   Federal Food, Drug, and Cosmetic Act (FFDCA) Considerations for Natamycin

                    Docket ID Number: EPA-HQ-OPP-2014-0352
                            Date: November 7, 2014
                                       
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 August 1, 2014 (79 FR 44729) (FRL-9911-67), 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 4F8233) by DSM Food Specialties B.V. (the Petitioner), Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands. The petition requested that 40 CFR part 180 be amended by establishing an exemption from the requirement of a tolerance for residues of natamycin for post-harvest indoor use on pineapples. The notice referenced a summary of the petition prepared by the Petitioner, which is available in Docket ID Number EPA-HQ-OPP-2014-0352 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 natamycin, 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 Natamycin	

Natamycin is a naturally occurring compound derived from the common soil microorganisms Streptomyces natalensis, Streptomyces lydicus, and Streptomyces chattanoogensis. Natamycin was originally discovered in Streptomyces natalensis in South Africa in the early 1950s, and was subsequently discovered to also occur naturally in North America in Streptomyces lydicus and Streptomyces chattanoogensis. It is commercially produced by a submerged oxygen-based fermentation of Streptomyces natalensis, Streptomyces lydicus, or Streptomyces chattanoogensis. Natamycin has been used as a food preservative worldwide for over 40 years (Ref.1) and is approved as a food additive/preservative by the European Union, the World Health Organization, and individual countries including New Zealand and Australia for use as a fungistat to suppress mold on cheese, meats and sausage. In the United States, natamycin is approved by the Food and Drug Administration (FDA) as a direct food additive/preservative for the inhibition of mold and yeast on the surface of cheeses (21CFR 172.155) and as an additive to the feed and drinking water of broiler chickens to retard the growth of specific molds (21CFR 573.685). Natamycin is also FDA approved for use as a treatment to suppress fungal eye infections such as blepharitis, conjunctivitis, and keratitis.

As a biochemical pesticide active ingredient, natamycin is intended for use as a fungistat to prevent and control the germination of mold and yeast spores in the growth media of mushrooms produced in enclosed mushroom production facilities (77 FR 29543), and to control fungal growth post-harvest on pineapples treated indoors. Natamycin has a non-toxic mode of action, has no effects on fungal mycelia, and development of antibiotic resistance to natamycin has not been reported during its entire history of use (77 FR 29543).

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 natamycin, including the consumption of food treated with this active ingredient in accordance with label directions and good agricultural practices. EPA has made this determination because 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.

B.  Biochemical Pesticide Toxicology Data Requirements

All applicable mammalian toxicology data requirements supporting the request for an amendment to the existing exemption from the requirement of a tolerance for residues of natamycin when used post-harvest, indoors, on pineapples, 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 natamycin (98.17% and 98.27% pure), 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 biochemical would be negligible. 

1.	The acute oral median lethal dose (LD50) in rats was greater than 2,000 milligrams per kilogram (mg/kg) bodyweight. There were no observed toxicological effects on the test subjects in the acute oral study submitted (MRID No. 48105505). Natamycin is classified as Toxicity Category III for acute oral toxicity. 

2.	The acute dermal LD50 in rats was greater than 5,050 mg/kg body weight (MRID 48105506). Natamycin is classified as Toxicity Category IV for acute dermal toxicity.

 3.	The acute inhalation median lethal concentration (LC50) was greater than 2.39 milligrams per liter (mg/L) in rats and showed no significant inhalation toxicity (MRID 48105507). Natamycin is classified as Toxicity Category IV for acute inhalation toxicity. 
 
 4.	A primary eye irritation study on rabbits indicates that natamycin is severely irritating to the eye but with no effects observed at 24 hours after treatment (MRID 48015508). Natamycin is classified as Toxicity Category III for primary eye irritation. 
 
 5.	A skin irritation study on rabbits indicates that natamycin is slightly irritating (MRID 48105509). Natamycin is classified as Toxicity Category IV for primary skin irritation. 
 6.	Data indicate that natamycin is not a dermal sensitizer (MRID 48105510). 
 
Mutagenicity: Two mutagenicity studies, using natamycin (98.17% and 98.27% pure) 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 natamycin. 
1. A Bacterial Reverse Gene Mutation Test (MRID No. 48105513) 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 in two independently repeated experiments. Therefore, natamycin is considered to be non-mutagenic under the conditions of this assay.
2. An in vitro Mammalian Cell Chromosome Aberration Test (MRID No. 48105514) tested natamycin genotoxicity on cultured peripheral human lymphocytes in the presence and absence of metabolic S9 activation. Natamycin did not induce a statistically significant or biologically relevant increase in the number of cells with chromosome aberrations in the absence and in the presence of S9-mix, in two independently repeated experiments. In addition, all of the negative, solvent, and positive controls gave appropriate responses. Therefore, under the conditions of this assay, natamycin is considered to be non-mutagenic and does not cause chromosome aberrations. 

Subchronic Toxicity: In a subchronic oral toxicity study using natamycin (98.17% and 98.27% pure) as the test substance, doses of 125 and 500 mg/kg/day showed no treatment related findings. The highest concentration level, 2,000 mg/kg/day, showed reduced weight for both male and female rats (MRID 48105511). The Agency does not consider the temporary decrease in body weight or food intake observed in the 2,000 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 (No Observed Adverse Effect Level) for this study as 2,000 mg/kg bw/day. A LOAEL (Lowest Observed Adverse Effect Level) was not identified, suggesting that the test animals could have tolerated a higher dose.

Developmental Toxicity: A developmental toxicity study using natamycin (98.17% and 98.27% pure) as the test substance (MRID 48105512) showed no discernable effects on growth, reproduction, teratological or mutagenic responses, or on gross and microscopic pathology, at concentration levels 0, 5, 15 and 50 mg/kg bw/day. 

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 natamycin via pesticidal use is expected to be insignificant, even in the event of exposure. Some dietary exposure to natamycin might occur through other nonpesticidal sources as a result of its use as a food additive/preservative. Should exposure occur, however, minimal to no risk is expected for the general population, including infants and children, due to the low toxicity of natamycin. The active ingredient is of low acute toxicity and is not a developmental toxicant, a mutagen, or toxic via repeat oral exposure.

Drinking Water Exposure:  Exposure of humans to natamycin in drinking water is not expected because natamycin is approved for application indoors only (enclosed mushroom houses or pineapple packing facilities). 

Other Non-occupational Exposure: Non-occupational exposure is not expected because natamycin 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 natamycin to share a common mechanism of toxicity with any other substances, and natamycin 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 natamycin 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 natamycin 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 natamycin as a pesticide (fungicide) on mushrooms in enclosed mushroom facilities and on pineapples when label instructions and good agricultural practices are followed. The available data and information indicate that the chemical is of low toxicity and not a developmental toxicant. 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 natamycin 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 natamycin 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 natamycin. Therefore, an exemption is established for residues of the biochemical pesticide natamycin when used on mushrooms in enclosed mushroom production facilities and when used on pineapples in accordance with label directions and good agricultural practices.

VII.  References

1. Joint FAO/WHO Expert Committee on Food Additives (JECFA). 1968, 1969, 1976, 2002, 2006, and
      2007. See EFSA 2009 for specific reference citations.

2. EPA (2014) Environmental Protection Agency (EPA) Risk Assessment: 
Request for new food use (post-harvest treatment of pineapples) to the active ingredient, Natamycin. October 1, 2014. 

