described the pesticide chemical as "sterile grain inoculated with Muscodor albus strain SA-13". After conducting a review of this petition and evaluating a tolerance exemption established in 2005 for another strain of Muscodor albus (QST 20799) (70 FR 56569), which has the same mode of action as Muscodor albus strain SA-13, EPA is changing the pesticide chemical name to "Muscodor albus strain SA-13 and the volatiles produced on rehydration". This revision better reflects the possible residues that may occur on food commodities and the data/information submitted to support the petition.  
II. Toxicological Profile
Consistent with FFDCA section 408(b)(2)(D), EPA reviewed the available scientific data and other relevant information on Muscodor albus strain SA-13 and the volatiles produced on rehydration, and considered its validity, completeness, and reliability, as well as the relationship of this information to human risk. EPA also considered available information concerning the variability of the sensitivities of major identifiable subgroups of consumers, including infants and children.  
A. Overview of Muscodor albus Strain SA-13 and the Volatiles Produced on Rehydration

Muscodor albus strain SA-13 is a naturally occurring fungus that was isolated from the honey mesquite tree in South Africa. It is capable of colonizing plant tissues beneath the epidermal cell layers without causing any apparent harm to the host. When applied as a pesticide, Muscodor albus strain SA-13 is intended to suppress soil-borne plant diseases and control plant-parasitic nematodes in horticultural and agricultural soils, and it is used to control nematodes and plant diseases in home gardens. After it is inoculated on sterile barley and properly activated, Muscodor albus strain SA-13 produces volatile organic compounds that inhibit the growth of or kill target pests. For the horticultural and agricultural applications, the pesticide is incorporated into the soil with discs or other similar equipment before planting, or applied in furrow or post planting along the planting rows, and watered in to activate the volatile compounds.

B. Microbial Pesticide Toxicology Data Requirements

All applicable mammalian toxicology data requirements supporting the request for an exemption from the requirement of a tolerance for residues of Muscodor albus strain SA-13 and the volatiles produced on rehydration in or on all food commodities have been fulfilled with data submitted by the petitioner or data waiver requests that have been granted by EPA.
	
The toxicity tests (acute oral, dermal, and inhalation toxicity) and irritation tests (acute eye and primary dermal irritation) that address potential routes of exposure to the active ingredient or its volatiles are classified in Toxicity Category III or IV (see section II.B. of Ref. 1) and reveal no toxicity or irritation attributed to Muscodor albus strain SA-13 or its volatiles. Moreover, during typical toxicity/pathogenicity testing done with microbial pesticides, Muscodor albus strain SA-13 showed no toxicity, no pathogenicity, and no infectivity via the pulmonary route of exposure. For acute oral and intravenous toxicity/pathogenicity testing, EPA granted waiver requests based on scientific rationale submitted by the petitioner. Finally, the petitioner reported that, to date, no hypersensitivity incidents have occurred during research, development, or testing of this fungus. The conclusions and classifications from all toxicological information associated with the active ingredient or its volatiles and submitted by the petitioner are briefly described below. 

1. Acute oral toxicity  -  rat (Harmonized Guideline 870.1100; Master Record Identification Number (MRID No.) 493176-06). An acceptable acute oral toxicity study demonstrated that Muscodor albus strain SA-13 is not toxic when administered via the oral route in a single dose of 1.92 X 10[4] colony-forming units (CFU) per animal. In terms of an oral median lethal dose (LD50), which is a statistically derived single dose that can be expected to cause death in 50% of test animals, the animals showed no signs of toxicity at 3,000 milligrams/kilogram of bodyweight (Toxicity Category III) (Ref. 2).   

2. Acute pulmonary toxicity/pathogenicity  -  rat (Harmonized Guideline 885.3150; MRID No. 499246-02). An acceptable acute pulmonary toxicity/pathogenicity study demonstrated that Muscodor albus strain SA-13 is not toxic, pathogenic or infective when administered via the intratracheal route in a single dose of 1.8 X 10[2] CFU per animal. Further, Muscodor albus strain SA-13 showed no persistence in the organs of the animals, except for one male rat that may have been injured during the intratracheal dosing (Ref. 3).   

3. Acute oral toxicity/pathogenicity and acute injection toxicity/pathogenicity (Harmonized Guidelines 885.3050 and 885.3200; MRID No. 493176-18). Upon consideration of the petitioner's scientific rationale, EPA waived acute oral and injection toxicity/pathogenicity testing based on the results of the acute oral toxicity and acute pulmonary toxicity/pathogenicity tests. When considered collectively, EPA believes this information indicates that this fungus would not be toxic, pathogenic or infective through the oral or injection routes of exposure and that further testing is not necessary (See 1 and 2 above and Refs. 2 and 3).

4. Hypersensitivity incidents (Harmonized Guideline 885.3400; MRID No. 493176-18). The petitioner stated that no hypersensitivity incidents have been reported in the research, development, or testing of Muscodor albus strain SA-13 (Ref. 2).

5. Cell culture (Harmonized Guideline 885.3500; MRID No. 493176-18). Not required because Muscodor albus strain SA-13 is not a virus (refer to test note #4 of 40 CFR § 158.2140(d)) (Ref. 2).

6. Acute dermal toxicity  -  rat (Harmonized Guideline 870.1200; MRID No. 493176-07). An acceptable acute dermal toxicity study demonstrated that Muscodor albus strain SA-13 is not toxic to test animals when dermally dosed at 5,050 mg/kg of bodyweight for 24 hours. The dermal LD50 is greater than 5,050 mg/kg for both male and female rats combined (Toxicity Category IV) (Ref. 2).

7. Acute inhalation toxicity  -  rat (Harmonized Guideline 870.1300; MRID No. 493176-08). An acceptable acute inhalation study demonstrated that the volatiles produced by Muscodor albus strain SA-13 on rehydration are not toxic to test animals when inhaled for 4 hours at a concentration of 5.28 mg/L. The inhalation median lethal concentration (LC50), which is a statistically derived concentration that can be expected to cause death in 50% of test animals, is greater than 5.28 mg/L for both male and female rats combined (Toxicity Category IV) (Ref. 2).

8. Acute eye irritation  -  rabbit (Harmonized Guideline 870.2400; MRID No. 493176-09). An acceptable acute eye irritation study demonstrated that Muscodor albus strain SA-13 is essentially non-irritating to the eyes of rabbits (No corneal opacity, conjunctival irritation or iritis noted throughout the study; Toxicity Category IV) (Ref. 2).

9. Primary dermal irritation  -  rabbit (Harmonized Guideline 870.2500; MRID No. 493176-10). An acceptable primary dermal irritation study demonstrated that Muscodor albus strain SA-13 is essentially non-irritating to the skin of rabbits (No dermal erythema or edema noted throughout the study; Toxicity Category IV) (Ref. 2).

III. Aggregate Exposure

In examining aggregate exposure, FFDCA section 408 directs EPA to consider available information concerning exposures from the pesticide residue in food and all other non-occupational exposures, including drinking water from ground water or surface water and exposure through pesticide use in gardens, lawns, or buildings (residential and other indoor uses).

Food Exposure: EPA believes exposure to residues of Muscodor albus strain SA-13, a naturally occurring fungus, in consumed food would be very low, and exposure to residues of Muscodor albus strain SA-13's volatiles in consumed food would not be likely. For control of nematodes and suppression of plant diseases, Muscodor albus strain SA-13 will be applied to many food crops by soil application in-furrow and then covered over at planting. Once the carrier, barley, is exhausted, the microbe dies. Muscodor albus strain SA-13 is a non-spore forming fungus and does not have a dormant stage that can remain viable over time. No dietary hazard is expected from the volatile organic compounds produced by the fungus because they are at low levels, and no exposure is expected because the compounds biodegrade and diffuse rapidly. Processing procedures (e.g., peeling and washing) may reduce any residues of Muscodor albus strain SA-13 (Ref. 4). Should Muscodor albus strain SA-13 be present in or on food, supporting toxicological data and information indicate that no toxicity, pathogenicity, or infectivity is likely to occur with this type of exposure resulting from the use of this microbial pesticide when applied in accordance with label directions and good agricultural practices (see additional discussion in section II above).  
Drinking Water Exposure: EPA does not expect exposure to residues of Muscodor albus strain SA-13 or its volatiles in drinking water. Following application in agricultural fields, Muscodor albus strain SA-13 is not likely to enter ground water or surface water, and it only could reach a freshwater environment if it was applied near a water way or if heavy flooding carried the fungus on the barley to a freshwater environment. In the event that Muscodor albus strain SA-13 makes its way into surface waters, Muscodor albus strain SA-13 is not expected to persist because this fungus cannot survive in an anaerobic environment. Likewise, the volatile organic compounds biodegrade in the soil and are not likely to enter ground or surface water. If Muscodor albus strain SA-13 was to somehow persist and be transferred to ground waters, it likely would not survive the conditions water is subjected to in wastewater treatment systems and drinking facilities (e.g., pH adjustments and chlorination) (Refs. 5 and 6). Should Muscodor albus strain SA-13 be present in drinking water, supporting toxicological data and information indicate that no toxicity, pathogenicity, or infectivity is likely to occur with this type of exposure resulting from the use of this microbial pesticide when applied in accordance with label directions and good agricultural practices (see additional discussion in section II above).
Other Non-occupational Exposure: Dermal and inhalation exposure to the general population from the use of Muscodor albus strain SA-13 and the volatiles produced on rehydration could occur from residential use of the pesticide by home gardeners. Even if non-occupational exposures to Muscodor albus strain SA-13 and the volatiles produced on rehydration should occur, minimal effects are anticipated given testing that, at high doses, indicates Muscodor albus strain SA-13 is not toxic, pathogenic, or infective through the pulmonary route of exposure; Muscodor albus strain SA-13 is essentially non-irritating and is not toxic through the dermal route of exposure; and Muscodor albus strain SA-13's volatiles are not toxic through inhalation (see additional discussion in Section II above).   

IV. Cumulative Effects from Substances with a Common Mechanism of Toxicity

Section 408(b)(2)(D)(v) of FFDCA requires that, when considering whether to establish, modify, or revoke a tolerance, EPA consider "available information concerning the cumulative effects of [a particular pesticide's] . . . residues and other substances that have a common mechanism of toxicity."

Muscodor albus strain SA-13 and the volatiles produced on rehydration are not toxic and do not have a common mechanism of toxicity with other substances. Consequently, FFDCA section 408(b)(2)(D)(v) does not apply.  

V. Determination of Safety for the U.S. Population, Infants and Children

A. U.S. Population

For all of the reasons discussed previously, EPA concludes that there is reasonable certainty that no harm will result to the U.S. population, including infants and children, from aggregate exposure to residues of Muscodor albus strain SA-13 and the volatiles produced on rehydration. This includes all anticipated dietary exposures and all other exposures for which there is reliable information.


B. Infants and Children

FFDCA section 408(b)(2)(C) provides that EPA shall apply an additional tenfold (10X) margin of safety for infants and children in the case of threshold effects to account for prenatal and postnatal toxicity and the completeness of the database on toxicity and exposure, unless EPA determines based on reliable data that a different margin of safety will be safe for infants and children. This additional margin of safety is commonly referred to as the Food Quality Protection Act Safety Factor. In applying this provision, EPA either retains the default value of 10X or uses a different additional safety factor when reliable data available to EPA support the choice of a different factor. As discussed above, EPA has concluded that Muscodor albus strain SA-13 is not toxic, pathogenic, or infective and its volatiles are not toxic to mammals, including infants and children. Because there are no threshold levels of concern to infants, children, and adults when Muscodor albus strain SA-13 and the volatiles produced on rehydration are used according to label directions and good agricultural practices, EPA concludes that no additional margin of safety is necessary to protect infants and children.

VI. Conclusions
EPA concludes that there is a reasonable certainty that no harm will result to the U.S. population, including infants and children, from aggregate exposure to residues of Muscodor albus strain SA-13 and the volatiles produced on rehydration. Therefore, an exemption from the requirement of a tolerance is established for residues of Muscodor albus strain SA-13 and the volatiles produced on rehydration in or on all food commodities when used in accordance with label directions and good agricultural practices.

VII. References

1. U.S. EPA. 2014. Chapter 7 of the Label Review Manual (Precautionary Statements) (Revised July 2014). Available from https://www.epa.gov/sites/production/files/2015-03/documents/chap-07-jul-2014.pdf. 

2. U.S. EPA. 2015. Review of MBI-601 EP containing Muscodor albus strain SA-13. Memorandum from J.V. Gagliardi, Ph.D. through J.L. Kough, Ph.D. to M. Glikes, dated April 16, 2015 (available as a "Supporting Document" within docket ID number EPA-HQ-OPP-2014-0901 at http://www.regulations.gov). 

3. U.S. EPA. 2016. Acute Pulmonary Toxicity and Pathogenicity and One Year Storage Stability of Muscodor albus strain SA-13 (end use product, MBI-601 EP), submitted by Marrone Bio Innovations.  Memorandum from M.S. Djurickovic, M.S. through J.L. Kough, Ph.D. to M. Glikes, dated August 16, 2016 (available as a "Supporting Document" within docket ID number EPA-HQ-OPP-2014-0901 at http://www.regulations.gov).  

4. U.S. EPA. 1996. Microbial Pesticide Test Guidelines  -  Background for Residue Analysis of Microbial 
Pest Control Agents (OPPTS 885.2000) (Dated February 1996). Available from http://www.epa.gov/test-guidelines-pesticides-and-toxic-substances/series-885-microbial-pesticide-test-guidelines.

5. Centers for Disease Control and Prevention. 2015. Water Treatment. Available from http://www.cdc.gov/healthywater/drinking/public/water_treatment.html.

6. U.S. EPA. 2004. Primer for Municipal Wastewater Treatment Systems (Dated September 2004). Available from http://www.epa.gov/npdes/pubs/primer.pdf. 
