Federal Food, Drug, and Cosmetic Act (FFDCA) Considerations for Prohydrojasmon (PDJ), propyl-3-oxo-2-pentylcyclo-pentylacetate 

                    Docket ID Number: EPA-HQ-OPP-2012-0832
                             Date: August 23, 2013
                                       
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), which require the EPA to give special consideration to exposure of infants and children to the pesticide chemical residue in establishing a 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 the EPA consider "available information concerning the cumulative effects of [a particular pesticide's] . . . residues and other substances that have a common mechanism of toxicity."
The EPA performs a number of analyses to determine the risks from aggregate exposure to pesticide residues. First, the EPA determines the toxicity of pesticides. Second, the EPA examines exposure to the pesticide through food, drinking water, and through other exposures that occur as a result of pesticide use in residential settings.
I.  Summary of Petitioned-for Tolerance Exemption
In the Federal Register of January 9, 2013, (Vol. 78 FR 1798) (FRL-9374-2), 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 2F8056) by Fine Agrochemicals Ltd. (the Petitioner), on behalf of SciReg, Inc., 12733 Director's Loop, Woodbridge, VA, 22192. The petition requested that 40 CFR part 180 be amended by establishing an exemption from the requirement of a tolerance for residues of prohydrojasmon (PDJ), propyl-3-oxo-2-pentylcyclo-pentylacetate, in or on red apples and grapes. The notice referenced a summary of the petition prepared by the Petitioner, which is available in Docket ID Number EPA-HQ-OPP-2012-0832 via http://www.regulations.gov.
II.  Toxicological Profile
Consistent with section 408(b)(2)(D) of FFDCA, the EPA reviewed the available scientific data and other relevant information on PDJ, and considered its validity, completeness, and reliability, as well as the relationship of this information to human risk. The EPA also considered available information concerning the variability of the sensitivities of major identifiable subgroups of consumers, including infants and children.
A.  Overview of PDJ	

PDJ is a synthetically made plant growth regulator that is structurally similar and functionally identical to jasmonic acid (JA), a naturally occurring plant regulator present in all vascular plants. The jasmonates  of which JA is a member, is a group of plant hormones involved in multiple stages of plant development and defense, including the ability to stimulate fruit ripening (Ref. 1). The highest levels of naturally occurring JA are found in actively growing plant tissues such as leaves, flowers, and developing fruit (Ref. 1; Ref. 3), thus JA has always been a natural component of diets containing plant materials. To date, there have been no reported toxic effects associated with the consumption of JA in fruits and vegetables. 

PDJ, a synthetic version of JA, is expected to behave in the same manner and have the same low toxicity profile as JA because it is structurally similar and functionally identical to naturally occurring JA. Studies submitted by the applicant in support of this exemption from the requirement of a tolerance, and reviewed by the Agency, indicate that PDJ is not acutely toxic. Specifically, no toxic endpoints were established, and no significant toxicological effects were observed in any of the acute toxicity studies. In addition, studies submitted indicate that PDJ is not genotoxic, has no subchronic toxic effects, and is not a developmental toxicant. 

Based on the data submitted in support of this petition (summarized in Unit II. B., below) and the comprehensive risk assessment conducted by the Agency (Ref. 2, below), EPA concludes that there is a reasonable certainty of no harm from aggregate exposures to PDJ, including the consumption of food treated with this active ingredient in accordance with label directions and good agricultural practices. EPA has made this determination for the following reasons: (1) available toxicology data indicate that the active ingredient is of low acute toxicity and is not a developmental toxicant, a mutagen, or toxic via repeat oral exposure, and (2) available information from the scientific literature indicates that humans are already exposed to the structurally similar and functionally identical naturally occurring compound, jasmonic acid (JA), a compound present in all vascular plants. 

B.  Biochemical 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 PDJ in or on apple and grape have been fulfilled with data submitted by the petitioner. The following is a summary of EPA's review of the toxicity profile of this biochemical:
  
Acute Toxicity: Acute toxicity studies on the technical grade active ingredient (TGAI) for PDJ, containing 97.98% PDJ, confirm a low toxicity profile. The acute toxicity data show virtual nontoxicity for all routes of exposure. Therefore, it can be concluded that any dietary risks associated with this plant regulator would be negligible. 

1.	The acute oral median lethal dose (LD50) in rats was greater than 5,000 milligrams per kilogram (mg/kg) bodyweight. There were no observed toxicological effects on the test subjects in the acute oral study submitted (MRID No. 47927825).  PDJ is classified as Toxicity Category IV for acute oral toxicity. 

2.	The acute dermal LD50 in rats was greater than 2,000 mg/kg body weight (MRID 47927826). PDJ is classified as Toxicity Category III for acute dermal toxicity.

 3.	The acute inhalation median lethal concentration (LC50) was greater than 2.8 milligrams per liter (mg/L) in rats and showed no significant inhalation toxicity (MRID 47927827). PDJ is classified as Toxicity Category IV for acute inhalation toxicity. 
 
 4.	A primary eye irritation study on rabbits indicates that PDJ is minimally irritating to the eye (MRID 47927828). PDJ is classified as Toxicity Category IV for primary eye irritation. 
 
 5.	A skin irritation study on rabbits indicates that PDJ is not irritating to the skin (MRID 47927829). PDJ is classified as Toxicity Category IV for primary skin irritation. 
 6.	Data indicate that PDJ is not a dermal sensitizer (MRID 47927830). 
 
Mutagenicity: Two mutagenicity studies, using the TGAI of PDJ (97.98% PDJ) as the test substance, were performed. These studies are sufficient to confirm that there are no expected dietary or non-occupational risks of mutagenicity with regard to food use of PDJ. 
1. A Bacterial Reverse Gene Mutation Test (MRID No. 47927833) investigating doses of test substance up to those that were cytotoxic, both with and without metabolic S9 activation, found no incidences of a 2-fold or greater increase in the number of revertants compared to the corresponding solvent control. Therefore, PDJ is considered to be non-mutagenic under the conditions of this assay.
2. An in vitro Mammalian Cell Chromosome Aberration Test (MRID No. 47927834) tested PDJ genotoxicity on Chinese hamster lung cells (CHL/IU) up to the cytotoxic dose level (80 micrograms per milliliter [ug/mL], based on reduced mitotic activity) without S9 activation, and up to the limit concentration of 5000 ug/mL with S9 activation. None of the test substance concentrations induced a significant increase in the incidence of cells with chromosomal abnormalities, either in the absence or presence of S9 activation. In both experiments, the fraction of cells with chromosomal aberrations was below 5%, indicating a negative response of the test substance. There was also no indication of a dose-response effect either with or without metabolic activation. All of the negative, solvent, and positive controls gave appropriate responses. Therefore, under the conditions of this assay, PDJ is considered to be non-mutagenic and does not cause chromosome aberrations. 

Subchronic Toxicity: In a subchronic oral toxicity study using the TGAI of PDJ (97.98% PDJ) as the test substance, no clinically or toxicologically significant effects were found in any treatment group (MRID 47927831). Therefore, the no observed adverse effect level (NOAEL) for PDJ has been established as the highest test substance dose, 10,000 parts per million (ppm) (equivalent to 566 mg/kg bw/day for male test animals and 587 mg/kg bw/day for female test animals).  A lowest observed adverse effect level (LOAEL) was not established, suggesting that the test animals could have tolerated a higher dose. In sum, the data submitted to the Agency indicate that PDJ has no subchronic toxicological effect.

Developmental Toxicity: In a developmental toxicity study, using the TGAI of PDJ (97.98% PDJ) as the test substance (MRID 47927832), there were no treatment-related effects found at necropsy in maternal animals nor were there effects on copra lutei, number of implanta - tions, sex ratio, fetal body weight, or preimplantation embryonic mortality. The Agency does not consider the temporary decrease in body weight or food intake observed in the 500 mg/kg bw/day test group to be an adverse effect, as this is likely due to the palatability of the food containing this high dose of test substance. Therefore, the Agency  establishes the NOAEL for this study as 500 mg/kg bw/day. A LOAEL was not identified for maternal effects, suggesting that the test animals could have tolerated a higher dose. No treatment-related developmental effects were found on external examination of the fetuses. Visceral examination showed a slight increase in the incidence of thymic remnants; however, the increase was within the range of the performing laboratories historical control data. Therefore, the Agency does not consider this a treatment-related effect. There was also a slight increase in the incidence of a 14[th] rib, which is a common variation in this strain of rat and is therefore not considered an adverse effect. This variation was not accompanied by an increased incidence of abnormal embryos, either on external, skeletal, or visceral examination, and did not appear at a higher than normal rate. Based on the study results, the developmental effects NOAEL for the study is the highest dose tested 500 mg/kg bw/day. A LOAEL was not identified for developmental effects, suggesting that the test animals could have tolerated a higher dose. In sum, the data submitted to the Agency indicate that PDJ is not a developmental toxicant. 

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: Dietary exposure to residues of PDJ is expected to be insignificant, even in the event of exposure. In a worst case scenario, such as no degradation of the applied compound, PDJ residues consumed by a 70 kg person are four orders of magnitude below the No Observed Adverse Effect Level (NOAEL ) that was calculated for this compound (Ref. 2). Furthermore, dietary exposure to residues of PDJ via exposure to treated fruit or foliage is not expected to exist above background levels of naturally occurring JA (Ref. 2).

Drinking Water Exposure:  Exposure of humans to PDJ in drinking water is unlikely since products are labeled for application directly to terrestrial plants and because data demonstrate a soil half-life for this chemical from 1.6-2.3 hours, as well as rapid degradation in water (Ref. 2). Furthermore, the expected concentrations in surface water are well below (6 to 7 orders of magnitude) the maximum doses used in laboratory testing, where no toxic effects were seen (i.e., Acute Oral Toxicity LD50 > 5,000 mg/kg; Developmental Toxicity NOAEL > 500 mg/kg) (Ref. 2).

Other Non-occupational Exposure: 
Non-occupational exposure is not expected because PDJ is not approved for residential uses. The active ingredient is applied directly to commodities and degrades rapidly.
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, the EPA consider "available information concerning the cumulative effects of [a particular pesticide's] . . . residues and other substances that have a common mechanism of toxicity."

The EPA has not found PDJ to share a common mechanism of toxicity with any other substances, and PDJ does not appear to produce a toxic metabolite produced by other substances. For the purposes of this tolerance action, therefore, the EPA has assumed that PDJ does not have a common mechanism of toxicity with other substances. Following from this, the EPA concludes that there are no cumulative effects associated with PDJ that need to be considered. For information regarding the EPA's efforts to determine chemicals that have a common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the EPA's website at http://www.epa.gov/pesticides/cumulative. 

V.  Determination of Safety for the United States Population, Infants and Children
	
FFDCA section 408(b)(2)(C) provides that, in considering the establishment of a tolerance or tolerance exemption for a pesticide chemical residue, the EPA shall assess the available information about consumption patterns among infants and children, special susceptibility of infants and children to pesticide chemical residues, and the cumulative effects on infants and children of the residues and other substances with a common mechanism of toxicity. In addition, FFDCA section 408(b)(2)(C) provides that the 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 the EPA determines 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, the EPA either retains the default value of 10X, or uses a different additional or no safety factor when reliable data are available to support a different additional or no safety factor. 

Because there are no threshold effects associated with this biochemical, an additional margin of safety for infants and children is not necessary.  

EPA has determined that there are no foreseeable dietary risks to the U.S. population, including infants and children, from the use of PDJ as a pesticide (plant growth regulator) on apple and grape, when label instructions and good agricultural practices are followed. The available data and information indicate that the chemical (1) is of low toxicity and not a developmental toxicant, and (2) is structurally similar and functionally identical to jasmonic acid (JA), a compound naturally occurring in the human diet. When compared to the amount of JA that is likely already consumed in the human diet, dietary exposure from pesticidal use of PDJ is not anticipated to significantly increase overall dietary exposure of infants and children. 

Therefore, 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 the residues of PDJ when it is used as labeled and in accordance with good agricultural practices. Such exposure includes all anticipated dietary exposures and all other exposures for which there is reliable information. EPA has arrived at this conclusion because the data and information available on PDJ do not demonstrate significant toxic potential to mammals, including 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 PDJ. Therefore, an exemption is established for residues of the biochemical pesticide PDJ in or on apple and grape when used as a plant growth regulator pre-harvest and in accordance with label directions and good agricultural practices.

VII.  References

   1.    Creelman, R.A. and J.E. Mullet (1995) Jasmonic acid distribution and action in 
      plants: Regulation during development and response to biotic and abiotic stress. Proceedings of the National Academies of Science, 92: 4114-4119.
      
   2.    EPA (2013) Environmental Protection Agency (EPA) Risk Assessment: 
Request for new registration for prohydrojasmon technical and product registration Section 3 for BLUSH 5.25% ai with tolerance exemption. May 12, 2013. 

3.   Mason, H.S., DeWald, D.B., Creelman, R.A., Mullet J.E. (1992) Coregulation of
      Soybean and Vegetative Storage Protein Gene Expression by Methyl Jasmonate and Soluble Sugars. Plant Physiology, 98: 859-867.

