July 1, 2014 

U.S. Environmental Protection Agency 

Office of Pollution Prevention and Toxics 

Confidential Business Information Center (CBIC) – TS7407M 

Attention: Audrey Binder 

EPA East Building, Room 6428 

1201 Constitution Avenue, NW 

Washington, DC 20004-3302 

Dear Ms. Binder: 

Reference: PMN P-12-0425 

 Submission Report Number – 

Interim Results of 28-Day Subacute Inhalation Toxicity Study 

As disclosed in our letter to the Agency dated 16 August 2013, a 28-Day Subacute Inhalation Toxicity 

Study was scheduled for the PMN substance. The objective of this inhalation study was to evaluate the 

potential subchronic toxicity of the test substance when administered 6 hours per day, 5 days per week by 

inhalation to male and female rats for a period of approximately 28 days. This letter is to inform you of 

the interim results of this study with the PMN substance (PMN P-12-0425). 

Under the conditions of this study, the no-observed-adverse-effect-concentration (NOAEC) for 

in male rats was 2500 ppm based upon test substance-related diuresis-induced dehydration associated 

with increased serum total protein, albumin and globulins as well as a single incidence of 

degeneration/atrophy of ameloblastic epithelium observed in males exposed to 5100 ppm. The NOAEC 

for female rats was 5100 ppm, the highest exposure concentration tested in this study. The estimated 

completion date for this final report is July 2014. 

The objective of this study was to assess the potential subchronic toxicity of in rats. Four groups 

of 20 male and 20 female Crl:CD(SD) rats each were exposed whole body, 6 hours per day, 5 days per 

week to 0.00 ± 0.00 (air-exposed control), 1000 ± 4.8, 2500 ± 14 or 5100 ± 25 ppm (mean ± S.E.M) over 

a 4-week period for a total of 21 exposures. Animals were weighed, observed for clincial signs of toxicity 

and had body weight and food consumption evaluations throughout the study. Animals were subject to 

an ophthalmology exam and neurobehavioral evaluation prior to initiation of exposures and during the 4th

week of exposure. Following 4-weeks of exposure to groups of 10 male and 10 female rats from 

each exposure level were fasted, blood and urine samples collected for clinical pathology and sacrificed 

one day following their final exposure for anatomical pathology evaluation including microscopic tissue 

evaluation. Following a 14-day recovery period, groups of 10 male and 10 female rats were fasted, blood 

and urine samples collected for clinical pathology and were sacrificed for anatomical pathology evaluation 

including microscopic tissue evaluation. 
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Male rats exposed to 5100 ppm demonstrated a statistically significant reduction (5.7%) in body 

weight one day following their final exposure when compared to the air exposed control group. There was 

no test substance-related adverse effects on body weight gain, food consumption, clincial signs of toxicity 

or in the ophthalmology exams in male or females at any exposure level to . There was also no 

test substance-related effects on any neurobehavioral parameter evaluated in male or females at any 

exposure level. did not have an effect in the micronucleus assay in any animals exposed during 

this study as assessed by the number of micronucleated polychromatic erythrocytes. 

Consistent with exposure to a fluorinated compound, plasma fluoride was increased in the 2500 and 5100 

ppm male and female groups, and urine fluoride was increased in all male and female exposure groups. 

Following the 14-day recovery period, plasma fluoride concentration was the same as controls in all male 

and female exposure groups. Urine fluoride levels had not returned to control levels following the 14-day 

recovery but were decreased to 48, 24, and 15% of their previous (end-of-exposure) values in the 1000, 

2500, and 5100 ppm male groups, respectively. In recovery group females, urine fluoride levels were 

decreased to 42, 23, and 10% of the end-of-exposure values, respectively. 

Exposure of male rats to 5100 ppm was associated with increased urine volume and decreased urine 

specific gravity consistent with diuresis, increased serum proteins (albumin, globulin and total proteins), 

and decreased body weight. Increases in serum proteins occurring in association with decrements in body 

weight in the 5100 ppm male group were considered to be indicative of an adverse, albeit minimal, effect 

on hydration status (dehydration), likely occurring secondary to fluoride diuresis. Although evidence of 

diuresis was also present in males at 1000 and 2500 ppm and in females at 2500 and 5100 ppm, and 

minimal increases in serum proteins were present in the 1000 and 2500 ppm male groups, these changes 

were not associated with effects on body weight parameters, indicating that hydration status was not 

significantly altered at these exposure concentrations. Therefore, these changes were likely test 

substance-related but were considered to be non-adverse. Changes in urinalysis and serum protein 

parameters were reversible following the two-week recovery period. There were no changes in clinical 

pathology parameters considered to be adverse in males at 1000 and 2500 ppm or in females at any of the 

exposure concentrations tested. 

Liver hepatocellular hypertrophy occurred in both sexes at 5100 ppm and in males at 1000 and 2500 ppm 

at the terminal necropsy and in males at 5100 ppm at the recovery necropsy. This is considered an 

adaptive response associated with metabolism of xenobiotics and non-adverse. Hyperplasia/squamous 

metaplasia of the larynx occurred in all exposure groups at the terminal necropsy and at 1000 and 5100 

ppm in males at the recovery necropsy and in a single female at 5100 ppm at the recovery necropsy. 

Goblet cell hypertrophy/hyperplasia occurred in all exposure groups at both the terminal and recovery 

necropsy. These laryngeal and nasal changes are considered an adaptive response to irritation and in the 

absence of severe changes, as occurred in this study, are not considered adverse. Microscopic evidence of 

fluoride exposure was noted in the incisor teeth of males at 2500 and 5100 ppm with 

degeneration/atrophy of ameloblastic epithelium noted in a single 5100 ppm male which was considered 

adverse. Other findings associated with the fluoride exposure included very slight lamination of dentin at 

5100 and 2500 ppm (a single male affected at 2500 ppm), and incomplete decalcification of 

enamel/dentin at 2500 and 5100 ppm. These latter changes were not considered adverse as the 

lamination was very minimal and the incomplete decalcification, while indicative of exposure, is not an 

adverse finding in the animal. 

Once again, under the conditions of this study, the NOAEC in male rats was 2500 ppm based upon test 

substance-related diuresis-induced dehydration associated with increased serum total protein, albumin 

and globulins as well as a single incidence of degeneration/atrophy of ameloblastic epithelium observed in 

males exposed to 5100 ppm. The NOAEC for female rats was 5100 ppm, the highest exposure 

concentration tested in this study. 
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Please contact me if you have any questions about this submission or need further clarification. 

Via eTSCA Client 

cc: Rebecca von dem Hagen (EPA, Office of Air and Radiation, Stratospheric Protection Division)