NAC Proposed 1: October 2009 1

2

3

4 

## ACUTE EXPOSURE GUIDELINE LEVELS (AEGLs) 5



## FOR 6



## AUTOMOTIVE GASOLINE (UNLEADED) 7


## (CAS Reg. No. 86290-81-5; 8006-61-9) 8

9

10

11

12

13 

## PROPOSED 14

15

16

17

18

19AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 2 of 41

PREFACE 1

2 Under the authority of the Federal Adviso ry Committee Act (FACA) P. L. 92-463 of 3 1972, the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous 4 Substances (NAC/AEGL Committee) has been es tablished to identify, review and interpret 5 relevant toxicologic and other scientific data and develop AEGLs for high priority, acutely toxic 6
chemicals. 7

8 AEGLs represent threshold exposure limits for the general public and are applicable to 9 emergency exposure periods ranging from 10 minut es to 8 hours. Three levels – AEGL-1, 10 AEGL-2 and AEGL-3 – are developed for each of five exposure periods (10 and 30 minutes, 1 11 hour, 4 hours, and 8 hours) and are distinguished by va rying degrees of severity of toxic effects. 12
The three AEGLs are defined as follows: 13

14 AEGL-1 is the airborne concentration (expressed as parts per million or milligrams per 15 cubic meter [ppm or mg/m 3 ]) of a substance above which it is predicted that the general 16 population, including susceptible individuals, could experience notable discomfort, irritation, or 17 certain asymptomatic, non-sensory effects. Ho wever, the effects are not disabling and are 18 transient and reversible upon cessation of exposure. 19

20 AEGL-2 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above 21 which it is predicted that the general population, including susceptible individuals, could 22 experience irreversible or other serious, long-lasting adverse health effects or an impaired ability 23
to escape. 24

25 AEGL-3 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above 26 which it is predicted that the general population, including susceptible individuals, could 27 experience life-threatening health effects or death. 28

29 Airborne concentrations below the AEGL-1 represent exposure levels that could produce 30 mild and progressively increasing but transi ent and nondisabling odor, taste, and sensory 31 irritation or certain asymptomatic, non-sensory eff ects. With increasing airborne concentrations 32 above each AEGL, there is a progressive increase in the likelihood of occurrence and the 33 severity of effects described for each corresponding AEGL. Although the AEGL values 34 represent threshold levels for the general public, including susceptible subpopulations, such as 35 infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized 36 that individuals, subject to unique or idiosyncratic responses, could experience the effects 37 described at concentrations below the corresponding AEGL. 38

39AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 3 of 41

TABLE OF CONTENTS 1

PREFACE........................................................................................................................ .............................2 2

LIST OF TABLES................................................................................................................. .......................5 3

SUMMARY........................................................................................................................ ..........................6 4

1. INTRODUC TION................................................................................................................... .............8 5

2. HUMAN TOXICI TY DATA............................................................................................................ ...9 6

2.2.1. Odor Threshold................................................................................................................. ...........9 7

2.2.2. Clinical Studies............................................................................................................... ...........10 8

3. ANIMAL TOXICI TY DATA........................................................................................................... .12 9

3.1. Acute Toxicity ................................................................................................................. ..........13 10

3.2. Repeat-Exposure Studies........................................................................................................ ...14 11

3.3. Neurotoxicity.................................................................................................................. ...........17 12

3.4. Developmental/Reproductive Toxicity......................................................................................18 13

3.5. Genotoxicity ................................................................................................................... ...........19 14

3.6. Chronic Toxicity/Carcinogenicity .............................................................................................19 15

3.7. Summary........................................................................................................................ ............20 16

4. SPECIAL CONSID ERATIONS ........................................................................................................2 0 17

4.1. Metabolism and Disposition..................................................................................................... .20 18

4.2. Mechanism of Toxicity.......................................................................................................... ....21 19

4.3. Structure-Activity Relationships ............................................................................................... 22 20

4.4. Other Relevant Information..................................................................................................... ..22 21

4.4.1. Species Va riability ............................................................................................................ ....22 22

4.4.2. Susceptible Populations ........................................................................................................ 22 23

4.4.3. Concentration-Exposure Duration Relationship ...................................................................22 24

4.4.4. Concurrent Exposure Issues..................................................................................................23 25

5. DATA ANALYSIS FOR AEGL-1 ....................................................................................................23 26

5.1. Summary of Human Data Relevant to AEGL-1........................................................................23 27

5.2. Summary of Animal Data Relevant to AEGL-1........................................................................23 28

5.3. Derivation of AEGL-1........................................................................................................... ....23 29

6. DATA ANALYSIS FOR AEGL-2 ....................................................................................................24 30

6.1. Summary of Human Data Relevant to AEGL-2........................................................................24 31AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 4 of 41

6.2. Summary of Animal Data Relevant to AEGL-2........................................................................24 1

6.3. Derivation of AEGL-2........................................................................................................... ....24 2

7. DATA ANALYSIS FOR AEGL-3 ....................................................................................................25 3

7.1. Summary of Human Data Relevant to AEGL-3........................................................................25 4

7.2. Summary of Animal Data Relevant to AEGL-3........................................................................26 5

7.3. Derivation of AEGL-3........................................................................................................... ....26 6

8. SUMMARY OF AEGLs............................................................................................................... .....26 7

8.1. AEGL Values and Toxicity Endpoints......................................................................................26 8

8.2. Comparison with Other Standards and Guidelines....................................................................27 9

8.3. Data Adequacy and Research Needs .........................................................................................28 10

9. REFERENCES..................................................................................................................... ..............28 11

APPENDIX A: Major Hydrocarbons found in Gasoline Vapor................................................................33 12

APPENDIX B: Derivation of Level of Odor Awareness...........................................................................34 13

APPENDIX C: Derivati on of Gasoline AEGLs ...................................................................................... ..35 14

APPENDIX D: Category Graph of AEGL Va lues and Toxicity Data for Gasoline..................................37 15

APPENDIX E: Derivation Summa ry for Gasoline AEGLs.......................................................................39 16AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 5 of 41

LIST OF TABLES 1

2 TABLE S 1. Summary of AEGL Values for Gasoline ................................................................................ 7 3
4 TABLE 1. Chemical and Physical Properties...................................................................................... .........9 5

TABLE 2. Odor Detection and Odor R ecognition Thresholds for Gasoline..............................................10 6 TABLE 3. Clinical Study with Gasoline and Gasoline Vapor (Drinker et al. 1943)..................................11 7 TABLE 4. Clinical Study with Gasoline Vapor (Davis et al. 1960)..........................................................11 8 TABLE 5. Acute Toxicity of Gasolin e Blending Stream Vapor to Rats ...................................................13 9 TABLE 6. Repeat-Exposure, Subchronic and Ch ronic Exposure, Developmental Toxicity, and 10 Genotoxicity Studies with Gasoline Vapor....................................................................................... .15 11

TABLE 7. AEGL-1 Va lues for Gasoline Vapor..................................................................................... ...24 12

TABLE 8. AEGL-2 Va lues for Gasoline Vapor..................................................................................... ...25 13

TABLE 9. AEGL-3 Va lues for Gasoline Vapor..................................................................................... ...26 14 TABLE 10. Summary of AEGL Values for Gasoline Vapor ....................................................................26 15 TABLE 11. Standards and Guidelines for Gasoline Vapor ........................................................................27 16 17AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 6 of 41

SUMMARY 1

2 Automotive gasoline (CAS No. 86290-81-5) is a clear, amber colored volatile and 3 flammable liquid with a characteristic odor. The most serious immediate hazard from the 4 accidental release of gasoline is the threat of fire or explosion. Gasoline is a complex substance 5 made by blending various refinery streams containing many hydrocarbon components. The 6 hydrocarbons consist of paraffins, cycloparaffins and aromatic and olefinic hydrocarbons having 7 carbon numbers predominantly in the C 3 to C 11 range. Composition is variable depending on the 8 crude oil or petroleum source, refining facilities, and total petroleum product demand. Carbon 9 numbers in gasoline vapor range from C 4 -C 6 . The major hydrocarbon found in gasoline vapor is 10 isopentane (C 5 H 12 , 34%). Automotive gasoline may also contain oxygenates such as ethanol or 11 ethers and proprietary additives. 12

13 A level of distinct odor awareness (LOA) of 7.4 ppm (approximately 22 mg/m 3 ) was 14 calculated for a gasoline blend comprised of summer and winter blends. The LOA represents the 15 concentration above which it is predicted that more than half of the exposed population will 16 experience at least a distinct odor intensity, and about 10% of the population will experience a 17 strong odor intensity. The LOA should help chemical emergency responders in assessing the 18 public awareness of the exposure due to odor perception. 19

20 Relatively high concentrations of gasoline vapor may be irritating to the eyes. Data on 21 sensory irritation were available from a clinical study. At sufficiently high vapor concentrations, 22 gasoline is neurotoxic, inducing narcosis. Data were available on acute, repeat-exposure, 23 subchronic exposure, neurotoxicity, reproductiv e and developmental toxicity, and chronic 24 toxicity/carcinogenicity. Most of these studies used the rat as the animal model. Results of the 25 available toxicity studies indicate that various bl ending streams of gasoline have similar toxicity. 26

27 The AEGL-1 is based on the sensory irritation study of Davis et al. (1960) in which 28 volunteers were exposed to three different blends of gasoline vapor on separate occasions. Each 29 blend was tested at approximately 880, 2200, and 4400 mg/m 3 for 30 minutes. The 30-minute 30 exposure to all three blends of gasoline vapor at 2200 mg/m 3 produced subjective eye irritation 31 at a higher incidence (15/30 subjects) than under control conditions (1/20 subjects). The 32 incidence of objective eye irritation, although scored as slight (+1 on a scale of 1 to 4), was 33 higher in the 2200 mg/m 3 group (15/30) than in the control group (2/20). Incidences of ocular 34 tearing were similar in this group (3/30) and th e control group (2/20). Incidences of subjective 35 and objective eye irritation, including tearing, we re higher at the higher concentration of 4400 36 mg/m 3 . Because the eye irritation when measured objectively was slight (less than marked), an 37 intraspecies uncertainty factor of 3 (instead of 10) was applied to protect sensitive subjects. 38 There is adaptation to the slight irritation that de fines the AEGL-1. Therefore, the same value of 39 730 mg/m 3 (2200 mg/m 3 /3) was used across all exposure durations. 40

41 Although anecdotal human experience indicates acute inhalation of high concentrations 42 can cause acute neurological effects (gasoline sniffers ), tested concentrations in rodent studies of 43 acute duration were not high enough to induce narcotic effects. The acute studies were 44 conducted for 4 hours at the limit concentration of 5000 mg/m 3 . The AEGL-2 values were based 45 on the subchronic study of Schreiner et al. (2000) in which male and female Sprague-Dawley 46 rats inhaled 22,500 mg/m 3 gasoline vapor (whole-body) for 6 hours/day, 5 days/week for 13 47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 7 of 41

weeks. This concentration was the highest tested concentration in the subchronic studies. At 1 this concentration, the rats failed to show clinical signs indicative of neurotoxicity during 2 exposure. The point of departure, the 6-hour exposure to 22,500 mg/m 3 , was divided by 3 interspecies and intraspecies uncertainty factor s of 1 and 3, respectively for a total uncertainty 4 factor of 3. An interspecies uncertainty fact or of 1 is sufficient because solvent uptake is 5 generally greater in rodents than in humans ba sed on higher blood:air partition coefficients for 6 related hydrocarbons. In addition, the higher respiratory rate and greater cardiac output in 7 rodents, on a body weight basis compared with humans, indicates faster uptake. Although 8 humans differ in the rate at which they metabolize chemicals, the susceptibility of the general 9 population to central nervous system depressants vari es by no more than 2- to 3-fold as indicated 10 by the minimum alveolar concentration, the concentration of an anesthetic that produces 11 immobility in 50% of patients. Therefore, an intraspecies uncertainty factor of 3 is considered 12 sufficient. Higher uncertainty factors would result in values inconsistent with the clinical study 13 of Davis et al. (1960). Time scaling may not be relevant for hydrocarbons that act as anesthetics 14 because blood concentrations of the major light components of gasoline rapidly approach steady15 state. Therefore, the 6-hour value of 7500 mg/m 3 (22,500 mg/m 3 /3) was used across all AEGL-2 16 exposure durations. The 7500 mg/m 3 value is supported by the study of Kuna and Ulrich (1984) 17 in which no toxic signs were observed in squirrel monkeys exposed to 6350 mg/m 3 for six 18 hours/day for 13 weeks. Partially vaporized gasoline was not a reproductive or developmental 19 toxicant following repeat exposures to 20,000 to 23,900 mg/m 3 (McKee et al. 2000; Roberts et 20 al. 2001). 21

22
None of the concentrations tested in acute or subchronic studies with rodents resulted in 23 mortality, and there are no reports of human fatalities from exposure to gasoline vapors. It is not 24 apparent that concentrations high enough to cause death from inhalation of gasoline vapor can be 25 attained. Based on the likelihood that lethal concentrations of gasoline vapor cannot be 26 attained/sustained under ambient conditions, an AEGL-3 was not determined. 27

28
The calculated values are listed in the table below. 29

30

TABLE S 1. Summary of AEGL Values for Gasoline

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

AEGL

B 1 (Nondisabling) 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3 Slight eye irritation in humans (Davis et al. 1960)

AEGL

B 2 (Disabling) 7500 mg/m 3

* 7500 mg/m 3

* 7500 mg/m 3

* 7500 mg/m 3

* 7500 mg/m 3

* No clinical signs at highest tested
concentration of 22,500 mg/m 3 – rat (Schreiner et al. 2000)

AEGL

B 3 (Lethal) Not
determined Not
determined Not
determined Not
determined Not
determined No data**

*The AEGL-2 value is higher than 1/10 of the lower e xplosive limit (LEL) of gasoline in air (LEL = 14,000 ppm). Therefore, safety considerations against hazar d of explosion must be taken into account.
**A lethal concentration was not attained in the available acute, subchronic, and chronic toxicity studies. Automotive gasoline vapor may act as a simple asphyxiant in sensitive individuals at 990,000 mg/m 3

. 31AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 8 of 41

1. INTRODUCTION 1

2 Automotive gasoline (CAS No. 86290-81-5) is a clear, amber colored volatile and 3 flammable liquid with a characteristic odor. Gasoline is a complex substance made by blending 4 various refinery streams with many hydrocarbon components. The hydrocarbons consist of 5 paraffins, cycloparaffins and aromatic a nd olefinic hydrocarbons having carbon numbers 6 predominantly in the C 3 to C 11 range. Definitions and examples of these classes of chemicals are 7 provided in Appendix A. Carbon numbers of the major components of liquid gasoline range 8
from C 5 -C 9 . Composition is variable depending on the crude oil or petroleum source, refining 9 facilities, and total petroleum product demand. Ranges of major hydrocarbons in gasoline 10 (vol%) are paraffins and cycloparaffins (59-66%), aromatics (26-32%), and olefins (8-9%). 11 Carbon numbers in gasoline vapor range from C 4 -C 6 ; at room temperature the C 4 hydrocarbons 12 are gases. The major hydrocarbon found in gasoline vapor is isopentane (C 5 H 12 , 35%). 13 Predominant components found in gasoline vapor and gasoline vapor containing 10% ethanol are 14 listed in Appendix A. The lighter components, primarily isomers of butane and pentane are 15 present in the vapor. 16

17 Various additives are blended into automotive gasoline (Appendix A). These include 18 octane enhancers such as methyl t -butyl ether (MTBE; 15% v/v), t -amyl methyl ether (TAME), 19 ethyl t -butyl ether (ETBE 17% v/v), t -butyl alcohol (TBA), ethanol (EtOH, 10%), and methanol; 20 antioxidants such as butylated methyl, ethyl, a nd dimethyl phenols; metal deactivators; ignition 21 controllers; icing inhibitors; corrosion inhibitors; and detergents/dispersants. These additives 22 have low vapor pressures. Gasoline sold in the United States is unleaded and contains 10% 23
ethanol. Ethanol is added at the marketi ng terminal (ATSDR 1995; API 2002; White 2009). 24 Chemical and physical properties of automotive gasoline are listed in Table 1. 25

26 The commercial production of gasoline begins with crude oil which is refined into the 27 following fractions: light naphtha, heavy naphtha, ke rosene and light gas-oil, heavy gas-oil, and 28 reduced crude. Each refinery stream has been assigned a CAS number. The light naphtha is 29 used as a component of finished gasoline without further refining. Heavy oils can be treated by 30 catalytic or thermal cracking which breaks down the higher boiling hydrocarbons into lower 31 boiling ones; these can be used as components of gasoline. After various streams have been 32 blended, sulfur compounds may be removed by hydrogenation. Additives and blending agents 33 are added to improve the performance and stability of the gasoline. Typical retail gasoline 34 contains 200-300 compounds. The benzene content of finished gasoline is 1-1.5% (ATSDR 35 1995; White 2009). European blends of gasoline may contain up to 7.5% benzene (Dutch 36 Intervention Values 2009). 37

38 Gasoline is a high volume commercial product (McKee et al. 2000). U.S. production 39 volume of motor gasoline in 1989 was 306.6 million gallons/day (ATSDR 1995). Several 40 million gallons/day are imported. Recent production data were not located. 41

42 The most serious immediate hazard from the accidental release of gasoline is the threat of 43 fire or explosion (Anonymous 1989). The lower and upper flammability limits are 1.4 and 7.4% 44 or 14,000 and 74,000 ppm. The autoignition temperature is between 280 and 486oC, and the 45 flashpoint is -46oC (ATSDR 1995). 46

47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 9 of 41

A review of monitoring studies of workplaces for a variety of jobs in the manufacture, 1 transport, and sale of gasoline shows that C 4 and C 5 compounds represent 54-81% of the total 2 hydrocarbons in industrial hygiene samples (Dalbey et al. 1996). Thus, although the 3 hydrocarbons comprising gasoline are predominantly in the range of C 3 to C 11 , exposure of 4 humans would be to the more volatile components in the range of C 4 to C 6 (Bruckner et al. 2008; 5 White 2009). The C 4 to C 5 hydrocarbons are generally regarded as less toxic than the higher6 molecular-weight counterparts (Reese and Kimbrough 1993). Studies that address the toxicity of 7 both wholly vaporized gasoline and gasoline vapor containing the more volatile components are 8 discussed in the following sections. 9

10 Because gasoline is a complex substance, concentrations are reported in mg/m 3 . Many of 11 the studies reviewed here reported concentrations in ppm. Concentrations are listed as they were 12 reported. Appropriate conversions were made for calculation of AEGL values. 13

14

15

TABLE 1. Chemical and Physical Properties

Parameter Value Reference
Synonyms Petrol; benzin; motor fuel; O’Neil 2001; ATSDR 1995
Chemical formula Not applicable (mixture) Molecular weight 108 (avg. whole gasoline); 72.6-80 (vapor) ATSDR 1995; AIHA 2008

CAS Reg. No. 86290-81-5; 8006-61-9* Physical state liquid, cl ear, amber-colored AIHA 2008 Solubility in water Insoluble 20oC O’Neil 2001 Vapor pressure 275-475 mm Hg at 20oC Amerada Hess 2004 Vapor density, saturated (air =1) 3 to 4 Amerada Hess 2004 Liquid density (water =1) 0.7-0.8 g/cm at 21oC AIHA 2008; ATSDR 1995 Melting point not relevant Boiling point 32-210 oC O’Neil 2001 Flammability limits in air 1.4-7.4% ATSDR 1995 Conversion factors Whole gasoline: 1 ppm = 4.42 mg/m 3
1 mg/m 3 = 0.23 ppm Gasoline vapor: 1 ppm = 2.99 mg/m 3
1 mg/m 3 = 0.33 ppm Calculated (based on average molecular weights of 108 and 73, respectively)

* CAS No. 86290-81-5 is unleaded gasoline that meets 1990 industry average specifications. CAS No. 8006-61-9 is 16 assigned to natural gasoline, a complex combination of hydrocarbons separated from natural gas by processes such 17 as refrigeration or absorption. Individual refine ry process streams have additional CAS numbers. 18
19
2. HUMAN TOXICITY DATA 20

2.2.1. Odor Threshold 21

22 Gasoline has a characteristic odor. The odor threshold and odor recognition 23 concentrations have been reported for gasoline and gasoline containing MTBE and TAME 24 (Amerada Hess 2004). For non-oxygenated gasoline the odor detection and odor recognition 25 thresholds were 0.5-0.6 ppm and 0.8-1.1 ppm. For gasoline with 15% MTBE, the respective 26 thresholds were 0.2-0.3 ppm and 0.4-0.7 ppm, and for gasoline with 15% TAME, the respective 27 thresholds were 0.1 ppm and 0.2 ppm. 28AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 10 of 41

1 The American Petroleum Institute (API 1994) reported odor threshold, recognition, and 2 intensity thresholds for summer and winter blends of gasoline and for blends containing 3 oxygenates (Table 2). Trained panelists participated in a forced choice sniff test by identifying 4 which of three ports contained the odor. The lowest average odor detection and recognition 5 thresholds were for the summer blend of gasoline containing 15% ETBE (97% purity). For 6 MTBE, the odor detection threshold decreased with increases in MTBE concentration. Odor 7 intensity values for gasoline blends without oxygenates ranged from 2.03-3.33. Odor intensity 8 values for the blends ranged from 2.95-4.60. Most panelists described the odor for both the 9 blends of gasoline as well as gasoline containing oxygenates as gasoline. 10

11 Using the data of API (1994) a level of distinct odor awareness (LOA) was calculated for 12 gasoline. The LOA of 7.4 ppm (approximately 22 mg/m 3 ) was calculated for gasoline based on 13 the odor detection value of 0.474 ppm for a composite of summer and winter blends. The 14 calculation is shown in Appendix B. The LOA represents the concentration above which it is 15 predicted that more than half of the exposed population will experience at least a distinct odor 16 intensity, and about 10% of the population will experience a strong odor intensity. 17

18

TABLE 2. Odor Detection and Odor Recognition Thresholds for Gasoline
Gasoline blend Odor Detection Odor Recognition
Gasoline – summer blend 0.576 ppm 0.802 ppm Gasoline – winter blend 0.479 ppm 1.121 ppm Gasoline – composite 0.474 ppm 0.765 ppm Gasoline – summer blend + 3% MTBE 0.500 ppm 0.696 ppm Gasoline – summer blend + 11% MTBE 0.275 ppm 0.710 ppm Gasoline – summer blend + 15% MTBE 0.264 ppm 0.686 ppm Gasoline – winter blend + 15% MTBE 0.219 ppm 0.398 ppm Gasoline – composite + 15% MTBE 0.085 ppm 0.185 ppm Gasoline – summer blend + 15% ETBE 0.064 ppm 0.139 ppm Gasoline – summer blend + 15% TAME 0.114 ppm 0.207 ppm MTBE (97% purity) 0.053 ppm 0.125 ppm

Source: API 1994. 19 20

2.2.2. Clinical Studies 21

22 Drinker et al. (1943) conducted a clinical study with male and female volunteers exposed 23 to various concentrations of straight lead-free commercial gasoline and the volatile fraction of 24 gasoline distilled below 110oC. Except for two exposures with a face mask, the exposures took 25 place in a 16x22x9-ft chamber. Gasoline was metered into the ventilating air at the top of the 26 chamber and exited at the floor. Concentrations were computed from the volume of gasoline 27 vaporized and checked by vapor pressure and charcoal adsorption methods. Male volunteers, 28 ages 23 to 45 years, and female volunteers, ages 17-32 years, participated in the study as 29 outlined in Table 3. At concentrations up to 900 ppm, only slight sensory irritation was reported. 30 While no dizziness was reported during the exposure to 900 ppm, two of six men reported 31 feeling unsteady following the exposure. One subject experienced nausea during the 1-hour 32 exposure to 2600 ppm, and all subjects felt slightly lightheaded. The slight irritation reported at 33 low concentrations of whole gasoline was not pr esent during the exposure to the light fraction. 34AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 11 of 41

The authors also noted that inhalation of gasoline causes slight gastrointestinal disturbance in 1 about 10% of the population. 2

3

4

TABLE 3. Clinical Study with Gasoline and Gasoline Vapor (Drinker et al. 1943)
Concentration in ppm/Subjects Exposure Duration Response
Whole Gasoline Vapor
160 (8 females) 8 hours Odor detection for various periods of time; slight irritation of eyes and throat 270 (13 males) 8 hours Odor detection throughout day, slight irritation of eyes and throat 11,200 (3 males, 1 female) vapor delivered by face mask 5-5.5 minutes Nose and throat irritation within 20 seconds; feeling of incoordination
Gasoline Vapor Distilled below 110oC
140 (10 females) 8 hours Odor detection; no definitive irritation 150 (8 females) 8 hours Odor detection; very slight irritation of the eyes and throat 500 (9 males) 1 hour Slight irritation of the eyes and throat 900 (6 males) 1 hour Slight irritation of the eyes and throat;
threshold for unsteadiness 2600 (5 males, 1 female) 1 hour Strong odor; slight dizziness, transient eye
irritation 10,700 (4 men) vapor delivered by face mask 4-7 minutes Unsteadiness (compared to euphoria from alcohol or ether)
5
6 Ten healthy male volunteers, ages 23 to 40 years, were exposed to three varieties of 7 unleaded vaporized gasoline for 30 minutes (Davis et al. 1960). The subjects were blind to the 8 test material. The gasoline sample composition varied as follows: A: 25% paraffins, 30% 9 naphthenes (cycloparaffins), 40% aromatics; B: 40% paraffins, 35% naphthenes, 20% aromatics; 10 and C: 30% paraffins, 5% naphthenes, 65% aroma tics. Volunteers were exposed individually in 11 a 10x7x9.5-ft chamber. Gasoline was metered into the top of the chamber and exhausted near 12 the floor. Chamber air samples were collected on silica gel, eluted with n -dodecane, and 13 analyzed by gas chromatography. Concentrations averaged 200, 500, and 1000 ppm. Because 14 three different blends were tested, it is assumed that the gasoline was almost wholly vaporized. 15 Therefore, concentrations in mg/m 3 would be 880, 2200, and 4400 mg/m 3 , respectively. Each 16 subject filled out a 21-part questionnaire followi ng exposure. The questionnaire addressed odor; 17 irritation of the eyes, nose, and throat; headache, dizziness, drowsiness/fatigue, and headache. A 18 photograph of each subject’s left eye was taken before and after exposure. The photographs 19 showed conjunctival blood vessels in detail (graded over a range of 1-4, with 1 representing very 20 slight change, 2 and 3 representing intermediate change, and 4 representing marked change). 21 Total positive responses of the 10 subjects to 12 questions and the highest responses are 22
summarized in Table 4. 23

24

25

TABLE 4. Clinical Study with Gasoline Vapor (Davis et al. 1960)
Concentration in ppm (mg/m 3 ) Total Responses a Highest Response (number of subjects) b

Control 1
Control 2 6

4 Transient cough (2); drowsiness (2) Responses evenly distributedAUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 12 of 41

Sample A 200 (880) 528 (2323) 1054 (4638) 9

15

9 Itching or burning of eyes (3); headache (3) Itching or burning of eyes (7); headache (2) Itching or burning of eyes (4) Sample B 186 (818) 497 (2187) 996 (4382) 7

12

26 Transient cough (2) Itching or burning of eyes (6); ocular tearing (2) Itching or burning of eyes (9); ocular tearing (4); nose irritation, cough, nausea, drowsiness, fatigue (2) Sample C 164 (722) 501 (2204) 984 (4330) 8

11

16 Itching or burning of eyes (3); drowsiness (2) Itching or burning of eyes (5); headache (2) Itching or burning of eyes (9); ocular tearing (3) itching of nose (2)
n = ten subjects. 1 All exposure durations were 30 minutes. 2

a Total responses of 10 subjects answeri ng 12 questions (possible score of 120). 3

b Single responses not recorded. 4

5 The data in Table 4 show that the response to itching or burning eyes was most frequent, 6 with an apparent concentration-response relationship. An analysis of variance of the rescored 7 data (corrected for control responses) showed that the responses as a group lacked significance. 8 Incidences of drowsiness in the control and 4400 mg/m 3 exposure were 3/30 and 2/20. Ocular 9 tearing was similar in the control and 2200 mg/m 3 groups (10%), but was higher (27%) in the 10 group exposed to 4400 mg/m 3 . Objective eye irritation was graded +1 (very slight) or +2 11 (intermediate) with only one subject’s eye graded +3 (in one group exposed to 4400 mg/m 3 ); this 12 subject’s scores were +1 and 0 following the other two exposures to 4400 mg/m 3 . In the 4400 13 mg/m 3 exposure group, objective eye irritation scores averaged 0.9 to 1.4 out of 4. Numerous 14 negative scores of -1 and 0 were also recorded following exposure. Subjective eye irritation was 15 concentration related, with the higher scores at the higher concentrations. Subjective eye 16 irritation did not fully correlate with responses of objective (photographed) eye irritation. No 17 differences in irritation were noted between the gasoline vapor samples at approximately the 18
same concentrations. 19

20 Neurological effects have been observed in i ndividuals that habitually sniff gasoline for 21 its euphoric/hallucinogenic properties (ATSDR 1995). These effects include postural tremor, 22 ataxia, abnormal gait, affected speech, fatigue, headaches, memory loss, and sleep problems. 23

24 Cytogenetic monitoring studies and cancer epidemiology studies of workers exposed to 25 gasoline have produced inconclusive results (ATSDR 1995). Most of these studies were 26 considered inadequate due to inherent limitations including unreported exposure concentrations, 27 length of exposure, and concurrent exposure to other substances. Exposure of human 28 lymphoblastoid cells to 0.6% and 1.2% unleaded gasoline, with or without metabolic activation, 29 failed to induce mutations at the TK+ locus (Richardson et al. 1986). Assays for mutagenicity 30 and sister chromatid exchange were also negative. 31

32
3. ANIMAL TOXICITY DATA 33

34 Using standard protocols, ARCO clear gasolin e with MTBE was tested for acute oral and 35 dermal toxicity and skin and eye irritation and sensitization (ARCO Chemical Co. 1984). The 36AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 13 of 41

acute oral LD 50 was >5.0 g/kg in rats. The acute dermal toxicity in rabbits was >2.0 g/kg. The 1 ARCO gasoline was considered a moderate dermal irritant and was a minimal irritant to the 2 rabbit eye (instillation of 0.1 mL). Gasoline was a weak sensitizing agent in the guinea pig. 3

4 3.1. Acute Toxicity 5

6 The acute inhalation toxicity of various blending streams of gasoline has been reported 7 with the rat as the test species (Table 5). All exposure durations were for four hours. All studies 8 followed the same methodology (provided in the fo llowing example). A group of five male and 9 five female Sprague-Dawley rats inhaled a measured concentration of 5200 mg/m 3 sweetened 10 naphtha (API No. 81-08; CAS No. 64741-87-3), whole-body, for 4 hours (API 1982). A second 11 group was exposed to air only and served as the control group. Exposures took place in 160-L 12 glass and stainless steel chambers. The atmospheres were generated by delivering test material 13 liquid to a glass bead column. Air, heated to 55oC and delivered in a counter-current manner 14 relative to the liquid, vaporized the liquid. The vapor was diluted with air and piped to the 15 exposure chamber. Concentrations were measured throughout the exposure period by a total 16 hydrocarbon analytical method. Animals were obs erved for clinical signs during the exposure 17 period, hourly for four hours following the exposure, and twice daily for 14 days post-exposure. 18 Rats were weighed prior to exposure and on days 7 and 14. Surviving rats were sacrificed and 19 organs and tissues were examined macroscopically. The lungs and trachea were examined 20 microscopically. There were no deaths and no significant clinical signs observed during or 21 following exposure. Two male rats and one female rat showed a slight clear nasal discharge 22 during exposure. Females gained slightly less weight than expected over the 14-day recovery 23 period. There were no microscopic changes in the lungs or trachea that could be attributed to 24

treatment. 25

26 In some of the studies listed in Table 5, languid behavior (hypoactivity) was observed 27 during exposure (light alkylate naphtha) and nasa l discharge was observed in two animals on day 28 2 post-exposure (light, catalytically cracked na phtha) (API 1995). Lower body weight gain, seen 29
with API 81-08 was not observed in most of th e studies. There were no significant gross 30 observations at necropsy and no histological ch anges observed in the lungs in any study. 31

32

TABLE 5. Acute Toxicity of Gasoline Blending Stream Vapor to Rats Blending Stream LC 50 (mg/m 3 )
Naphtha, light catalytic cracked (API 81-04) >5300 Naphtha, heavy catalytic cracked (API 83-18) >5000 Naphtha, light catalytic reformed (API 83-04) >5200 Naphtha, heavy catalytic reformed (API 83-06) >5000 Naththa, full range catalytic reformed (API 83-05) >5000 Naphtha, sweetened (API 81-08) >5200 Naphtha, light alkylate (API 83-19) >5000 Naphtha, heavy thermally cracked (API 84-02) >5000
All studies were conducted for four hours at the limit concentration of 5000 mg/m 3

. 33 Sources: API 2008a,b; CONCAWE 1992. 34

35 A group of five male and five female Sprague-Dawley rats inhaled 5200 mg/m 3 of ARCO 36 clear gasoline with MTBE for 4 hours (ARCO Chemical Co. 1984). Chamber atmospheres were 37 generated by metering the test material to a flask maintained at 100oC and then mixing with 38AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 14 of 41

room air. Rats were observed during exposure and at set intervals for 14 days post-exposure. 1 Animals appeared unaffected during exposure. Upon removal from the chamber, lacrimation 2 was noted in 2 of 10 animals, mucoid nasal discharge in 7 of 10 animals, red nasal discharge and 3 dry rales in 2 of 10 animals, and reduced righting reflex in 4 of 10 animals. These signs 4 continued into the next day, but generally ab ated during the 14-day observation period. There 5 were no deaths, and rats gained weight during the post-exposure period. At necropsy, discolored 6 kidneys were observed in 4 of 5 males and 2 of 5 females. 7

8 3.2. Repeat-Exposure and Subchronic Studies 9

10 Groups of 5-6 B6C3F 1 mice inhaled 0 (filtered air), MTBE (7814 ppm), API-91-01 11 unleaded gasoline (2014 ppm), or PS-blend unleaded gasoline (2028 ppm) for 6 hours/day, 5 12 days/week, for 3 or 21 days (Moser et al. 1996) (T able 6). Neither blend of gasoline contained 13 significant amounts of MTBE. The API-91-01 blend contains a slightly greater percentage of 14 aromatics and olefins than the PS-6 blend. Mice were sacrificed 18 hours after the last exposure. 15 During exposure, abnormal gait, hypoactivity, decreased muscle tone, and increased lacrimation 16 were observed in the group exposed to MTBE. Occasional hypoactivity was observed in mice 17 exposed to the unleaded gasolines. Compared to the control, relative liver weight was increased 18 in all groups after 3 and 21 days, and relative uterine weight was decreased for all groups after 3 19 days and in the MTBE- and API-91-01-treated groups after 21 days. 20

21 Chu et al. (2005) exposed groups of 15 male and 15 female Sprague-Dawley rats to 22 filtered air, 6130 ppm ethanol, 500 ppm gasoline, or a mixture of 85% ethanol and 15% gasoline 23 (6130 ppm ethanol and 500 ppm gasoline) for 6 hours/day, 5 days/week for 4 weeks. Ten rats of 24 each gender were sacrificed after 4 weeks, and the remaining rats were held for a 4-week 25 recovery period. No clinical signs of toxicity were observed. Body weight gain was reversibly 26 suppressed by 21% in female rats that inhaled the ethanol-gasoline mixture. Reversible 27 inflammation of the upper respiratory tract was observed only in the gasoline-ethanol group. 28 The authors concluded that treatment with gasoline and ethanol produced mild, reversible 29 biochemical, hematological, and histological effect s (adrenal cortical vacuolation), with some 30 indication of interaction when the vapors were co-administered. 31

32 Halder et al. (1986) exposed groups of ten Sprague-Dawley rats/sex to 0, 120, 1150, or 33 11,800 mg/m 3 of the C 4 and C 5 hydrocarbons that comprise typical gasoline vapor. Atmospheres 34
consisted of 25% each n -butane, n -pentane, isobutene and isopentane. Exposure was for 6 35 hours/day, 5 days/week for 3 weeks. No adverse clinical signs were observed. No treatment36 related changes were found in body weight, serum chemistry, hematology, histopathology of 37 tissues, or organ weight. 38

39 Groups of 20 male and 20 female Sprague-Dawley rats inhaled vapor of either unleaded 40 gasoline at concentrations of 0, 1570 or 6350 mg/m 3 or leaded gasoline at 420 or 1530 mg/m 3 for 41 90 days (Kuna and Ulrich 1984). Groups of four male and four female squirrel monkeys inhaled 42 the same concentrations. Exposures were for 6 hours/day, 5 days/week. Gasoline was wholly 43 vaporized in an atomizer with heated nitrogen; and then mixed with the exposure chamber air 44 inflow. Atmospheres were analyzed with a total hydrocarbon analyzer connected to an 45 automatic sampling device. No “remarkable” changes were observed in body weight; 46 hematology; CNS response (flash-evoked response time, tested in monkeys); pulmonary function 47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 15 of 41

tests (in monkeys); urinalysis; deposition of IgG in the renal glomerulus; lead levels in blood, 1 urine, and tissue; organ weight; organ-to-body we ight ratio; or histopathology. Minor changes in 2 some parameters in rats are listed in Table 6. Male rats exposed to 6350 mg/m 3 unleaded 3 gasoline showed male-rat-specific changes in the kidney tubules. 4

5 Groups of 20 Sprague-Dawley rats (10/sex) and 20 CD-1 mice (10/sex) were exposed 6 whole body to vapors of light catalytically cracked naphtha at measured concentrations of 0, 530, 7 2060, or 7690 mg/m 3 for 13 weeks (Dalbey et al. 1996). Exposure was for 6 hours/day, 5 8 days/week. Atmospheres were analyzed by gas chromatography. No significant treatment9 related changes were found in clinical signs, body weight, serum chemistry, hematology, 10 histopathology of 24 tissues, or organ weight. In rats, a marginal increase was noted in the 11 number of sperm per gram of epididymis in the 7690 mg/m 3 group, compared to sham-exposed 12 controls, but not compared to untreated controls. 13

14 In a study conducted in the same manner, groups of 15 male and 15 female Sprague15 Dawley rats inhaled 0, 410, 1970, or 8050 mg/m 3 of partially vaporized full range catalytic 16 reformed naphtha for 13 weeks (Dalbey and Fe uston 1996). No significant treatment-related 17 effects were found in clinical signs, serum chemistry, hematology, or histopathology of 24 18 organs. Body weight and weights of liver and kidney were marginally increased in males in the 19 8050 mg/m 3 group. 20

21 Additional studies including neurotoxicit y, developmental toxicity, and chronic 22 toxicity/carcinogenicity are summarized in Table 6. 23

24

25

TABLE 6. Repeat-Exposure, Subchronic and Chronic Ex posure, Developmental Toxicity, and Genotoxicity Studies with Gasoline Vapor
Type of Study (species) Material
Characterization Concentrations (mg/m 3 ) Effect Reference

General toxicity 3, 21 days (mouse) PS-6 blend

API-91-01 0, 2056 ppm 0, 2014 ppm Occasional hypoactivity Occasional hypoactivity Moser et al. 1996

General toxicity
4 weeks (rat) ethanol gasoline ethanol+gasoline 6130 ppm 500 ppm 6130+500 ppm No clinical signs No clinical signs Reversible body weight suppression in female rats; reversible nasal inflammation; biochemical changes Chu et al. 2005

General toxicity,
3 weeks (rat) Combination of 25% n-butane, 25% isobutene, 25% n-pentane, 25% isopentane 0, 120, 1150, 11,800 No adverse clinical signs or

effects Halder et al. 1986

General toxicity,
subchronic (rat, monkey) Wholly vaporized leaded
and unleaded gasoline 0, 1570, 6350 Alpha 2-microglobulin mediated nephropathy in male rats; slight increases in thrombocyte and reticulocyte counts and liver weight in male rats receiving 6570 mg/m 3 ; slight increase in tissue lead content in rats receiving leaded Kuna and Ulrich

1984AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 16 of 41

gasoline Monkeys – no significant toxic

effect General toxicity,
subchronic (rat, mouse) Partially vaporized light catalytically cracked naphtha 0, 530, 2060,

7690 No treatment related clinical signs, or changes in body weight, serum chemistry, hematology, histopathology, organ weight; marginal decrease in sperm in male rats at 7690 mg/m 3 Dalbey et al. 1996

General toxicity,
subchronic (rat) Partially vaporized full range catalytic
reformed naphtha 0, 410, 1970, or

8050 No treatment-related clinical signs, no effect on serum chemistry or male reproductive parameters; lower white blood cell count (up to 24% at highest concentration); increased liver and kidney weight; no microscopic lesions Dalbey and Feuston

1996

Neurotoxicity,
subchronic (rat) Vapor from light catalytic
reformed naphtha 0, 750, 2500, 7500 ppm (0, 2250, 7500, 22,500) No clinical signs during exposure; no change in motor activity other parameters during an FOB; transient decreases in hematology parameters Schreiner et al. 2000

Neurotoxicity,
subchronic (rat) Gasoline vapor
condensate with
or without
additives: MTBE, ETBE, TAME, DIPE, ethanol, TBA 0, 2000, 10,000, 20,000 No neuropathology; negative FOB; motor activity affected by gasoline containing TBA with effect resolving during recovery O’Callaghan et al.

2004

Reproductive toxicity, two generation (rat) volatile fraction from a gasoline
terminal 5076, 10,247, or 20,241 No significant effects other than male rat specific nephropathy McKee et al. 2000

Reproductivetoxicity, onegeneration; two generation (rat) GVC with or
without
additives: MTBE, ETBE, TAME, DIPE, ethanol, TBA 0, 2000, 10,000, 20,000 No impact on reproduction Gray et al. 2004

Developmental toxicity,

GD 6-19 (rat) Gasoline vapor condensate (API 94-02) 0, 2653, 7960, 23,900 No maternal toxicity; no developmental effects Roberts et al. 2001

Developmental toxicity, GD 0-19 (rat) Light catalytically cracked naphtha 0, 2150, 7660

GD 6-19 No treatment-related clinical signs or effects on reproductive parameters other than increased resorptions at 7660 mg/m 3 Dalbey et al. 1996

Developmental toxicity GD 6-19 (rat) Partially vaporized full range catalytic
reformed naphtha 0, 2160, 7800 Reproductive performance unaffected; no affect on body weight gain; serum glucose decreased and serum potassium
increased Dalbey and Feuston

1996

Genetic toxicity GVC with or
without
additives: 0, 2000, 10,000, 20,000 Assay results negative for
micronuclei formation in bone marrow; sister chromatid Schreiner et al. 2004AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 17 of 41

MTBE, ETBE, TAME, DIPE, ethanol, TBA exchange assay positive for gasoline vapor condensate and condensate containing MTBE Chronic toxicity/ carcinogenicity (rat, mouse) Wholly vaporized gasoline containing 2%
benzene 296, 1290. 9080 Survival unaffected; decreased body weight gain at 9080 mg/m 3 both species; male rat nephropathy; liver tumors in
sensitive strain of female mice MacFarland et al.

1984

Chronic toxicity/ carcinogenicity (rat) GVC with or
without
additives: MTBE, ETBE, TAME, DIPE, ethanol, TBA 0, 2000, 10,000 or 20,000 Survival unaffected; reversible changes in body weight (gasoline +ethanol and gasoline + ETBE); reversible FOB motor activity change (gasoline + TBA); neuropathology negative; Benson et al. 2004

Subchronic exposures are for 13 weeks, 6 hours/day, 5 days/week. 1 Rat studies were conducted with male and female Sprague-D awley rats; CD-1 mice were additionally tested in the 2 toxicity study of Dalbey et al. (1996), and squirrel monkeys were additionally tested in the study of Kuna and Ulrich 3

1984. 4 FOB = functional observational battery. 5 GVC = gasoline vapor condensate consisting of approxima tely 15-20% of starting gasoline which was slowly 6 vaporized at near maximum gasoline in-use tank temperature (130oC) and condensed. 7 GD = gestation day. 8
9

10 3.3. Neurotoxicity 11

12 Neurotoxicity assessments were not performe d following acute exposures. Clinical signs 13 were generally absent with the exception of languid behavior and hunched appearance exhibited 14 during a 4-hour exposure of rats to 5000 mg/m 3 light alkylate naphtha (API 1995). 15

16 In a subchronic (13 week) study, Schreiner et al. (2000) exposed groups of 16 male and 17 16 female Sprague–Dawley rats (whole-body) to 0, 750, 2500, or 7500 ppm (approximately 0, 18 2250, 7500, or 22,500 mg/m 3 ) of vapors of a light catalytic reformed naphtha distillate (CAS No. 19 64741-63-6). 1 Standard parameters of subchronic toxicity were measured throughout the study. 20 At necropsy, organs were weighed and tissues were examined microscopically. There was no 21 mortality and no clinical signs such as tremors, ataxia, or lethargy were seem. Compared to the 22 control group, there were no changes in motor activity or other parameters during a standard 23 functional observational battery (FOB). Changes in some hematology parameters such as a 24 decrease in white blood cell count in males in the 22,500 mg/m 3 group generally abated during a 25 four-week recovery period. In male rats that inhaled 22,500 mg/m 3 , a small increase in relative 26 kidney weight and decreases in absolute and relative spleen weight were reversible at the end of 27 the recovery period. These parameters were unaffected in female rats. Rats in the 22,500 mg/m 3 28 group showed a male-rat specific light hydrocarbon nephropathy. 29

30 A 13-week neurotoxicity study was conducted with gasoline vapor generated by 31 vaporizing gasoline at near-maximum in-use automotive fuel tank temperature conditions 32 (O’Callaghan et al. 2004). The starting materi al, described in Daughtrey et al. (2004), was 33

1 Light catalytic reformed naphtha is comprised of hydrocarbons having carbon numbers predominantly in the C 5 -C 11 range. It contains a relatively large proportion of arom atics and branched chain hydrocarbons and may contain as much as 10% benzene by volume. Finished gasoline cont ains 20-30% of this light catalytic reformed naphtha.AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 18 of 41

slowly vaporized, separated, condensed and recovered. This fraction, termed gasoline vapor 1 condensate (GVC) was used in multiple studies. Sa mples of GVC to which one of four ethers or 2 one of two alcohols was added were also tested (See Appendix A for volume percent additives). 3 Male and female Sprague Dawley rats were exposed to 0, 2000, 10,000 or 20,000 mg/m 3 of each 4 test material, 6 hours/day, 5 days/week for 13 weeks. A standard FOB and motor activity tests 5 were administered at 3 weeks and several times thereafter. At study termination, brains were 6 evaluated for glial fibrillary acidic protein (GFAP), a biomarker of brain damage. Except for 7 vapor containing the oxygenate t -butyl alcohol, FOB and motor activity were unaffected. 8 Behavioral effects (undefined change in motor activity) for the group exposed to gasoline vapor 9 containing t-butyl alcohol resolved during a r ecovery period. Neuropathology was negative in 10 all groups. Analysis of GFAP revealed a mild gliosis only in males exposed to gasoline vapor 11 condensate containing ethyl alcohol. 12

13 3.4. Developmental/Reproductive Toxicity 14

15 In a two-generation reproductive toxicity study, groups of 30 male and female Sprague16 Dawley rats inhaled gasoline vapor daily for 6 hours/day, 7 days/week, for 10 weeks prior to 17 mating and throughout the mating period (up to 3 w eeks) (McKee et al. 2000). Selected first 18 generation pups were treated in the same manner. The study was conducted in accordance with 19 United States and European guidelines (OECD Guideline 416). In order to assess vapor 20 representative of the exposure of handlers and customers at gasoline service stations, the vapor 21 consisted of the volatile fraction from a gasoline terminal vapor recovery unit at a distribution 22 terminal in the Netherlands. The assigned CAS Reg. No. was 68514-15-8. Exposure took place 23
in 1.5 m 3 chambers; measured concentrations were 5076, 10,247, and 20,241 mg/m 3 (the latter 24 reported as 50% of the LEL). The vapor consisted of primarily C 4 and C 5 hydrocarbons. There 25 were no treatment-related effects in parental animals. Microscopic changes were limited to 26 males and involved hydrocarbon droplet nephropathy of the kidney, specific to male rats. There 27 were no deleterious effects on offspring surviv al and growth. The potential for endocrine 28 modulation was assessed by analysis of sperm count and quality as well as time to onset of 29 developmental landmarks in females. No toxico logically significant effects were observed. The 30 NOAEL for reproductive toxicity in this study was >20,000 mg/m 3

. 31

32 In a one-generation study, groups of 26 male and 26 female Sprague-Dawley rats inhaled 33 the evaporative emissions of gasoline or gasoline containing the ether or alcohol oxygenates, 34 TAME, ETBE, DIPE, ethanol, or TBA, at 0, 2000, 10,000, or 20,000 mg/m 3 , 6 hours/day prior to 35 mating and up to weaning of the F 1 on lactation day 28 (Gray et al. 2004). There were no 36 differences in male or female fertility with any exposure. Reduced weight gain was observed in 37 groups inhaling gasoline vapor and gasoline/MTBE, ethanol, ETBE, and TBA. All exposures 38 caused increases in the kidney weight of male rats. Weight changes and discolorations in other 39 organs were not accompanied by histopathological ch anges, and so were not considered adverse. 40

41 A developmental toxicity study was conducted according to U.S. EPA TSCA Guideline 42 No. 798-4350 (Roberts et al. 2001). Groups of 21 to 24 pregnant Sprague-Dawley rats inhaled 43 measured concentrations of 0, 2653, 7960, or 23,900 mg/m 3 (the latter reported as 75% of the 44 LEL), 6 hours/day, on days 6 to 19 of gestation. The test material was gasoline vapor 45 condensate derived from unleaded gasoline that met 1990 industry average specification (the 46 1990 Clean Air Act required increased oxygen content in gasoline). All rats were sacrificed on 47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 19 of 41

gestation day 20. No maternal toxicity was observed. Developmentally, there were no 1 differences between treated and control groups in fetal malformations, total variations, 2 resorptions, body weight or viability. Under conditions of this study, the developmental NOAEL 3 was >23,900 mg/m 3

. 4

5 Groups of 15 pregnant Sprague Dawley rats i nhaled vapor of light catalytically cracked 6 naphtha, whole-body, at concentrations of 0, 2150, or 7660 mg/m 3 for 6 hours/day on gestation 7 days 0-19 (Dalbey et al. 1996). Dams were s acrificed on gestation day 20. There were no 8
skeletal or visceral effects in the fetuses. Th e only observed effect was an increase in resorptions 9 in the dams that received 7660 mg/m 3 . In a study conducted in the same manner, groups of 11- 10 12 pregnant Sprague-Dawley rats inhaled 0, 2160, or 7800 mg/m 3 of partially vaporized full 11 range catalytic reformed naphtha for 6 hours/da y on gestation days 6-19 (Dalbey and Feuston 12 1996). At sacrifice on day 20, no maternal or fetal effects were observed. 13

14 3.5. Genotoxicity 15

16 The genetic toxicity of gasoline was reviewed by ATSDR (1995). The weight of 17
evidence from in vivo animal studies suggests that unleaded gasoline is not genotoxic to rats and 18 not strongly genotoxic to mice. In vitro rodent studies produced mixed results. Mutagenicity 19 tests with Salmonella typhimurium TA1535, TA1537, TA1538, TA98, or TA100, with and 20 without metabolic activation were largely negative. Mutations were observed only at toxic 21 concentrations. Assays for gene mutation in rodent lymphoma cells were negative. Assays for 22 unscheduled DNA synthesis in rodent primary hepatocytes were positive only as gasoline 23 concentrations approached toxic levels. Results of an assay for unscheduled DNA synthesis in 24 rat kidney cells were negative. 25

26 In a subchronic inhalation study with male and female Sprague-Dawley rats exposed to 0, 27 2000, 10,000, or 20,000 mg/m 3 of gasoline vapor concentrate, with and without oxygenates, all 28 assays for micronucleus formation in bone marrow were negative (Schreiner et al. 2004). 29 Statistically significant increases in sister chromatid exchange over several doses were observed 30 in cultured lymphocytes of rats that inhaled gasoline vapor condensate or gasoline vapor 31 condensate containing MTBE. Females appeared more sensitive than males. Gasoline vapor 32 condensate containing TAME induced increased sister chromatid exchanges in both sexes at the 33 highest dose only. 34

35 3.6. Chronic Toxicity/Carcinogenicity 36

37 Gasoline vapor with and without MTBE was tested for chronic toxicity and 38 carcinogenicity in male and female F344 rats (Benson et al. 2004). Whole-body exposures were 39 to 0, 2000, 10,000, or 20,000 mg/m 3 , 6 hours/day, 5 days/week for 104 weeks. Survival to study 40 termination was unaffected by either concentrate. Final body weight in males and females 41 inhaling 20,000 mg/m 3 gasoline vapor condensate was decreased by 9% and 8% respectively. 42 Reductions in final body weight in male and fe males rats inhaling gasoline vapor containing 43 MTBE were both 8%. Incidences of hepatic ad enomas or carcinomas were unaffected by either 44 exposure compared with the respective control groups. Male-rat specific nephropathy was 45
observed in both control and treated rats. 46

47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 20 of 41

In an earlier study, chronic inhalation of unleaded gasoline vapor resulted in increased 1 hepatocellular adenomas and carcinomas in B6C3F 1 female mice (MacFarland et al. 1984). 2 Tumors appeared in female mice between 18 months and terminal sacrifice in the highest 3 exposure group, 2056 ppm, 6 hours/day. This increase may have been due to the promotion of 4 spontaneously initiated cells that occur with unusually high frequency in this mouse strain 5 (Bruckner et al. 2008). Male rats also exhib ited male-rat-specific nephropathy. Inhalation of 6 unleaded gasoline vapor promoted the development of N -nitrosodiethylamine initiated tumors in 7
male but not female B6C3F 1 mice (Standeven et al. 1995). 8

9 In addition to increased hepatocellular adenomas and carcinomas in B6C3F 1 mice, 10 gasoline has been shown to induce P450 activity and produce hepatomegaly and a transient 11 increase in hepatocyte proliferation, all considered relevant to tumor-promoting activity 12 (Bruckner et al. 2008). However, based on epidemiological evidence, an association between 13 gasoline exposure and cancer in humans is inconclusive (IARC 1989). 14

15 3.7. Summary 16

17 Acute toxicity is similar for all blending streams of gasoline. No deaths were reported in 18 male and female rats that inhaled the limit concentration of 5000 mg/m 3 of various blending 19 streams of gasoline for 4 hours (API 2008a,b). No mortality was reported in male and female 20 rats that inhaled 20,000 mg/m 3 gasoline for more than 10 weeks (McKee et al. 2000) or in male 21 and female rats that inhaled 22,500 mg/m 3 of a blending stream for 13 weeks (Schreiner et al. 22 (2000). In the latter study, no clinical signs were noted during exposure. Studies of subchronic 23
and chronic duration and studies that addressed developmental and reproductive toxicity showed 24 no significant toxic effects. Genotoxic ity studies were generally negative. 25

26
4. SPECIAL CONSIDERATIONS 27 4.1. Metabolism and Disposition 28

29
There are no relevant studies of rates or exte nt of absorption, distribution, metabolism, or 30 excretion of gasoline in humans. The metabolic pathways of many of the components of 31 gasoline have been studied in animal models, but information on the toxicokinetics of complex 32 substances is sparse. Individual hydrocarbons such as pentane are hydroxylated by hepatic 33 cytochrome P-450 enzymes to pentanol, conjugated with glucuronic acid and excreted. 34 Dennison et al. (2003) used physiologically-based pharmacokinetic (PBPK) modeling to 35 characterize the pharmacokinetics of gasoline in rats. Most gasoline components are 36 metabolized or oxidized primarily in the liver by cytochrome P-450/2E1. It was assumed that 37 essentially all of the components of gasoline serv e as competitive inhibitors of oxidation of the 38 other components. Therefore, a lumped approach was used to model the pharmacokinetics of 39 whole gasoline. Selected target components of gasoline were n -hexane, benzene, toluene, 40 ethylbenzene, and o -xylene. Male F344 rats were exposed in a closed chamber for 6 hours to the 41 single chemicals at concentrations between 500 and 2000 ppm, to various mixtures of all five 42 chemicals at 50 to 1000 ppm each, to mixtures of the chemicals at the same concentration of 43 100-500 ppm each, and to winter and summer blends of gasoline at 500, 1000, and 1500 ppm. 44 The experimental data from all combinations of chemicals and computer simulation results from 45 the model matched well. The PBPK model analysis indicated that metabolism of individual 46 components was inhibited up to 27% during the 6-hour experiments of gasoline uptake. 47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 21 of 41

1 4.2. Mechanism of Toxicity 2

3 Automotive gasoline is a complex substance consisting of many hydrocarbon 4 components. Although gasoline components vary within limits with octane number and engine 5 requirements, the acute toxic effects do not di ffer significantly (ACGIH 1992; Niemeier 2001). 6 Some gasoline additives are of toxic interest, but their generally low concentration and low 7 volatility make a negligible contribution to the vapor phase. 8

9 Exposure to very high concentrations of hydrocarbons may cause excitement, loss of 10 equilibrium, stupor, and coma (Cavender 1994a, 1994b, 1994c; Bruckner et al. 2008). The 11 effectiveness of the individual components of gasoline as CNS depressants is related to their 12 volatilization, potency, and blood/air partition coeffici ents. Recovery from CNS effects is rapid 13 and complete in the majority of cases. Death is postulated to be due to either central nervous 14 system depression due to asphyxia leading to respiratory failure, or cardiac sensitization to 15 circulating catecholamines leading to a fatal arrhythmia (ATSDR 1995). 16

17 Because hydrocarbons are lipophilic, they partition into and accumulate in neuronal 18 membranes and myelin. The more lipophilic the hydrocarbon (i.e., the higher its neuronal 19 tissue:blood partition coefficient), the more potent a CNS depressant it is. The mere presence of 20 hydrocarbons has generally been thought to disrupt the ability of the neuron to propagate an 21 action potential and repolarize. Recent research has revealed that hydrocarbons might act by 22 more specific mechanisms and might affect specific neurotransmitters and membrane receptors 23 (i.e., by enhancing gamma-aminobutyric acid A receptor function, or activating dopaminergic 24 systems). 25

26 Many volatile hydrocarbons are of low acute toxicity. Concentrations that cause CNS 27 depression are generally non-injurious to the lung. Exposure of rats to gasoline vapor at 20,000 28 mg/m 3 for more than 10 weeks was without effect (McKee et al. 2000). The aromatic 29 hydrocarbons are more toxic than the aliphatic and alicyclic hydrocarbons but, due to their lower 30 boiling point, are present to a much smaller extent in gasoline vapor. 31

32 Long-term exposure to some hydrocarbons results in α 2u -globulin nephropathy and 33 associated renal carcinogenicity specific to male rats (Bruckner et al. 2008). The nephropathy is 34 characterized by hyaline droplet formation and necr osis of kidney cells. The toxic affect is 35
attributed to the α 2u -microglobulin protein which is unique to the male rat. The α 2u 36 microglobulin protein is synthesized in the liver of male rats and is readily excreted in the 37 glomerular filtrate. Select hydrocarbons combin e with the protein to form poorly digestible 38 complexes and prevent efficient catabolism of the protein following resorption from the 39 glomerular filtrate. The tubular epithelial cells become engorged with the protein, resulting in 40 metabolic disturbances followed by cell death and exfoliation. Exfoliated necrotic cells form 41 tubular casts which plug the nephron near the corticomedullary junction. The casts become 42 mineralized and may be flushed into the medullary segments where they may remain. α 2u 43 Microglobulin nephropathy is unique to male rats. This protein is not synthesized in humans 44 (U.S. EPA 1991). Therefore, this adverse effect is not considered relevant to human exposure to 45 gasoline vapor. 46

47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 22 of 41

4.3. Structure-Activity Relationships 1

2 Gasoline vapor is a complex substance composed of volatile hydrocarbons, primarily in 3
the C 4 to C 6 range. The predominant hydrocarbons in vapor such as butane and pentane, have 4 high vapor pressures, low blood/air partition coeffi cients (Dahl et al. 1988) and are practically 5 nontoxic (Galvin and Marashi 1999). Individual co mponents of gasoline vapor are not addressed 6
in detail in this document. 7

8
4.4. Other Relevant Information 9 4.4.1. Species Variability 10

11 All acute toxicity studies were conducted with the rat as the test species. Therefore, no 12 information on species variability during acute inhalation exposure could be ascertained. 13 Subchronic studies with rats, mice (up to 7690 mg/m 3 ), and monkeys (up to 6570 mg/m 3 ) failed 14 to provide data on relative sensitivity. Although data were available only for a few 15 hydrocarbons, the C 7 hydrocarbon n -heptane and xylene components, in vitro studies of 16 blood/air partition coefficients show that uptak e of hydrocarbons is greater by rat blood than 17 human blood (Gargas et al. 1989). Human and rat blood to air partition coefficients for n

18 heptane were 2.9 and 4.8, respectively, and human and rat blood to air partition coefficients for 19

m -xylene were 33 and 46. Greater chemical uptake by rats than humans is also due to the more 20 rapid respiration rate and greater cardiac output in rodents compared with humans on a body 21 weight basis. 22

23 4.4.2. Susceptible Populations 24

25 No information was available on susceptible human populations. No information was 26 located on age-related sensitivity. Children and the elderly may be more or less sensitive to the 27 toxic effects of solvents and vapors, but age-dependent susceptibility to acute effects of such 28 vapors usually differs by no more than two- to threefold (Bruckner et al. 2008). Although 29 humans differ in the rate at which they metabolize chemicals, the susceptibility of the general 30 population to central nervous system depressants vari es by no more than 2- to 3-fold as indicated 31 by the minimum alveolar concentration, the concentration of an inhaled anesthetic that produces 32 immobility in 50% of patients (Kennedy and Longnecker 1996; Marshall and Longnecker 1996). 33

34 4.4.3. Concentration-Exposure Duration Relationship 35

36 No data were located that provided information on the concentration-exposure duration 37 relationship for either the slight eye irritation experienced at gasoline vapor concentrations 38

≤ 4400 mg/m 3 (Drinker et al. 1943; Davis et al. 1960) or the vapor’s effect on the central nervous 39 system. For the endpoints of both sensory irritati on and depression of the central nervous system 40 by solvents, there is generally a concentration threshold. For neurotoxicity, time to steady state 41 for individual components depends on lipophilicity as well as chemical interactions. Once 42 steady-state is attained, the CNS effect observed with exposure to high concentrations is most 43 likely a concentration-dependent effect with exposure duration of lesser importance. For 44 example, for n -nonane, inhaled by F344 rats at 100, 500, or 1000 ppm for 4 hours, steady-state 45 was approached in the blood within two hours at the two higher concentrations (Robinson 2000). 46 The blood:air partition coefficient was 5.13. 47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 23 of 41

1 4.4.4. Concurrent Exposure Issues 2

3 Gasoline is a complex substance of hydrocarbon components. The effect of inhalation of 4 multiple similar hydrocarbons appears to be additive (Dennison et al. 2003). The highly volatile 5 “light ends” which include hydrocarbons such as isopentane (C 5 H 12 ), are practically non-toxic. 6
The 4-hour LC 50 for isopentane is 280,000 mg/m 3 (Matheson Tri-Gas, Inc. 2009). The aromatics 7 such as toluene are more toxic, with a 3-hour LC 50 value in the mouse of 32,250 mg/m 3 (U.S. 8 EPA 2002). 9

10
5. DATA ANALYSIS FOR AEGL-1 11 5.1. Summary of Human Data Relevant to AEGL-1 12

13 Drinker et al. (1943) exposed male and/or female subjects to whole gasoline vapor 14 (unleaded) at concentrations of 160 and 270 ppm and to gasoline vapor distilled below 110oC at 15 concentrations of 140 and 150 ppm for 8 hours. Ma le and/or female subjects were also exposed 16 to the distillate vapor at 500, 900 or 2600 ppm for 1 hour. Additional exposures via face masks 17 and lasting only a few minutes utilized concentrations of 11,200 ppm (whole gasoline vapor) and 18 10,700 ppm (distillate vapor). Odor detection and very slight irritation were reported at 19 concentrations up to and including 900 ppm. At th is concentration, a slight neurotoxic effect 20 was apparent only after the exposure. Unfortunately, the study employed a 17-year-old female 21 college student and thus does not meet the U. S. EPA ethical criteria for human exposure. 22

23 On separate occasions, Davis et al. (1960) exposed 10 male subjects to three different 24 samples of unleaded gasoline vapor for 30 minutes. Target concentrations were 880, 2200, and 25 4400 mg/m 3 . Concentration-related itching or burning of the eyes was the primary reported 26 symptom. Objective irritation of the eye, as measured by redness, was negative or slight at 880 27 and 2200 mg/m 3 (score range of -2 to +1) and intermediate at 4400 mg/m 3 (score range of -1 to 28 +3 in the three exposures). The scores in the control groups ranged from -1 to +1, but the eyes of 29 more subjects in the 880 and 2200 mg/m 3 groups were assigned a +1 than in the control groups. 30 Incidences of ocular tearing in the control, 880, 2200, and 4400 mg/m 3 groups were 2/20, 1/30, 31 3/30, and 8/30, respectively. Drowsiness wa s reported by two subjects inhaling 4400 mg/m 3 and 32 as well as by two control subjects. 33

34 5.2. Summary of Animal Data Relevant to AEGL-1 35

36
All acute inhalation studies were conducted with rats as the test animal. A 4-hour 37 exposure to 5000 mg/m 3 vapor of various gasoline blending streams was generally without a 38 significant toxic effect (API 2008a,b). In subchr onic studies, the highest concentrations tested, 39 20,000 and 22,500 mg/m 3 (rat), 7690 mg/m 3 (mouse), and 6570 mg/m 3 (monkey) were without 40 toxic effects (Schreiner et al. 2000; O’Callaghan et al. 2004; Dalbey et al. 1996; Kuna and Ulrich 41 1984). 42

43
5.3. Derivation of AEGL-1 44

45 The AEGL-1 is based on the sensory irrita tion study of Davis et al. (1960). The 30- 46 minute exposures to three different blends of gasoline vapor at approximately 2200 mg/m 3 47AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 24 of 41

(measured concentrations of 2323, 2187, and 2204 mg/m 3 ) produced subjective eye irritation at a 1 higher incidence (15/30) than under control conditions (1/20). The incidence of objective eye 2 irritation, although scored as slight (+1 on a scale of 1 to 4), was higher in the 2200 mg/m 3 group 3 (15/30) than in the control group (2/20). Incidences of subjective and objective eye irritation, 4 including ocular tearing were higher at the higher concentration of 4400 mg/m 3 . Incidences of 5 ocular tearing were similar in the 2200 mg/m 3 group (3/30) and the control group (2/20). 6 Because the eye irritation when measured objectively was slight (less than marked), an 7 intraspecies uncertainty factor of 3 was applied to protect sensitive subjects. There is adaptation 8 to the slight irritation that defines the AEGL-1. Therefore, the same value of 730 mg/m 3 (2200 9 mg/m 3 /3) was used across all exposure durations. AEGL-1 values are summarized in Table 7. 10 Calculations are in Appendix C and a category gra ph of the toxicity data in relation to AEGL 11 values is in Appendix D. 12

13

TABLE 7. AEGL-1 Values for Automotive Gasoline Vapor

10-min 30-min 1-h 4-h 8-hour 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3

14

15
6. DATA ANALYSIS FOR AEGL-2 16 6.1. Summary of Human Data Relevant to AEGL-2 17

18 Davis et al. (1960) exposed 10 male subjects to three different samples of unleaded 19 gasoline vapor for 30 minutes. Target concentrations were 880, 2200, and 4400 mg/m 3

. 20 Drowsiness was reported by two subjects inhaling 4400 mg/m 3 and in two control subjects. 21

22 6.2. Summary of Animal Data Relevant to AEGL-2 23

24
All acute inhalation studies were conducted with rats as the test model. A 4-hour 25 exposure to 5000 mg/m 3 of vapor of various gasoline blending streams was generally without a 26 toxic effect (API 2008a,b; ARCO Chemical Co. 1984) . No higher concentrations were tested in 27 acute studies. In subchronic studies, the hi ghest concentrations tested, 20,000 and 22,500 mg/m 3 28 (rat), 7690 mg/m 3 (mouse), and 6570 mg/m 3 (monkey) were also without apparent toxic effects 29 (Schreiner et al. 2000; O’Callaghan et al. 2004; Dalbey et al. 1996; Kuna and Ulrich 1984), 30 although clinical signs were specifically addresse d only in the study of Schreiner et al. (2000). 31 Schreiner et al. (2000) reported an absence of ne urotoxicity (tremors, ataxia, lethargy) in rats 32 during subchronic exposure to 22,500 mg/m 3

. 33

34
6.3. Derivation of AEGL-2 35

36 The study of Davis et al. (1960) does not a ddress effects helpful in determining an 37 AEGL-2. For substances with anesthetic effects, the threshold for neurotoxicity is the point of 38 departure. In a series of studies of the acute inhalation toxicity of blending streams of gasoline, 39 the limit concentration of 5000 mg/m 3 (range, 5000-5300 mg/m 3 ) was generally without effect. 40 Clinical signs of slight nasal discharge, lacrima tion in a few animals, and reduced righting reflex 41 were observed in some of the studies (API 2008a,b; ARCO Chemical Co. 1984). 42

43AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 25 of 41

Because acute studies do not address endpoints consistent with the definition of the 1 AEGL-2, observations from longer-term studies ar e relevant. Male and female Sprague-Dawley 2 rats exposed to 22,500 mg/m 3 of a gasoline blending stream failed to show neurotoxic signs 3 during a 6 hour/day exposure over 90 days (Schreiner et al. 2000). Rats were observed 4 specifically for tremors, ataxia, and lethargy. The point of departure, 22,500 mg/m 3 , was divided 5 by interspecies and intraspecies uncertainty factors of 1 and 3, respectively, for a total of 3, 6 giving an AEGL-2 value of 7500 mg/m 3 (22,500 mg/m 3 /3). An interspecies uncertainty factor of 7 1 is sufficient because solvent uptake is generally greater in rodents than in humans (based on 8 higher blood:air partition coefficients for relate d hydrocarbons (Bruckner et al. 2008; Gargas et 9 al 1989)]. In addition, chemical uptake is faster in rodents than in humans based on higher 10 respiratory rate and greater cardiac output on a body weight basis. Although humans differ in 11 the rate at which they metabolize chemicals, the susceptibility of the general population to 12 central nervous system depressants varies by no more than 2- to 3-fold as indicated by the 13 minimum alveolar concentration, the concentration of an inhaled anesthetic that produces 14 immobility in 50% of patients (Kennedy and Longnecker 1996; Marshall and Longnecker 1996). 15 Therefore, an intraspecies uncertainty factor of 3 (rather than the default of 10) is considered 16 sufficient. Higher uncertainty factors would result in values inconsistent with the clinical study 17 of Davis et al. (1960). Time scaling may not be relevant for hydrocarbons that act as anesthetics 18 as blood concentrations rapidly approach stea dy-state. Therefore, the 6-hour value of 7500 19 mg/m 3 was used across all exposure durations. AEGL-2 values are summarized in Table 8. 20 Calculations are in Appendix C and a category gra ph of the toxicity data in relation to AEGL 21 values is in Appendix D. 22

23

24

TABLE 8. AEGL-2 Values for Automotive Gasoline Vapor

10-min 30-min 1-h 4-h 8-h 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * *The AEGL-2 value is higher than 1/10 of the lower explosive limit (LEL) of gasoline in air (LEL = 14,000 ppm or 42,000 mg/m 3 ). Therefore, safety considerations against hazard of explosion must be taken into account.
25 The subchronic study of Kuna and Ulrich (1984) in which squirrel monkeys inhaling 26 6350 mg/m 3 for 6 hours/day showed no toxic signs supports the calculated AEGL-2 value, and 27 by extension, the interspecies uncertainty factor of 1. Lack of toxicologically significant effects 28 in reproductive and developmental repeat-exposure studies at concentrations of 20,000 to 23,900 29 mg/m 3 (McKee et al. 2000; Roberts et al. 2001; Gray et al. 2004) support the key study. 30

31 The toxicity of individual hydrocarbons comprising gasoline vapor may also be 32 supportive of the values derived for gasoline vapor. In a subchronic study of n -pentane toxicity 33 with male and female Sprague-Dawley rats, 20,000 mg/m 3 /day for 6 hours/day, 5 days/week for 34 13 weeks was a NOAEL for lethality and changes in body weight gain, hematology parameters, 35 clinical chemistry, gross findings, ophthalmol ogy, and histopathology of major tissues and 36 organs (McKee et al. 1998). This value is similar to the NOAEL for a blending stream in the 37 AEGL-2 key study. 38

39
7. DATA ANALYSIS FOR AEGL-3 40 7.1. Summary of Human Data Relevant to AEGL-3 41

42
No human data relevant to calculation of AEGL-3 values were located. 43AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 26 of 41

1 7.2. Summary of Animal Data Relevant to AEGL-3 2

3 None of the acute or subchronic studies with gasoline vapor or gasoline vapor plus 4 additives resulted in mortality in rats. The highest exposures for 4-hour acute and 6 hour/day 5 subchronic studies were approximately 5000 mg/m 3 (API 2008a,b) and 22,500 mg/m 3 (Schreiner 6 et al. 2000), respectively. There was no mortality in these studies. The 4-hour LC 50 for 7 isopentane is 280,000 mg/m 3 (Matheson Tri-Gas, Inc. 2009). 8

9
7.3. Derivation of AEGL-3 10

11 It is not apparent that concentrations high enough to cause death from inhalation of 12 automotive gasoline vapor can be attained except in occasional accidental or misuse cases. 13 Based on the likelihood that lethal concentrations of gasoline vapor cannot be attained/sustained 14 under ambient conditions, an AEGL-3 was not determined (Table 9). 15

16 At sufficiently high concentrations, toxicologically inert chemicals may act as simple 17 asphyxiants by displacing atmospheric oxygen (Leikauf and Prows 2001). For the sensitive 18 population of people with pulmonary diseases (edema or emphysema) or cardiovascular 19 diseases, an arterial oxygen saturation of 65% may be the threshold for a life threatening 20 condition. Using the SatCur model (2009), 65% oxygen saturation in a sensitive subject 21 performing light exercise corresponds to 14% atmospheric oxygen. This corresponds to a 33% 22 atmosphere of a simple asphyxiant (330,000 ppm or 990,000 mg/m 3 ). 23
24

TABLE 9. AEGL-3 Values for Automotive Gasoline Vapor

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

Not determined* Not determined* Not dete rmined Not determined Not determined

* AEGL-3 values were not determined due to insufficien t data. Automotive gasoline vapor may act as a simple 25 asphyxiant in sensitive individuals at 990,000 mg/m 3

. 26
27
8. SUMMARY OF AEGLs 28 8.1. AEGL Values and Toxicity Endpoints 29

30 AEGL values are summarized in Table 10. Derivations summaries are in Appendix E. 31

32

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

AEGL-1 (Nondisabling) 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3

AEGL-2 (Disabling) 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 *

AEGL-3 (Lethal)** Not determined Not determined Not determined Not determined Not determined

*The AEGL-2 value is higher than 1/10 of the lower e xplosive limit (LEL) of gasoline in air (LEL = 14,000 ppm). 33 Therefore, safety considerations against h azard of explosion must be taken into account. 34

**AEGL-3 values were not determined due to insufficien t data. Automotive gasoline vapor may act as a simple 35 asphyxiant in sensitive individuals at 990,000 mg/m 3

. 36
37AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 27 of 41

8.2. Comparison with Other Standards and Guidelines 1

2 Standards and guidelines for automotive gasoline are listed in Table 11. The American 3 Conference of Government Industrial Hygienis ts (ACGIH) Threshold Limit Value of 300 ppm 4 (890 mg/m 3 ) is based on Runion (1975). Runion (1975) cites the study of Drinker et al. (1943) 5 as showing eye irritation at 160-270 ppm duri ng 8-hour exposures. The ACGIH short-term 6 exposure limit is 500 ppm (1480 mg/m 3 ). 7

8 The Emergency Response Planning Guideline-1 (ERPG-1) of 200 ppm (654 mg/m 3 ) is 9 based on the study of Drinker et al. (1943) in which eye irritation was reported at 140 ppm 10 during an 8-hour exposure. It is believed that the threshold for eye irritation would be 200 ppm 11 for shorter exposure periods. The ERPG-2 of 1000 ppm (3270 mg/m 3 ) was based on the onset of 12 mild central nervous system depression in workers. The ERPG-3 of 4000 ppm (13,080 mg/m 3 ) 13 was considered non-life-threatening. The ERPG values used the conversion factor of 3.27 14 (molecular weight of 80 for gasoline vapor) to convert from ppm to mg/m 3

. 15

16

TABLE 11. Standards and Guidelines for Automotive Gasoline Vapor
Exposure Duration Guideline 10 min 30 min 1 h 4 h 8 h
AEGL-1 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3
AEGL-2 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 *

AEGL-3** Not determined Not determined Not determined Not determined Not determined ERPG-1 (AIHA) a 654 mg/m 3
ERPG-2 (AIHA) 3270 mg/m 3
ERPG-3 (AIHA) 13,080 mg/m 3

Dutch VRW b 2 mg/m 3
Dutch AGW 1000 mg/m 3
Dutch LBW 5000 mg/m 3

IDLH (NIOSH) c ─ Ca

REL-TWA (NIOSH) d Ca

OSHA PEL (NIOSH) e ─

TLV-TWA (ACGIH) f 890 mg/m 3 ; 1480 mg/m 3
(15-min STEL) MAK (Germany) g

─ MAC (The Netherlands) h 240 mg/m 3 ; 480 mg/m 3 (15- min excursion)
*The AEGL-2 value is higher than 1/10 of the lower e xplosive limit (LEL) of gasoline in air (LEL = 14,000 ppm or 17 42,000 mg/m 3 ). Therefore, safety considerations against hazard of explosion must be taken into account. 18 ** Automotive gasoline vapor may act as a simple asphyxiant in sensitive individuals at 990,000 mg/m 3

. 19 VRW = Voorlichtingsrichtwaarde, threshold at which the general public needs to be informed (based on odor). 20 AGW = Alarmeringsgrenswaarde, threshold for irritation. 21 LBW = Levensbedreigende waarde, neurotoxicity. 22 Ca = potential occupational carcinogen. 23 24

a ERPG (Emergency Response Planning Guide lines, American Industrial Hygiene Association (AIHA 2008). 25

The ERPG-1 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 26 exposed for up to one hour without experiencing other than mild, transient adverse health effects or without 27AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 28 of 41

perceiving a clearly defined objectionable odor. 1

The ERPG-2 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 2 exposed for up to one hour without experiencing or devel oping irreversible or other serious health effects or 3 symptoms that could impair an individual = s ability to take protective action. 4

The ERPG-3 is the maximum airborne concentration belo w which it is believed nearly all individuals could be 5 exposed for up to one hour without experiencing or developing life-threatening health effects. 6 7

b Dutch Intervention Values are similar to the ERPG values and the 1- hour AEGL values, but are based on slighter 8 effects – odor, irritation, and neurotoxicity, respectively. 9 10

c IDLH (Immediately Dangerous to Life and Health, Nati onal Institute of Occupational Safety and Health) 11 (NIOSH 2005) represents the maximum concentration from which one could escape within 30 minutes without any 12 escape-impairing symptoms, or any irreversible health effects. 13 14

d NIOSH REL-TWA (National Institute of Occupational Safety and Health, Recommended Exposure Limits - 15 Time Weighted Average) (NIOSH 2005) is defined analogous to the ACGIH-TLV-TWA. 16 17

e OSHA PEL-TWA (Occupational Safety and Health Ad ministration, Permissible Exposure Limits - Time 18 Weighted Average) (NIOSH 2005) is defined analogous to the ACGIH-TLV-TWA, but is for exposures of no more 19 than 10 hours/day, 40 hours/week (no value assigned). 20 21

f ACGIH TLV-TWA (American Conference of Governmental Industrial Hygienists, Threshold Limit Value - 22 Time Weighted Average) (ACGIH 1992) is the time-weighted averag e concentration for a normal 8-hour workday 23 and a 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse 24

effect. 25 26

g MAK (Maximale Arbeitsplatzkonzentrat ion [Maximum Workplace Concentration]) (Deutsche 27 Forschungsgemeinschaft [German Research Association 2008] is defined analogous to the ACGIH-TLV-TWA (no 28 value assigned). 29 30

h MAC (Maximaal Aanvaarde Concentratie [Maximal Accepted Concentration]) (SDU Uitgevers [under the 31 auspices of the Ministry of Social Affairs and Employmen t], The Hague, The Netherlands is defined similar to the 32 ACGIH TLV. The 15-minute ceiling is 480 mg/m 3 . Note: automotive gasoline is called benzene. 33
34 8.3. Data Adequacy and Research Needs 35

36 The data base for gasoline is rich. Clinical studies addressed subjective and objective eye 37 irritation. Studies with laboratory rodents a ddressed acute and subchronic toxicity, chronic 38 toxicity/carcinogenicity, neurotoxicity, reproductive and developmental toxicity and 39 genotoxicity. 40

41
9. REFERENCES 42
43 ACGIH (American Conference of Government and Indus trial Hygienists). 1992. Documentation of the 44 Threshold Limit Values and Biological Exposure Indices. Cincinnati, OH: ACGIH. 45
46 AIHA (American Industrial Health Association). 2008. Emergency Response Planning Guidelines: 47 Gasoline. Fairfax, VA (Preprint). 48
49 Amerada Hess Corporation. 2004. Material Safety Sheet: Gasoline, All Grades. MSDS No. 9950, 50 Amerada Hess, Woodbridge, NJ. 51
52 Anonymous. 1989. Toxicology update. J. Appl. Toxicol. 9:203-210. 53
54AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 29 of 41

API (American Petroleum Institute). no date. Gasoline Blending Streams Test Plan. Submitted to the 1 US EPA by The American Petroleum Institute, Petroleum HPV Testing Group. Consortium 2 Registration #1100997. 3
4 API (American Petroleum Institute). 1982. LC 50 Acute Inhalation Toxicity Evaluation in Rats (API-No. 5 81-08). API Medical Research Publication 30-31990. Study conducted by the International Research 6 and Development Corporation for the American Petr oleum Institute, with amendment dated February 7 14, 1983. Washington, DC: American Petroleum Institute. 8
9 API (American Petroleum Institute). 1994. Odor th reshold studies performed with gasoline and gasoline 10 combined with MTBE, ETBE and TAME, with cove r letter dated 02/22/95. API Publication 4592, 11 prepared by TRC Environmental, Windsor, CT. OTS0557644, available from the National Technical 12 Information Service, Springfield, VA. 13
14 API (American Petroleum Institute). 1995. Index and Abstracts of API Health-Related Research, 13 th 15 ed., 1959-1994. American Petroleum Institute, H ealth and Environmental Sciences Department, 16

Publication Number 4534. 17
18 API (American Petroleum Institute). 2002. Robust Summary of Information on Gasoline. API, 19 Washington, DC. 20
21 API (American Petroleum Institute). 2008a G asoline Blending Streams Category: Robust Studies 22 Summary. File provided by R. White, API, Washington, DC: 23 2008_aug21_gasoline_catanalysis_final_robust_study_summaries. 24
25 API (American Petroleum Institute). 2008b Gasoline Blending Streams Category Assessment 26 Document. Submitted to the U.S. EPA by the American Petroleum Institute, Petroleum HPV Testing 27 Group, Consortium Registration #1100997. 28
29 ARCO Chemical Co. 1984. Toxicology Report: Acute Toxicity Studies of ARCO Clear Gasoline with 30 MTBE (1984) and Submission of Inhalation Studies Done on Rats with MTBE with Cover Letter 31 Dated 021987. Studies performed by Bio/dynamics Inc., for the Atlantic Richfield Company, Los 32 Angeles, CA. 33
34 ATSDR (Agency for Toxic Substances and Disease Registry). 1995. Toxicological Profile for 35 Automotive Gasoline. U.S. Department of Health & Human Services, Public Health Service, Atlanta, 36

GA. 37
38 Benson, J., C.R. Clark, E.B. Barr, A.P. Gigliotti, T.H. March, C.A. Elliot, A.P. Gomez, B.M. Tibbetts, 39 and R. White. 2004. Inhalation Toxicity of Gasoline & Fuel Oxygenates: Chronic Toxicity. Poster 40 presented at the 43 rd Annual Meeting of the Society of Toxicology held in Baltimore, MD. 41
42 Bruckner, J.V., S. S. Anand, and D. A. Warren. 2008. Chapter 24: Toxic Effects of Solvents and Vapors. 43 Pp. 981- 1051 in Casarett & Doull’s Toxicology: The Basic Science of Poisons, 7 th ed. New York: 44

McGraw Hill Medical. 45
46 Cavender, F. 1994a. Chapter 19: Aliphatic hydrocarbons. In: Patty = s Industrial Hygiene and 47 Toxicology, 4th ed., vol. II, Part B. John Wiley & Sons, New York, pp. 1221-1266. 48
49 Cavender, F. 1994b. Chapter 20: Alicyclic hydrocarbons. In: Patty = s Industrial Hygiene and 50 Toxicology, 4th ed., vol. II, Part B. John Wiley & Sons, New York, pp. 1267-1299. 51
52AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 30 of 41

Cavender, F. 1994c. Chapter 21: Aromatic hydrocarbons. In: Patty = s Industrial Hygiene and 1 Toxicology, 4th ed., vol. II, Part B. John Wiley & Sons, New York, pp. 1301-1442. 2
3 Chu, I., R. Poon, V. Valli, A. Yagminas, W.J. Bowers, R. Seegal, and R. Vincent. 2005. Effects of an 4 ethanol-gasoline mixture: results of a 4-week inhala tion study in rats. J. Appl. Toxicol. 25:193-199. 5
6 CONCAWE (Conservation of Clean Air and Water in Europe). 1992. Gasolines. Product Dossier No. 7

92/103. Brussels: CONCAWE. 8
9 Dahl, A.R., E.G. Damon, J.L. Mauderly, S.J. Roth enberg, F.A. Seiler, and R.O. McClellan. 1988. 10 Uptake of 19 hydrocarbon vapors inhaled by F344 rats. Fund. Appl. Toxicol. 10:262-269. 11
12 Dalbey, W.E. and M.H. Feuston. 1996. Partially vaporized full range catalytic reformed naphtha: 13 subchronic and developmental toxicity studi es in rats. Inhal. Toxicol. 8:271-284. 14
15 Dalbey, W.E., M.H. Feuston, and J.J. Yang. 1996. Light catalytically cracked naphtha: subchronic 16 toxicity of vapors in rats and mice and developmenta l toxicity screen in mice. J. Toxicol. Environ. 17

Health 47:77-91. 18
19 Daughtrey, W.C., D.M. Burnett, P. Podhasky, M. Henl ey, and R.D. White. 2004. Inhalation Toxicity of 20 Gasoline & Fuel Oxygenates: Test Sample Preparation. Poster presented at the 43 rd Annual Meeting 21 of the Society of Toxicology held in Baltimore, MD. 22
23 Davis, A., L. Schafer, and Z. Bell. 1960. The e ffects on human volunteers of exposure to air containing 24 gasoline vapor. Arch. Environ. Health 1:545-554. 25
26 Dennison, J.E., M.E. Andersen, and R.S.H. Yang. 2003. Characterization of the pharmacokinetics of 27 gasoline using PBPK modeling with a complex mixtures chemical lumping approach. Inhal. Toxicol. 28

15:961-986. 29
30 Drinker, P., C. Yaglou, and J. Warren. 1943. The th reshold toxicology of gasoline vapor. J. Ind. Hyg. 31

Toxicol. 25:225-232. 32
33

Dutch Intervention Values. 2009. Gasoline. Publishe d by the Ministry of Housing, Spatial Planning and 34 Environment, The Hague, The Netherlands. 35
36 Galvin, J.B., and F. Marashi. 1999. 2-Methylbutane (i sopentane). J. Toxicol. Environ. Health, Part A, 37

58:23-33. 38
39 Gargas, M.L., R.J. Burgess, D.E. Voisard, G.H. Cas on, and M.E. Andersen. 1989. Partition coefficients 40 of low-molecular-weight volatile chemicals in various liquids and tissues. Toxicol. Appl. Pharmacol. 41

98: 87-99. 42
43 German Research Association (Deutsche Forschungsgemeinschaft). 2008. List of MAK and BAT 44 Values 2007. Report No. 44, Commission for the Investigation of Health Hazards of Chemical 45 Compounds in the Work Area. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. 46
47 Gray, T.M., K.P. Haxelden, D.R. Steup, J.P. O’Callaghan, G.M. Hoffman, and L.G. Roberts. 2004. 48 Inhalation toxicity of gasoline & fuel oxygenates; reproductive toxicity assessment. Poster presented 49

at the 43 rd Annual Meeting of the Society of Toxicology held in Baltimore, MD. 50
51AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 31 of 41

Halder, C.A., G.S. van Gorp, N.S. Hatoum, and T.M. Warne. 1986. Gasoline vapor exposures. Part II. 1 Evaluation of the nephrotoxicity of the major C 4 /C 5 hydrocarbon components. Am. Ind. Hyg. Assoc. 2

J. 47:173-175. 3
4 IARC (International Agency for Research on Cance r). 1989. IARC Monographs on the Evaluation of 5 Carcinogenic Risks to Humans. Some Chemicals that Cause Tumors of the Kidney or Urinary 6

Bladder in Rodents and Some Other Substances. Vo l. 73, Lyons, France, World Health Organization. 7
8 Kennedy, S.K. and D.E. Longnecker. 1996. History and Principles of Anesthesiology. P. 302 in 9

Goodman & Gilman = s The Pharmacological Basis of Therapeuti cs, 9th Ed., J.G. Hardman et al., eds. 10

New York: McGraw-Hill. 11
12 Kuna, R.A. and C.E. Ulrich. 1984. Subchronic inhala tion toxicity of two motor fuels. J. Am. Coll. 13

Toxicol. 3:217-230. 14
15 Leikauf, G.D. and D.R. Prows. 2001. Chapter 47: Inorganic Compounds of Carbon, Nitrogen, and 16 Oxygen. In Patty’s Industrial Hygiene and Toxico logy, Vol. 3. John Wiley & Sons, New York, pp. 17

657-661. 18
19 MacFarland, H.N., C.E. Ulrich, C.E. Holdsworth. 1984. A chronic inhalation study with unleaded 20 gasoline vapor. J. Am. Coll. Toxicol. 3:231-248. 21
22 Marshall, B.E. and D.E. Longnecker. 1996. Ge neral Anesthetics. P. 307 in Goodman & Gilman = s The 23 Pharmacological Basis of Therapeutics, 9th Ed., J. G. Hardman et al., eds. New York: McGraw-Hill. 24
25 Matheson Tri-Gas, Inc. 2009. Material Safety Da ta Sheet for Isopentane. Matheson Tri-Gas, Inc. 26 Basking Ridge, NJ. 27
28 McKee, R., E. Frank, J. Heath, D. Owen, R. Przygoda , G. Trimmer, and F. Whitman. 1998. Toxicity of 29

n -pentane (CAS No. 109-66-0). J. Appl. Toxicol. 18:431-442. 30
31 McKee, R.H., S. Dally, B.A. Dmytrasz, J.F. Gonnet, R.E. Hagermann, C. Mackerer, C.S. Nessel, R.A.J. 32 Priston, A.J. Riley, and J.H. Urbanus. 2000. An Assessment of the Reproductive Toxicity of 33 Gasoline Vapor. CONCAWE report no. 00/53. Available online: 34 http://www.concawe.org/DocShareNoFrame/do cs/2/CAAIBNPACFICDAJIDIEHJBOHPDBY9DBY 35 AY9DW3571KM/CEnet/docs/DLS/2002-00232-01-E.pdf

. 36
37 Moser, G.J., B.A. Wong, D.C. Wolf, O.R. Moss, and T.L. Goldworthy. 1996. Comparative short-term 38 effects of methyl tertiary butyl ether and unleaded gasoline vapor in female B6C3F1 mice. Fund. 39 Appl. Toxicol. 31:173-183. 40
41 Niemeier, R.W. 2001. Chapter 22; Petroleum, Coal Tar, and Related Products . Pp. 786-789 In Patty’s 42 Toxicology, 5 th ed., Vol. 1. New York: John Wiley & Sons, Inc. 43
44

NIOSH. 2005. NIOSH Pocket Guide to Chemical Hazar ds. Online data base, U.S. Department of Health 45

and Human Services: http://www.cdc.gov/niosh/npg. 46
47 O’Callaghan, J.P., C.M. Felton, B.K. Billig, W.C. Da ughtrey. 2004. Inhalation Toxicity of Gasoline & 48 Fuel Oxygenates: Neurotoxicity. Poster presented at the 43 rd Annual Meeting of the Society of 49 Toxicology held in Baltimore, MD. 50
51AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 32 of 41

O’Neil, M.J., A. Smith, and P.E. Heckelman. 2001. Gasoline. The Merck Index. Whitehouse Station, 1 NJ: Merck & Co., Inc., p. 4382. 2
3 Reese, E. and R.D. Kimbrough. 1993. Acute Toxicity of gasoline and some additives. Environ. Health 4 Persp. 101(Suppl. 6):115-131. Available online: 5 http://www.pubmedcentral.nih.gov/picr ender.fcgi?artid =1520023&blobtype=pdf

. 6
7 Richardson, K.A., J.L. Wilmer, D. Smith-Simpson, and T.R. Skopek. 1986. Assessment of the genotoxic 8 potential of unleaded gasoline and 2,2,4-trimethylpentane in human lymphoblasts in vitro . Toxicol. 9 Appl. Pharmacol. 82:316-322. 10
11 Roberts, L., R. White, Q. Bui, W. Daughtrey, F. Kosch ier, S. Rodney, C. Shreiner, D. Steup, R. Breglia, 12 R. Rhoden, R. Schroeder, and P. Newton. 2001. Developmental toxicity evaluation of unleaded 13 gasoline vapor in the rat. Reprod. Toxicol. 15:487-494. 14
15 Robinson, P.J. 2000. Pharmacokinetic Modeling of JP-8 Jet Fuel Components. I. Nonane and C9-C12 16 Aliphatic Components. AFRL-HE-WP-T R-2000-0046, Wright Patterson AFB, OH. 17
18 Runion, H.E. 1975. Benzene in gasoline. Amer. Ind. Hyg. Assoc. J. 36:338-350. 19
20 SatCur. 2009. A Program Teaching the Hemoglobin Oxygen Saturation Curve. Available online: 21 http://www.baloh.nl

. 22
23 Schreiner, C., Q. Bui, R. Breglia, D. Burnett, F. Ko schier, E. Lapadula, P. Podhasky, and R. White. 2000. 24 Toxicity evaluations of petroleum blending str eams: inhalation subchronic toxicity/neurotoxicity 25 study of a light catalytic reformed naphtha distillate in rats. J. Toxicol. Environ. Health, Part A, 26

60:489-512. 27
28 Schreiner, C., G. Hoffman, C. Mason, and R. Gudi . 2004. Inhalation toxicity of gasoline and fuel 29 oxygenates: micronucleus and sister chromatid exchange tests. Poster presented at the 43 rd Annual 30 Meeting of the Society of Toxicology held in Baltimore, MD. 31
32 SDU Uitgevers. 2000. Nationale MAC List. Under the auspices of the Ministry of Social Affairs and 33 Employment. The Netherlands: The Hague. 34
35 Standeven A.M., D.C. Wolf, and T.L. Goldsworthy. 1995. Promotion of hepatic preneoplastic lesions in 36 male B6C3F1 mice by unleaded gasoline. Environ. Health Persp. 103:696-700. 37
38 U.S. EPA (U.S. Environmental Protection Agency ). 1991. Alpha-2-globulin: Association with 39 chemically-induced renal toxicity and neoplasia in the male rat. EPA/625/3-91/019F, Risk 40 Assessment Forum, U.S. Environmental Protection Agency, Washington, DC. 41
42 U.S. EPA (U.S. Environmental Protection Agency). 2002. Interim AEGL Values for Toluene. Available 43 online: http://www.epa.gov/oppt/aegl/pubs/results32.htm. 44
45 van Doorn, R., M. Ruijten and T. van Harreveld. 2002. Guidance for the Application of Odor in 46 Chemical Emergency Responses, Unpublishe d report, Version 2.1, August 29, 2002. 47
48 White, R. 2009. Gasoline: Composition and Toxi cology. Presentation to the National Advisory 49 Committee for Acute Exposure Guideline Levels, April 15, 2009. 50
51
52AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 33 of 41

1 APPENDIX A: Major Hydrocarbons found in Gasoline Vapor Condensate 2 (representative composition) 3
4
Hydrocarbon Gasoline Vapor Condens ate (%) Gasoline Vapor Condensate containing 10% Ethanol (%)
Isobutane (C 4 H 10 ) 2.8 2.2

n -Butane (C 4 H 10 ) 13.1 11.6 Isopentane (C 5 H 12 ) 34.8 34

n -Pentane (C 5 H 12 ) 13.7 10.2 trans-2 Pentene (C 5 H 10 ) 2.6 2.1 2-Methylpentane (C 6 H 14 ) 6.8 5.1

n -Hexane (C 6 H 14 ) 3.1 2.4 Benzene (C 6 H 6 ) 2.2 1.6 3-Methyl hexane (C 7 H 16 ) 1.4 1.2 Isooctane (C 8 H 18 ) 1.5 1.3 Toluene (C 7 H 8 ) 3.3 2.4 Ethanol (C 2 H 6 O) 0.0 13.3
Note: as measured by % gas chromatography area. 5 Source: White (2009). 6
7 Typical Oxygenate Levels (v/v) 8 (only one used in any gasoline) 9
10
Methyl t -butyl ether (MTBE) 21.3

t -Amyl methyl ether (TAME) 11.9 Ethyl t -butyl ether (ETBE) 16.3 Diisopropyl ether (DIPE) 17.8

Ethanol 13.3

t -Butyl alcohol (TBA) 16.8
Source: Daughtrey et al. (2004). 11
12
13 Petroleum Chemistry Definitions (Source: API n.d.) : 14
15

Paraffins: C

n H 2n+2 : carbon atoms are joined by a single bond; may be linear or branched 16 example: n -pentane 17

Olefins: C

n H 2n : contain at least one double bond; may be linear, branched, or cyclic 18 example: cyclohexene 19 Cycloparaffins (naphthenes): 5-6 carbon atoms arranged in a ring, saturated 20 example: cyclohexane 21 Aromatics: carbon atoms arranged in a ring, unsaturated 22 examples: benzene, toluene 23AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 34 of 41

1
APPENDIX B: Derivation of Level of Odor Awareness 2
3 The level of distinct odor awareness (LOA) represents the concentration above which it 4 is predicted that more than half of the exposed population will experience at least a distinct odor 5 intensity, and about 10% of the population will experience a strong odor intensity. The LOA 6 should help chemical emergency responders in assessing the public awareness of the exposure 7 due to odor perception. The LOA derivation follo ws the guidance given by van Doorn et al. 8 (2002). 9

10 The lowest odor detection threshold (OT 50 ) for gasoline without additives was for the summer 11 and winter composite blend, 0.474 ppm. (API 1994). 12

13 The concentration (C) leading to an odor intensity (I) of distinct odor detection (I=3) is derived 14 using the Fechner function: 15

16 I = kw x log (C /OT 50 ) + 0.5 17

18 For the Fechner coefficient, the default of kw = 2.33 will be used due to the lack of chemical19 specific data: 20

21 3 = 2.33 x log (C /0.474) + 0.5 which can be rearranged to 22 log (C /0.474) = (3 - 0.5) / 2.33 = 1.07 and results in 23 C = (10 1.07 ) x 0.474 = 5.6 ppm 24

25 The resulting concentration is multiplied by an empirical field correction factor. It takes 26 into account that in every day life factors such as sex, age, sleep, smoking, upper airway 27 infections and allergy, as well as distraction, may increase the odor detection threshold by up to a 28 factor of 4. In addition, it takes into account that odor perception is very fast (about 5 seconds) 29 which leads to the perception of concentration peaks. Based on the current knowledge, a factor 30 of 1/3 is applied to adjust for peak exposure. Adjustment for distraction and peak exposure lead 31
to a correction factor of 4 / 3 = 1.33 32

33 LOA = C x 1.33 = 5.57 ppm x 1.33 = 7.4 ppm 34

35 The LOA for gasoline is 7.4 ppm (approximately 22 mg/m 3 ). 36

37AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 35 of 41

1
APPENDIX C: Derivation of Gasoline AEGLs 2

3
Derivation of AEGL-1 Values 4
5 Key Study: Davis, A., L. Schafer, and Z. Bell. 1960. The effects on human volunteers 6 of exposure to air containing gasoline vapor. Arch. Environ. Health 1:545- 7

554. 8
9 Toxicity endpoint: Slight to subjective and objective eye irritation in human subjects at 2200 10 mg/m 3 for 30 minutes 11
12 Time scaling None; there is adaptation to the slight irritation that defines the AEGL-1 13
14 Uncertainty factors: Interspecies: not applied to human subjects 15 Intraspecies: 3, generally applied to slight to mild sensory irritation studies 16 to protect sensitive individuals; adaptation to irritation was demonstrated 17
18 Calculations: 2200 mg/m 3 /3 = 730 mg/m 3 19
20 10-min AEGL-1: C = 730 mg/m 3 21
22 30-min AEGL-1: C = 730 mg/m 3 23
24 1-h AEGL-1: C = 730 mg/m 3 25
26 4-h AEGL-1: C = 730 mg/m 3 27
28 8-h AEGL-1: C = 730 mg/m 3 29
30

31AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 36 of 41

Derivation of AEGL-2 Values 1
2 Key Study: Schreiner, C., Q. Bui, R. Breglia, D. Burnett, F. Koschier, E. Lapadula, P. 3 Podhasky, and R. White. 2000. Toxic ity evaluations of petroleum blending 4 streams: inhalation subchronic toxicity/neurotoxicity study of a light catalytic 5 reformed naphtha distillate in rats. J. Toxicol. Environ. Health, Part A, 6

60:489-512. 7
8 Toxicity endpoint: No clinical signs in rats at highest chronic exposure, 22,5000 mg/m 3 for 6 9 hours/day, 5 days/week, subchronic 10
11 Time scaling None applied; steady-state in the blood is rapidly approached by 12 hydrocarbon solvents 13
14 Uncertainty factors: Interspecies: 1, rodents ha ve higher blood:air partition coefficients for many 15 chemicals; in addition they have higher respiratory rates and cardiac output 16 resulting in greater chemical uptake than in humans 17 Intraspecies: 3, for hydrocarbon solvents the minimum alveolar concentration 18 at which narcosis occurs differs by no more than two- to threefold among 19

humans. 20
21 Calculations: 22,500 mg/m 3 /3 = 7500 mg/m 3 22
23 10-min AEGL-2: C = 7500 mg/m 3 24
25 30-min AEGL-2: C = 7500 mg/m 3 26
27 1-h AEGL-2: C = 7500 mg/m 3 28
29 4-h AEGL-2: C = 7500 mg/m 3 30
31 8-h AEGL-2: C = 7500 mg/m 3 32
33
34

35
Derivation of AEGL-3 Values 36
37 Not determined. None of the rodent studies reported lethality at the highest concentrations tested. 38 Therefore, AEGL-3 values cannot be determined. Gasoline vapor may act as a simple asphyxiant in 39 sensitive individuals at a concentration of 990,000 mg/m 3

. 40
41
42
43AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 37 of 41

APPENDIX D: Category Graph of AEGL Values and Toxicity Data for Gasoline 1

2

100 1000 10000 100000mg/m3

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 AEGL-1 AEGL-2

3 4

5

Data: 6

For Category: 0 = No effect, 1 = Discomfort, 2 = Disabling, SL = Some Lethality, 3 = Lethal

Source Species mg/m 3 Minutes Category

NAC/AEGL-1 730 10 AEGL

NAC/AEGL-1 730 30 AEGL

NAC/AEGL-1 730 60 AEGL

NAC/AEGL-1 730 240 AEGL

NAC/AEGL-1 730 480 AEGL

NAC/AEGL-2 7500 10 AEGL

NAC/AEGL-2 7500 30 AEGL

NAC/AEGL-2 7500 60 AEGL

NAC/AEGL-2 7500 240 AEGL

NAC/AEGL-2 7500 480 AEGL

NAC/AEGL-3 Not determined 10 AEGL

NAC/AEGL-3 Not determined 30 AEGL

NAC/AEGL-3 Not determined 60 AEGL

NAC/AEGL-3 Not determined 240 AEGL

NAC/AEGL-3 Not determined 480 AEGLAUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 38 of 41

Drinker et al. 1943 Human 420 480 0 (no irritation) Human 450 480 0 (very slight irritation) Human 480 480 0 (slight irritation) Human 810 480 0 (slight irritation) Human 1500 60 0 (slight irritation) Human 2700 60 1 (slight irritation; threshold for unsteadiness) Human 7800 60 1 (slight dizziness) Human 32,100 5 2 (unsteadiness) Human 33,600 5 2 (feeling of incoordination)

Davis et al. 1960 Human 880 30 0 (minor irritation) Human 2200 30 1 (slight eye irritation) Human 4400 30 1 (slight to intermediate eye irritation)

API 2008a Rat 5000 240 0 (no effect) Rat 5200 240 0 (no effect) Rat 5300 240 0 (no effect)

ARCO Chemical Co.

1984 Rat 5200 240 0 (no effect)

Multiple studies:
McKee et al. 2000
Benson et al. 2004 Rat 20,000 360 0 (no effect)

Schreiner et al. 2000 Rat 22,500 360 0 (no effect)

The 360-minute data points (20,000 and 22,500 mg/m 3 ) are repeat-exposure (McKee et al. 2000), chronic exposure (Benson et al. 2004), and subchronic exposure (Schreiner et al. 2000) studies.

1AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 39 of 41

1


### APPENDIX E: Derivation Su mmary for Gasoline AEGLs 2 Acute Exposure Guideline Levels For Gasoline 3 (CAS Reg. No. 86290-81-5) 4

5

AEGL-1 VALUES

10-min 30-min 1-h 4-h 8-hour 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3 730 mg/m 3

Key Reference : Davis, A., L. Schafer, and Z. Bell. 1960. The effects on human volunteers of exposure to air containing gasoline vapor. Arch. Environ. Health 1:545-554. Test Species/Strain/Sex/Number : Human/males/10 Exposure Route/Concentration/Duration : Inhalation/0, 880, 2200, 4400 mg/m 3 for 30 minutes

Effects : Slight subjective and objective eye irritation at 2200 mg/m 3

Endpoint/Concentration/Rationale : Slight subjective and objective eye irritation at 2200 mg/m 3 ) Uncertainty Factors/Rationale : Total uncertainty factor: 3

Interspecies : None, human subjects Intraspecies : 3, generally applied to slight irritation in se nsory irritation studies; adaptation to the irritation Modifying Factor : None Animal to Human Dosimetric Adjustment : Not applicable Time Scaling : None; there is adaptation to the sli ght irritation that defines the AEGL-1. Data Adequacy : The study was well-conducted and reported. Olde r clinical studies reported in several reviews support the derived values.
6 7AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 40 of 41

1

AEGL-2 VALUES

10-min 30-min 1-h 4-h 8-h 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 * 7500 mg/m 3 *
Key Reference : Schreiner, C., Q. Bui, R. Breglia, D. Burnett, F. Koschier, E. Lapadula, P. Podhasky, and R. White. 2000. Toxicity evaluations of petr oleum blending streams: inhalation subchronic toxicity/neurotoxicity study of a light catalytic re formed naphtha distillate in rats. J. Toxicol. Environ. Health, Part A, 60:489-512. Test Species/Strain/Number : Rat/Sprague-Dawley/15/sex/group Exposure Route/Concentration/Duration : Inhalation/0, 2250, 7500, 22,500 mg/m 3 /6 hours/day, 5 days/week,
for 13 weeks

Effects : No clinical signs of lethargy Endpoint/Concentration/Rationale : Although no lethargy/narcosis was observed, 22,500 mg/m 3 was the highest exposure in any study Uncertainty Factors/Rationale : Total uncertainty factor : 3

Interspecies: 1, for many hydrocarbons, rodents have higher blood:air partition coefficients; in addition they have higher respiratory rates and cardiac output resulting in greater chemical uptake than in humans Intraspecies : 3, for hydrocarbon solvents the minimum alveol ar concentration at which narcosis occurs differs by no more than two- to threefold among humans. Modifying Factor : None applied Animal to Human Dosimetric Adjustment : Not applicable Time Scaling : None; Data Adequacy : The data base for gasoline is rich with studies at similar concentrations (20,000 mg/m 3 ) and using different blending streams addressing general t oxicity, neurotoxicity, reproductive and developmental toxicity and chronic toxicity/carcinogenicity.
*The AEGL-2 value is higher than 1/10 of the lower e xplosive limit (LEL) of gasoline in air (LEL = 14,000 ppm). 2 Therefore, safety considerations against h azard of explosion must be taken into account. 3 4 5AUTOMOTIVE GASOLINE NAC Proposed 1: October 2009/ Page 41 of 41

1

AEGL-3 VALUES

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

Not determined Not determined Not determined Not determined Not determined
Key References: Test Species/Strain/Number : Exposure Route/Concentration/Duration:

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

Interspecies: Intraspecies : : Modifying Factor : Animal to Human Dosimetric Adjustment : Time Scaling : Data Adequacy: No studies were available that reported the threshold for lethality

2