Proposed: April 2009 1
2
3
4 

## ACUTE EXPOSURE GUIDELINE LEVELS (AEGLs) 5



## FOR 6


## PERFLUOROISOBUTYLENE (PFIB) 7

8 

## (CAS Reg. No. 382-21-8) 9

10 

## C 4 

## F 8 11

12

13 14
15 

## PROPOSED 16

17
18PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 2 of 43

1

2

3 

## ACUTE EXPOSURE GUIDELINE LEVELS (AEGLs) 4



## FOR 5


## PERFLUOROISOBUTYLENE (PFIB) 6


## (CAS Reg. No. 382-21-8) 7

8

9
10
11 

## PROPOSED 12

13
14
15
16
17
18
19
20
21PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 3 of 43

1
2
3
PREFACE 4
5 Under the authority of the Federal Adviso ry Committee Act (FACA) P. L. 92-463 of 6 1972, the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous 7 Substances (NAC/AEGL Committee) has been es tablished to identify, review and interpret 8 relevant toxicologic and other scientific data and develop AEGLs for high priority, acutely toxic 9
chemicals. 10
11 AEGLs represent threshold exposure limits for the general public and are applicable to 12 emergency exposure periods ranging from 10 minut es to 8 hours. Three levels – AEGL-1, 13
AEGL-2 and AEGL-3

Care developed for each of five exposure periods (10 and 30 minutes, 1 14 hour, 4 hours, and 8 hours) and are distinguished by va rying degrees of severity of toxic effects. 15
The three AEGLs are defined as follows: 16
17 AEGL-1 is the airborne concentration (expressed as parts per million or milligrams per 18 cubic meter [ppm or mg/m 3 ]) of a substance above which it is predicted that the general 19 population, including susceptible individuals, could experience notable discomfort, irritation, or 20 certain asymptomatic, non-sensory effects. Ho wever, the effects are not disabling and are 21 transient and reversible upon cessation of exposure. 22
23 AEGL-2 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above 24 which it is predicted that the general population, including susceptible individuals, could 25 experience irreversible or other serious, long-lasting adverse health effects or an impaired ability 26 to escape. 27
28 AEGL-3 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above 29 which it is predicted that the general population, including susceptible individuals, could 30 experience life-threatening health effects or death. 31
32 Airborne concentrations below the AEGL-1 represent exposure levels that could produce 33 mild and progressively increasing but transi ent and nondisabling odor, taste, and sensory 34 irritation or certain asymptomatic, non-sensory eff ects. With increasing airborne concentrations 35 above each AEGL, there is a progressive increase in the likelihood of occurrence and the 36 severity of effects described for each corresponding AEGL. Although the AEGL values 37 represent threshold levels for the general public, including susceptible subpopulations, such as 38 infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized 39 that individuals, subject to unique or idiosyncratic responses, could experience the effects 40 described at concentrations below the corresponding AEGL. 41
42PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 4 of 43

TABLE OF CONTENTS 1

PREFACE ....................................................................................................................... 3 2

TABLE OF CO NTENTS.................................................................................................. 4 3

LIST OF TABLES ........................................................................................................... 6 4

SUMMARY ...................................................................................................................... 7 5

1. INTRODUCT ION................................................................................................................... ...........................9 6

2. HUMAN TOXICI TY DATA............................................................................................................ .................9 7

2.1. Acute lethality

............................................................................................................................... ............9 8

2.2 Nonlethal acute toxicity ..........................................................................................................................10 9

2.3. Developmental/Reproductive Toxicity ..................................................................................................10 10

2.4. Genotoxicit y .............................................................................................................................. ..............10 11

2.5. Summary

............................................................................................................................... ..................10 12

3. ANIMAL TOXICI TY DATA........................................................................................................... ...............10 13

3.1. Acute Lethality

............................................................................................................................... .........10 14

3.1.1. Rats

............................................................................................................................... ......................10 15

3.1.2. Mice

............................................................................................................................... ......................15 16

3.1.3. Guinea pigs

............................................................................................................................... ..........16 17

3.1.4. Rabbits

............................................................................................................................... .................16 18

3.1.5. Cats

............................................................................................................................... ..........................17 19

3.2. Nonlethal Acute Toxicity ........................................................................................................................17 20

3.2.1. Rats

............................................................................................................................... ......................17 21

3.3. Repeat Dose Studies

............................................................................................................................... .17 22

3.4. Developmental/Reproductive Toxicity ..................................................................................................18 23

3.5. Genotoxicity

............................................................................................................................... .............18 24

3.6. Chronic Toxicity/Carcinogenicity .........................................................................................................18 25

3.7. Summary

............................................................................................................................... ..................18 26

4. SPECIAL CONS IDERAT IONS ......................................................................................................... ............21 27

4.1. Metabolism and Disposition ...................................................................................................................21 28

4.2. Mechanism of Toxicity ...........................................................................................................................21 29

4.3. Other Relevant Information ..................................................................................................................23 30

4.3.1. Interspecies Variability .....................................................................................................................23 31

4.3.2. Intraspecies Variability .....................................................................................................................23 32

4.3.3 Structure Activity

............................................................................................................................... 24 33

4.3.4. Concentration-Exposure Duration Relationship .............................................................................24 34

5. DATA ANALYSIS FOR AE GL-1 ....................................................................................................... ...........25 35

5.1. Summary of Human Data Relevant to AEGL-1 ..................................................................................25 36

5.2. Summary of Animal Data Relevant to AEGL-1 ...................................................................................25 37

5.3. Derivation of AEGL-1 ............................................................................................................................25 38

6. DATA ANALYSIS FOR AE GL-2 ....................................................................................................... ...........25 39

6.1. Summary of Human Data Relevant to AEGL-2 ..................................................................................25 40

6.2. Summary of Animal Data Relevant to AEGL-2 ...................................................................................25 41

6.3. Derivation of AEGL-2 ............................................................................................................................25 42PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 5 of 43

7. DATA ANALYSIS FOR AE GL-3 ....................................................................................................... ...........26 1

7.1. Summary of Human Data Relevant to AEGL-3 ..................................................................................26 2

7.2. Summary of Animal Data Relevant to AEGL-3 ...................................................................................26 3

7.3. Derivation of AEGL-3 ............................................................................................................................26 4

8. SUMMARY OF AEGLs ............................................................................................................... ...................27 5

8.1. AEGL Values and Toxicity Endpoints ..................................................................................................27 6

8.2. Comparison with Other Standards and Guidelines .............................................................................28 7

9. REFERENCES..................................................................................................................... ............................29 8

APPENDIX A: DERIVATION OF PFIB AEGLS........................................................... 33 9

APPENDIX B: TIME S CALING CALCUL ATIONS ....................................................... 36 10

APPENDIX C: DERIVATION SUMMARY FO R PFIB.................................................. 38 11

APPENDIX D: CATEGORY PLOT FOR PFIB.............................................................. 41 12

13
14PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 6 of 43

LIST OF TABLES 1
2

S 1. SUMMARY OF AEGL VALUES FOR PFIB ...................................................................................................8 3 4

TABLE 1. CHEMICAL AND PHYSICAL PROPERTIES .....................................................................................9 5

TABLE 2. SUMMARY OF MORTALITY DATA IN RATS EXPOSED TO PFIB FOR UP TO 6 HOURS. ..11 6

TABLE 3. SUMMARY OF MORTALITY DATA IN RATS EXPOSED TO PFI B FOR 4 HO URS. ...............11 7

TABLE 4. SUMMARY OF MORTALITY DATA IN RATS EXPOSED TO PFIB FOR 0.25 TO 10 8

MINUTES........................................................................................................................ .................................12 9

TABLE 5. SUMMARY OF MORTALITY DATA FOR ANIMALS EXPOSED TO HEAVY 10

PRODUCTS/HIGH BOILER S FOR 2 HOURS............................................................................................15 11

TABLE 6. SUMMARY OF MORTALITY DATA IN MICE EXPOSED TO PFIB FOR 10 MINUTES.........15 12

TABLE 7. SUMMARY OF MORTALITY DATA IN MI CE EXPOSED TO PFI B FOR 1 MINUTE..............16 13

TABLE 8. SUMMARY OF SELECTED ANIMAL INHALATI ON DATA ........................................................19 14

TABLE 9. COMPARISON OF PFIB LC 50 VALUES FOR VARIOUS ANIMAL SPEC IES............................23 15

TABLE 10. AEGL-1 VALUES FO R PFIB............................................................................................... ...............25 16

TABLE 11. AEGL-2 VALUES FO R PFIB............................................................................................... ...............26 17

TABLE 12. AEGL-3 VALUES FO R PFIB............................................................................................... ...............27 18

TABLE 13. SUMMARY OF AEGL VALUES............................................................................................... .........28 19

TABLE 14. STANDARDS AND GUID ELINES FOR PFIB..................................................................................28 20
21PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 7 of 43

SUMMARY 1
2 Perfluoroisobutylene (PFIB) is a colorle ss gas that is formed during the production of 3 tetrafluoroethylene. It is also produced in relatively small amounts during the heated 4 decomposition of polytetrafluoroethylene (PTFE or Teflon ® ) and some closely related plastics. 5 It is also produced by the thermal decomposition of the fluorinated primary fluid in the 6 condensation reflow soldering process. PFIB may be synthesized by atmospheric-pressure 7 pyrolysis of tetrafluoroethylene dimer (i.e., oc tafluorocyclobutane), which gives a 50% yield of 8
PFIB. 9
10 Data were insufficient for derivation of AEGL-1 values; therefore, AEGL-1 values are not 11
recommended for PFIB. 12
13 In the absence of appropriate chemical-specific data, the AEGL-3 values were divided by 3 14 to derive AEGL-2 values for PFIB (NRC, 2001). This approach is justified by the steep 15 concentration-response curve observed in several animal studies. No rats died when exposed to 16 0.25 ppm PFIB for 4 hours; whereas 100% lethality (6/6) was noted at 0.5 ppm for 4 hours 17 (DuPont, 1966). No mortality was noted in rats exposed to 228 ppm PFIB for 0.25 min and 18 100% mortality (10/10) was noted at 468 ppm. No mortality was noted in rats exposed to 20 19 ppm PFIB for 5 min and 9/10 rats died at 32 ppm. In rats exposed for 10 minutes, no mortality 20 was noted at 10 ppm and 8/10 rats died at 20 ppm (Smith et al., 1982). No mortality was noted 21 in mice exposed to 98 ppm PFIB for 1 minute; whereas, 6/6 mice died at 116 ppm (Fusheng et 22 al., 1992), and no mice died when exposed to 10 ppm for 10 minutes and 10/10 mice died at 65 23 ppm (Bide et al., 2000). Finally, no mortality was noted in rats, mice, guinea pigs, and rabbits 24 exposed to approximately 0.70 ppm PFIB for 2 hours; whereas, 10/10 rats, 10/10 mice, 4/5 25 guinea pigs, and 3/3 rabbits died when exposed to 1.5 ppm (Paulet and Bernard, 1968). 26
27 The highest concentration causing no mortality in rats exposed to PFIB for 4-hours (0.25 28 ppm) was used as the point-of-departure for AE GL-3 values (DuPont, 1966). Clinical signs 29 noted at this concentration included face washing, hyperemia, sneezing, hypernea, dyspnea, and 30 decreased responsiveness. There was 100% mortality (6/6) at the next highest concentration 31 tested (0.5 ppm). An interspecies uncertainty factor of 1 and an intraspecies uncertainty factor of 32 3 were applied. The interspecies UF of 1 is considered sufficient because lethality data available 33 for several animal species suggest little interspecies variability; LC 50 values for given exposure 34 durations are essentially equivalent (Table 9). Reported 1-min LC 50 values are 107 ppm for mice 35 (Fusheng et al., 1992) and 122 ppm for rats (Smith et al., 1982); 10-minute values are 11.8 ppm 36 for mice (Bide et al., 2000) and 17 ppm for rats (Smith et al., 1982); 15 minute values are 6.1 37 ppm for mice and 6.7 ppm for rats (Karpov, 1977); and reported 2-hour values are 0.98 ppm 38 (Paulet and Bernard, 1968) and 1.6 ppm for mice (Karpov, 1977), 1.05 ppm for rats and guinea 39 pigs (Paulet and Bernard, 1968), and 1.20 ppm for rabbits (Karpov, 1977). The intraspecies UF 40 of 3 is supported by the steep concentration-response curve for PFIB (described above for 41 AEGL-2), implying limited intraspecies variability. Values were scaled across time using the c n 42 x t = k, relationship where the exponent, n, is the chemical-specific value of 1.0, derived from rat 43
LC 50 data ranging from 0.25 to 120 minutes. 44
45
The calculated values are listed in the table below. 46
47PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 8 of 43

S 1. Summary of AEGL Values for PFIB

Classification 10-min 30-min 1-h 4-h 8-h Endpoint (Reference)

AEGL

B 1 (Nondisabling) NR NR NR NR NR Insufficient data

AEGL

B 2 (Disabling) 0.67 ppm (5.5 mg/m 3 ) 0.22 ppm (1.8 mg/m 3 ) 0.11 ppm (0.90 mg/m 3 ) 0.028 ppm (0.23 mg/m 3 ) 0.014 ppm (0.11 mg/m 3 ) 1/3 the AEGL-3
values.

AEGL

B 3 (Lethal) 2.0 ppm (16 mg/m 3 ) 0.67 ppm (5.5 mg/m 3 ) 0.33 ppm (2.7 mg/m 3 ) 0.083 ppm (0.68 mg/m 3 ) 0.042 ppm (0.34 mg/m 3 ) Highest concentration causing no lethality in rats (0.25 ppm; 4-hr). 100% mortality at
next concentration (0.5 ppm) tested (DuPont, 1966)

NR: Not Recommended due to insufficient data. Absence of an AEGL-1 value does not imply that concentrations
below the AEGL-2 are without effect.

1PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 9 of 43

1
1. INTRODUCTION 2
3 Perfluoroisobutylene (PFIB) is a colorless gas that is formed during the production of 4 tetrafluoroethylene (Kennedy, 1990; Gangal, 2004). It is also produced in relatively small 5 amounts during the heated decomposition of polytetrafluoroethylene (PTFE or Teflon ® ) and 6 some closely related plastics. It is also produced by the thermal decomposition of the fluorinated 7 primary fluid in the condensation reflow solder ing process (Shih et al., 1990). PFIB may be 8 synthesized by atmospheric-pressure pyrolys is of tetrafluoroethylene dimer (i.e., 9 octafluorocyclobutane), which gives a 50% yiel d of PFIB. No production information was 10 located. Chemical and physical property data are limited; available information is presented in 11
Table 1. 12

13

TABLE 1. Chemical and Physical Properties

Parameter Value ReferenceSynonyms PFIB; Octafluoroisobutylene; Octafluoro-secbutylene; 1-Propene, 1,1,3,3,3-pentafluoro-2- (tri fluoromethyl) AIHA, 2000; ACGIH, 1991

Chemical formula C 4 F 8 ACGIH, 1991 Molecular weight 200 AIHA, 2000 CAS Reg. No. 382-21-8 AIHA, 2000 Physical state Colorless gas AIHA, 2000 Density 1.5922 g/ml at 0 oC (liquid) AIHA, 2000 Boiling point 7oC at 760 mmHg AIHA, 2000 Conversion factors 1 ppm = 8.2 mg/m 3 1 mg/m 3 = 0.12 ppm AIHA, 2000

14
15
2. HUMAN TOXICITY DATA 16 2.1. Acute lethality 17
18 Makulova (1965) monitored 5 patients (2 men and 3 women) accidentally exposed to 19 PFIB at work. Two were chemical plant operators and the other three were chemical engineer 20 technologists involved in laboratory work. All but one [female] patient reported that the contact 21 with PFIB lasted less than one minute during which time 2 to 5 breaths were taken. Immediately 22 after exposure, all patients developed cough, difficulty breathing, and deep chest pains. 23 Approximately 6 to 8 hours after exposure, these symptoms increased in severity. No ocular or 24 upper respiratory irritation was noted. All patients ran fevers that lasted between 2 and 25 days, 25 and all developed pulmonary edema. The duration of the in-patient stay of the three patients was 26 13, 17, and 23 days. They were discharged as healthy, and follow-up checkups over 2 years 27 revealed no complications in these patients. One [male] patient remained hospitalized for over 2 28 months due to exudative pleuritis. Another [female] patient died two days after exposure; post29 mortem examination confirmed toxic fluid pneumonia and lung edema, hemorrhage into the left 30 adrenal and full bloodiness of internal organs. 31
32 Five workers were accidentally exposed to a gas that contained 2% PFIB, and they 33 reported irritation of the respiratory tract with in 24 hours (DuPont, 1976). A majority developed 34PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 10 of 43

a cough and exhibited choking or shortness of breath, and a few experienced wheezing. One of 1 the five workers died 11 days after exposure, and another one died 13 days after exposure. 2 Pathological examination revealed pulmonary congestion. 3
4 2.2 Nonlethal acute toxicity 5
6 A worker was exposed to PFIB for approximately 3 minutes after a spill of a 2% PFIB 7 mixture (DuPont, 1976). He reported a bad odor, ba d taste in the mouth, nausea, and weakness. 8 After returning to fresh air, he recovered and experienced no more symptoms. A PFIB 9 concentration of 0.04 ppm was measured one-half hour post-exposure, and it was estimated that 10 the worker could have been exposed to more than 4 ppm PFIB (assumes 10 to 40 air 11 changes/hour for a factory) (Kennedy and Geisen, 1985). 12
13 2.3. Developmental/Reproductive Toxicity 14
15 One of the exposed workers in the Makulova (1965) study was 15-16 weeks pregnant at 16 the time of exposure. The pregnancy ended in a normal, term delivery, the child was reportedly 17 healthy. 18
19
2.4. Genotoxicit y 20
21
No data were located. 22
23 2.5. Summary 24
25 Human data are limited to occupational exposures with no definitive concentration or 26 duration parameters. Clinical signs included cough, difficulty breathing, wheezing, nausea, chest 27 pain, weakness, and bad taste. Pulmonary edema and congestion were noted at autopsy. 28
29
30
31
3. ANIMAL TOXICITY DATA 32 3.1. Acute Lethality 33
34
3.1.1. Rats 35
36 Groups of two male albino rats were exposed whole-body for up to six hours to nominal 37 concentrations of 0.3, 0.5, or 1.0 ppm of PFIB from a supply cylinder and diluted with an air 38 stream in a mixing chamber (DuPont, 1956; 1961). Nominal concentrations were calculated 39 from the flow rates of PFIB gas and air. Clinical signs of respiratory impairment were noted at 40 0.5 and 1.0 ppm. At 0.5 ppm, slight dyspnea was noted at the end of the exposure period, and 41 both of these rats died the following night. At 1.0 ppm clinical signs progressed from labored 42 respiration noted during the first two hours of exposure, to gasping, cyanosis, and terminal 43 convulsions, with both rats being dead by 5 hours and 25 minutes after the start of treatment. 44 Pulmonary edema was noted in rats exposed to 0.5 and 1.0 ppm; rats in the 1.0 ppm group also 45 exhibited congestion of the brain. The rats exposed to 0.3 ppm did not show any signs of 46PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 11 of 43

toxicity during the exposure; however, a slight increase in respiration rate was noted on the first 1 day after exposure. No treatment-related effects were noted at terminal sacrifice (10 days post2 exposure). Data are summarized in Table 2. 3
4 TABLE 2. Summary of mortality data in rats exposed to PFIB for up to 6 hours. Concentration (ppm) Duration (hours) Mo rtality Clinical Signs Necropsy findings
0.3 6 0/2 none none 0.5 6 2/2 slight dyspnea Pulmonary edema 1.0 4.25 2/2 dyspnea; cyanosis Pulmonary edema DuPont, 1956; 1961 5
6 Groups of six male ChR-CD rats were exposed whole body for up to 4 hours to 0.25, 7 0.50, or 1.00 ppm PFIB (DuPont, 1966). Using a Harvard syringe drive, the gas was metered 8 into a T-tube, and a stream of air carried the gas into the 16-liter exposure chamber for the 9 treatment. Concentrations were measured by gas chromatography. All 6 rats exposed to 1.00 10 ppm died. Clinical signs noted during exposur e at 1.0 ppm included face washing, hyperemia, 11 dyspnea, pale ears, rapid respiration, and convulsions (in one animal). All 6 rats exposed for 4 12 hours at 0.50 ppm were found dead the following day. Clinical signs were similar to those 13 described for the 1.0 ppm group except that no convulsions occurred. Two groups of 6 rats each 14 were exposed to 0.25 ppm for 4 hours. None died fr om the exposure. No gross effects attributed 15 to the treatment were seen at necropsy in these 12 rats. Clinical signs during exposure included 16 face washing, hyperemia, sneezing, hyperpnea, dyspnea, and they were “mildly responsive”. 17 Half of the rats experienced dyspnea, which lasted for 3 hours after the end of the exposure. 18
Data are summarized in Table 3. 19
20 TABLE 3. Summary of mortality data in rats exposed to PFIB for 4 hours.
Conc. (ppm) Mortality Fate Clinical signs

During exposure Post-exposure 0.25 0/6 2/6 sacrificed 1-day post-exposure 2/6 sacrificed 2days post-exposure 2/6 sacrificed 7-days post-exposure Face washing, hyperemia, sneezing, hypernea, dyspnea, mildly responsive Dyspnea for 3 hr (3/6)

0.25 0/6 6/6 sacrificed 14-days post-e xposure Same as above Same as above 0.5 6/6 Found dead 1-day post-exposure Same as 1.0 ppm except no convulsions; mildly responsive -

1.0 6/6 Found dead during exposure (1:36- 2:19 hrs elapsed) Face washing, hyperemia, hypernea, dyspnea, pale ears, rapid respiration, convulsions (1/6) -

DuPont, 1966 21
22 Groups of 10 male ChR-CD ® albino rats were exposed nose-only to varying 23 concentrations of PFIB for 0.25, 0.50, 1, 2, 5, or 10 minutes, followed by a 14-day observation 24 period (Smith et al., 1982). A metered flow of PFIB (>99% pure) from a compressed gas 25 cylinder was dispersed into the small volume exposure chamber using a high rate of flow to 26 rapidly achieve chamber equilibrium. It was diluted with houseline air at 15.6 liters per minute 27 for dispersal into the exposure chamber. Rats were enclosed individually in sealed Parafilm ®

- 28 wrapped wire-mesh restraining cages and were positioned in the portals so that only their snouts 29 protruded into the chamber. Gross pathological examinations were given to at least two 30 representative rats that died within 24 hours after each exposure. Two to three gas samples per 31PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 12 of 43

exposure were collected from the different sampling ports and were analyzed by gas 1 chromatography. There were no deaths or clin ical signs noted during exposure; however, the 2 lack of clinical observations may be due to the fact that animals were exposed in nose-only 3 restraints. Most deaths occurred between eight and 24 hours after the exposure. Clinical signs 4 24 hours after the exposures were similar for all exposure scenarios. Mild to moderate weight 5 loss was observed, sometimes continuing up to 48 hours. At the higher concentrations there 6 were also signs of respiratory impairment (wheezing and labored breathing), but those 7 disappeared within 48 hours. Deaths were often accompanied by nasal and oral discharge of a 8 clear yellow fluid. Pathological examination re vealed heavy lungs that contained a foamy 9 exudate characteristic of acute pulmonary edema. Mortality data are summarized in Table 4. 10
11 TABLE 4. Summary of mortality data in rats exposed to PFIB for 0.25 to 10 minutes. Exposure Duration (min) Average Concentration (ppm) Mortality LC 50 (ppm) (±95%)
228 0/10
248 2/10
318 5/10
334 2/10
430 6/10 0.25

468 10/10 361 (321-415)

144 0/10
159 3/10
216 6/10
260 8/10 0.5

442 9/10 214 (179-261)

100 1/10
102 0/10
106 5/10
130 6/10
158 9/10 1

832 10/10 122 (113-139)

71 1/10
81 1/10
86 6/10
92 7/10 2

100 9/10 86 (82-91)

20 0/10
24 1/10
27 7/10
28 3/10 5

32 9/10 28 (26-29)

10 0/10
15 2/10
17 5/10 10

20 8/10 17 (15-19)

Smith et al., 1982 12
13 Danishevskii and Kochanov (1961) reported a 2-hour “maximal tolerance” 14 concentration of 1.5 ppm and “absolute lethal” (assumed to be 100% lethality) concentration of 15 1.8 ppm for albino rats. Histology showed pulmonary hemorrhages and edema, degenerative 16 changes in the kidney, and fatty changes in the liver. No other details were provided. 17PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 13 of 43

Karpov (1977) reported a 15-min LC 50 of 6.7 ppm for rats. Karpov (1977) reported a 2- 1
hour LC 50 of 11.6 ppm for white rats, and stated that rats exposed to 61-183 ppm PFIB died 2 within 1 minute. Pulmonary edema was given as the cause of death. 3
4 Moore, Jaeger and Jaax (1991) studied the eff ect of exercise on the pulmonary toxicity of 5 PFIB in male Sprague-Dawley rats. Groups of 12 rats trained to exercise on a treadmill were 6 sham-exposed or exposed to 12.2 ppm of PFIB vapor for 10 minutes. They were then exercised 7 on a treadmill until they were so exhausted that they refused to run when prodded with an 8 electric shock. Following 24 hours of observation, they were sacrificed, weighed, and their 9 livers, hearts and kidneys were examined for pathological changes. There was a significant 10 (p<0.01) difference in the endurance times of the two groups, with the PFIB-exposed group 11 having about 10 minutes more of endurance (64.71 vs 53.29 min for the PFIB and sham exposed 12 rats, respectively). The PFIB-exposed group showed significantly decreased activity and 13 piloerection starting 6 hours after exposure. Tw o of the 12 PFIB-exposed rats had breathing 14 difficulty and died 14 and 17 hours after exposure. The PFIB-exposed rats had increased 15 absolute and relative lung weights regardless of whether they had been exercised; however, the 16 PFIB-induced edema was more severe in the exposed rats that had been exercised. No effects of 17 the treatment were seen on the livers, hearts, or kidneys. 18

Lehnert et al. (1995) also investigated the e ffects of exercise on PFIB-treated male Fischer 19 344 rats exposed to 12 ppm for 10 minutes. This treatment regimen reportedly results in a 20 latency period of approximately 8 hours before the occurrence of overt pulmonary edema. The 21 study examined the effect of exercise on these animals during and after the latency period. 22 Initial results indicated that exercise during the latency period did not potentiate the injurious 23 response, as judged by conventional lung gravimet ric and histopathologic criteria. However, 24 when overt pulmonary edema was preexistent, exercise had a potentiating effect. 25

26 Brown and Rice (1991) conducted an electron microscopy study on female Porton rat lungs 27 during the first 24 hours after a single 1.5-minute exposure to 78 ppm PFIB (96% purity). Rats 28 were sacrificed within 5 minutes of exposure or at 1, 2, 3, 4, 6, 8, 12, 16, or 24 hours post29 exposure. Within five minutes after the head-only exposures, changes in the bronchioles and 30 peribronchial alveoli were observed that took the form of alterations in cilial structure, increased 31 pinocytosis and electron lucency. There was occas ional vesicle formation of type I alveolar 32 epithelial cells. Intercellular leakage was also noted with minimal fluid accumulation in the 33 alveolar spaces. Gradually there was development of pulmonary edema, which was visible 34 histologically between two and three hours after treatment. Deaths occurred starting at seven 35 hours post-exposure. Rats that were killed for examination 24 hours after treatment had 36 widespread pulmonary edema and interstitial infiltration by lympho-mononuclear cells and 37 macrophages. 38
39 Lehnert et al. (1993) also studied damage to the lungs of PFIB-treated rats. Adult male 40 Wistar rats were exposed for 10 minutes to 6.1, 10, 11, 13, or 24 ppm of PFIB. Groups of rats 41 were killed at various times after the exposures for gravimetric and histopathological 42 examination of the lungs. Gravimetric measurements included lung wet weight (LWW), right 43 cranial lobe dry weight (RCLDW), and wet weight . In a second series that involved exposures 44 to 12 and 24 ppm, lungs were examined by tr ansmission electron microscopy. Body weight 45 losses of about 3% were seen within the first 8 hours after exposure and continued for 48 to 72 46PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 14 of 43

hours. No gravimetric increases or pathological changes were noted after exposures to PFIB at 1 6.1 and 10 ppm. LWW and RCLDW values revealed the clear development of pulmonary 2 edema. At exposure to 11 ppm, the lung injuries began to show up histologically, within hours 3 after the exposure, and the latency periods were inversely proportional to the PFIB 4 concentrations. Significant accumulations of edema fluid were not apparent until 9 hours 5 following the exposure, in correspondence with the gravimetric data. At 18 to 24 hours after 6 exposure, significant amounts of fibrin were det ected in the alveolar spaces, but no fibrin was 7 seen at 48 to 72 hours. At the highest concentration, there was no latency period. 8
9 An influx of polymorphonuclear neutrophils was not seen until 12 to 24 hours after exposure 10 to 12 ppm of PFIB (Lehnert et al., 1993). Signi ficant increases in alveolar macrophages were 11 seen 10 hours after exposure, with peak increases between 24 and 48 hours. As revealed by 12 transmission electron microscopy, the alveolar epithelial cells and endothelial cells showed 13 abnormal vacuolization and blebbing already at one hour after exposure. The alveolar surface 14 was progressively denuded, leading to the fl ooding of the alveolar area with vascular 15 constituents including red blood cells. Alveolar macrophages seemed to be relatively insensitive 16
to the toxic effects of PFIB. 17
18 Nold et al. (1991) conducted light and electr on microscopy to morphologically characterize 19 the development of lung injury following a 2-minute whole-body exposure of thirty-five Wistar 20 Porton female rats to 64 ppm PFIB vapor. Concentrations in the exposure chamber were 21 monitored by a Miran infrared spectrophotometer. Five rats each were necropsied at post22 exposure intervals of 5 minutes, 30 minutes, 90 minutes and 4, 12, 24, and 72 hours. At 5 23 minutes, there was minimal, multifocal, perivascular edema with minimal to moderate 24 eosinophilic pulmonary perivasculitis. By 90 minutes, all rats had mild multifocal perivascular 25 edema in all lung lobes and mild, pulmonary, eosinophilic perivascular inflammation. By 12 26 hours, and also at 24 hours, all rats showed diffuse severe alveolar edema with deposition of 27 fibrin. The alveolar septa were thickened, and the alveoli contained increased numbers of 28 macrophages as well as occasional eosinophils and neutrofils. There was significant resolution 29 of the pulmonary edema and fibrin deposition by 72 hours. 30
31
32 Paulet and Bernard (1968) exposed groups of ten rats to “heavy products/high boilers” for 33 2 hours. The “heavy products/high boilers” are by-products formed at high temperatures 34 (700°C) during the synthesis of tetrafluoroethyl ene from chlorodifluoromethane. Certain 35 volatile and relatively inert by-products readily dissipate; however, other heavier more unstable 36 by-products with high boiling points (above 40°C) accumulate at the base of the distillation 37 column. The physical properties of these compounds lead to the name “heavy products/high 38 boilers.” Analyses of these “heavy products/high boilers” suggested that PFIB (found in 39 concentrations ranging from 0.1 to 3%) is responsible for the high toxicity of “heavy 40 products/high boilers”. A concentration of 0.15% PFIB was assumed in this study. A 2-hr LC 50 41 of 1.05 ppm was calculated for PFIB (the 2-hr LC 50 was 700 ppm for heavy products/high 42 boilers). Data are summarized in Table 5. 43
44

45
46PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 15 of 43

TABLE 5. Summary of mortality data for animals exposed to heavy products/high boilers for 2 hours “Heavy
Product”

(HP)
Concentration (ppm) Estimated

PFIB
Concentration (ppm) Rat Mouse Guinea pig Rabbit

Mortality Average
survival Mortality Average
survival Mortality Average
survival Mortality Average
survival
270 0.49 0/10 - 0/10 - 0/5 - 0/3 -
480 0.70 0/10 - 0/10 - 0/5 - 0/3 -
750 1.10 8/10 24 hr 10/10 - 7/10 - 1/5 -
1000 1.50 10/10 15 hr 10/10 7 hr 4/5 24 hr 3/3 12 hr
1530 2.30 10/10 - 10/10 3 hr 20 5/5 - 3/3 -
2000 3.00 10/10 - 10/10 - 5/5 - 3/3 -
3000 4.50 10/10 2 hr 10/10 2 hr 30 5/5 2 hr 3/3 2 hr
3500 5.20 10/10 2 hr 10/10 3 hr 5/5 2 hr 15 3/3 2 hr
5200 7.90 10/10 1 hr 20 10/10 1 hr 10 5/5 0 hr 50 3/3 1 hr 10

PFIB LC 50 1.05 ppm 0.98 ppm 1.05 ppm 1.20 ppm

HP LC 50 700 ppm 650 ppm 700 ppm 800 ppm Paulet and Bernard, 1968 1
2
3
3.1.2. Mice 4
5 As part of a study to examine inhalation toxicologic procedures in small laboratory animals, 6 Bide et al. (2000) whole body exposed male and female CD-1 mice to PFIB for 10 minutes. 7 Animals were observed for at least 20 days after the exposure. The 6 L exposure chamber was a 8 Plexiglas box with conical ends. Concentrations were determined using a MIRAN Analyzer. 9
The LC 50 was estimated to be 11.8 ppm, with most deaths occurring between 24 and 48 hours 10 after the treatment. In all cases lung edema was the cause of death. Data are summarized in 11
Table 6. 12
13 TABLE 6. Summary of mortality data in mice exposed to PFIB for 10 minutes. Number of deaths by day Concentration (ppm) Mortality
1 2 3 4

8.3 0/10 - - - -
9.2 0/10 - - - -
10* 0/10 - - - -
10* 2/10 - 2 - -
12* 2/5 - 2 - -
12* 1/5 - 1 - -
13* 5/5 1 1 2 1
13* 4/5 - 3 1 -
15* 9/9 5 4 - -
15* 8/8 4 4 - -
65 10/10 10 - - - Bide et al., 2000 14 *Although not stated in the study report, it is assume d that the duplicate exposures represent males and 15 females separately. 16
17 Fusheng et al. (1992) exposed groups of six Kunming mice whole body to 98, 104, 110, 18PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 16 of 43

116, or 123 ppm PFIB (97.5% purity) for 1-minute. PFIB concentrations were determined by 1 gas chromatography. The mice showed no clinical signs during the first 3 hours after exposure. 2 After that they gradually showed a decrease in spontaneous movement, depressed respiration, 3 staggering, inflammation of the eyes, prostrati on, and finally weakness and convulsions leading 4 to death. Surviving animals appeared to recover fully. An LC 50 value of 107 ppm (95% CI 104- 5 110 ppm) was reported. Mortality data are summarized in Table 7. 6
7 TABLE 7. Summary of mortality data in mice exposed to PFIB for 1 minute. Concentration (ppm) Mortality Death time after exposure (hr)
98 0/6 - 104 2/6 23, 26 110 4/6 14, 16, 20, 26 116 6/6 10, 27, 28, 29, 39, 40 123 6/6 10, 16, 17, 8, 18, 18 Fusheng et al., 1992 8
9
10
11 Danishevskii and Kochanov (1961) reported a 2-hour “maximal tolerance” 12 concentration of 0.61 ppm, “minimal lethal” concentration of 1.2 ppm and “absolute lethal” 13 (assumed to be 100% lethality) concentration of 1.8 ppm for albino mice. Histology showed 14 pulmonary hemorrhages and edema, degenerative changes in the kidney, and fatty changes in the 15 liver. No other details were provided. 16
17 Karpov (1977) reported a 15-min LC 50 of 6.1 ppm for white mice. Karpov (1977) also 18 reported a 2-hour LC 50 of 1.6 ppm for white mice, and stated that mice exposed to 61-183 ppm 19 PFIB died within 1 minute. Pulmonary edema was given as the cause of death. 20
21 Paulet and Bernard (1968) exposed groups of ten mice to “heavy products/high boilers” for 2 22
hours as described in section 3.1.1. A 2-hr LC 50 of 0.98 ppm was calculated for PFIB (the 2-hr 23
LC 50 was 650 ppm for heavy products/high boilers). Data are summarized in Table 5. 24
25
26 3.1.3. Guinea pigs 27
28 Paulet and Bernard (1968) exposed groups of five or ten guinea pigs to “heavy 29 products/high boilers” for 2 hours as described in section 3.1.1. A 2-hr LC 50 of 1.05 ppm was 30 calculated for PFIB (the 2-hr LC 50 was 700 ppm for heavy products/high boilers). Data are 31
summarized in Table 5. 32
33
34
3.1.4. Rabbits 35
36 Karpov (1977) reported a 15-min LC 50 of 12.2 ppm for rabbits. Karpov (1977) also 37 reported a 2-hour LC 50 of 4.3 ppm, and stated that rabbits exposed to 61-183 ppm PFIB died 38 within 1 minute. Pulmonary edema was given as the cause of death. 39
40 Paulet and Bernard (1968) exposed groups of three or five rabbits to “heavy 41PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 17 of 43

products/high boilers” for 2 hours as described in section 3.1.1. A 2-hr LC 50 of 1.20 ppm was 1 calculated for PFIB (the 2-hr LC 50 was 800 ppm for heavy products/high boilers). Data are 2
summarized in Table 5. 3
4
3.1.5. Cats 5
6 Karpov (1977) reported a 2-hour LC 50 of 3.1 ppm for cats. Pulmonary edema was given 7
as the cause of death. 8
9
10 3.2. Nonlethal Acute Toxicity 11
12
3.2.1. Rats 13
14 Groups of white rats were exposed to 0, 0.12, 0.24, or 0.49 ppm PFIB for 4 hours (Karpov, 15 1977). “Impairment of conditioned reflexive activity” was noted in animals exposed to 0.24 and 16 0.49 ppm. Liver transaminase activity was also increased in these rats (33% and 55% increases 17 for the 0.24 and 0.49 ppm groups, respectively). Pulmonary edema was reported in the 0.24 and 18 0.49 ppm groups. No significant treatment-related effects were noted at 0.12 ppm. 19
20
21 3.3. Repeat Dose Studies 22
23 Four male albino rats were exposed to 0.1 ppm PFIB 6 hours/day for 10 days (DuPont, 24 1956; 1961). Rats were sacrificed at the end of the exposure period. The PFIB gas was mixed 25 with air in a carboy and then passed into a bell jar containing the rats. Nominal concentrations 26 were calculated from the flow rates of PFIB gas and air. During the exposures, the rats were 27 occasionally restless and had mild respiratory impairment that sometimes proceeded to cyanosis; 28 two of the rats developed moist rales. Occasional body weight loss was noted in two rats during 29 the first week of exposure only. There were no c linical observations or effects on weight gain. 30 All rats survived the treatment period. There we re no gross or histopathological effects or organ 31 weight effects noted at necropsy. 32
33 In another study, ten male ChR-CD rats were exposed to 0 or 0.098 ppm of PFIB 6 34 hours/day, 5 days/week for two weeks (DuPont, 1975). PFIB chamber concentrations were 35 determined by gas chromatography using an electron capture detector. Five rats/concentration 36 were sacrificed at 0 and 14-days post-exposure. No treatment-related gross or microscopic 37 changes were observed at the end of the exposure period or after the14-day follow-up period. 38
39 McMaster et al. (1989) exposed ten male Sprague-Dawley rats to PFIB by inhalation. 40 The rats had been trained to press a lever for a food reward under a multiple time-out fixed ratio 41 of reinforcement. At certain times in this activity, 30 lever presses resulted in a reward pellet. 42 Multiple 10-minute head-only exposures to PFIB starting at 1.2 ppm were administered at 43 unspecified intervals of no less than one week. The exposures were increased in 2.4 ppm 44 increments an unspecified number of times. During the experiment, all rats continued to respond 45 within the range of their baseline levels at exposure concentrations below 180 ppm x minutes 46PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 18 of 43

(presumably cumulative). As the cumulative exposure concentrations approached what would 1
be the estimated LC 50 , performance deficits were seen in some animals. The animals with 2 performance deficits showed pulmonary edema and histologically-damaged lungs. 3
4 3.4. Developmental/Reproductive Toxicity 5
6
No data were located. 7
8 3.5. Genotoxicity 9
10
No data were located. 11
12 3.6. Chronic Toxicity/Carcinogenicity 13
14
No data were located. 15
16
17 3.7. Summary 18
19 Animal lethality data are available for rats, mice, guinea pigs, rabbits, and cats, with the most 20 robust data sets being for rats and mice. Clinical signs include dyspnea, cyanosis, face washing, 21 hyperemia, sneezing, mild responsiveness, rapid respiration, and convulsions. Death is 22 attributed to pulmonary edema which is a consistent necropsy finding. The concentration23 response curve is very steep for many species with regard to lethality. For example, no rats died 24 when exposed to 0.25 ppm PFIB for 4 hours; whereas 100% lethality (6/6) was noted at 0.5 ppm 25 for 4 hours (DuPont, 1966). No mortality was noted in rats exposed to 228 ppm PFIB for 0.25 26 min and 100% mortality (10/10) was noted at 468 ppm. No mortality was noted in rats exposed 27 to 20 ppm PFIB for 5 min and 9/10 rats died at 32 ppm. In rats exposed for 10 minutes, no 28 mortality was noted at 10 ppm and 8/10 rats died at 20 ppm (Smith et al., 1982). No mortality 29 was noted in mice exposed to 98 ppm PFIB for 1 minute; whereas, 6/6 mice died at 116 ppm 30 (Fusheng et al., 1992), and no mice died when exposed to 10 ppm for 10 minutes and 10/10 mice 31 died at 65 ppm (Bide et al., 2000). Finally, no mortality was noted in rats, mice, guinea pigs, and 32 rabbits exposed to approximately 0.70 ppm PFIB for 2 hours; whereas, 10/10 rats, 10/10 mice, 33 4/5 guinea pigs, and 3/3 rabbits died when exposed to 1.5 ppm (Paulet and Bernard, 1968). No 34 developmental/reproductive, genotoxicity, chronic t oxicity, or carcinogenicity data were located. 35
Selected animal data are summarized in Table 8. 36PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 19 of 43

1

TABLE 8. Summary of selected animal inhalation data

Species Duration Concentration (ppm) Endpoint Reference

Rat 0.25 minutes 228 No mortality. Weight loss (10) a Smith et al., 1982

Rat 0.25 minutes 361 LC 50 (10) Smith et al., 1982

Rat 0.5 minutes 144 No mortality. Weight loss (10) Smith et al., 1982

Rat 0.5 minutes 214 LC 50 (10) Smith et al., 1982

Mouse 1 minute 98 No mortality. Decreased movement, decreased respiration, staggering, ocular inflammation, prostration (6) Fusheng et al., 1992

Rat 1 minute 100 10% mortality (10) Smith et al., 1982

Mouse 1 minute 107 LC 50 (6) Fusheng et al., 1992

Rat 1 minute 122 LC 50 (10) Smith et al., 1982

Rat 2 minutes 71 10% mortality (10) Smith et al., 1982

Rat 2 minutes 86 LC 50 (10) Smith et al., 1982

Rat 5 minutes 20 No mortality. Weight loss (10) Smith et al., 1982

Rat 5 minutes 28 LC 50 (10) Smith et al., 1982

Mouse 10 minutes 9.2 No mortality. Clinical signs not reported (10) Bide et al., 2000

Rat 10 minutes 10 No mortality. Weight loss (10) Smith et al., 1982

Mouse 10 minutes 11.8 LC 50 (10) Bide et al., 2000

Rat 10 minutes 17 LC 50 (10) Smith et al., 1982

Mouse 15 minutes 6.1 LC 50 Karpov, 1977

Rat 15 minutes 6.7 LC 50 Karpov, 1977

Rabbit 15 minutes 12.2 LC 50 Karpov, 1977

Rat 2 hours 0.25 No mortality. Face washing, hyperemia, sneezing, hypernea, dyspnea, mildly responsive (6) DuPont, 1966

Rat, mouse, guinea pig,

rabbit 2 hours 0.70 b No mortality (3-10) Paulet and Bernard, 1968

Mouse 2 hours 0.98 b LC 50 (10) Paulet and Bernard, 1968

Rat 2 hours 1.05 b LC 50 (10) Paulet and Bernard, 1968

Guinea pig 2 hours 1.05 b LC 50 (5-10) Paulet and Bernard, 1968PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 20 of 43

Rabbit 2 hours 1.20 b LC 50 (3-5) Paulet and Bernard, 1968

Mouse 2 hours 1.2 ALC a Karpov, 1977

Mouse 2 hours 1.6 LC 50 Karpov, 1977

Mouse 2 hours 1.8 100% mortality Danishevskii and Kochanov, 1961

Rat 2 hours 1.8 100% mortality Danishevskii and Kochanov, 1961

Cat 2 hours 3.1 LC 50 Karpov, 1977

Rabbit 2 hours 4.3 LC 50 Karpov, 1977

Rat 2 hours 11.6 LC 50 Karpov, 1977

Rat 4 hours 0.50 100% mortality (6) DuPont, 1966

Rat 4 hours 1.0 100% mortality (6) DuPont, 1966

Rat 4.25 hours 1.0 100% mortality (2) DuPont, 1956; 1961

Rat 6 hours 0.3 No effects (2) DuPont, 1956; 1961

Rat 6 hours 0.50 100% mortality (2) DuPont, 1956; 1961 1

a Number in round brackets is the number of an imals exposed/group, wh en this is known. 2

b PFIB Concentration estimated assuming 0. 15% PFIB in Heavy Products/High Boilers 3

c ALC = Approximate Lethal Concentration, a concentration at which at least one animal died after a single inhalation 4

exposure 5 6PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 21 of 43

4. SPECIAL CONSIDERATIONS 1 4.1. Metabolism and Disposition 2
3 Essentially no information was located concerning the metabolism and disposition of 4 PFIB. However, Maidment and Upshall (1992) st udied retention of inhaled PFIB using female 5 rats that were restrained by stocks at the neck in a head-out plethysmograph while being exposed 6 for 2.25 minutes to 1.2, 6, or 30 ppm of PFIB in a number of repeated exposures. The total 7 exposures amounted to 0.1, 0.5, and 2.5 times a reported LC 50 . There was no evidence of 8 changes in minute volume or breathing rate that could be related to the repeated exposures. The 9 uptake of PFIB at the tested concentrations was said to be an apparent first-order process in that 10 the percentage of the inhaled PFIB that was retained remained constant, and the rate of uptake 11 increased proportionately with the inhaled dosage. Early tissue damage, if any, did not influence 12 retention in the respiratory tract. 13
14
15 4.2. Mechanism of Toxicity 16
17 Arroyo (1997) studied the chemistry of PFIB by using electron paramagnetic resonance spin18 trapping techniques and concluded that this highly electrophilic chemical likely undergoes 19 electron transfer that leads to several highly reactive intermediates. PFIB is reactive towards 20 nucleophilic reagents to yield substitution and addition radical byproducts. PFIB reacts with 21 almost all known nucleophiles. 22
23 Lailey et al. (1991) suggested that PFIB ma y exert its toxic effect by depletion of 24 intracellular nucleophiles, including amines, thiols and alcohols. When a lethal concentration of 25 PFIB (purity >96.1%) was inhaled by Porton strain rats, total non-protein thiol (NPSH) and 26 glutathione (GSH) in the lung were reduced by between 30 and 49%, respectively (Lailey et al., 27 1991). If rats were pretreated to reduce endogenous thiol levels in the lungs before PFIB 28 treatment, the rats were more susceptible to the lethal effects of the gas. Treatments that raised 29 levels of cysteine (CySH) in the lungs before tr eatment with PFIB protected rats from the lethal 30 effects of PFIB. In a study of the effects of pretreatment of rats with oral N-acetylcyteine 31 (Lailey, 1997), it was found that plasma levels of cysteine, glutathione, and N-acetylcystein were 32 increased for up to seven hours following oral administration of N-acetylcysteine, and this 33 treatment provided substantial protection for rats against the lethal effects of inhaling PFIB. 34
35 The pattern of pulmonary damage induced by PFIB is characteristic of highly hydrophobic 36 gases that penetrate into the deep lung. The first sign of cellular damage is at the pulmonary 37 epithelium. However, there is evidence of interstitial edema and increased lymph flow before 38 there is alveolar filling, which suggests that damage to the endothelial cells is an early event. 39 After exposure to an LC 50 of PFIB, there is no increase in lung weight for up to six hours, after 40 which there is a progressive filling of the alveoli. That filling may lead to death from pulmonary 41 edema between eight and 12 hours after the exposure. No significant pathology is apparent 42 outside the lung other than the congestion induced by flow resistance that is caused by the severe 43 pulmonary edema (Lailey et al., 1991). 44
45 Maidment et al. (1994) also noted that there is little evidence of direct pathological damage 46PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 22 of 43

to tissues outside the respiratory tract by PFIB. All PFIB-induced tissue damage appears to 1 result from rapid interaction with cells that are either in, or in close proximity to, the respiratory 2 airways. PFIB is a hydrophobic gas that induces a permeability-type edema. Maidment et al. 3 (1994) stated that extensive unreported studies in rats of the toxicopathology of PFIB in their 4 laboratory had “failed to reveal any significan t macroscopic or microscopic pathology outside 5 the respiratory system at a number of time points up to 14 days after exposure, when resolution 6 of the initial pulmonary injury is complete.” 7
8 Gurley et al. (1991) used high-performance capillary electrophoresis to identify proteins 9 from the fluid lining of the lungs of male rats given whole-body exposures to 12 ppm of PFIB for 10 10 minutes. Comparisons were made with untr eated controls. The PFIB concentration was 11 measured using a dual-column gas chromatograph fitted with an electron-capture detector that 12 was sensitive to 1 ppb of PFIB. The lung fluid was obtained using a bronchoalveolar lavage 13 procedure. The edema that was induced involve d the translocation of proteins from the blood 14 compartment into the lung’s alveolar compartment. Three of the major proteins that were 15 translocated in this way were albumin, transferrin and IgG. 16
17 Pathogen-free male Sprague-Dawley rats and pathogen-free male Kunming mice 18 (5/group/species) were exposed whole-body to sublethal concentrations of PFIB in order to 19 determine how PFIB causes lung injury (Wang et al., 2001). A separate group of rats and mice, 20 made neutropenic by i.p. injection with cyclophosphamide, were exposed to PFIB to determine 21 the effect of depleted polymorphonuclear leukoc ytes (PMN) on PFIB-induced lung injury. All 22 exposures lasted five minutes, and measurement of lung myeloperoxidase (MPO) activity, and 23 lung wet-to-dry ratio, lung lavage, and histopa thological examinations were conducted over 24 time. In the first experiment, rats were exposed to 16.8 ppm and mice were exposed to 15.6 ppm 25 for five minutes. The rats were sacrificed 24 hours post exposure for ultrastructural examination. 26 In rats, the total protein concentration in the bronchoalveolar lavage fluid was increased as early 27 as two hours post exposure and reached a peak at 24 hours. A decrease in protein was found at 28 48 and 72 hours post exposure, but still remained significantly higher than baseline. In mice, 29 lung MPO activity increased as early as 1-hour post exposure and peaked at 20 hours, but it had 30 returned to normal by 60 hours. The lung wet-to-dry weight increased drastically from 20 to 24 31 hours and recovered slowly from 24-48 hours. In the PMN depletion study, mice were exposed 32 to 22.8 ppm of PFIB for five minutes and followed for up to seven days post exposure. The rats 33 were exposed to 16.8 ppm and sacrificed 24 hours post exposure. After 5 min of exposure, 10 of 34 16 mice exposed to PFIB without depleted PMN died by 7 days after treatment compared to only 35 1 of 16 in the PMN-depleted mice, with this di fference being statistically significant. There was 36 a lack of increase in MPO activity, but the lung wet-to-dry ratio was slightly increased in the 37 mice. The total protein concentration in the bronchoalveolar lavage fluid of the PMN-depleted 38 and PFIB-exposed rats was significantly increased compared to that of the controls but to a 39 lesser degree in the rats exposed to PFIB only. Vascular congestion, interstitial and intra40 alveolar edema, alveolar hemorrhage, and increased numbers of inflammatory cells were 41 observed in the lungs of the rats exposed only to PFIB. Ultrastructural examination showed 42 severe damage to the alveolar structure, excessive vesiculation, exfoliated epithelial cells, and 43 alveoli with exudated erythrocytes, fibrin, a nd inflammatory cells. The PMN-depleted and 44 PFIB-exposed rats had moderate septal thickeni ng, intra-alveolar edema, fibrin deposition, and 45 macrophage accumulation in the alveolar spaces. Th e alveolar structures of the PMN-depleted 46 and PFIB-exposed rats were intact, but vacuoles and blebs in endothelial and epithelial cells 47PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 23 of 43

were seen. The authors concluded that neutrophil sequestration and accumulation in the lungs is 1 a key factor in acute PFIB-induced lung injury and mortality. They indicated that 2 polymorphonuclear leukocytes (PMN) are not the only contributor to PFIB inhalation-induced 3 lung damage and edema, and suggested that the roles of other effector cells such as monocytes 4 and macrophages should also be clarified. 5
6
7
4.3. Other Relevant Information 8 4.3.1. Interspecies Variability 9
10 Lethality data, available for several animal species, suggest little interspecies variability 11 (Table 9). LC 50 values for given exposure durations are essentially equivalent except for one 12 two-hour rat value (Karpov, 1977) which is inconsistent with the overall data set. This value 13 suggests that the rat is much less sensitive than would be expected from the other LC 50 values. 14
15
16 TABLE 9. Comparison of PFIB LC 50 values for various animal species Duration Species LC 50 (ppm) Ratio of LC 50 values (maximum) Reference

Mouse 107 Fusheng et al., 1992 1 minute

Rat 122 1.1 Smith et al., 1982 Mouse 11.8 Bide et al., 2000 10 minutes

Rat 17 1.4 Smith et al., 1982 Mouse 6.1 Karpov, 1977 15 minutes

Rat 6.7 1.1 Karpov, 1977

Mouse 0.98

Rat 1.05 Guinea pig 1.05

Rabbit 1.20 Paulet and Bernard,
1968

Mouse 1.6 Karpov, 1977 1.6 2 hours

Rat* 11.6* 11.8* Karpov, 1977
*LC 50 value inconsistent with overall data base (Karpov (1977) 15-minute rat value and reports from other authors). 17
18
19
4.3.2. Intraspecies Variability 20
21 Specific data concerning susceptible populations are not available; however the 22 concentration-response curve for PFIB is very steep, thus, implying limited intraspecies 23 variability. [Data showing steepness of the concentration response curve are as follows: No rats 24 died when exposed to 0.25 ppm PFIB for 4 hours; whereas 100% lethality (6/6) was noted at 0.5 25 ppm for 4 hours (DuPont, 1966). No mortality was noted in rats exposed to 228 ppm PFIB for 26 0.25 min and 100% mortality (10/10) was noted at 468 ppm. No mortality was noted in rats 27 exposed to 20 ppm PFIB for 5 min and 9/10 rats died at 32 ppm. In rats exposed for 10 minutes, 28 no mortality was noted at 10 ppm and 8/10 rats died at 20 ppm (Smith et al., 1982). No mortality 29 was noted in mice exposed to 98 ppm PFIB for 1 minute; whereas, 6/6 mice died at 116 ppm 30 (Fusheng et al., 1992), and no mice died when exposed to 10 ppm for 10 minutes and 10/10 mice 31 died at 65 ppm (Bide et al., 2000). No mortality was noted in rats, mice, guinea pigs, and rabbits 32PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 24 of 43

exposed to approximately 0.70 ppm PFIB for 2 hours; whereas, 10/10 rats, 10/10 mice, 4/5 1 guinea pigs, and 3/3 rabbits died when exposed to 1.5 ppm (Paulet and Bernard, 1968).] 2
3
4

5
4.3.3 Structure Activity 6
7 Clayton (1977) reported that the susceptibility of fluoroalkenes to nucleophilic attack 8 parallels the inhalation toxicity of these compounds: PFIB > hexafluoropropylene > 9 tetrafluoroethylene. However, experimental data supporting this potential relationship are not 10
available. 11
12 Clayton (1977) also compared the acute rat inhalation toxicity of several fluoroalkenes. 13 While toxicity may appear to be inversely related to the number of fluorine atoms, there are no 14 mechanistic data to support this assumption. It is more likely that toxicity is related instead to 15
the double bond. 16
17 Jugg et al. (1999) investigated the differen ces in action between PFIB and phosgene, both 18 of which produce pulmonary permeability-type edema. The study attempted to distinguish 19 between damage to the surfactant system of alve oli and effects on type II pneumocytes in the rat 20 lung. Alterations of the lung surfactant system were demonstrated. The progression of the 21 injury was followed for 48 hours after exposure with one or the other of these gases at a 22 concentration equal to the LC 30 by analyzing the inflammatory cells and protein in 23 bronchoalveolar lavage fluid. Six lung phospholipids were measured by high-performance 24 liquid chromatography after solid phase extracti on from lavage fluid. These two gases differed 25 both with respect to the percentage compos ition of surfactant and the total amount of 26 phospholipids present. PFIB produced increases in phosphatidylglycerol and 27 phosphatidylcholine within the first hour, followed by a substantial decrease in these 28 phospholipids. In contrast, phosgene caused a late increase in all phospholipids beginning 6 29 hours after the exposure. These findings show that phosgene and PFIB have different 30 mechanisms of action at the alveolar surface. PFIB also caused a large neutrophilia at 24 hours 31 post-treatment, with large numbers of monocytes being present from then on. Phosgene 32 exposure also led to a large neutrophilia between 24 and 48 hours after treatment. Both gases 33 caused a significant reduction in the number of alveolar macrophages. 34
35
36 4.3.4. Concentration-Exposure Duration Relationship 37
38 The concentration-exposure time relationship for many irritant and systemically-acting 39 vapors and gases has been described by the relationship c n x t = k, where the exponent, n, 40 typically ranges from 0.8 to 3.5 (ten Berge et al., 1986). When the rat 0.25 to 120 minute- LC 50 41 values from Table 8 are considered in the derivation of the exponent, a value of 1.0 is obtained. 42
When the mouse 1 to 120 minute- LC 50 values from Table 8 are considered in the derivation of 43 the exponent, a value of 1.1 is obtained (Appendix B). 44PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 25 of 43

1
5. DATA ANALYSIS FOR AEGL-1 2 5.1. Summary of Human Data Relevant to AEGL-1 3
4 No human studies were available for development of AEGL-1 values. 5
6 5.2. Summary of Animal Data Relevant to AEGL-1 7
8 No animal studies were available for development of AEGL-1 values. 9
10
5.3. Derivation of AEGL-1 11
12
No human or animal data were available for derivation of AEGL-1 values for PFIB. 13 Therefore, AEGL-1 values are not recommended (Table 10). 14
15 16

TABLE 10. AEGL-1 Values for PFIB

10-min 30-min 1-h 4-h 8-hour

NR NR NR NR NR

NR: Not Recommended due to insufficient data. Absence of an AEGL-1 value does not imply that concentrations 17

below the AEGL-2 are without effect. 18
19
20
6. DATA ANALYSIS FOR AEGL-2 21 6.1. Summary of Human Data Relevant to AEGL-2 22
23 No human studies were available for development of AEGL-2 values. 24
25 6.2. Summary of Animal Data Relevant to AEGL-2 26
27 Animal data showing clinical signs consistent with the definition of AEGL-2 are available; 28 however, mortality was observed at the next highest concentration tested. Therefore, these data 29 are more appropriate for derivation of AEGL-3 values. 30
31
6.3. Derivation of AEGL-2 32
33 In the absence of appropriate chemical-specific data, the AEGL-3 values will be divided by 3 34 to derive AEGL-2 values for PFIB (NRC, 2001). This approach is justified by the steep 35 concentration-response curve observed in several animal studies. No rats died when exposed to 36 0.25 ppm PFIB for 4 hours; whereas 100% lethality (6/6) was noted at 0.5 ppm for 4 hours 37 (DuPont, 1966). No mortality was noted in rats exposed to 228 ppm PFIB for 0.25 min and 38 100% mortality (10/10) was noted at 468 ppm. No mortality was noted in rats exposed to 20 39 ppm PFIB for 5 min and 9/10 rats died at 32 ppm. In rats exposed for 10 minutes, no mortality 40 was noted at 10 ppm and 8/10 rats died at 20 ppm (Smith et al., 1982). No mortality was noted 41 in mice exposed to 98 ppm PFIB for 1 minute; whereas, 6/6 mice died at 116 ppm (Fusheng et 42 al., 1992), and no mice died when exposed to 10 ppm for 10 minutes and 10/10 mice died at 65 43 ppm (Bide et al., 2000). Finally, no mortality was noted in rats, mice, guinea pigs, and rabbits 44PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 26 of 43

exposed to approximately 0.70 ppm PFIB for 2 hours; whereas, 10/10 rats, 10/10 mice, 4/5 1 guinea pigs, and 3/3 rabbits died when exposed to 1.5 ppm (Paulet and Bernard, 1968). AEGL-2 2 values are summarized in Table 11 and calculations are in Appendix A. 3

4

TABLE 11. AEGL-2 Values for PFIB

10-min 30-min 1-h 4-h 8-h 0.67 ppm (5.5 mg/m 3 ) 0.22 ppm (1.8 mg/m 3 ) 0.11 ppm (0.90 mg/m 3 ) 0.028 ppm (0.23 mg/m 3 ) 0.014 ppm (0.11 mg/m 3 )

5
6
7
7. DATA ANALYSIS FOR AEGL-3 8 7.1. Summary of Human Data Relevant to AEGL-3 9
10 No human studies were available for development of AEGL-3 values. 11
12 7.2. Summary of Animal Data Relevant to AEGL-3 13
14 Animal lethality data are available for rats, mice, rabbits, guinea pigs, and cats exposed to 15 varying concentrations of PFIB for durations ranging from 0.25 minutes to 6 hours. Potential 16 AEGL-3 points-of-departure include the followi ng: the highest experimental concentration 17 causing no mortality in rats exposed to PFIB for 4-hours (0.25 ppm analytical concentration); 18 100% mortality was observed at the next highest concentration tested (0.5 ppm) (DuPont, 1966); 19 or the highest experimental concentration causing no mortality in rats exposed to PFIB for 6- 20 hours (0.3 ppm nominal concentration); 100% mortality (2/2 animals) was observed at the next 21 highest concentration tested (0.5 ppm) (DuPont, 1956; 1961). Calculated thresholds for lethality 22 in rats (data in Tables 2, 3, 4, & 5) or mice (data in Tables 5, 6, & 7) using the probit-analysis 23 dose-response program of ten Berge may also be used for derivation of AEGL-3 values. Use of 24 the ten Berge approach would utilize both nominal and analytical data. The highest 25 experimental concentration causing no mortality in rats, mice, guinea pigs, and rabbits exposed 26 to PFIB for 2-hours (0.70 ppm) (Paulet and Bernard, 1968) is also a potential point-of-departure. 27 Mortality was noted in all species at the next highest concentration tested (1.1 ppm); the PFIB 28 concentrations in this study were estimated assuming 0.15% PFIB in heavy products/high 29
boilers. 30
31
32
7.3. Derivation of AEGL-3 33
34 The highest concentration causing no mortality in rats exposed to PFIB for 4-hours (0.25 35 ppm) will be used as the point-of-departure for AEGL-3 values (DuPont, 1966). This approach 36 is chosen over the other approaches discussed in Section 7.2 because it is the only approach 37 utilizing entirely analytical data. Clinical signs noted at this concentration included face 38 washing, hyperemia, sneezing, hypernea, dyspnea, and decreased responsiveness. There was 39 100% mortality (6/6) at the next highest concentration tested (0.5 ppm). 40
41PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 27 of 43

An interspecies uncertainty factor of 1 and an intraspecies uncertainty factor of 3 will be 1 applied. The interspecies UF of 1 is considered sufficient because lethality data available for 2 several animal species suggest little interspecies variability; LC 50 values for given exposure 3 durations are essentially equivalent (Table 9). Reported 1-min LC 50 values are 107 ppm for mice 4 (Fusheng et al., 1992) and 122 ppm for rats (Smith et al., 1982); 10-minute values are 11.8 ppm 5 for mice (Bide et al., 2000) and 17 ppm for rats (Smith et al., 1982); 15 minute values are 6.1 6 ppm for mice and 6.7 ppm for rats (Karpov, 1977); and reported 2-hour values are 0.98 ppm 7 (Paulet and Bernard, 1968) and 1.6 ppm for mice (Karpov, 1977), 1.05 ppm for rats and guinea 8 pigs (Paulet and Bernard, 1968), and 1.20 ppm for rabbits (Karpov, 1977). 9
10 The intraspecies UF of 3 is supported by the steep concentration-response curve for PFIB, 11 implying limited intraspecies variability. No rats died when exposed to 0.25 ppm PFIB for 4 12 hours; whereas 100% lethality (6/6) was noted at 0.5 ppm for 4 hours (DuPont, 1966). No 13 mortality was noted in rats exposed to 228 ppm PFIB for 0.25 min and 100% mortality (10/10) 14 was noted at 468 ppm. No mortality was noted in rats exposed to 20 ppm PFIB for 5 min and 15 9/10 rats died at 32 ppm. In rats exposed for 10 minutes, no mortality was noted at 10 ppm and 16 8/10 rats died at 20 ppm (Smith et al., 1982). No mortality was noted in mice exposed to 98 ppm 17 PFIB for 1 minute; whereas, 6/6 mice died at 116 ppm (Fusheng et al., 1992), and no mice died 18 when exposed to 10 ppm for 10 minutes and 10/10 mice died at 65 ppm (Bide et al., 2000). No 19 mortality was noted in rats, mice, guinea pigs, and rabbits exposed to approximately 0.70 ppm 20 PFIB for 2 hours; whereas, 10/10 rats, 10/10 mice, 4/5 guinea pigs, and 3/3 rabbits died when 21 exposed to 1.5 ppm (Paulet and Bernard, 1968). 22
23 Values will be scaled across time using the c n x t = k, relationship where the exponent, n, is 24 the chemical-specific value of 1.0, derived from rat LC 50 data ranging from 0.25 to 120 minutes. 25
26 AEGL-3 values are summarized in Table 12 and calculations are in Appendix A. 27
28

TABLE 12. AEGL-3 Values for PFIB

10-min 30-min 1-h 4-h 8-h 2.0 ppm (16 mg/m 3 ) 0.67 ppm (5.5 mg/m 3 ) 0.33 ppm (2.7 mg/m 3 ) 0.083 ppm (0.68 mg/m 3 ) 0.042 ppm (0.34 mg/m 3 ) 29 Time scaling from 4-hours to 10-minutes is justified based on the fact that no mortality was 30 noted in rats exposed to 10 ppm PFIB (Smith et al., 1982) or mice exposed to 9.2 ppm PFIB 31 (Bide et al., 2000) for 10-minutes. Applying a total uncertainty factor of 3 to these 32 concentrations, yields 10-min AEGL-3 values of 3.3 and 3.1 ppm, suggesting that the derived 33
10-min AEGL-3 value is reasonable. 34
35
8. SUMMARY OF AEGLs 36 8.1. AEGL Values and Toxicity Endpoints 37
38
AEGL-1 values are not recommended due to insufficient data. AEGL-2 values are one39 third of the AEGL-3 values, and AEGL-3 values are based on a 4-hour threshold for lethality in 40
rats. AEGL values for PFIB are summarized in Table 13. 41
42PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 28 of 43

TABLE 13. Summary of AEGL Values
Exposure Duration Classification 10-min 30-min 1-h 4-h 8-h

AEGL-1 (Nondisabling) NR NR NR NR NR

AEGL-2 (Disabling) 0.67 ppm (5.5 mg/m 3 ) 0.22 ppm (1.8 mg/m 3 ) 0.11 ppm (0.90 mg/m 3 ) 0.028 ppm (0.23 mg/m 3 ) 0.014 ppm (0.11 mg/m 3 )

AEGL-3 (Lethal) 2.0 ppm (16 mg/m 3 ) 0.67 ppm (5.5 mg/m 3 ) 0.33 ppm (2.7 mg/m 3 ) 0.083 ppm (0.68 mg/m 3 ) 0.042 ppm (0.34 mg/m 3 )

NR: Not Recommended due to insufficient data. Absence of an AEGL-1 value does not imply that concentrations 1

below the AEGL-2 are without effect. 2
3
4 8.2. Comparison with Other Standards and Guidelines 5
6 Extant standards and guidelines for PFIB are presented in Table 14. 7
8

TABLE 14. Standards and Guidelines for PFIB
Exposure Duration Guideline 10-min 30-min 1-h 4-h 8-h

AEGL-1 NR NR NR NR NR AEGL-2 0.67 ppm 0.22 ppm 0.11 ppm 0.028 ppm 0.014 ppm AEGL-3 2.0 ppm 0.67 ppm 0.33 ppm 0.083 ppm 0.042 ppm

ERPG-1 (AIHA) a NA ERPG-2 (AIHA) a 0.1 ppm ERPG-3 (AIHA) a 0.3 ppm TLV-STEL (ACGIH) b 0.01 ppm (ceiling)

MAC ( The Netherlands ) c 0.01 ppm

9

a ERPG (Emergency Response Planning Guidelines, Am erican Industrial Hygiene Association (AIHA 2008) 10

The ERPG-1 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 11 exposed for up to one hour without experiencing other than mild, transient adverse health effects or without 12 perceiving a clearly defined objectionable odor. The ERPG-1 for PFIB is not established due to lack of data. 13 14

The ERPG-2 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 15 exposed for up to one hour without experiencing or devel oping irreversible or other serious health effects or 16 symptoms that could impair an individual = s ability to take protective action. The ERPG-2 for PFIB is just below 17 the level at which pulmonary edema (0.24 ppm) and clin ical signs of respiratory irritation (0.25 ppm) were 18 observed in rats exposed for 4-hours. 19 20

The ERPG-3 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 21 exposed for up to one hour without experiencing or devel oping life-threatening health effects. The ERPG-3 for 22 PFIB is based on CT product lethality data for animals. 23 24

b ACGIH TLV-STEL (American Conference of Governmental Industrial Hygienists, Threshold Limit Value - 25 Short Term Exposure Limit) (ACGIH 2008) is for a 15-minute exposure, ceiling. Recommended to minimize 26 the potential for acute pulmonary and adverse systemic effects in other organs. 27 28PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 29 of 43

c MAC (Maximaal Aanvaarde Concentratie [Maximal A ccepted Concentration]). SDU Uitgevers (under the 1 auspices of the Ministry of Social Affairs and Em ployment), The Hague, The Netherlands 2000, is defined 2 analogous to the ACGIH-TLV-TWA. 3 4
5
6
9. REFERENCES 7 8
9 ACGIH (American Conference of Government and Industrial Hygienists). 2008. TLVs and 10
BEIs Based on the Documentation of the Threshold Limit Values for Chemical Substances and 11 Physical Agents and Biological Exposure Indices : Perfluoroisobutylene. ACGIH, Cincinnati, 12
OH. 13
14 ACGIH (American Conference of Govern ment and Industrial Hygienists). 1991. 15 Perfluoroisobutylene. Documentation of the Threshold Limit Values and Biological Exposure 16 Indicies. Sixth Edition. Cincinnati, OH: ACGIH. 17
18 AIHA (American Industrial Hygiene Associ ation). 2008. The AIHA 2008 Emergency Response 19 Planning Guidelines and Workplace Environmental Exposure Level Handbook. Fairfax, VA. 20
21 AIHA (American Industrial Hygiene Associa tion). 2000. Emergency Response Planning 22 Guidelines for Perfluoroisobutylene. AIHA, Fairfax, VA. 23
24 Arroyo, CM. 1997. The chemistry of perfluoroisobutyl ene (PFIB) with nitrone and nitroso spin 25 traps: an EPRpin trapping study. Chem ico-Biological Interactions 105(2): 119-129. 26
27 Bide, R., D.J. Risk and D. Beifus. 2000. Inhalati on toxicologic procedures for exposure of small 28 laboratory animals to highly toxic materials: Pa rt A: Exposures to gases with notes on the 29 toxicity of PFIB. Technical Report DRES TR 2000-065. Defense Research Establishment 30 Suffield, England. 31
32 Brown, R.F.R. and P. Rice. 1991. Electron micr oscopy of rat lung following a single acute 33 exposure to perfluoroisobutylene (PFIB). A sequential study of the first 24 hours following 34 exposure. Int. J. Exper. Path. 72(4): 437-450. 35
36 Clayton, J.W. 1977. Toxicology of the fluoroalkenes: review and research needs. Environ. 37 Health Perspect. 21: 255-267. 38
39 Danishevskii, S.L. and M.M. Kochanov. 1961. [O n the toxicology of some fluoro-organic 40 compounds.] Gig. Truda Prof: Zabol. 5: 3-8. 41
42 DuPont (E.I. duPont de Nemours and Company, Inc.). 1956. Toxicity Studies of Pyrolysis 43 Products of Fluorinated Polymers (Teflon Poly tetrafluoroethylene) with Cover Letter Date 44 101292: Initial Submission. Haskell Laboratory Report No. 18-56. DuPont Co., Haskell 45 Laboratory, Newark. DE. 46
47PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 30 of 43

DuPont (E.I. duPont de Nemours and Company, Inc.). 1961. Initial submission: Inhalation 1 toxicity studies on perfluoroisobutylene w ith cover letter dated 101592. Haskell Laboratory 2 Report No. 1-61. DuPont Co., Haskell Laborator y for Toxicology and Industrial Medicine, 3
Newark. DE. 4
5 Du Pont Company: “Acute Inhalation Toxicity (Haskell Laboratory Report Number 34-66)”. 6 February 25, 1966. [Unpublished information.] E.I. DuPont de Nemours & Co., Haskell 7 Laboratory, Elkton Rd, P.O Box 50, Newark, DE 19714. 8
9 DuPont (E.I. duPont de Nemours and Company, Inc.). 1975. Two week inhalation toxicity study. 10 Haskell Laboratory Report No. 684-75. DuPont Co., Haskell Laboratory, Elkton Rd, P.O Box 11 50, Newark, DE 19714. 12
13 Du Pont Company. 1976. Personal Communication to the ERP Committee. October 14, 1976. 14 E.I. DuPont de Nemours & Co., Haskell La boratory, Elkton Rd, P.O Box 50, Newark, DE 15
19714. 16
17 Fusheng, L., L. Weigang, Y. Songmin, et al. 1992. Acute inhalation toxicology studies on three 18 perfluoroorganic compounds. The Proceedings of the Fourth International Symposium on 19 Protection Against Chemical Warfare Agents, pp. 183-190. 20

Gangal, S.V. 2004. Perfluorinated Polymers. Kirk-Othmer Encyclopedia of Chemical 21 Technology, 4 th Ed., M. Howe-Grant, ed. [Online] Available. 22 http://www.mrw.interscience.wiley.com/ emrw/ 9780471238966/ kirk/article/ 23 tetrgang.a02/current/html. 24
25 Gurley, L.R., Buchanan, J.S., J.E. London, et al. 1991. High-performance capillary 26 electrophoresis of proteins from the fluid lining of the lungs of rats exposed to 27 perfluoroisobutylene. Journal of Chromatography. 559(1-2): 411-429. 28
29 Jugg, B., J. Jenner and P. Rice. 1999. The effect of perfluoroisobutene and phosgene on rat 30 lavage fluid surfactant phospholipids. Hum. Exp. Toxicol. 18(11): 659-668. 31
32 Karpov, B.D. 1977. Establishment of upper and lower toxicity parameters of 33 perfluroisobutylene toxicity. Tr. Le nig. Sanit-Gig. Med. Inst. 111: 30-33. 34
35 Kennedy, G.L. and Geisen, R.J. 1985. Setting occupational exposure limits for 36 Perfluoroisobutylene, a highly toxic chemical following acute exposure. J. Occup. Med. 37
27:675. 38
39 Kennedy, G.L., Jr. 1990. Toxicology of fluorine- containing monomers. Critical Reviews in 40 Toxicology 21:149-170. 41
42 Lailey, A.F., L. Hill, I.W. Lawston, et al. 1991. Protection by cysteine esters against chemically 43 induced pulmonary edema. Biochem. Pharmacol. 42: S47-S54. 44

Lailey, A.F. 1997. Oral N-acetylcysteine protects ag ainst perfluoroisobutene toxicity in rats. 45PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 31 of 43

Human and Experimental Toxicology 16(4): 212-216. 1
2

Lehnert, B.E., D. Archuleta, M.J. Behr and D.M. Stavert. 1993. Lung injury after acute 3 inhalation of perfluoroisobutylene: Exposure c oncentration-response relationships. Inhalation 4 Toxicology 5(1): 1-32. 5

Lehnert, B.E., D. Archuleta, L. Gurley, et al. 1995. Exercise potentiation of lung injury 6 following inhalation of a pneumoedematogenic gas: perfluoroisobutylene. Exp. Lung Res. 21(2): 7
331-348. 8

Maidment, M.P. and D.G. Upshall. 1992. Retention of inhaled perfluoroisobutene in the rat. J. 9 Appl. Toxicol. 12: 393-400. 10

Maidment, M.P., P. Rice and D.G. Upshall. 1994. Retention of inhaled hexafluorocyclobutene in 11 the rat. J. of Applied Toxicolgy 14(6): 395-400. 12

Makulova, I.D. 1965. [Clinical picture of acute poisoning with perfluroisobutylene.] Gig. Tr. 13
Prof. Zabol. 9:20-23. 14

McMaster, S.B., K.G. Phillips, A.V. Finger and F. Feliciano. 1989. An analysis of potential 15 behavioral effects of multiple sub-lethal exposures to perfluoroisobutylene. Proceedings of the 16 1989 Medical Defense Biosciences Review. pp 175-178

. 17
18 Moore, D.H., J.J. Jaeger and N.K. Jax. 1991. Effects of exercise following exposure to 19 perfluoroisobutylene. Inhalation Toxicology 3(1): 113-122. 20
21 Nold, J.B., J.P. Petrali, H.G. Wall and D.H. Moore. 1991. Progressive pulmonary pathology of 22 two organofluorine compounds in rats. Inhalation Toxicol. 3: 123-137. 23

NRC (National Research Council). 2001. Standing operating procedures for developing acute 24 exposure guideline levels for hazardous chemicals. Committee on Toxicology, Board on 25 Toxicology and Environmental Health Hazards, Commission on Life Sciences, National 26 Research Council. National Academy Press, Washington, DC. 27
28 Paulet, G. and J.P. Bernard. 1968. Heavy produc ts appearing during the fabrication of 29 polytetrafluorethylene: Toxicity-physiopathologi c action; therapy. Biol-Med. (Paris) 57: 247- 30
301. 31

SDU. 2000. MAC (Maximaal Aanvaarde Concentra tie [Maximal Accepted Concentration]). 32 SDU Uitgevers (under the auspices of the Mini stry of Social Affairs and Employment), The 33 Hague, The Netherlands 2000 34

Shih, M.L., J.R. Smith and J.D. McMonagle. 1990. Gas chromatographic analysis of toxic 35 edemagenic inhalation compounds. Analytical Letters 23(9): 1711-1727. 36

Smith,W., R.J. Gardner and G.L. Kennedy. 1982. Short-term inhalation toxicity of 37 perfluoroisobutylene. Drug and Chemical Toxicology 5: 295-303. 38PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 32 of 43

ten Berge, W.F., A. Zwart and L.M. Appelman. 1986. Concentration-time mortality response 1 relationship of irritant and systemically acti ng vapors and gases. J. Hazard. Mater. 13(3): 301- 2
310. 3

Wang, H., Ding, R., Ruan, J., Yuan, B. Sun, X., Zhang X., Yu, S., Qu, W. 2001. Perfluoro4 isobutylene-induced acute lung injury and mortality are heralded by neutrophil sequestration and 5 accumulation. J. Occup. Health 43: 331-338. 6

7PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 33 of 43



### APPENDIX A: Derivation of PFIB AEGLs 1

2
Derivation of AEGL-1 Values 3
4
5
AEGL-1 values are not recommended due to insufficient data. Absence of AEGL-1 values does 6 not imply that concentrations below AEGL-2 are without effect. 7PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 34 of 43

1
Derivation of AEGL-2 Values 2 3
4 Key Study: None. In the absence of appropriate data, the AEGL-2 values are derived by taking 5 one-third of the respective AEGL-3 values. This approach is justified by a steep concentration6 response. [No rats died when exposed to 0.25 ppm PFIB for 4 hours; whereas 100% lethality 7 (6/6) was noted at 0.5 ppm for 4 hours (DuPont, 1966). No mortality was noted in rats exposed 8 to 228 ppm PFIB for 0.25 min and 100% mortality (10/10) was noted at 468 ppm. No mortality 9 was noted in rats exposed to 20 ppm PFIB for 5 min and 9/10 rats died at 32 ppm. In rats 10 exposed for 10 minutes, no mortality was noted at 10 ppm and 8/10 rats died at 20 ppm (Smith et 11 al., 1982). No mortality was noted in mice exposed to 98 ppm PFIB for 1 minute; whereas, 6/6 12 mice died at 116 ppm (Fusheng et al., 1992), and no mice died when exposed to 10 ppm for 10 13 minutes and 10/10 mice died at 65 ppm (Bide et al., 2000). Finally, no mortality was noted in 14 rats, mice, guinea pigs, and rabbits exposed to approximately 0.70 ppm PFIB for 2 hours; 15 whereas, 10/10 rats, 10/10 mice, 4/5 guinea pigs, and 3/3 rabbits died when exposed to 1.5 ppm 16 (Paulet and Bernard, 1968). ] 17
18
19
20
10-minute AEGL-2: 1⁄3 10-minute AEGL-3 = 2.0 ppm ÷ 3 = 0.67 ppm 21
22
30-minute AEGL-2: 1⁄3 30-minute AEGL-3 = 0.67 ppm ÷ 3 = 0.22 ppm 23
24
1-hour AEGL-2: 1⁄3 1-hour AEGL-3 = 0.33 ppm ÷ 3 = 0.11 ppm 25
26
4-hour AEGL-2: 1⁄3 4-hour AEGL-3 = 0.083 ppm ÷ 3 = 0.028 ppm 27
28
8-hour AEGL-2: 1⁄3 8-hour AEGL-3 = 0.042 ppm ÷ 3 = 0.014 ppm 29
30PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 35 of 43

1
Derivation of AEGL-3 Values 2
3 Key Study: DuPont, 1966 4
5 Toxicity endpoint: 0.25 ppm, 4-hours 6 Highest concentration causing no mortality in rats; 100% mortality (6/6) at the next highest 7 concentration tested (0.5 ppm) 8
9 Time scaling: c n x t = k, where the exponent, n, is the chemical-specific value of 1.0, derived 10
from rat LC 50 data ranging from 0.25 to 120 minutes 11
12
C 1.0 x t = k 13 (0.25 ppm) 1 x 4 hr = 1 ppm

⋅ hr 14
15
16 Uncertainty factors: 1 for interspecies variability. Considered sufficient because lethality data 17 available for several animal species suggest little interspecies variability; 18
LC 50 values for given exposure durations are essentially equivalent (Table 19 9). 20
21 3 for intraspecies variability. Supported by the steep concentration22 response curve for PFIB, implying limited intraspecies variability. 23
24
25
10-minute AEGL-3: C 1.0 x 0.167 hr = 1 ppm

⋅ hr 26
C 1 = 5.9 ppm 27 AEGL-3 = 5.9 ppm ÷ 3 = 2.0 ppm 28
29
30-minute AEGL-3: C 1.0 x 0.5 hr = 1 ppm

⋅ hr 30
C 1 = 2 ppm 31 AEGL-3 = 2 ppm ÷ 3 = 0.67 ppm 32
33
1-hour AEGL-3: C 1.0 x 1 hr = 1 ppm

⋅ hr 34
C 1 = 1 ppm 35 AEGL-3 = 1 ppm ÷ 3 = 0.33 ppm 36
37 4-hour AEGL-3: C = 0.25 ppm 38 AEGL-3 = 0.25 ppm ÷ 3 = 0.083 ppm 39
40
8-hour AEGL-3: C 1.0 x 8 hr = 1 ppm

⋅ hr 41
C 1 = 0.125 ppm 42 AEGL-3 = 0.125 ppm ÷ 3 = 0.042 ppm 43
44
45PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 36 of 43

APPENDIX B: Time Scaling Calculations 1
2
RAT DATA 3

Log Log Time Conc. Time Conc. Regression Output: 0.25 361 -0.6021 2.5575 Intercept 2.0774

0.5 214 -0.3010 2.3304 Slope -0.9618

1 122 0.0000 2.0864 R Squared 0.9870
2 86 0.3010 1.9345 Correlation -0.9935 5 28 0.6990 1.4472 Degrees of
Freedom 6

10 17 1.0000 1.2304 Observations 8

15 6.7 1.1761 0.8261
120 1.05 2.0792 0.0212

n = 1.04
k = 144.53

Minutes Conc. Hours Conc.

30 4.54 0.5 232.79
60 2.33 1.0 119.52
240 0.61 4.0 31.51
480 0.32 8.0 16.18 4
5

0 0.5

1 1.5

2 2.5

3Log Concentration

-1 -0.5 0 0.5 1 1.5 2 2.5 Log Time Best Fit Concentration x Time Curve

6PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 37 of 43

1
MOUSE DATA 2

Log Log Time Conc. Time Conc. Regression Output: 1 107 0.0000 2.0294 Intercept 1.9844 10 11.8 1.0000 1.0719 Slope -0.9220 15 6.1 1.1761 0.7853 R Squared 0.9847
120 0.98 2.0792 -0.0088 Correlation -0.9923 120 1.6 2.0792 0.2041 Degrees of
Freedom 3

Observations 5

n = 1.08
k = 142.03

Minutes Conc. Hours Conc.

30 4.19 0.5 182.80
60 2.21 1.0 96.48
240 0.62 4.0 26.87
480 0.33 8.0 14.18
3

-0.5 0 0.5

1 1.5

2 2.5Log Concentration

0 0.5 1 1.5 2 2.5 Log Time Best Fit Concentration x Time Curve

4 5PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 38 of 43

1 

### APPENDIX C: Derivation Summary for PFIB 2
3
4

AEGL-1 VALUES FOR PFIB

10-min 30-min 1-h 4-h 8-hour

NR NR NR NR NR Key Reference: Test Species/Strain/Number: Exposure Route/Concentration/Duration:

Effects:

Endpoint/Concentration/Rationale: Uncertainty Factors/Rationale: Total uncertainty factor:

Modifying Factor: Animal to Human Dosimetric Adjustment: Time Scaling: Data Adequacy: Data are insufficient for deriving AEGL-1 values for PFIB; therefor e, AEGL-1 values are not recommended. Absence of an AEGL-1 value does not impl y that concentrations below the AEGL-2 are without
effect.PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 39 of 43

AEGL-2 VALUES FOR PFIB

10 min 30 min 1 h 4 h 8 h 0.67 ppm (5.5 mg/m 3 ) 0.22 ppm (1.8 mg/m 3 ) 0.11 ppm (0.90 mg/m 3 ) 0.028 ppm (0.23 mg/m 3 ) 0.014 ppm (0.11 mg/m 3 )

Reference:

Test Species/Strain/Sex/Number: : Exposure Route/Concentrations/Durations:

Effects: Endpoint/Concentration/Rationale : One-third the AEGL-3 values. Justified by a steep concentration-response. [No rats died when exposed to 0.25 ppm PFIB for 4 hours; whereas 100% lethality (6/6) was noted at 0.5 ppm for 4 hours (DuPont, 1966). No mortality was noted in rats exposed to 228 ppm PFIB for 0.25 min and 100% mortality (10/10) was noted at 468 ppm. No mortality was noted in rats exposed to 20 ppm PFIB for 5 min and 9/10 rats died at 32 ppm. In rats exposed for 10 minutes, no mortality was noted at 10 ppm and 8/10 rats died at 20 ppm (Smith et al., 1982). No mortality was noted in mice exposed to 98 ppm PFIB for 1 minute; whereas, 6/6 mice died at 116 ppm (Fusheng et al., 1992), and no mice died when exposed to 10 ppm for 10 minutes and 10/10 mice died at 65 ppm (Bide et al., 2000). Finally, no mortality was noted in rats, mice, guinea pigs, and rabbits exposed to approximately 0.70 ppm PFIB for 2 hours; whereas, 10/10 rats, 10/10 mice, 4/5 guinea pigs, and 3/3 rabbits died when exposed to 1.5 ppm (Paulet and Bernard, 1968). Uncertainty Factors/Rationale:

Modifying Factor: Animal to Human Dosimetric Adjustment: Time Scaling: : Data Adequacy: Inadequate data set for AEGL-2 effects.
1PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 40 of 43

1

AEGL-3 VALUES FOR PFIB

10 min 30 min 1 h 4 h 8 h 2.0 ppm (16 mg/m 3 ) 0.67 ppm (5.5 mg/m 3 ) 0.33 ppm (2.7 mg/m 3 ) 0.083 ppm (0.68 mg/m 3 ) 0.042 ppm (0.34 mg/m 3 )
Reference: DuPont , 1966. Initial Submission: Acute inha lation toxicity of perfluoroisobutylene in rats with
cover letter dated 101592. OTS0571231. Test Species/Strain/Sex/Number: rat/ChR-CD /male/6 per group Exposure Route/Concentrations/Durations: Rats exposed to 0.25, 0.5, or 1.0 ppm for 4-hours

Effects: 0.25 ppm: No mortality. Clinical signs included face washing, hyperemia, sneezing, hypernea, dyspnea, mildly responsive

0.5 ppm: 100% Mortality (6/6; found dead 1-day post-expos ure). Clinical signs same as 1.0 ppm except no convulsions. Mildly responsive

1.0 ppm: 100% Mortality (6/6; found dead during exposure) . Clinical signs included face washing, hyperemia, hypernea, dyspnea, pale ears, rapi d respiration, convulsions (1/6) Endpoint/Concentration/Rationale: 0.25 ppm for 4-hr/ Highest concentration causing no mortality in rats; 100% mortality (6/6) at the next highest concentration tested Uncertainty Factors/Rationale: Total un certainty factor adjustment was 3. Interspecies: 1 – Considered sufficient because lethality data available for several animal species suggest little interspecies variability; LC 50 values for given exposure durations are e ssentially equivalent (Table 9). Reported
1-min LC 50 values are 107 ppm for mice (Fusheng et al., 1992) and 122 ppm for rats (Smith et al., 1982); 10- minute values are 11.8 ppm for mice (Bide et al., 2000) and 17 ppm for rats (Smith et al., 1982); 15 minute values are 6.1 ppm for mice and 6.7 ppm for rats (Karpov, 1977); and reported 2-hour values are 0.98 ppm (Paulet and Bernard, 1968) and 1.6 ppm for mice (Karpov, 1977), 1.05 ppm for rats and guinea pigs (Paulet and Bernard, 1968), and 1.20 ppm for rabbits (Karpov, 1977).

Intraspecies: 3 – Supported by the steep concentration-response curve for PFIB, implying limited intraspecies variability. No rats died when exposed to 0.25 ppm PFIB for 4 hours; whereas 100% lethality (6/6) was noted at 0.5 ppm for 4 hours (DuPont, 1966). No mort ality was noted in rats exposed to 228 ppm PFIB for 0.25 min and 100% mortality (10/10) was noted at 468 ppm. No mortality was noted in rats exposed to 20 ppm PFIB for 5 min and 9/10 rats died at 32 ppm. In rats exposed for 10 minutes, no mortality was noted at 10 ppm and 8/10 rats died at 20 ppm (Smith et al., 1982). No mortality was noted in mice exposed to 98 ppm PFIB for 1 minute; whereas, 6/6 mice died at 116 ppm (Fusheng et al., 1992), and no mice died when exposed to 10 ppm for 10 minutes and 10/10 mice died at 65 ppm (Bide et al., 2000). No mortality was noted in rats, mice, guinea pigs, and rabbits exposed to approximately 0.70 ppm PFIB for 2 hours; whereas, 10/10 rats, 10/10 mice, 4/5 guinea pigs, and 3/3 rabbits died when exposed to 1.5 ppm (Paulet and Bernard, 1968).

Modifying Factor: NA Animal to Human Dosimetric Adjustment: Not applicable Time Scaling: C n x t = k, where n=1.0, derived from rat LC 50 data ranging from 0.25 to 120 minutes. Time scaling from 4-hours to 10-minutes is justified based on the fact that no mortality was noted in rats exposed to 10 ppm PFIB (Smith et al., 1982) or mice exposed to 9.2 ppm PFIB (Bide et al., 2000) for 10-minutes. Applying an uncertainty factor of 3 to these concentrations, yields 10-min AEGL3 values of 3.3 and 3.1 ppm, suggesting that the derived 10-min AEGL-3 value is reasonable. Data Adequacy: Sufficient for AEGL-3 derivation.
2PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 41 of 43

APPENDIX D: CATEGORY PLOT FOR PFIB 1
2
3

0.0 0.1 1.0 10.0 100.0 1000.0ppm

0 60 120 180 240 300 360 420 480 Minutes Human - No Effect

Human - Discomfort

Human - Disabling

Animal - No Effect

Animal - Discomfort

Animal - Disabling

Animal - Some Lethality

Animal - Lethal

AEGL Chemical Toxicity
PFIB

AEGL-3

AEGL-2

4 5
6
7
8
9
10
11
12
13
14
15
16
17
18PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 42 of 43

1 Source Species ppm Minutes Category

NAC/AEGL-1 NR 10 AEGL
NAC/AEGL-1 NR 30 AEGL
NAC/AEGL-1 NR 60 AEGL
NAC/AEGL-1 NR 240 AEGL
NAC/AEGL-1 NR 480 AEGL

NAC/AEGL-2 0.67 10 AEGL
NAC/AEGL-2 0.22 30 AEGL
NAC/AEGL-2 0.11 60 AEGL
NAC/AEGL-2 0.028 240 AEGL
NAC/AEGL-2 0.014 480 AEGL

NAC/AEGL-3 2.0 10 AEGL
NAC/AEGL-3 0.67 30 AEGL
NAC/AEGL-3 0.33 60 AEGL
NAC/AEGL-3 0.083 240 AEGL
NAC/AEGL-3 0.042 480 AEGL

Rat 0.3 360 0 no effects (DuPont, 1956;1961) Rat 0.5 360 3 Mortality: 2/2 (DuPont, 1956; 1961) Rat 1 255 3 Mortality: 2/2 (DuPont, 1956; 1961) Rat 0.25 240 2 Face washing, hyperemia, sneezing, dyspnea, mildly responsive (DuPont, 1966) Rat 0.5 240 3 Mortality: 6/6 (DuPont, 1966) Rat 1 240 3 Mortality: 6/6 (DuPont, 1966) Rat 10 10 2 Wheezing, labored breathing (Smith et al., 1982) Rat 15 10 pl Mortality: 2/10 (Smith et al, 1982) Rat 17 10 pl Mortality: 5/10 (Smith et al, 1982) Rat 20 10 pl Mortality 8/10 (Smith et al., 1982) Rat 1.8 120 3 100% mortality (Danishevskii & Kochanov, 1961) Rat 6.7 15 pl LC50 (Karpov, 1977) Rat 11.6 120 pl LC50 (Karpov, 1977)
rat,

mouse, GP, rabbit 0.7 120 2 clinical signs (Paulet & Bernard, 1968)

rat,

mouse, GP, rabbit 1.1 120 pl Mortality: 8/10 rats, 10/10mice, 7/10 GP, 1/5 rabbit (Paulet & Bernard, 1968)

rat,

mouse, GP, rabbit 1.5 120 3 100% mortality (Paulet & Bernard, 1968)

mouse 9.2 10 2 “Clinical signs" (Bide et al., 2000) mouse 10 10 pl Mortality: 2/10(Bide et al, 2000) mouse 15 10 3 Mortality: 17/17 (Bide et al., 2000) mouse 98 1 2 Decreased movement, respiration, staggering, weakness (Fusheng, 1992) mouse 104 1 pl Mortality: 2/6 (Fusheng, 1992) mouse 116 1 3 Mortality: 6/6 (Fusheng, 1992) mouse 1.8 120 3 100% mortality (Danishevskii & Kochanov, 1961)PERFLUOROISOBUTYLENE (PFIB) Proposed: April 2009/ Page 43 of 43

mouse 1.2 120 pl minimal lethality (Danishevskii & Kochanov, 1961) mouse 6.1 15 pl LC50 (Karpov, 1977) mouse 1.6 120 pl LC50 (Karpov, 1977) rabbit 12.2 15 pl LC50 (Karpov, 1977) rabbit 4.3 120 pl LC50 (Karpov, 1977) Cat 3.1 120 pl LC50 (Karpov, 1977) Rat 0.24 240 2 Impaired reflexes (Karpov, 1977)
1