Document ID: EPA-HQ-OPP-2018-0244-0004
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2019-08-22T04:00Z

OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
              OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460

MEMORANDUM

DATE:		July 30, 2019

SUBJECT:	Federal Food, Drug, and Cosmetic Act (FFDCA) Safety Assessment for Exemption from the Requirement of a Tolerance for Residues of Lipochitooligosaccharide (LCO) MOR116

				Docket ID Number: EPA-HQ-OPP-2018-0244

                                                                  
FROM:		Gina Burnett, Senior Regulatory Advisor      
            Biochemical Pesticides Branch
            Biopesticides & Pollution Prevention Division (7511P)

THROUGH:	Linda Hollis, Chief	
            Biochemical Pesticides Branch
				Biopesticides & Pollution Prevention Division (7511P)

				
TO:			Robert McNally 
				Division Director
				Biopesticides & Pollution Prevention Division (7511P)
                                       

                                       
This memorandum provides the rationale for establishing an exemption from the requirement of a tolerance for residues of Lipochitooligosaccharide (LCO) MOR116 in or on all food commodities. 
Section 408(c)(2)(A)(i) of FFDCA allows the U.S. Environmental Protection Agency (EPA or the Agency) 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 the 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, the EPA must take into account the factors set forth in FFDCA section 408(b)(2)(C) and (D), including exposure of infants and children as well as other noted factors.  
This document summarizes the analyses of the Biopesticides and Pollution Prevention Division (BPPD) Risk Assessment and Biochemical Pesticide Branches (RAB and BPB) to assess the risks from aggregate exposure to residues of the pesticide LCO MOR116. This document summarizes the toxicity of the pesticide and any reasonably expected exposure to the pesticide through food, drinking water, and other non-occupational exposures. The safety of the reasonably expected aggregate exposure is assessed relative to the toxicity of the pesticide.
Based on this assessment, BPB recommends the establishment of an exemption from the requirement of a tolerance for residues of LCO MOR116 in or on all food commodities due to the lack of any risks of concern from exposure when used as a pesticide in accordance with label directions and good agricultural practices.

I.  Summary of Petitioned-for Establishment of an Exemption from the Requirement of a Tolerance

In the Federal Register of July 24, 2018 (83 FR 34968) (FRL-9980-31), EPA issued a document pursuant to FFDCA section 408(d)(3), 21 U.S.C. 346a(d)(3), announcing the filing of a pesticide tolerance petition (PP 8F8670) by Monsanto Company (now known as Bayer Crop Science LP), 800 N. Lindbergh Blvd., St. Louis, MO 63167. The petition requested that 40 CFR part 180 be amended by establishing an exemption from the requirement of a tolerance for residues of LCO MOR116 in or on all food commodities. That document referenced a summary of the petition prepared by the petitioner, Monsanto Company (now known as Bayer Crop Science LP), which is available in the docket via http://www.regulations.gov. There were no comments received in response to the notice of filing. 

II.  Toxicological Profile

Consistent with FFDCA section 408(b)(2)(D) of FFDCA, RAB and BPB reviewed the available scientific data and other relevant information on LCO MOR116, and considered its validity, completeness, and reliability, as well as the relationship of this information to human risk. RAB and BPB also considered available information concerning the variability of the sensitivities of major identifiable subgroups of consumers, including infants and children.
A.  Overview of LCO MOR116 Toxicity
LCO MOR116 is a synthetically derived member of the lipochitooligosaccharide (LCO) chemical class, that are signaling molecules involved in the initiation of plant-microbe endosymbioses in an estimated 70-80% of land plants (Reference 1, below). As a biopesticide, the compound is considered a plant growth regulator (PGR) and is intended for use to increase growth and decrease stress in growing crops. Typical of a PGR, LCO MOR116 should be applied at low concentrations because use at high concentrations can result in detrimental effects to the plant.  LCO MOR116 is not expected to be applied above 5.89 X 10[-][11] lb ai/lb seed. Further, exemptions from the requirement of a tolerance have already been established for the closely related compound MP LCO SP104 (PC Code 006388) due to its structural similarity, and for rhizobial inoculants (food use) in pesticide formulations per 40 CFR §180.1353 and §180.910, respectively. Rhizobial inoculants are generally known for their ability to produce LCOs (Reference 2). 

According to the Tier I mammalian toxicology acute toxicity studies on a manufacturing-use product containing LCO MOR116, this compound is not considered to be acutely toxic, is minimally irritating to the eye and skin, is not a dermal sensitizer, and is not a mutagen. Based on a weight of evidence (WOE) approach, considering all the available hazard data and proposed application rates and use pattern, EPA's Hazard and Science Policy Council (HASPOC) concluded that subchronic toxicity data for LCO MOR116 are not required to support the LCO MOR116 tolerance exemption (Reference 3).

 Acute Toxicity

To satisfy the Tier I mammalian acute toxicology data requirements for biochemical pesticides (listed at 40 CFR 158.2050, OCSPP Guideline numbers 870.1100, 870.1200, 870.1300, 870.2400, 870.2500, and 870.2600), acute toxicology studies on an LCO MOR116 manufacturing-use product (MP), as presented in Table 1, below, were submitted. According to this information, LCO MOR116 is not considered to be acutely toxic. The chemical is classified as Toxicity Category IV for acute oral, dermal and inhalation toxicity and dermal and eye irritation. The substance is not considered to be a dermal sensitizer. 

Table 1. Acute Mammalian Toxicology Data for LCO MOR116 MP (40 CFR § 158.2050)
                           Study/OCSPP Guideline No.
                                    Results
                              Toxicity Category/
                                  Description
                                     MRID
Acute oral toxicity 
(870.1100)
                          LD50 > 5,000 mg/kg (rat)
                                       
                                      IV
                                   50464807
Acute dermal toxicity 
(870.1200)
                          LD50 > 5,000 mg/kg (rat)
                                      IV
                              50738202, 50464808
Acute inhalation toxicity	
(870.1300)
                           LC50 > 5.14 mg/L (rat)
                                       
                                      IV
                              50738202, 50464809
Primary eye irritation 
(870.2400)
Minimally irritating (rabbit): minimal irritation observed at one-hour post instillation of the test substance with clearance by 24 hours
                                      IV
                                   50738202
Primary dermal irritation 
(870.2500)
Nonirritating (rabbit): no irritation noted at any point throughout the 72-hour study.
                                      IV
                         50464810, 50738202, 50464811
Dermal sensitization (Buehler)
(870.2600)
                         Not a sensitizer (guinea pig)
                                      N/A
                                   50738202

 Subchronic Toxicity

To satisfy the subchronic toxicity data requirements for LCO, in lieu of guideline studies, the applicant has requested waivers and cited information (eight studies) from the open scientific literature. These eight studies (2-28-day, 4-90-day, a 1-year, and a 2-year oral toxicity) are available for structurally similar compounds related to LCO's and are adequate for use in the risk assessment. The studies indicate a lack of adverse effects. These structurally-similar compounds are chitooligomers (LCO degradation product), chitosan oligosaccharide (also an LCO degradation product), chitin-glucan, chitin, N-acetylglucosamine, and oligo-N-acetylglucosamine. Summaries of the eight studies are provided below in Table 2, below. 

From these studies, no endpoints appropriate for risk assessment were identified. The full supporting basis for the acceptance of the waiver rationales, guideline-by-guideline, is described below. In summary, based on the available data and information, LCO MOR116 is not subchronically toxic.
 Table 2: Subchronic Toxicity information taken from the Open Literature for Compounds Structurally Similar to LCO MOR116
 
 Chemical
 Study Type
 NOAELs
 (mg/kg/day)
 LOAELs
 (mg/kg/day)
 Effects at LOAEL
 Reference
 Chitooligomers
 28-day rat
 3,000
                                       -
 No adverse effects at HDT
 (Qin et. al., 2006)
 COS
 28-day rat
 2,000
                                       -
 No adverse effects at HDT
 (Kim et. al., 2001)
 Chitin-glucan
 90-day rat
 6,600 M
 7,000 F
                                       -
 No adverse effects at HDT
 (Jonker et. al., 2010)
 Chitin
 90-day rat
 3,500
                                       -
 No adverse effects at HDT
 (Niho et. al., 1999)
 GlcNAc
 90-day rat
 2,476 M
 2,834 F
                                       -
 No adverse effects at HDT
 (Lee et. al., 2004)

 OAG

 90-day rat
 641 M
 3,640 F
 3,640 M

 M: decreased weight of submaxillary salivary gland[1]
 (Tago et. al., 2007)
 GlcNAc
 1 yr rat
 2,323 M
 2,545 F
                                       -
 No adverse effects at HDT
 (Takahashi et. al., 2009)

 GlcNAc

 2 yr rat
 2,323 M
 2,545 F

                                       -
 No adverse effects at HDT
 (not carcinogenic)
 
 
 (Takahashi et. al., 2009)
 F = female; M = male; HDT = highest dose tested; LOAEL = lowest-observed-adverse-effect-level; NOAEL = no-observed-adverse-effect-level

90-Day Oral
	
Based on a weight of evidence (WOE) approach, considering all the available LCO MOR116 hazard and other data on similar compounds, a 90-day oral study on LCO MOR116 is not required at this time. This approach included the following considerations: 1) several oral toxicity studies conducted on similar compounds to LCO MOR116 showed no adverse effects at the highest dose tested; 2) the acute toxicology studies for an LCO MOR116 MP demonstrate Toxicology Category IV, suggesting that the compound has low toxicity on an acute basis; 3) LCO MOR116 is structurally similar to LCO naturally occurring compounds that have long been part of the normal diet (seafood and plants); 4) prior data waivers for all subchronic toxicity requirements were granted by the Agency for use of chitin and chitosan as food additives and plant growth regulators, respectively; 5) mode of action is not relevant outside the plant kingdom; 6) there is an existing U.S. EPA tolerance exemption for chitin and chitosan; 7) ubiquity of LCOs in the environment; 8) due to low toxicity, a qualitative assessment will be performed; 9) the anticipated low application rates of LCO MOR116; and 10) worst case exposures fall well below generally accepted Threshold of Toxicological Concern (TTCs) for corn and canola, which is 1800 μg/chemical/person/day for Cramer Class I (Ref. 2).

90-Day Dermal

Based on a WOE approach, considering all the available LCO MOR116 hazard and other data on similar compounds, the HASPOC recommends that a 90-day dermal toxicity study on LCO MOR116 is not required at this time.

90-Day Inhalation

Based on a WOE approach, considering all the available LCO MOR116 hazard and other data on similar compounds, the HASPOC recommends that a 90-day inhalation toxicity study on LCO MOR116 is not required at this time.

 Mutagenicity 

Based on a WOE approach, considering all the available LCO MOR116 hazard and exposure data, genetic toxicity (mutagenicity) testing on LCO MOR116 is not required at this time. This requirement has been satisfied with a WOE approach. This approach included the following considerations: 1) available literature studies demonstrated a lack of genotoxicity for LCOs; 2) structure-activity relationships demonstrating a lack of genotoxic potential; 3) prior genotoxicity data waivers granted by the agency for use of (structurally similar) chitin and chitosan as food additives and plant growth regulators, respectively; 4) U.S. EPA has established a tolerance exemption for chitin and chitosan; 5) ubiquitous nature of LCOs in the environment; 6) a History of Safe Use (HOSU) of LCO's; 7) the maximum predicted exposure levels of LCO MOR116 are orders of magnitude lower than generally recognized Thresholds of Toxicological Concern (TTCs) (Refs 2 and 3).

 Developmental Toxicity

Based on a WOE approach, considering all the available hazard and exposure data on LCO MOR116, a Prenatal Developmental Study is not required at this time. This approach included the following considerations: 1) LCO MOR116 is structurally similar to LCO naturally occurring compounds that have long been part of the normal diet (seafood and plants); 2) the acute toxicology studies are classified as Toxicity Category IV, indicating low acute toxicity for LCO MOR116; 90-day oral toxicity studies of similarly-structured compounds (chitin-glucan, chitin, N-acetylglucosamine, and oligo-N-acetylglucosamine) have found NOAEL's greater than 2000 mg/kg in rats; 3) prior data waivers for all subchronic toxicity requirements were granted by the Agency for use of chitin and chitosan as food additives and plant growth regulators, respectively; 4) mode of action is not relevant outside the plant kingdom; 5) there is an existing U.S. EPA tolerance exemption for the related compounds, chitin and chitosan; 6) ubiquity of LCOs in the environment; 7) due to the low toxicity for this chemical, a qualitative assessment was performed; 8) the low application rates of LCO MOR116; and 9) worst-case exposures that fall well below the rabbit developmental Threshold of Toxicological Concern (TTCs) for corn and canola of 280 μg/chemical/person/day (Refs 2 and 3).

III.  Aggregate Exposure

In examining aggregate exposure, FFDCA section 408 directs the 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: There is potential for dietary exposure to LCO MOR116 as a pesticide, however, exposure is anticipated to be negligible compared to (naturally found) background levels. LCOs are present in the roots of food crops and in bacteria and fungi that are associated with the roots of food crops. Molecules identical to LCO breakdown products (such as chitin, vaccenic acid, and N-acetyl-D-glucosamine) are also present in insects, crustaceans, fungi, bacteria, and humans, and are regularly consumed as part of a normal diet. The chitin backbone can be broken down by the human gut into GlcNAc, which is naturally present in human tissues, human breastmilk, and is also commonly consumed as a dietary supplement. Pesticidal use of LCO MOR116 is unlikely to contribute significantly to overall human exposure due to its anticipated low application rate, high water solubility and because it is expected to degrade relatively rapidly once applied (and, therefore, is not likely to bioconcentrate). 

Drinking Water Exposure: Residues of LCO MOR116 in drinking water are not anticipated when products are used according to label instructions. The active ingredient is applied at low concentrations, is very soluble in water, and will dissociate within minutes once applied. Therefore, residues of LCO MOR116 in drinking water are unlikely. 

Other Non-occupational Exposure: LCO MOR116 is not currently registered for use in residential settings. It is intended for agricultural use only. Therefore, a residential assessment is not required and was not conducted.

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."

LCO MOR116 is not toxic and does not produce toxic metabolites; therefore, it does not have a common mechanism of toxicity with other substances and cumulative effects are not expected.   

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

A.  U.S. Population

Due to the lack of toxicity, 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 LCO MOR116. 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 safety factor when reliable data available to EPA support the choice of a different factor. 

As discussed above, EPA has not identified any toxicity with LCO MOR116. Because there are no threshold levels of concern to infants, children, or adults, EPA conducted a qualitative assessment without safety factors; therefore, no additional margin of safety is necessary to protect infants and children.

VI.  Conclusions
The available data support a determination 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 LCO MOR116. Therefore, BPB recommends that an exemption from the requirement of a tolerance be established for residues of LCO MOR116 in or on all food, when used in accordance with label directions and good agricultural practices. 

VII.  References
	
 Gough and Cullimore, 2011. Lipo-chitooligosaccharide Signaling in Endosymbiotic Plant-Microbe Interactions. Molecular Plant-Microbe Interactions 24:867-878.

 EPA, 2019a. Revised Final Human Health Risk Assessment: In Support of the Registration of LCO MOR116 MP Containing 0.013% Lipochitooligosaccharide (LCO) MOR116 (EPA File Symbol No. 524-ALU and Petition No. 8F8670) as its Active Ingredient and the End-Use Product LCO Liquid Additive (EPA File Symbol No 524-ALG) Containing 0.0000266% LCO MOR116 as its Active Ingredient. July 8, 2019.

 EPA, 2019b. Lipochitooligosaccharide (LCO) MOR116: Summary of Hazard and Science Policy Council (HASPOC) Meeting on May 2, 2019:  Recommendations on the Need for the Following Subchronic Studies: 90-Day Oral Study (OCSPP 870.3000), 90-Day Dermal (OCSPP 870.3250), 90-Day Inhalation (OCSPP 870.3465), Prenatal Developmental Study (OCSPP 870.3700), and Genetic Toxicity Testing (OCSPP 870.5100, 870.5300, 870.5375). May 3, 2019.