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EPA REGISTRATION DIVISION COMPANY NOTICE OF FILING FOR PESTICIDE 

PETITIONS PUBLISHED IN THE FEDERAL REGISTER 

EPA Registration Division contact: M. Dow, 703-305-5533

INSTRUCTIONS: Please utilize this outline in preparing the pesticide petition. In cases 

where the outline element does not apply, please insert “NA-Remove” and maintain the 

outline. Please do not change the margins, font, or format in your pesticide petition. Simply 

replace the instructions that appear in green, i.e., “[insert company name],” with the 

information specific to your action.

TEMPLATE:

Ecolab, Inc.

[IN-10525]

EPA has received a pesticide petition ([IN-10525]) from Ecolab, Inc., EPA Company 

Number 1677, 370 N. Wabasha Street, St. Paul, MN 55102 proposing, pursuant to section 408(d) 

of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR 

part 180.

(Options (pick one)

2. to establish an exemption from the requirement of a tolerance for

Propylene Glycol, CAS No. 57-55-6 for use as an inert ingredient in antimicrobial 

pesticide formulations applied to food-contact surfaces in public eating places, dairy processing 

equipment and food processing equipment and utensils in accordance with 40 CFR §180.940(a). 

EPA has determined that the petition contains data or information regarding the elements set 

forth in section 408 (d)(2) of FDDCA; however, EPA has not fully evaluated the sufficiency of 

the submitted data at this time or whether the data supports granting of the petition. Additional 

data may be needed before EPA rules on the petition.

A. Residue Chemistry

1. Plant metabolism. Not applicable to this inert ingredient petition.

2. Analytical method. Not applicable to this inert ingredient petition.

3. Magnitude of residues. Not applicable to this inert ingredient petition.
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B. Toxicological Profile

1. Acute toxicity. Propylene glycol is shown to be of low acute toxicity. Acute Oral LD50

values ranged from 8,000 mg/kg to >20,000 mg/kg and Acute Dermal LD50 values are greater 

than 20,000 mg/kg (EPA Toxicity Category IV). It is not an eye or skin irritant and is not a skin 

sensitizer.

2. Genotoxicty. Propylene glycol has been tested for mutagenic or genotoxic potential 

and previously found to be negative by EPA in a battery of studies: a bacterial gene mutation 

assay using Salmonella typhimurium, and in vitro Chinese hamster ovary (CHO) mutation 

assay, an in vitro Chinese hamster ovary (CHO) chromosomal aberration assay and an in 

vitro sister chromatid exchange assay. 

3. Reproductive and developmental toxicity. The toxicological database utilized by EPA 

for propylene glycol was comprised of published and unpublished studies either submitted to the 

Agency or obtained directly from the open literature. The Agency determined that the 

toxicological database was sufficient for reregistration and reassessment decisions and no 

toxicological endpoints of concern were identified. Additionally, UNEP concluded that 

propylene glycol is not a reproductive or developmental toxicant with NOELs in rats, mice, 

rabbits, or hamsters ranging from 1.2 to 1.6 g/kg bw/day in all four species.

4. Subchronic toxicity. The toxicological database utilized by EPA for propylene glycol 

was comprised of published and unpublished studies either submitted to the Agency or obtained 

directly from the open literature. The Agency determined that the toxicological database was 

sufficient for reregistration and reassessment decisions. No toxicological endpoints of concern 

were identified. 

5. Chronic toxicity. The toxicological database utilized by EPA for propylene glycol was 

comprised of published and unpublished studies either submitted to the Agency or obtained 

directly from the open literature. The Agency determined that the toxicological database was 

sufficient for reregistration and reassessment decisions. EPA concluded that propylene glycol 

was negative for carcinogenicity in studies conducted up to the testing limit doses established by 

the Agency; therefore, no further carcinogenic analysis was required. UNEP indicates that a 2-

year repeat dose exposure study in rats to propylene glycol in drinking water and feed did not 

result in adverse effects at levels up to 10% in water (about 10 g/kg bw/day) or 5% in feed (about 

2.5 g/kg bw/day). A 2-year rodent carcinogenicity study showed that propylene glycol is not a 

carcinogen, with no increase in tumors when administered in the diet (2.5 g/kg bw/day for 2 

years) or applied to skin of female rats for 14 months, or mice (2 g/kg bw/week; lifetime). 

6. Animal metabolism. Propylene glycol should be readily metabolized to lactic acid at 

the typical low-level exposures associated with the already approved pesticide inert ingredient 

registrations under 40 CFR §180.910 and 40 CFR §180.930 uses and the intended 40 CFR 

§180.940(a). At higher concentrations (absorbed doses), propylene glycol is primarily excreted 

unchanged in the urine.
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7. Metabolite toxicology. The toxicological database utilized by EPA for propylene 

glycol was comprised of published and unpublished studies either submitted to the Agency or 

obtained directly from the open literature. Although not all available studies met the 

requirements of the Agency’s OPPTS harmonized test guidelines published in 1998, EPA 

determined that these studies contained useful information adequate for hazard characterization 

of propylene glycol. These acceptable non-guideline studies included acute, subchronic, chronic, 

developmental, and reproductive toxicity, carcinogenicity, mutagenicity, 

metabolism/pharmacokinetics and dermal absorption studies. The Agency determined that the 

toxicological database was sufficient for reregistration and reassessment decisions. 

8. Endocrine disruption. EPA did not report having any available information to suggest 

that propylene glycol would have any endocrine effects. When the appropriate screening and/or 

testing protocols under the EDSP have been developed, propylene glycol may be subject to 

additional screening and/or testing to better characterize effects related to endocrine disruption. 

This does not impact the current regulatory status of propylene glycol.

C. Aggregate Exposure

Upon review of the available toxicity information, the Agency has previously concluded that 

there were no endpoints of concern for oral, dermal, or inhalation exposure to propylene glycol. 

This conclusion was based on the results of toxicity testing of propylene glycol in which dose 

levels were near or above testing limits (as established in the OPPTS 870 series harmonized test 

guidelines) in experimental animal studies and no significant toxicity was observed.

1. Dietary exposure. Risk estimates have not previously been calculated by EPA for 

potential exposures to propylene glycol on food or drinking water because there are no 

toxicological endpoints of concern according to a review of the available toxicity data. 

i. Food. Risk estimates have not previously been calculated by EPA for potential 

exposures to propylene glycol on food because there are no toxicological endpoints of concern 

according to a review of the available toxicity data. 

ii. Drinking water. Risk estimates have not previously been calculated by EPA for 

potential exposures to propylene glycol in drinking water because there are no toxicological 

endpoints of concern according to a review of the available toxicity data. 
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2. Non-dietary exposure. Risk estimates have not previously been calculated by EPA for 

potential exposures to propylene glycol as a result of use in residential settings because there are 

no toxicological endpoints of concern according to a review of the available toxicity data. 

D. Cumulative Effects

EPA has not made a common mechanism of toxicity finding for propylene glycol.

E. Safety Determination

1. U.S. population. As part of the FQPA tolerance reassessment process, EPA concluded 

that there are no toxicity endpoints of concern for oral, dermal, or inhalation exposure to 

propylene glycol. This conclusion was based on the results of toxicity testing of propylene glycol 

in which dose levels near or above testing limits (as established in the OPPTS 870 series 

harmonized test guidelines) were employed in experimental animal studies and no significant 

toxicity observed. The Agency determined that the established exemptions from the requirement 

for a tolerance for propylene glycol for current uses met the safety standards under the FQPA 

amendments to section 408(b)(2)(D) of the FFDCA, and that there is a reasonable certainty no 

harm will result to the general population or any subgroup from the use of propylene glycol. In 

reaching this conclusion, the Agency has considered all available information on the toxicity, use 

practices and exposure scenarios of propylene glycol. 

Because no toxicological endpoints were identified for propylene glycol, EPA previously 

determined that exposure to it does not result in human health effects of concern. Therefore, a 

quantitative risk assessment was deemed not necessary. 

2. Infants and children. EPA has removed the FQPA Safety Factor (i.e., reduced to 1X) 

for propylene glycol, because there is no pre- or post-natal evidence for increased susceptibility 

following exposure. Thus, the Agency determined that the established exemptions from the 

requirement of a tolerance for propylene glycol for the current uses in 40 CFR §180.910 and 

§180.930 formulations meet the safety standards under the FQPA amendments to section 

408(b)(2)(D) of the FFDCA. Moreover, there is a “reasonable certainty no harm” will result to 

the general population, or any sensitive subgroup, from the use of propylene glycol as an active 

ingredient or as an inert ingredient in pesticide formulations. In reaching this conclusion, as 

noted in the 2006 RED, EPA considered all available information on the toxicity, use practices 

and exposure scenarios of propylene glycol.

F. International Tolerances

Currently there are no Codex MRLs established for propylene glycol.