OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

 UNEP PUBLICATIONS 1

 FOREWORD INTRODUCTION

1,1-DIFLUOROETHANE (HFC-152a)

 CAS N°: 75-37-6
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

 UNEP PUBLICATIONS 2 

SIDS Initial Assessment Report 

For 

SIAM 22 

Paris, France, 18-21 April 2006 

1. Chemical Name: 1,1-Difluoroethane (HFC-152a) 

2. CAS Number: 75-37-6 

3. Sponsor Country: Republic of Korea 

Contact Point: 

Hyun-Mi KIM, Ph. D. 

National Institute of Environmental Research (NIER). 

Kyongseodong, Seogu, Incheon, 404-708, Korea 

Tel: +82-(0)32-560-7216 

FAX: +82-(0)32-560-7256 

4. Shared Partnership with: 

5. Roles/Responsibilities of 

the Partners: 

 

• Name of industry sponsor 

/consortium 

DuPont 

• Process used Industry collected data and prepared the draft versions of the 

IUCLID dossier, SIAR, and SIAP. 

6. Sponsorship History 

• How was the chemical or 

category brought into the 

OECD HPV Chemicals 

Programme? 

This substance is sponsored by Korea under the ICCA Initiative 

and is submitted for the first discussion at SIAM 22. 

7. Review Process Prior to 

the SIAM: 

NIER, Korea reviewed the documents and added the use volume 

and exposure information. 

8. Quality check process: The quality of the existing data was reviewed against the OECD 

criteria as described in the Manual for Investigation of HPV 

Chemicals. 

9. Date of Submission: 20 January, 2006 

10. Date of last Update: 29 June 2006 

11. Comments: 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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SIDS INITIAL ASSESSMENT PROFILE

CAS No. 75-37-6 

Chemical Name 1,1-Difluoroethane (HFC-152a) 

Structural Formula F2 – HC – CH3

SUMMARY CONCLUSIONS OF THE SIAR 

Human Health 

No toxicokinetic data for HFC-152a were found. 

HFC-152a has low acute inhalation toxicity, with a 4-hour rat approximate lethal concentration (ALC) of 383,000 

ppm. No valid acute oral toxicity studies are available. Although no standard test results are available, the repeat 

dose studies show some potential for irritation. 

As with most HFCs, HFC-152a has the potential to produce cardiac sensitization in dogs challenged 

simultaneously with high exposure concentrations and high doses of exogenous epinephrine. Marked responses, 

which included a cardiac arrhythmia were observed in 3 of 12 dogs at 150,000 ppm. No response was observed 

at 50,000 ppm. No sensitization studies were available. 

HFC-152a has low repeated dose toxicity. HFC-152a had anesthetic properties at a 100,000 ppm exposure level 

during a 2-week repeated dose inhalation study in rats. No other clinical, haematological, blood chemistry or 

histopathology effects were observed during the 2-week inhalation study. No adverse effects were observed in 

rats following a 3-month inhalation exposure to 25,000 ppm HFC-152a. 

HFC-152a was not mutagenic in the in vitro bacterial reverse mutation test (Ames test) in Salmonella 

typhimurium and Escherichia coli strains. However, HFC-152a showed evidence of weak clastogenicity in an in 

vitro human lymphocyte chromosome aberration test. Further evaluation of the chromosome aberration potential 

using an in vivo micronucleus test produced negative results. 

In a 2-year bioassay, HFC-152a was not carcinogenic to rats at inhalation exposure levels up to 25,000 ppm. 

In a developmental study, female rats were exposed via inhalation up to 50,000 ppm during days 6 to 15 of 

pregnancy for 6 hours per day. No compound related maternal and developmental effects were observed at any 

of the concentrations tested, hence, the NOEL is 50,000 ppm. No histopathological or weight effects on 

reproductive organs were observed in male and female rats exposed up to 25,000 ppm HFC-152a for 6 hours per 

day, 5 days per week for 3, 12 or 24 months. 

Environment 

On the basis of its physical properties HFC-152a may be expected, when released to the environment, to 

partition almost exclusively into the atmosphere as it is a gas, with a vapor pressure at 25o

C of 6065.2 hPa, and it 

has a water solubility of 2.671 g/l at 25o

C. Any HFC-152a, which might be present in aqueous waste streams 

discharged directly into rivers or lakes would be expected, by analogy with similar compounds, to have a halflife with respect to volatilization of days or at the very most a few weeks. HFC-152a is expected to exist solely 

in the vapor-phase in the ambient atmosphere. 

Vapor-phase HFC-152a is degraded in the atmosphere by reaction with photochemically-produced hydroxyl 

radicals with a lifetime of 1.4 years. The atmospheric lifetime of this chemical suggests that it will mix 

throughout the troposphere with a globally averaged concentration in 2003 of about 2.6 ppt. Because of its IR 

absorption, it will contribute a very small amount to climate change with a global warming potential (GWP) 

relative to CO2 of 140 for a time horizon of 100 years. 

In addition, some HFC-152a is expected to gradually diffuse into the stratosphere above the ozone layer where it 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

 UNEP PUBLICATIONS 4 

will slowly degrade due to reaction with hydroxyl radicals and direct photolysis from UV-C radiation. The 

ozone depletion potential (ODP) of HFC-152a has been determined to be negligible. 

HFC-152a is not expected to adsorb to sediment or particulate matter. Bioconcentration is expected to be low 

based on an estimated BCF value of approximately 2 using the measured n-octanol/water partition coefficient 

(log value is 0.75). A Mackay Level III fugacity model (EPIWIN v.3.05) predicts that HFC-152a will partition 

mainly to the air (99.9%), with very little going to water (0.111%), and virtually none going to soil or sediment 

(0.01 and <0.01%, respectively). 

Based on the ECOSAR predictions (96-hour LC50 in fish of 733 mg/L 48-hour EC50 in daphnids of 720 mg/L, 

and 96-hour EC50 in algae of 419 mg/L), actual toxicity test data for the analog chemical HFC-134a (96-hour 

LC50 in fish of 450 mg/L and 48-hour EC50 in daphnids of 980 mg/L), and the high Henry’s Law Constant for 

these compounds (0.02 atm-m3/mole for HFC-152a), the predicted toxicity of HFC-152a to aquatic organisms is 

low. 

Exposure 

The primary uses for HFC-152a are as an aerosol propellant and a foam expansion agent. Other potential uses 

include refrigeration blends and catalyst regeneration. Production capacities are confidential, but are in excess of 

5000 metric tonnes per year. In Korea, it is also used in maintaining of a catalytic activity and estimated usage 

volume of 1,1-difluoroethane was 4.63, 4.85, and 3.14 tonnes/year in 2003, 2004, and 2005, respectively. 

Emissions from HFC-152a manufacturing facilities are small. In the sponsor country, small amounts of HFC152a are used in a closed system. HFC-152a is treated with steam and emitted to wastewater plant. Fluorine is 

below the detection limit (1 mg/L) in discharged water. There are no reported natural sources of HFC-152a. 

HFC-152a used in propellant and foaming applications will be emitted to the atmosphere. 

Industrial hygiene monitoring data during manufacture and industrial use show exposure to be well under 

acceptable exposure limits. The current AIHA WEEL (Workplace Environmental Exposure Limit) and DuPont 

AEL (Acceptable Exposure Limit) are 1000 ppm, 8-hour TWA (time-weighted average). Though consumer 

exposure has not been measured directly, modeling based on measurement of similar uses shows consumer 

exposure to be minimal during intended uses. 

RECOMMENDATION AND RATIONALE FOR THE RECOMMENDATION AND NATURE OF 

FURTHER WORK RECOMMENDED 

The chemical is currently of low priority for further work, due to its low hazard profile. Its global warming 

potential is acknowledged and is being addressed by other programs. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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SIDS Initial Assessment Report 

1 IDENTITY 

1.1 Identification of the Substance 

CAS Number: 75-37-6 

IUPAC Name: 1,1-Difluoroethane 

Molecular Formula: C2H4F2

Structural Formula: F2 – HC – CH3

Molecular Weight: 66.1 

Synonyms: Ethane, 1,1-difluoroHFC-152a (name to be used throughout dossier) 

Freon 152a 

Ethylidene fluoride 

Genetron 152a 

Algofrene 67 

Dymel 152 

Dymel 152a 

F152A 

FC152a 

FKW 152a 

HFA 152a 

R 152a 

Ethylene fluoride 

Ethylidene difluoride 

Genetron 100 (CHEMLIST, 1999; HSDB; 2000). 

Since solubility and physical characteristics are similar, data for analogous chemicals, 1,1,1,2,2-

pentafluoroethane (HFC-125) and 1,1,1,2-tetrafluoroethane (HFC-134a), are used where data are 

lacking for 1,1-difluoroethane (HFC-152a) (DuPont, 2002a; 2003). 

1.2 Purity/Impurities/Additives 

Purity: > 99.9 % 

Impurities/Additives: Typical impurities in HFC-152a include low level (ppm) water, low level 

(ppb) residual HCl and/or HF acids (DuPont Co., 2006). 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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1.3 Physico-Chemical Properties 

Table 1 Summary of Physico-Chemical Properties 

Property Value 

Physical state Gas 

Melting point -117 °C Lewis, 1993 

Boiling point -24.7 °C Lewis, 1993 

Density 0.91 g/mL @ 21 °C Kirk-Othmer, 1991 

Vapour pressure 4,550 mmHg (6,065.2 hPa) @ 25 °C Daubert and Danner, 1989a 

Water solubility (calculated) 2.671 g/L @ 25 °C Meylan and Howard, 1996 

Partition coefficient n-octanol/water 

(log value) (measured) 0.75 Jow and Hansch, n.d. 

Henry’s law constant (calculated) 0.02 atm-m3

/mole 

(2,026.5 Pa-m3

/mole) 

Daubert and Danner, 1989b 

Ruelle and Kesselring, 1997 

SRC, n.d. 

Flammability limits 3.7 % - 18 % (in air) Sax and Lewis, 1987 

2 GENERAL INFORMATION ON EXPOSURE 

2.1 Production Volumes and Use Pattern 

HFC-152a is produced in a closed system by catalytic reaction of vinyl chloride with hydrofluoric 

acid and is purified based on market specification. Production capacities are confidential, but are in 

excess of 5,000 metric tonne (10 million pounds) per year. In Korea, estimated usage volume of 

1,1-difluoroethane was 4.63, 4.85, and 3.14 tonnes/year in 2003, 2004, and 2005, respectively 

(NIER, 2005). 

Approximately 80 % of HFC-152a is used as an aerosol propellant and approximately 15 % is used 

as a foam expansion agent. The remaining 5 % of the HFC-152a is for other potential uses, which 

include refrigeration blends and catalyst regeneration. In Korea, it is also used in maintaining of a 

catalytic activity (NIER, 2005). 

Because of its low vapor pressure, HFC-152a is handled as a liquefied gas during manufacture and 

shipping. Therefore, HFC-152a is handled in closed pressurize systems so that exposure typically 

does not occur in the manufacturing, except for during maintenance or an abnormal process 

situation, such as a leak (DuPont, 2004). 

HFC-152a is used in aerosol consumer personal care and household products and is dispensed with 

the product during use. Typically there is no HFC-152a left in the container when it is disposed 

(DuPont, n.d.). 

HFC-152a used to manufacture foam is contained within the foam, and remains in the foam for a 

long period of time. The HFC-152a will be disposed with the foam (DuPont, 2002b). 

HFC-152a used in refrigerants is contained in the refrigeration system until such time as it is 

collected for recycle or disposal (DuPont, 2005). 
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2.2 Environmental Exposure and Fate 

On the basis of its physical properties, HFC-152a may be expected, when released to the 

environment, to partition almost exclusively into the atmosphere as: 

• it is a gas, with a vapour pressure at 25 °C of 4,550 mmHg. 

• it has a limited water solubility of 2.7 g/L at 25 °C. 

Any HFC-152a that might be present in aqueous waste streams discharged directly into rivers or 

lakes would be expected, by analogy with similar compounds, to have a half-life with respect to 

volatilisation of days or at the very most a few weeks. In the sponsor country, small amounts of 

HFC-152a are used in a closed system. HFC-152a is treated with steam and emitted to wastewater 

plant. Fluorine is below the detection limit in discharged water (NIER, 2005). 

2.2.1 Sources of Environmental Exposure 

There are no reported natural sources of HFC-152a. HFC-152a used in propellant and foaming 

applications will be emitted to the atmosphere. 

2.2.2 Photodegradation 

1,1-Difluoroethane (HFC-152a) is expected to exist solely in the vapor-phase in the ambient 

atmosphere. Vapor-phase HFC-152a is degraded in the atmosphere by reaction with 

photochemically-produced hydroxyl radicals with an atmospheric lifetime of 1.4 years. The 

atmospheric lifetime of this chemical suggests that some HFC-152a is expected to gradually diffuse 

into the stratosphere above the ozone layer where it will degrade due to direct photolysis from UVC radiation (Nimitz and Skaggs, 1992; SRC, n.d.). 

The molecular breakdown to give CO, CO2, H2O, and C(O)F2 proceeds via various free-radical 

intermediates. C(O)F2 is incorporated into rain, cloud, or fog water and is hydrolyzed to form HF 

and CO2 (AFEAS, 1989). 

2.2.3 Stability in Water 

HFC-152a is predicted to be stable in water under environmentally relevant conditions, and 

hydrolysis is not expected to occur, as indicated by HydroWin calculations. 

2.2.4 Transport between Environmental Compartments 

Mackay Level III fugacity model (EPIWIN v.3.05) predicts that HFC-152a will partition mainly to 

the air (99.9 %), with very little going to water (0.111 %), and virtually none going to soil or 

sediment (0.01 and < 0.01 %, respectively). The following input parameters were used: Molecular 

Weight: 66.05; Henry’s Law Constant: 0.0203 atm-m3

/mole; Vapor Pressure: 3.86 x 103; log Kow: 

0.75; Soil Koc: 2.31. 

If released to water, HFC-152a is not expected to adsorb to sediment or particulate matter based 

upon the estimated Koc of 60 (SRC, n.d.). HFC-152a is expected to volatilize rapidly from water 

surfaces based upon this compound’s estimated Henry’s Law constant. Estimated half-lives for a 

model river and model lake are 2 and 77 hours, respectively (Lyman et al., 1990; SRC, n.d.). 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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2.2.5 Biodegradation 

Modeling of several physical-chemical parameters and fate processes (Table 2) was conducted to 

help provide insight into the behavior in the environment of a homologous series of 4 fluorocarbon 

compounds (HFC-152a, HFC-134a, and HFC-125). 

Syracuse Research Corporation models for estimating physical-chemical properties and fate 

processes were used to estimate log10 Kow (Meylan and Howard, 1995), water solubility at 25  ̊C 

(Meylan and Howard, 1996), Henry’s Law Constant (Meylan and Howard, 1991), and ultimate 

biodegradation (Boethling et al., 1994). The dominant fate process controlling distribution of these 

compounds in the environment is volatilisation (Mackay et al., 1996). 

Table 2 Environmental Fate Parameters 

Compound log10 Kow 

(Estimated) 

Water Solubility 

(Estimated) 

Henry’s Law 

Constant 

(Estimated) 

Ultimate 

Degradation 

(Estimated) 

HFC-152a 

(1,1-Difluoroethane) 

 (C2H4F2) 

1.13 2,671 mg/L 0.38 atm-m3

/mole Weeks 

HFC-134a 

(1,1,1,2-Tetrafluoroethane) 

 (C2H2F4) 

1.68 768 mg/L 1.5 atm-m3

/mole Weeks-months 

 HFC-125 

(1,1,1,2,2-Pentafluoroethane) 

 (C2HF5) 

1.55 867 mg/L 3.1 atm-m3

/mole Weeks-months 

Highly chlorinated/fluorinated compounds are not expected to biodegrade rapidly (Boethling et al., 

1994). Based on the expected lack of sorption to soil, sediment, or particulate matter from fugacity 

modeling and its high vapour pressure, biodegradation is not expected to be an important 

environmental fate process for HFC-152a (HSDB, 2000). In addition, biodegradation testing with 

similar compounds, e.g. difluoromethane (HFC-32), which was degraded 8 % after 28 days, and 

1,1,1,2-tetrafluoroethane (HFC-134a), which was degraded 4 % after 28 days, has indicated that 

these types of compounds are not readily biodegradable (Tobeta 1989; 1992). 

2.2.6 Bioaccumulation 

Bioconcentration is expected to be low based upon an estimated BCF value of 2 (SRC, n.d.). 

2.2.7 Other Information on Environmental Fate 

Due to the absence of chlorine and bromine atoms in the molecule, and the ozone depletion 

potential of other hydrofluorocarbons (HFC’s), the contribution of HFC-152a to atmospheric ozone 

depletion can be considered negligible. 

Global Warming potential (GWP) values of 410, 120, and 37 relative to carbon dioxide (GWP = 1) 

were calculated for integration time horizons of 20, 100, and 500 years, respectively (IPCC TAR, 

2001). An official value of 140 was adopted by the Kyoto Protocol (IPCC AAR, 1996) for at time 

horizon of 100 years, indicating a potential contribution to global warming. 
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The Advanced Global Atmospheric Gasses Experiment observed the tropospheric abundance of 

HFC-152a to be 2.6 ppt in 2003 (IPCC/TEAP, 2005). 

2.3 Human Exposure 

HFC-152a is a gas at room temperature. Therefore, the main route of human exposure is via 

inhalation. On the basis of its physico-chemical properties, if released into the environment HFC152a will partition mostly into the atmosphere. 

2.3.1 Occupational Exposure 

Emissions from DuPont HFC-152a manufacturing facilities are small and industrial hygiene 

monitoring data during manufacture and industrial use show exposure to be well under acceptable 

exposure limits. In the sponsor country, HFC-152a is handled in a closed system. Workers typically 

do not have a potential exposure to HFC-152a except for during maintenance or a leak. No 

industrial hygiene monitoring data were available (NIER, 2005). 

The current AIHA WEEL (Workplace Environmental Exposure Limit) and DuPont AEL 

(Acceptable Exposure Limit) are 1000 ppm, 8-hour TWA (time-weighted average) (AIHA, 1994; 

DuPont Co., 1998). 

2.3.2 Consumer Exposure 

HFC-152a consumer exposures have been modeled based on similar use scenarios. The predicted 

aggregate exposure of the general public while using key products is minimal (DuPont, 2001a). 

3 HUMAN HEALTH HAZARDS 

3.1 Effects on Human Health 

3.1.1 Toxicokinetics, Metabolism and Distribution 

No kinetic, metabolism, and distribution studies in animals or humans were identified. 

3.1.2 Acute Toxicity 

Studies in Animals

Inhalation 

The 4-hour inhalation ALC (approximate lethal concentration) in male rats was 383,000 ppm. 

Labored breathing, lethargy, and unresponsiveness to sound were observed during exposure, but no 

clinical signs were noted following exposure. No compound-related gross pathology changes were 

observed (DuPont Co., 1975). Acute inhalation studies are summarized in Table 3: 
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Table 3 Acute Inhalation Studies in Animals 

Species Duration of 

Exposure 

Concentration 

(ppm) 

Effect Reference 

Rat (ChR-CD®) 4 hours 66,400 

175,200 

319,000 

383,000 

437,500 

ALC = 383,000 ppm DuPont Co., 1975 

Rat (strain not 

reported) 

30 minutes 100,000 - 550,000 No postural reflex (200,000 ppm); 

no righting reflex (250,000 ppm); 

no corneal reflex (450,000 ppm); 

acute irritation of lungs 

(≥400,000 ppm); lethality 

(≥500,000 ppm) 

Lester and 

Greenberg, 1950 

Rat (strain not 

reported) 

2 hours 74,000 

100,000 

200,000 

Occasional trembling and 

incoordination 

DuPont Co., 1951 

Rat (ChR-CD) 15 minutes 1100 °C 

1200 °C 

1300 °C 

(pyrolysis products) 

Ptosis (≥1100 °C); apnea(≥1100 

°C); pale ears (≥1100 °C); 

hyperemia (≥1100 °C); dyspnea 

(≥1100 °C); irregular respiration 

(≥1100 °C); lacrimation (≥1100 

°C); chromodacryorrhea (≥1100 

°C); salivation (≥1100 °C); gasping 

(1300 °C); convulsions (1300°C) 

DuPont Co., 1966 

Dog (Beagle) Not Reported 500,000 Light surgical anesthesia; no change 

in EKG 

Van Poznak and 

Artusio (1960). 

Dermal 

No acute dermal studies in animals were identified. 

Oral 

There was no reliable acute oral study. 

Other Available Data

Cardiotoxicity studies in rats and dogs performed at levels up to 40 % HFC-152a showed varying 

effects listed in Table 4 below (Simaan and Aviado, 1975; Aviado and Belej, 1975). Male beagle 

dogs were exposed to 50,000 or 150,000 ppm HFC-152a in a cardiac sensitisation study. Marked 

responses, which included a cardiac arrhythmia that was considered to pose a serious threat to life, 

were observed in 3 of 12 dogs at 150,000 ppm. No response was observed at 50,000 ppm (DuPont 

Co., 1969; Reinhardt et al., 1971). 
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Table 4 Cardiotoxicity Studies in Animals 

Species Concentration (ppm) Effect Reference 

Dog (Mongrel) 200,000 Decrease in mean 

pulmonary arterial flow 

Simaan and Aviado, 1975 

Dog (strain not reported) 25,000 - 200,000 Depression of force of 

contraction (≥ 100,000 

ppm); displacement of 

ventricular function curve 

(≥100,000 ppm) 

Aviado and Belej, 1975 

Studies in Humans

Inhalation 

No reliable inhalation studies in humans were identified. 

Dermal 

No dermal studies in humans were identified. 

Oral 

No oral studies in humans were identified. 

Other Routes of Exposure 

No additional studies were identified. 

Conclusion

Although there is no standard studies available, information from a limited study indicates that 

HFC-152a is of low acute oral toxicity. HFC-152a has low acute inhalation toxicity, with a 4-hour 

rat ALC of 383,000 ppm. As with most HFCs, HFC-152a has the potential to produce cardiac 

sensitisation in dogs challenged simultaneously with high exposure concentrations (150,000 ppm) 

and high doses of exogenous epinephrine. 

3.1.3 Irritation 

In an acute-inhalation study in rats, there was considerable effusion of fluid from the respiratory 

tract, indicative of acute irritation of the lungs, at concentrations ≥ 400,000 ppm. When exposed at 

100,000 ppm for 16 hours/day for 2 months, a mild diffuse infiltration of round cells (suggestive of 

mild chronic irritation) was the only finding noted (Lester and Greenberg, 1950). In a 2-year 

carcinogenicity study, nasal discharge in rats was reported (DuPont Co., 1982; 1992), suggesting 

that chronic low level nasal irritation occurred. 

3.1.4 Sensitisation 

No skin or respiratory tract sensitisation studies in animals or humans were identified. 
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3.1.5 Repeated Dose Toxicity 

Studies in Animals

Inhalation 

ChR-CD rats exposed to 100,000 ppm HFC-152a for 6 hours/day, 5 days/week for 2 weeks 

appeared to be anesthetized during exposure. Although there was a slight increase in urinary 

fluoride following the last exposure, no other effects were observed in clinical, haematological, 

blood chemistry, or histopathology endpoints (DuPont Co., 1976). When exposed at 100,000 ppm 

for 16 hours/day for 2 months, a mild diffuse infiltration of round cells in the lung (suggestive of 

mild chronic irritation) was the only finding noted (Lester and Greenberg, 1950). During a 2-year 

inhalation study in Crl:CD®Br rats, no adverse effects were observed at the 3-month interim 

evaluation point. The NOAEL was 25,000 ppm (67,500 mg/m3

) (DuPont Co., 1982; 1992). 

Additional results of the 2-year inhalation study are detailed in section 3.1.7 Carcinogenicity – in 

vivo studies in animals. 

Dermal 

No dermal repeated dose studies in animals were identified. 

Oral 

No oral repeated dose studies in animals were identified. 

Studies in Humans

No repeated dose inhalation, dermal, or oral studies in humans were identified. 

Conclusion

HFC-152a has low repeated dose toxicity. Indications of respiratory tract irritation were observed 

acutely at concentrations ≥ 400,000 ppm and after repeated concentrations of 100,000 ppm. 

HFC-152a had anaesthetic properties at a 100,000-ppm exposure level during a 2-week repeated 

dose inhalation study in rats. No other clinical, haematological, blood chemistry, or histopathology 

effects were observed. No adverse effects were observed in rats following a 3-month inhalation 

exposure to 25,000 ppm HFC-152a. 

3.1.6 Mutagenicity 

Studies in Animals

In vitro Studies 

HFC-152a was not mutagenic in the in vitro bacterial reverse mutation test (Ames test), following 

OECD Guideline 471, in Salmonella typhimurium and Escherichia coli strains, when tested with or 

without metabolic activation (DuPont Co., 2000a). 

In vivo Studies 

HFC-152a was negative in a rat in vivo micronucleus assay following OECD Guideline 474 

(DuPont Co., 2001b), but was positive in the Drosophila SLRL test (Garrett and Fuerst, 1974). 
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Studies in Humans

HFC-152a showed evidence of weak clastogenicity, only in the absence of metabolic activation, in 

an in vitro human lymphocyte chromosome aberration test following OECD Guideline 473 

(DuPont, 2000b). 

Conclusion

HFC-152a was not mutagenic in the in vitro bacterial reverse mutation test (Ames test) in 

Salmonella typhimurium and Escherichia coli strains. However, HFC-152a showed evidence of 

weak clastogenicity in an in vitro human lymphocyte chromosome aberration test. Further 

evaluation of the chromosome aberration potential using an in vivo micronucleus test produced 

negative results. 

3.1.7 Carcinogenicity 

In vitro Studies

No in vitro carcinogenicity studies were identified. 

In vivo Studies in Animals

Inhalation 

Male and female rats were exposed to 0, 2,000, 10,000, or 25,000 ppm HFC-152a for 6 hours per 

day, 5 days per week for 2 years. During the course of the study, no differences in body weights or 

body weight gains were observed. Clinical signs observed included ocular/nasal discharge, 

wet/stained perinea, stained body/face, and/or swollen ears. 

Clinical chemistry effects noted throughout the study included increased mean corpuscular 

volumes, increased serum bilirubin, increased hematocrits, and/or increased urobilinogin. In the 

absence of any abnormalities in hematopoietic tissues or red blood cells or changes in serum 

bilirubin, these observations, which would be consistent with a haemolytic effect, provide 

inconclusive evidence of such a condition. A decrease in eosinophils and/or monocytes was 

observed. A dose-dependent increase in urinary fluoride concentration, but no fluorosis was 

observed. An increase in serum creatinine and urine volume, and a decrease in urine osmolality 

were observed in female rats. 

At the end of the 2-year study, no treatment-related differences in organ weights were observed in 

male rats, but significant organ weight changes were observed in female rats at all concentrations 

with unclear biological significance. No treatment-related tumors were observed in male and female 

rats. Therefore, HFC-152a was not carcinogenic and did not produce life-shortening toxic effects 

(DuPont Co., 1982; 1992). 

Dermal 

No dermal carcinogenicity studies in animals were identified. 

Oral 

No oral carcinogenicity studies in animals were identified. 

Studies in Humans

No carcinogenicity studies in humans were identified. 
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Conclusion

HFC-152a was not carcinogenic to rats. 

3.1.8 Toxicity for Reproduction 

Studies in Animals

Effects on Fertility 

Although no specific reproduction studies have been performed with HFC-152a, histopathology of 

reproductive organs was examined in a 2-year chronic and carcinogenicity study. No 

histopathological or weight effects on reproductive organs were observed in male and female rats 

exposed to HFC-152a via inhalation for 6 hours per day, 5 days per week for 2 years. The NOAEL 

was 25,000 ppm (DuPont Co., 1982). 

Developmental Toxicity 

Pregnant female rats were exposed to 0, 5,000, or 50,000 ppm HFC-152a for 6 hours per day on 

gestation days 6 - 15. No maternal or developmental toxicity was observed. The NOEL for maternal 

and developmental toxicity was 50,000 ppm, the highest level tested (DuPont Co., 1979). 

Studies in Humans

Effects on Fertility 

No reproduction studies in humans were identified. 

Developmental Toxicity 

No developmental toxicity studies in humans were identified. 

Conclusion

HFC-152a was not a developmental toxin in rats. No histopathological or weight effects on 

reproductive organs were observed in male and female rats exposed to HFC-152a for 6 hours per 

day, 5 days per week for 2 years. 

3.2 Initial Assessment for Human Health 

HFC-152a has a very low potential for producing adverse health effects in workers or the general 

population. HFC-152a has low acute inhalation toxicity, with a rat 4-hour approximate lethal 

concentration of 383,000 ppm. Male beagle dogs treated with exogenous epinephrine were exposed 

to 50,000 or 150,000 ppm HFC-152a in a cardiac sensitisation study. Marked responses, which 

included a cardiac arrhythmia, were observed in 3 of 12 dogs at 150,000 ppm. No response was 

observed at 50,000 ppm. Although significant organ weight changes were observed at all 

concentrations tested after 90 days of exposure, the biological significance is unclear. The NOAEL 

for developmental toxicity was 50,000 ppm (the highest dose tested), and no adverse effects on 

reproductive organ weight were observed following 3 months of exposure to 25,000 ppm. HFC152a was not mutagenic in the in vitro bacterial reverse mutation test (Ames test) in Salmonella 

typhimurium and Escherichia coli strains. However, HFC-152a showed evidence of weak 

clastogenicity in an in vitro human lymphocyte chromosome aberration test. Further evaluation of 

the chromosome aberration potential using an in vivo micronucleus test produced negative results. 

As no significant increase in tumors were observed, HFC-152a was not carcinogenic and did not 

produce life-shortening toxic effects at doses ranging from 2,000 to 25,000 ppm. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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4 HAZARDS TO THE ENVIRONMENT 

4.1 Aquatic Effects 

Acute Toxicity Test Results

No ecotoxicological studies have been conducted with HFC-152a and there is very little or no 

ecotoxicology data for similar non-chlorinated, fluorocarbon compounds. The related compounds 

HFC-134a (1,1,1,2-tetrafluoroethane) and HFC-125 (1,1,1,2,2-pentafluoroethane) have been 

included here for comparison with HFC-152a as they are both fluorinated ethane substances, and 

test data for HFC134a are available. ECOSAR was used to predict the aquatic toxicity of these 

fluorocarbons to green algae, daphnids (planktonic freshwater crustaceans), and fish (Table 5). 

ECOSAR predictions are based on actual toxicity test data for classes of compounds with similar 

modes of action, i.e., narcosis in the case of fluorocarbons. Predicted log10 Kow values were used as 

input for the ECOSAR model. To help gauge the sensitivity of the prediction to this parameter, 

ECOSAR predictions were made using 2 Kow values. The initial Kow value was based on the 

estimated value from the Syracuse Research Corporation model except for the measured value of 

0.75 for HFC-152a (Jow and Hansch, n.d.). The second Kow value was empirically selected to be 

approximately log10 0.5 greater than the initial measured or estimated value. 

Table 5 Aquatic Toxicity Values 

Compound log10 Kow 

(Estimated) 

Algae, 96-hr 

EC50 (Estimated) 

(mg/L) 

Daphnid, 48-hr 

EC50 (Estimated) 

(mg/L) 

Fish, 96-hr LC50 

(Estimated) 

(mg/L) 

HFC-152a 

(1,1-Difluoroethane) 

 (C2H4F2) 

0.75* 

1.5 

419 

91 

720 

150 

733 

145 

HFC-134a 

(1,1,1,2-Tetrafluoroethane) 

 (C2H2F4) 

1.5 

2.0 

140 

51 

231 

81 

223 

76 

HFC-125 

(1,1,1,2,2-Pentafluoroethane) 

 (C2HF5) 

1.5 

2.0 

165 

60 

272 

95 

263 

89 

* measured value 

The only test data available are for HFC-134a. Results of aquatic testing of HFC-134a with 

daphnids and fish indicated that the daphnid 48-hour EC50 was 980 mg/L and the 96-hour fish LC50

was 450 mg/L (Stewart and Thompson, 1991; Thompson, 1991). The lower measured log Kow of 

0.75 would lead to estimated toxicity values that would be even closer to the actual data. Based on 

the ECOSAR predictions, the actual toxicity test data, and the high Henry’s Law Constant for these 

compounds, HFC-152a is considered a low hazard to aquatic organisms. 

Chronic Toxicity Test Results

No chronic toxicity studies were identified. 

Toxicity to Microorganisms

No toxicity studies to microorganisms were identified. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

 UNEP PUBLICATIONS 16

4.2 Terrestrial Effects 

Acute Toxicity Test Results

No acute toxicity studies were identified. 

Chronic Toxicity Test Results

No chronic toxicity studies were identified. 

4.3 Other Environmental Effects 

No additional data were identified. 

4.4 Initial Assessment for the Environment 

HFC-152a is expected to exist solely in the vapour-phase in the ambient atmosphere. Vapour-phase 

HFC-152a is degraded in the atmosphere by reaction with photochemically-produced hydroxyl 

radicals with an atmospheric half-life of about 472 days. The long atmospheric lifetime of this 

chemical suggests that some HFC-152a is expected to gradually diffuse into the stratosphere above 

the ozone layer, where it will slowly degrade due to direct photolysis from UV-C radiation (Nimitz 

and Skaggs, 1992; SRC, n.d.). HFC-152a is not expected to adsorb to sediment or particulate 

matter. Bioconcentration is expected to be low based on an estimated BCF value of approximately 

2. The predicted toxicity of HFC-152a to aquatic organisms is low. 

5 RECOMMENDATIONS 

The chemical is currently of low priority for further work, due to its low hazard profile. Its global 

warming potential is acknowledged and is being addressed by other programmes. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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6 REFERENCES 

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Chemicals Data Compilation, Amer. Inst. Chem. Eng., Hemisphere Pub. Corp., New York 

(HSDB/5205). 

DuPont (n.d.). Technical Information Bulletin, DuPont Dymel® 152a. 

DuPont Co. (1951). Unpublished Data, Haskell Laboratory Report No. 2 - 52, “Inhalation Toxicity 

Studies of Various Freon Compounds” (December 26). 

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Products” (November 2). 

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Sensitization” (November 7). 

DuPont Co. (1975). Unpublished Data, Haskell Laboratory Report No. 699 - 75, “Acute Inhalation 

Toxicity” (November 18). 

DuPont Co. (1976). Unpublished Data, Haskell Laboratory Report No. 158 - 76, “Subacute 

Two-Week Inhalation Toxicity” (March 2). 

DuPont Co. (1979). Unpublished Data, Haskell Laboratory Report No. 437 - 79, “Embryotoxicity 

and Teratogenicity Studies in Rats with HFC-152a” (March 10). 

DuPont Co. (1982). Unpublished Data, Haskell Laboratory Report No. 8 - 82, “Two-Year 

Inhalation Study with HFC-152a in Rats” (November 30) (also cited in TSCA Fiche OTS0520846). 

DuPont Co. (1990). Unpublished Data, Haskell Laboratory Report No. 524 - 90, “Approximate 

Lethal Dose (ALD) of HFC-152a in Rats” (September 26) (also cited in TSCA fiche OTS0530083). 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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DuPont Co. (1992). Pathology Associates Inc., “Pathology Peer Review of a Two-Year Inhalation 

Study of HFC-152a in CD Rats” (May 19). 

DuPont Co. (1998). Material Safety Data Sheet No. DU001260 (November 4). 

DuPont Co. (2000a). Unpublished Data, Haskell Laboratory Report No. DuPont-4032, “Bacterial 

Reverse Mutation Test: Plate Incorporation Assay with a Gas” (September 15). 

DuPont Co. (2000b). Unpublished Data, Haskell Laboratory Report No. DuPont-4016, “In vitro

Mammalian Chromosome Aberration Test in Human Lymphocytes” (August 25). 

DuPont Co. (2001a). Initial Human Health and Environmental Screening Assessment for Dimethyl 

Ether (DME) Technical Summary (revised August 29). 

DuPont Co. (2001b). Unpublished Data, Haskell Laboratory Report No. DuPont-5426, “Rat 

Micronucleus Test” (May 18). 

DuPont Co. (2002a). Material Safety Data Sheet 2187FR, SUVA 134a (November 4). 

DuPont Co. (2002b). DuPont Product Literature, DuPont Formacel® Z-2. 

DuPont Co. (2003). Material Safety Data Sheet 6016FR, HFC-125 Sterilant (March 10). 

DuPont Co. (2004). Material Safety Data Sheet 3024FR, Formacel Z-2 Blowing Agent (September 

15). 

DuPont Co. (2005). Refrigerants Product Literature - Safety of DuPont SUVA® and ISCEON® 9 

Series Refrigerants (AS-1). 

DuPont Co. (2006). Unpublished Data, DSPEC database. 

ECOSAR v0.99h. 

Garrett S and Fuerst R (1974). Sex-linked mutations in Drosophila after exposure to various 

mixtures of gas atmospheres. Environ. Res., 7(3):286 - 293. 

HSDB (2000). Hazardous Substance Data Bank (HSDB/5205). 

IPCC SAR (1996). Climate Change 1995. The Science of Climate Change, Cambridge University 

Press, Great Britain. 

IPCC/TAR (2001). Climate Change 2001: The Scientific Basis, Cambridge University Press, New 

York, NY. 

IPCC/TEAP (2005). Safeguarding the Ozone Layer and the Global Climate System. Issues Related 

to Hydrofluorocarbons and Perfluorocarbons, Cambridge University Press, New York, NY. 

Jow, P. and Hansch, C. (n.d.). Pomona College, unpublished analysis (cited in Hansch, C. and A. 

Leo (1995). Exploring QSAR Fundamentals and Applications in Chemistry and Biology, Amer. 

Chem. Soc., Washington, DC). 

Kirk-Othmer Encyclopedia of Chemical Technology (1991). Volume 1, p. 677, John Wiley and 

Sons, New York. 

Ko MKW and Sze ND (1997). Final Report on Modeling Studies to Assess the Environmental 

Effects of Alternative CFCs (TSCA Fiche OTS0558956). 
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 UNEP PUBLICATIONS 19

Lester D and Greenberg LA (1950). Acute and chronic toxicity of some halogenated derivatives of 

methane and ethane. Arch. Ind. Hyg. Occup. Med., 2:335 - 344. 

Lewis, R. J., Sr. (1993). Hawley’s Condensed Chemical Dictionary, 12th ed., p. 399, Van Nostrand 

Reinhold Co., New York. 

Life Sciences Research (1992a). Unpublished Data, Report 91/0935, “HCFC-123: Determination 

of its EC50 to Selenastrum capricornutum” (April 22). 

Life Sciences Research (1992b). Unpublished Data, Report 91/0972, “HCFC-123: Acute Toxicity 

to Daphnia magna” (April 22). 

Life Sciences Research (1992c). Unpublished Data, Report 91/0939, “HCFC-123: Acute Toxicity to 

Rainbow Trout” (April 22). 

Life Sciences Research (1992d). Unpublished Data, Report 91/PFE008/0477, “HCFC 123 (Liquid): 

Biotic Degradation Closed Bottle Test” (April 22) (cited in TSCA Fiche OTS0546420). 

Lyman, W. J. et al. (1990). Handbook of Chemical Property Estimation Methods, pp. 4 - 9, 5 - 4, 5 - 

10, 15 - 1 to 15 - 29, Amer. Chem. Soc., Washington, DC (HSDB/5205). 

Mackay D, Di Guardo A, Paterson S, and Cowan CE (1996). Evaluating the environmental fate of a 

variety of types of chemicals using the EQC model. Environ. Toxicol. Chem., 15(9):1627 - 1637. 

Meylan, W. M. and P. H. Howard (1991). Bond contribution method for estimating Henry’s Law 

constants. Environ. Toxicol. Chem., 10:1283 - 1293 (HENRYWIN Software available from 

Syracuse Research corp., Environmental Science Center, Syracuse, NY 13210). 

Meylan WM and Howard PH (1995). Atom/fragment contribution method for estimating octanolwater partition coefficients. J. Pharm. Sci., 84:83 - 92. 

Meylan WM and Howard PH (1996). Improved method for estimating water solubility from 

octanol/water partition coefficient. Environ. Toxicol. Chem., 15:100 - 106. 

NIER (2005). Survey on circulation volume and use pattern of 1,1-difluoroethane in Korea, 2005, 

National Institute of Environmental Research, Korea. 

Nimitz, J. S. and S. R. Skaggs (1992). Estimating tropospheric lifetimes and ozone-depletion 

potentials of one- and two-carbon hydrofluorocarbons and hydrochlorofluorocarbons. Environ Sci. 

Technol., 26:739 - 744 (HSDB/5205). 

Reinhardt CF, Azar A, Maxfield ME, Smithe PE, Jr., and Mullin LS (1971). Cardiac arrhythmias 

and aerosol “sniffing.” Arch. Environ. Health, 22:265 - 279. 

Ruelle, P. and U. W. Kesselring (1997). Aqueous solubility prediction of environmentally important 

chemicals from the mobile order thermodynamics. Chemosphere, 34:275 - 298 (HSDB/5205). 

Sax, N. I. and R. J. Lewis, Sr. (1987). Hawley’s Condensed Chemical Dictionary, 11th ed., p. 397, 

Van Nostrand Reinhold Co., New York. 

Simaan JA and Aviado DM (1975). Hemodynamic effects of aerosol propellants. I. Cardiac 

depression in the dog. Toxicology, 5:127 - 138. 

SRC (Syracuse Research Corporation) (n.d.). (HSDB/5205). 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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Stewart, K. M. and R. S. Thompson (1991). ICI Group Environmental Laboratory Report No. 

BL3908/B, ICI, UK (cited in Berends, A. G. et al. (1999). Arch. Environ. Contam. Toxicol., 

36(2):146 - 151). 

Thompson, R. S. (1991). ICI Group Environmental Laboratory Report No. BL4035/B, ICI, UK 

(cited in Berends, A. G. et al. (1999). Arch Environ. Contam. Toxicol., 36(2):146 - 151). 

Tobeta Y (1989). Test on biodegradability of HFC-134 a by microorganisms, Kurume Research 

Laboratories, Fukuoka, Japan (cited in Berends AG, de Rooij CG, Shin-ya S, and Thompson RS 

(1999). Biodegradation and ecotoxicity of HFCs and HCFCs. Arch. Environ. Contam. Toxicol., 

36(2):146 - 151). 

Tobeta Y (1992). Test on biodegradability of HFC-32 a by microorganisms (closed bottle test), 

Kurume Research Laboratories Report No. 12121, Fukuoka, Japan (cited in Berends AG, de Rooij 

CG, Shin-ya S, and Thompson RS (1999). Biodegradation and ecotoxicity of HFCs and HCFCs. 

Arch. Environ. Contam. Toxicol., 36(2):146 - 151). 

Van Poznak A and Artusio JF, Jr. (1960). Anesthetic properties of a series of fluorinated 

compounds. I. Fluorinated hydrocarbons. Toxicol. Appl. Pharmacol., 2:363 - 373. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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S I D S 

Dossier 

Existing Chemical : ID: 75-37-6 

CAS No. : 75-37-6 

Substance name : Ethane, 1,1-difluoro 

Synonym : HFC-152a 

Producer related part 

Company : E. I. du Pont de Nemours and Company 

Creation date : 15.01.2003 

Substance related part 

Company : E. I. du Pont de Nemours and Company 

Creation date : 15.01.2003 

Status : 

Memo : 

Printing date : 29.06.2006 

Revision date : 

Date of last update : 29.06.2006 

Number of pages : 80 

Chapter (profile) : Chapter: 1, 2, 3, 4, 5, 6, 7, 8, 10 

Reliability (profile) : Reliability: without reliability, 1, 2, 3, 4 

Flags (profile) : Flags: without flag, confidential, non confidential, WGK (DE), TALuft (DE), Material Safety Dataset, Risk Assessment, Directive 

67/548/EEC, SIDS 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

1. GENERAL INFORMATION ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 22

1.0.1 APPLICANT AND COMPANY INFORMATION 

Type : manufacturer 

Name : E. I. du Pont de Nemours and Company 

Contact person : 

Date : 

Street : 1007 Market Street 

Town : 19898 Wilmington, Delaware 

Country : United States 

Phone : 

Telefax : 

Telex : 

Cedex : 

Email : 

Homepage : 

22.09.2005

1.0.2 LOCATION OF PRODUCTION SITE, IMPORTER OR FORMULATOR 

Type : manufacturer 

Name of plant : DuPont- Corpus Christi 

Street : 

Town : Corpus Christi 

Country : United States 

Phone : 

Telefax : 

Telex : 

Cedex : 

Email : 

Homepage : 

22.09.2005

1.0.3 IDENTITY OF RECIPIENTS 

1.0.4 DETAILS ON CATEGORY/TEMPLATE 

1.1.0 SUBSTANCE IDENTIFICATION 

IUPAC Name : 1,1-Difluoroethane 

Smiles Code : FC(F)C 

Molecular formula : C2H4F2

Molecular weight : 66.05 

Petrol class : 

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OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

1. GENERAL INFORMATION ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 23

1.1.1 GENERAL SUBSTANCE INFORMATION 

Purity type : typical for marketed substance 

Substance type : organic 

Physical status : gaseous 

Purity : > 99.9 % w/w 

Colour : Clear, colorless 

Odour : Slight ethereal odor 

Attached document : HFC-152a structure.bmp 

31.03.2006 (26)

1.1.2 SPECTRA 

Type of spectra : other 

Attached document : spectra.bmp 

1.2 SYNONYMS AND TRADENAMES 

Algofrene 67 

15.01.2003

Dymel 152 

15.01.2003

Dymel 152a 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

1. GENERAL INFORMATION ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 24

15.01.2003

Ethylene fluoride 

15.01.2003

Ethylidene difluoride 

15.01.2003

Ethylidene fluoride 

15.01.2003

F152A 

15.01.2003

FC152a 

15.01.2003

FKW 152a 

15.01.2003

Freon(R) 152a 

15.01.2003

Genetron 100 

15.01.2003

Genetron(R) 152a 

15.01.2003

HFA 152a 

15.01.2003

HFC-152a (name to be used throughout dossier) 

23.03.2006

R 152a 

30.05.2006 (10) (41)

1.3 IMPURITIES 

Remark : Typical impurities in HFC-152a include low level (ppm) water, low 

level (ppb) residual HCl and/or HF acids. 

29.06.2006 (33)

1.4 ADDITIVES 

Remark : None. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

1. GENERAL INFORMATION ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 25

14.06.2005

1.5 TOTAL QUANTITY 

Remark : Production capacities are confidential, but are in excess of 5,000 

metric tones (10 million pounds) per year. 

29.06.2006 (34)

Remark : In Korea, estimated usage volume of 1,1-difluoroethane was 4.63, 

4.85, and 3.14 tonnes/year in 2003, 2004, and 2005, respectively. 

30.05.2006 (55)

1.6.1 LABELLING 

Remark : Flammable gas. 

30.05.2006 (25) (26)

1.6.2 CLASSIFICATION 

1.6.3 PACKAGING 

Memo : HFC-152a is sold in small packages (steel reusable cylinders ranging 

from 95 lbs to 2,000 lbs), and in bulk containers (ISO tanks, tank 

trailers, and rail cars). 

29.06.2006 (31)

1.7 USE PATTERN 

Remark : Approximately 80 % of HFC-152a is used as a propellant in aerosol 

products. It is present in the aerosol container, liquified under 

pressure as part of the aerosol formulation. The vapor pressure of the 

152a provides the driving force for dispensing the product. 

Approximately 15 % of HFC-152a is used as a foam expansion agent. 

In foam manufacture HFC-152a is the formulation ingredient used to 

foam the polymer. It is stored as an ingredient and feed to the 

foaming process directly. The HFC-152a is contained in process 

equipment and the closed-cell foam product, so that exposure to 

workers and consumer is negligible. 

Approximately 5 % of HFC-152a is used for other potential uses, 

which include catalyst regeneration, as well as HFC-152a being 

blended with other fluorocarbons for use as in refrigeration systems. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

1. GENERAL INFORMATION ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 26

The refrigerant blends are contained in closed pressurized containers 

and refrigeration systems. Potential for exposures would occur only 

during servicing or an abnormal situation such as a leak. 

29.06.2006 (14) (30) (31)

Remark : In Korea, it is used in maintaining of a catalytic activity. 

10.03.2006 (55)

1.7.1 DETAILED USE PATTERN 

1.7.2 METHODS OF MANUFACTURE 

Origin of substance : other 

Type : 

Remark : HFC-152a is produced by catalytic reaction of vinyl chloride with 

hydrofluoric acid. 

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1.8 REGULATORY MEASURES 

1.8.1 OCCUPATIONAL EXPOSURE LIMIT VALUES 

Type of limit : other: AIHA WEEL 8-hour TWA 

Limit value : 1,000 other: ppm 

30.05.2006 (1)

Type of limit : other: DuPont Acceptable Exposure Limit (AEL) 8-hour TWA 

Limit value : 1,000 other: ppm 

30.05.2006 (25) (26)

1.8.2 ACCEPTABLE RESIDUES LEVELS 

Proposed residues 

level 

: HFC-152a is volatile and generally leaves no residue. 

Maximum residue 

level 

: mg/kg 

29.06.2006 (41)

1.8.3 WATER POLLUTION 

Remark : None. 

14.06.2005
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

1. GENERAL INFORMATION ID: 75-37-6 

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 UNEP PUBLICATIONS 27

1.8.4 MAJOR ACCIDENT HAZARDS 

Remark : Hazards include pressure, flammability, and potential for liquid 

exposure to cause frostbite. 

30.05.2006 (25) (26)

1.8.5 AIR POLLUTION 

Remark : HFC-152a has no ozone depletion potential, low global warming 

potential, and is not regulated as a volatile organic compound. 

29.06.2006 (14)

1.8.6 LISTINGS E.G. CHEMICAL INVENTORIES 

Type : EINECS 

Additional 

information 

: EINECS Inventory 

CAS RN: 75-37-6 

Name: 1,1-Difluoroethane 

EINECS Inventory Number: 200-866-1 

30.05.2006 (10)

1.9.1 DEGRADATION/TRANSFORMATION PRODUCTS 

Remark : Hydrogen Fluoride. 

23.03.2006 (25) (26)

Remark : The atmospheric degradation of hydrofluorocarbons (HFCs) have 

been extensively studied through different research programmes from 

industry (AFEAS) and from EU (Step halocside project (STEPHALOCSIDE/AFEAS, 1993) and were reported in the different 

WMO-UNEP scientific assessments on stratospheric ozone (WMO, 

1989; 1991; 1994) 

30.05.2006 (67) (68)

1.9.2 COMPONENTS 

1.10 SOURCE OF EXPOSURE 

Source of exposure : Human: exposure by production 

Exposure to the : 

Remark : As a liquefied gas HFC-152a has to be handled in closed pressurize 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

1. GENERAL INFORMATION ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 28

systems so that exposure typically does not occur in the 

manufacturing, except for during maintenance or an abnormal 

process situations, such as a leak. 

29.06.2006 (31)

Source of exposure : Human: exposure by production 

Exposure to the : 

Remark : HFC-152a used to manufacture foam is contained within the foam, 

and remains in the foam for a long period of time. The HFC-152a will 

be disposed with the foam. 

29.06.2006 (30)

Source of exposure : Human: exposure of the consumer/bystander 

Exposure to the : 

Remark : HFC-152a is used in aerosol consumer personal care and household 

products and is dispensed with the product during use. Typically 

there is no 152a left in the container when it is disposed. 

29.06.2006 (14)

Source of exposure : other 

Exposure to the : 

Remark : HFC-152a used in refrigerants is contained in the refrigeration system 

until such time as it is collected for recycle or disposal. 

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1.11 ADDITIONAL REMARKS 

1.12 LAST LITERATURE SEARCH 

1.13 REVIEWS 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

2. PHYSICO-CHEMICAL DATA ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 29

2.1 MELTING POINT 

Value : -117 °C 

Decomposition : no, at °C 

Sublimation : 

Method : 

Year : 1993 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2g. Data from handbook or collection of data. 

Flag : Critical study for SIDS endpoint 

14.06.2005 (47)

2.2 BOILING POINT 

Value : -24.7 °C at 

Decomposition : 

Method : 

Year : 1993 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2g. Data from handbook or collection of data. 

Flag : Critical study for SIDS endpoint 

14.06.2005 (47)

Value : -25 °C at 

Decomposition : 

Method : 

Year : 

GLP : 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (4) not assignable 

 4b. Secondary literature. 

24.03.2006 (26)

2.3 DENSITY 

Type : 

Value : .91 at 21 °C 

Method : 

Year : 1991 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Result : Density is 0.91 g/mL at 21°C. 

Reliability : (2) valid with restrictions 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

2. PHYSICO-CHEMICAL DATA ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 30

 2g. Data from handbook or collection of data. 

Flag : Critical study for SIDS endpoint 

24.03.2006 (44)

Type : 

Value : .9 at 25 °C 

Method : 

Year : 1998 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Remark : Density was determined for liquid density, units are in mg/L. 

Reliability : (4) not assignable 

 4b. Secondary literature. 

24.03.2006 (25)

2.3.1 GRANULOMETRY 

2.4 VAPOUR PRESSURE 

Value : 6,065.2 hPa at 25 °C 

Decomposition : 

Method : other (measured) 

Year : 1989 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2g. Data from handbook or collection of data. 

Flag : Critical study for SIDS endpoint 

31.03.2006 (12)

Value : 5,998.5 hPa at 25 °C 

Decomposition : 

Method : 

Year : 

GLP : 

Test substance : as prescribed by 1.1 - 1.4 

Remark : Vapor pressure was reported as 87 psia at 25°C 

Reliability : (4) not assignable 

 4b. Secondary literature. 

09.01.2006 (26)

Value : 4,343.7 hPa at 20 °C 

Decomposition : 

Method : 

Year : 1975 

GLP : no data 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

2. PHYSICO-CHEMICAL DATA ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 31

Test substance : as prescribed by 1.1 - 1.4 

Remark : Vapor pressure was listed as 63 psig. 

Reliability : (4) not assignable 

 4e. Documentation insufficient for assessment. 

23.03.2006 (5)

Value : 5,146.2 hPa at 25 °C 

Decomposition : 

Method : other (calculated) 

Year : 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

30.03.2006 (37)

2.5 PARTITION COEFFICIENT 

Partition coefficient : octanol-water 

Log pow : .75 at °C 

pH value : 

Method : other (measured) 

Year : 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2g. Data from handbook or collection of data. 

Flag : Critical study for SIDS endpoint 

23.03.2006 (43)

Partition coefficient : octanol-water 

Log pow : 1.13 at °C 

pH value : 

Method : other (calculated) 

Year : 1995 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

24.03.2006 (52)

2.6.1 SOLUBILITY IN DIFFERENT MEDIA 

Solubility in : 

Value : 2,671 mg/l at 25 °C 

pH value : 

 concentration : at °C 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

2. PHYSICO-CHEMICAL DATA ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 32

Temperature effects : 

Examine different 

pol. 

: 

pKa : at 25 °C 

Description : 

Stable : 

Deg. product : 

Method : other: Estimated 

Year : 1996 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Method : The method used is a new mew calculation method that outperformed 

other widely used general-purpose equations based on log Kow. 

The program uses the following equation if a melting point is 

available: 

log S = 0.693 - 0.96 log Kow - 0.0092(Tm-25) - 0.00314(MW) + 

summation of f1 

The program uses the following equation if no melting point is 

available: 

log S = 0.796 - 0.854 log Kow - 0.00728(MW) + summation of f1 

where: 

S= water solubility in moles/L 

Kow = n-octanol:water partition coefficient 

Tm = melting temperature in °C 

Summation of f1 = summation of all correction factors applicable to a 

given compound 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

Flag : Critical study for SIDS endpoint 

24.03.2006 (53)

Solubility in : Water 

Value : 17.8 g/l at 25 °C 

pH value : 

 concentration : at °C 

Temperature effects : 

Examine different 

pol. 

: 

pKa : at 25 °C 

Description : 

Stable : 

Deg. product : 

Method : 

Year : 1997 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

2. PHYSICO-CHEMICAL DATA ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 33

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

11.01.2006 (57)

Solubility in : Water 

Value : 2.8 g/l at 25 °C 

pH value : 

 concentration : at °C 

Temperature effects : 

Examine different 

pol. 

: 

pKa : at 25 °C 

Description : 

Stable : 

Deg. product : 

Method : 

Year : 1998 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (4) not assignable 

 4b. Secondary literature. 

09.01.2006 (25)

Solubility in : Water 

Value : 3,200 mg/l at 20 °C 

pH value : 

 concentration : at °C 

Temperature effects : 

Examine different 

pol. 

: 

pKa : at 25 °C 

Description : 

Stable : 

Deg. product : 

Method : other: experimental 

Year : 1982 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Test substance : HFC-152a, purity not reported 

Reliability : (4) not assignable 

 4b. Secondary literature. 

30.03.2006 (40)

2.6.2 SURFACE TENSION 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

2. PHYSICO-CHEMICAL DATA ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 34

2.7 FLASH POINT 

Value : < -50 °C 

Type : open cup 

Method : 

Year : 1998 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (4) not assignable 

 4b. Secondary literature. 

09.01.2006 (25)

2.8 AUTO FLAMMABILITY 

2.9 FLAMMABILITY 

Result : other: 3.7 % - 18 % (in air) 

Method : 

Year : 1987 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (2) valid with restrictions 

 2g. Data from handbook or collection of data. 

14.06.2005 (58)

Result : other: 3.9 % - 16.9 % (in air) 

Method : 

Year : 1998 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Reliability : (4) not assignable 

 4b. Secondary literature. 

09.01.2006 (25)

2.10 EXPLOSIVE PROPERTIES 

2.11 OXIDIZING PROPERTIES 

2.12 DISSOCIATION CONSTANT 

2.13 VISCOSITY 

2.14 ADDITIONAL REMARKS 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 35

3.1.1 PHOTODEGRADATION 

Type : other: modeled 

Light source : 

Light spectrum : nm 

Relative intensity : based on intensity of sunlight 

Deg. product : 

Method : other (calculated) 

Year : 

GLP : 

Test substance : as prescribed by 1.1 - 1.4 

Method : According to a model of gas/particle partitioning of semivolatile 

organic compounds in the atmosphere (Bidleman TF (1988). 

Atmospheric processes. Environ. Sci. Technol., 22:361 - 367 

(HSDB/5205), 1,1-difluoroethane is expected to exist solely as a 

vapor in the ambient atmosphere. 

Result : The rate constant of 3.4E+14 cm3

/molecule-sec corresponds to an 

atmospheric half-life of about 472 days at an atmospheric 

concentration of 5E+5 hydroxyl radicals per cm3

 Atkinson R (1989). 

J. Phys. and Chem. Reference Data (HSDB/5205). 

The long atmospheric lifetime of this chemical suggests some 1,1-

difluoroethane is expected to gradually diffuse into the stratosphere 

above the ozone layer where it will slowly degrade due to direct 

photolysis from UV-radiation (Nimitz JS and Skaggs SR (1992). 

Estimating tropospheric lifetimes and ozone-depletion potentials of 

one- and two-carbon hydrofluorocarbons and 

hydrochlorofluorocarbons. Environ Sci. Technol., 26:739 - 44 

(HSDB/5205); SRC (Syracuse Research Corporation) (n.d.). 

(HSDB/5205). 

1,1-Difluoroethane is not expected to undergo hydrolysis or direct 

photolysis in the troposphere due to the lack of functional groups to 

hydrolyze or absorb UV light at environmentally significant 

wavelengths (SRC (Syracuse Research Corporation) (n.d.). 

(HSDB/5205). 

Reliability : (2) valid with restrictions 

 2g. Data from handbook or collection of data. 

Flag : Critical study for SIDS endpoint 

04.04.2006 (41)

Deg. product : 

Method : other (calculated) 

Year : 1997 

GLP : 

Test substance : as prescribed by 1.1 - 1.4 

Remark : Using the AER (Atmospheric and Environmental Research) model, 

the lifetime global warming potential value for HFC-152a was 

calculated to be 1.5 years. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 36

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

11.01.2006 (45)

Type : air 

Light source : 

Light spectrum : nm 

Relative intensity : based on intensity of sunlight 

Deg. product : 

Method : 

Year : 1992 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Remark : Reaction of several HFCs and HCFCs with Cl radicals were studied. 

concentration of reagents and products were monitored by a FT-IR 

absorption spectrometer. Chlorine radicals were used in order to 

study the degradation pathways, as a surrogate of OH radicals. 

RESULTS: 

Reaction of HFC-152a with Cl2 for 20 minutes gave C(O)F2 as 

product, with a yield of 100 %. 

The proposed mechanism was: 

Cl + CHF2CH3 -> HCl + CHF2CH2

CHF2CH2 + O2 -> CHF2CH2O2

2CHF2CH2O2 -> 2CHF2CH2O + O2

CHF2CH2O -> HCH(O) +CHF2 

CHF2 + O2 -> CHF2O2

2CHF2O2 -> 2CHF2O + O2

2CHF2O + O2 -> C(O)F2 + HO2

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

Flag : Critical study for SIDS endpoint 

31.03.2006 (36)

Deg. product : 

Method : other (calculated): AOPWIN v1.91 

Year : 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Result : Overall OH Rate Constant = 0.0348E-12 cm3

/molecule-sec 

Half-life = 307.163 days (12-hour day; 1.56E+6 OH/cm3

). 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

23.03.2006 (37)
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 37

3.1.2 STABILITY IN WATER 

Deg. product : 

Method : other (calculated): HYDROWIN v1.67 

Year : 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Result : 

 R2 

 | 

R1-C-H 

 | 

 R3 

X: -F (leaving halogen in R1) 

R1: -CH-F2 

R2: -H 

R3: -H 

Kb hydrolysis at atom #4: 1.157E-13 L/mol-sec 

Total Kb for pH > 8 at 25 °C: 1.157E-13 L/mol-sec 

Kb half-Life at pH 8: 1.898E+11 years 

Kb Half-Life at pH 7: 1.898E+12 years 

The rate constant estimated for the Alkyl Halide DOES NOT include 

the neutral hydrolysis rate constant! For some alkyl halides, the 

neutral rate constant is the dominant hydrolysis rate at environmental 

pHs. If the neutral rate constant is important, the HYDRO estimated 

rate will under estimate the actual rate. 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

Flag : Critical study for SIDS endpoint 

08.03.2006 (37)

3.1.3 STABILITY IN SOIL 

3.2.1 MONITORING DATA 

3.2.2 FIELD STUDIES 

3.3.1 TRANSPORT BETWEEN ENVIRONMENTAL COMPARTMENTS 

Type : fugacity model level III 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 38

Media : other: air-water-soil-sediment 

Air : % (Fugacity Model Level I) 

Water : % (Fugacity Model Level I) 

Soil : % (Fugacity Model Level I) 

Biota : % (Fugacity Model Level II/III) 

Soil : % (Fugacity Model Level II/III) 

Method : other: Mackay, Level III Fugacity Model 

Year : 

Method : Calculated according to Mackay, Level III, Syracuse Research 

Corporation Epiwin Version 3.05 Emissions to Air (1,000 kg/hr) EPA 

Model Defaults. 

Data Used: 

Molecular Weight: 66.05 

Henry's Law Constant: 0.0203 atm-m3

/mole (Henry database) 

Vapor Pressure: 4,550 mmHg at 25 °C (user entered) 

Log Kow: 0.75 (Jow and Hansch, n.d.) 

Soil Koc: 2.31 (calculated by model) 

Result : Distributions: 

Air 99.9 % 

Water 0.111 % 

Soil 0.0113 % 

Sediment 0.000214 % 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

30.03.2006 (43) (49) (50) (51)

Type : 

Media : 

Air : % (Fugacity Model Level I) 

Water : % (Fugacity Model Level I) 

Soil : % (Fugacity Model Level I) 

Biota : % (Fugacity Model Level II/III) 

Soil : % (Fugacity Model Level II/III) 

Method : other: modeled 

Year : 

Result : Estimated half-lives for a model river (1 m deep, flowing 1 m/sec, 

wind velocity of 3 m/sec) and model lake (1 m deep, flowing 0.05 

m/sec, wind velocity of 0.5 m/sec) are 2 and 77 hours, respectively 

(Lyman et al., 1990; SRC, n.d.). Based on a recommended 

classification scheme (Swann et al., 1983), an estimated Koc value of 

60 (SRC, n.d.), determined from a measured log Kow of 0.75 (Jow 

and Hansch, n.d.) and a recommended regression-derived equation 

(Lyman et al., 1990), 1,1-difluoroethane is not expected to adsorb to 

suspended solids and sediment in water (SRC, n.d.). 1,1-

Difluoroethane is expected to volatilize rapidly from water surfaces 

(Lyman et al., 1990; SRC, n.d.) based on an estimated Henry's Law 

constant of 0.02 atm-m3

/mole (Daubert and Danner, 1989); Ruelle 

and Kesselring, 1997; SRC, n.d.). 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 39

References for modeling: 

Lyman WJ, Reehl WF, and Rosenblatt DH (1990). Handbook of 

Chemical Property Estimation Methods, pp. 4 - 9, 5 - 4, 5 - 10, 15 - 

1 to 15 - 29, Amer. Chem. Soc., Washington, DC (HSDB/5205) 

SRC (Syracuse Research Corporation) (n.d.). (HSDB/5205). 

Swann RL, Laskowski DA, McCall PJ, Vander Kuy K, and 

Dishburger HJ (1983). A rapid method for the estimation of the 

environmental parameters octanol/water partition coefficient, soil 

sorption constant, water to air ratio, and water solubility. Res. Rev., 

85:23 (HSDB/5205). 

Jow P and Hansch C (n.d.). Pomona College, unpublished analysis 

(cited in Hansch C and Leo A (1995). Exploring QSAR 

Fundamentals and Applications in Chemistry and Biology, Amer. 

Chem. Soc., Washington, DC (HSDB/5205). 

Daubert TE and Danner RP (1989). Physical and Thermodynamic 

Properties of Pure Chemicals Data Compilation, Amer. Inst. Chem. 

Eng., Hemisphere Pub. Corp., New York (HSDB/5205). 

Ruelle P and Kesselring UW (1997). Aqueous solubility prediction 

of environmentally important chemicals from the mobile order 

thermodynamics. Chemosphere, 34:275 - 298 (also cited in 

HSDB/5205). 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

30.03.2006 (41)

3.3.2 DISTRIBUTION 

Method : Determined from a measured log Kow of 0.75. 

Remark : Estimated Koc = 60 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

11.01.2006 (60)

Remark : Estimated Henry's Law constant = 0.02 atm-m3

/mole (2026.5 Pam3

/mol), determined from a vapor pressure of 4,550 mmHg and water 

solubility of 17,800 mg/L. 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

04.04.2006 (11) (57) (60)

Method : PCKOC v1.66 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 40

Remark : Estimated Koc = 35 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

30.03.2006 (37)

3.4 MODE OF DEGRADATION IN ACTUAL USE 

3.5 BIODEGRADATION 

Type : aerobic 

Inoculum : other: filtered sample of secondary effluent from a sewage plant 

Contact time : 

Degradation : 4 (±) % after 28 day(s) 

Result : other: not readily biodegradable 

Deg. product : 

Method : OECD Guide-line 301 D "Ready Biodegradability: Closed Bottle 

Test" 

Year : 1989 

GLP : no data 

Test substance : other TS 

Method : The test was performed in accordance with OECD guideline 301D 

and EEC guideline C.6. A solution of the test substance in mineral 

medium was inoculated with a filtered sample of secondary effluent 

from a sewage plant. The initial test substance concentration was 

1.44 mg/L. Bottles were completely filled, closed, and incubated in 

the dark for a period of 28 days at 20 ± 1 °C. The decrease of the 

oxygen content in the medium over a period of 28 days was used to 

calculate the percentage of aerobic biodegradation. To correct for the 

endogenous oxygen consumption of the inoculum, blanks with 

secondary effluent but without test substance were included in the 

test. 

The biodegradation was also based on the gas chromatgraphic 

analysis of the test substance in the solutions at the end of the study. 

Measured concentrations in bottles with mineral medium and test 

substance were compared with concentrations in bottles with mineral 

medium, test substance, and inoculum. The biodegradation was 

determined using the difference in the measured concentration. To 

verify the procedures used, the biodegradability of a reference 

compound (sodium n-dodecylsulfate) was measured. 

Result : The TOD (based on biomass integral) was 0.7. The measured 

decrease of oxygen content was 0.03 mg/L. 

Test substance : other TS: HFC-134a (1,1,1,2-tetrafluoroethane), purity not specified 

Reliability : (1) valid without restriction 

 1a. GLP guideline study. 

30.03.2006 (63)
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 41

Type : aerobic 

Inoculum : other: filtered sample of secondary effluent from a sewage plant 

Contact time : 

Degradation : 8 (±) % after 28 day(s) 

Result : other: not readily biodegradable 

Deg. product : 

Method : OECD Guide-line 301 D "Ready Biodegradability: Closed Bottle 

Test" 

Year : 1992 

GLP : no data 

Test substance : other TS 

Method : The test was performed in accordance with OECD guideline 301D 

and EEC guideline C.6. A solution of the test substance in mineral 

medium was inoculated with a filtered sample of secondary effluent 

from a sewage plant. The initial test substance concentration was 

3.38 mg/L. Bottles were completely filled, closed, and incubated in 

the dark for a period of 28 days at 20 ± 1 °C. The decrease of the 

oxygen content in the medium over a period of 28 days was used to 

calculate the percentage of aerobic biodegradation. To correct for the 

endogenous oxygen consumption of the inoculum, blanks with 

secondary effluent but without test substance were included in the 

test. 

The biodegradation was also based on the gas chromatgraphic 

analysis of the test substance in the solutions at the end of the study. 

Measured concentrations in bottles with mineral medium and test 

substance were compared with concentrations in bottles with mineral 

medium, test substance, and inoculum. The biodegradation was 

determined using the difference in the measured concentration. To 

verify the procedures used, the biodegradability of a reference 

compound (sodium n-dodecylsulfate) was measured. 

Result : The TOD (based on biomass integral) was 2.1. The measured 

decrease of oxygen content was 0.16 mg/L. 

Test substance : other TS: HFC-32 (difluoromethane), purity not specified 

Reliability : (1) valid without restriction 

 1a. GLP guideline study. 

30.03.2006 (64)

3.6 BOD5, COD OR BOD5/COD RATIO 

3.7 BIOACCUMULATION 

BCF : 2 

Elimination : 

Method : other: Modeled 

Year : 

GLP : 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

3. ENVIRONMENTAL FATE AND PATHWAYS ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 42

Test substance : as prescribed by 1.1 - 1.4 

Method : BCF was determined using a measured log Kow of 0.75 (Jow P and 

Hansch C (n.d.). Pomona College, unpublished analysis (cited in 

Hansch C and Leo A (1995). Exploring QSAR Fundamentals and 

Applications in Chemistry and Biology, Amer. Chem. Soc., 

Washington, DC)) and a recommended regression-derived equation 

(Lyman WJ, Reehl WF, and Rosenblatt DH (1990). Handbook of 

Chemical Property Estimation Methods, pp. 4 - 9, 5 - 4, 5 - 10, 15 - 1 

to 15 - 29, Amer. Chem. Soc., Washington, DC (HSDB/5205)). 

Result : According to a classification scheme (Franke C, Studinger G, Berger 

G, Böhling S, Bruckmann U, Cohors-Fresenborg U, and Jöhncke U 

(1994). The assessment of bioaccumulation. Chemosphere, 29:1501-

1514 (HSDB/5205)), the estimated BCF value of 2 suggests that 

bioconcentration in aquatic organisms is low SRC (Syracuse 

Research Corporation) (n.d.). (HSDB/5205)). 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

09.01.2006 (41)

3.8 ADDITIONAL REMARKS 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

4. ECOTOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 43

4.1 ACUTE/PROLONGED TOXICITY TO FISH 

Type : other: Modeled 

Species : other: Fish 

Exposure period : 96 hour(s) 

Unit : mg/l 

LC50 : 733 

Method : other: calculated ECOSAR v0.99h 

Year : 

GLP : 

Test substance : as prescribed by 1.1 - 1.4 

Remark : log10 Kow of 0.75 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

Flag : Critical study for SIDS endpoint 

09.01.2006 (35)

Type : semistatic 

Species : Oncorhynchus mykiss (Fish, fresh water) 

Exposure period : 96 hour(s) 

Unit : mg/l 

LC50 : 450 

Limit test : 

Analytical monitoring : yes 

Method : Directive 84/449/EEC, C.1 "Acute toxicity for fish" 

Year : 1991 

GLP : yes 

Test substance : other TS 

Method : To prevent loss of the substance from the solutions, closed vessels 

were used. The test was conducted under semistatic conditions with 

daily renewal of the test solutions. Chemical analyses of the test 

solutions were performed to check the exposure of the organisms to 

the test chemical. If the difference between nominal and mean 

measured concentrations was more than 20 %, the endpoint of the test 

was based on mean measured concentrations. 

Saturated solutions were prepared. HFC-134a was bubbled for 60 

minutes through medium via a sintered glass diffuser. This solution 

was diluted with oxygen saturated solutions to restore the amount of 

oxygen in the test solutions. 

The EC50 value was determined using the method of Stephan, 1977 

(Stephan, C. E. (1977). Methods for calculating an LC50. Proceedings 

first annual symposium on aquatic toxicology. In: Mayer, F. L. and J. 

L. Hamelink (eds). Aquatic toxicology and hazard evaluation, ASTM 

STP 634:65-84). 

Remark : Data provided on analog chemical (similar non-chlorinated 

fluorocarbon) to strengthen the use of ECOSAR to characterize the 

toxicity of HFC-152a. 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

4. ECOTOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 44

Result : No mortality was found after 96 hours of exposure at mean measured 

concentrations of 180 and 300 mg/L, but symptoms of toxicity were 

observed at these concentrations (dark discoloration, quiescence, and 

sounding behavior). No symptoms of toxicity occurred at a mean 

measured concentration of 87 mg/L. 

Test substance : other TS: HFC-134a (1,1,1,2-tetrafluoroethane), purity not specified 

Reliability : (2) valid with restrictions 

 2a. Guideline study without detailed documentation. 

Flag : Critical study for SIDS endpoint 

04.04.2006 (62)

4.2 ACUTE TOXICITY TO AQUATIC INVERTEBRATES 

Type : other: Modeled 

Species : other: Daphnid 

Exposure period : 48 hour(s) 

Unit : mg/l 

EC50 : 720 

Method : other: calculated ECOSAR v0.99h 

Year : 

GLP : 

Test substance : as prescribed by 1.1 - 1.4 

Remark : log10 Kow of 0.75 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

Flag : Critical study for SIDS endpoint 

23.03.2006 (35)

 

Type : static 

Species : Daphnia magna (Crustacea) 

Exposure period : 48 hour(s) 

Unit : mg/l 

EC50 : 980 

Analytical monitoring : yes 

Method : Directive 84/449/EEC, C.2 "Acute toxicity for Daphnia" 

Year : 1991 

GLP : yes 

Test substance : other TS 

Method : To prevent loss of the substance from the solutions, closed vessels 

were used. The test was conducted under static conditions. Chemical 

analyses of the test solutions were performed to check the exposure 

of the organisms to the test chemical. If the difference between 

nominal and mean measured concentrations was more than 20 %, the 

endpoint of the test was based on mean measured concentrations. 

Saturated solutions were prepared. HFC-134a was bubbled for 60 

minutes through medium via a sintered glass diffuser. This solution 

was diluted with oxygen saturated solutions to restore the amount of 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

4. ECOTOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 45

oxygen in the test solutions. 

The EC50 value was determined using the method of Stephan, 1977 

(Stephan, C. E. (1977). Methods for calculating an LC50. Proceedings 

first annual symposium on aquatic toxicology. In: Mayer, F. L. and J. 

L. Hamelink (eds). Aquatic toxicology and hazard evaluation, ASTM 

STP 634:65 - 84). 

Remark : Data provided on analog chemical (similar non-chlorinated 

fluorocarbon) to strengthen the use of ECOSAR to characterize the 

toxicity of HFC-152a. 

Result : The acute test with Daphnia magna showed a steep concentrationimmobility curve. At mean measured concentrations of 870 and 1,100 

mg/L the immobility after 48 hours was 0 and 100 %, respectively. 

Test substance : other TS: HFC-134a (1,1,1,2-tetrafluoroethane), purity not specified 

Reliability : (2) valid with restrictions 

 2a. Guideline study without detailed documentation. 

Flag : Critical study for SIDS endpoint 

04.04.2006 (61)

4.3 TOXICITY TO AQUATIC PLANTS E.G. ALGAE 

Species : other algae 

Endpoint : other: Modeled: Inhibition of growth measured as number of cells 

Exposure period : 96 hour(s) 

Unit : mg/l 

EC50 : 419 

Method : other: calculated ECOSAR v0.99h 

Year : 

GLP : 

Test substance : as prescribed by 1.1 - 1.4 

Remark : log10 Kow of 0.75 

Reliability : (2) valid with restrictions 

 2f. Accepted calculation method. 

Flag : Critical study for SIDS endpoint 

09.01.2006 (35)

4.4 TOXICITY TO MICROORGANISMS E.G. BACTERIA 

4.5.1 CHRONIC TOXICITY TO FISH 

4.5.2 CHRONIC TOXICITY TO AQUATIC INVERTEBRATES 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

4. ECOTOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 46

4.6.1 TOXICITY TO SEDIMENT DWELLING ORGANISMS 

4.6.2 TOXICITY TO TERRESTRIAL PLANTS 

4.6.3 TOXICITY TO SOIL DWELLING ORGANISMS 

4.6.4 TOX. TO OTHER NON MAMM. TERR. SPECIES 

4.7 BIOLOGICAL EFFECTS MONITORING 

4.8 BIOTRANSFORMATION AND KINETICS 

4.9 ADDITIONAL REMARKS 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 47

5.0 TOXICOKINETICS, METABOLISM AND DISTRIBUTION 

5.1.1 ACUTE ORAL TOXICITY 

Type : other: Approximate Lethal Dose (ALD) 

Value : > 1,500 mg/kg bw 

Species : rat 

Strain : other: Crl:CD(R)BR 

Sex : male 

Number of animals : 6 

Vehicle : other: corn oil 

Doses : 200, 300, 450, 670, 1,000, 1,500 mg/kg 

Method : other 

Year : 1990 

GLP : yes 

Test substance : as prescribed by 1.1 - 1.4 

Method : Food and water were available to the rats ad libitum. Rats were 

approximately 7 weeks old upon arrival. HFC-152a was dissolved in 

corn oil (23 or 46 mg/mL) and kept under pressure in aerosol cans 

that were maintained in an ice bath. The cans were fitted with a 

septum from which the dosing solution was withdrawn. One rat per 

dose group was administered the compound by gavage. Dose levels 

were 200, 300, 450, 670, 1,000, or 1,500 mg/kg. Doses of 450 mg/kg 

and above were administered in 2 portions about 15 minutes apart. A 

dose of 1,500 mg/kg was the maximum feasible dose. Rats were 

observed for mortality, clinical signs, and body weight over a 14-day 

period. 

Result : No mortality occurred at any dose level. Immediately after dosing, 

abdominal distention related to gas evolution was evident in all rats. 

Lethargy was observed at 1,000 and 1,500 mg/kg. High carriage, wet 

and yellow stained perineum, and diarrhea were observed in all rats 1 

to 2 days post-dosing. No other toxicologically significant effects 

occurred. 

Test substance : HFC-152a, purity 99.9 % 

Reliability : (3) invalid 

 3c. Unsuitable test system. 

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5.1.2 ACUTE INHALATION TOXICITY 

Type : other: Approximate Lethal Concentration (ALC) 

Value : 383,000 ppm 

Species : rat 

Strain : other: ChR-CD(R) 

Sex : male 

Number of animals : 30 

Vehicle : 
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 UNEP PUBLICATIONS 48

Doses : 66,400, 175,200, 319,000, 383,000, 437,500 ppm 

Exposure time : 4 hour(s) 

Method : other 

Year : 1975 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : Groups of 6 rats were exposed whole-body to 66,400, 175,200, 

319,000, 383,000, and 437,500 ppm. The age of the rats was not 

specified, however, the initial body weight of the rats was 240 - 297 

grams. The gas was regulated through a calibrated flowmeter into a 

mixing chamber. Regulated flows of air and/or oxygen were used as 

the carrier gas from the mixing chamber to the exposure chamber. At 

the 66,400 ppm level, air was used as the carrier gas. At 175,200 

ppm, chamber concentrations were 16 – 17 %. Oxygen level was 

maintained at about 20 % for the exposure concentrations at or above 

319,000 ppm. Chamber atmospheres were sampled at 30-minute 

intervals and analyzed by thermal conductivity gas chromatography. 

Clinical observations were recorded during the exposure and postexposure. Gross pathology was performed on surviving rats after a 

14-day observation period. 

Remark : Reliability: High because a scientifically defensible or guidelined 

method was used. 

Result : Mortality ratio of 1/6 occurred at 383,000 ppm and 2/6 occurred at 

437,500 ppm. Labored breathing, lethargy, and unresponsiveness to 

sound were observed during exposure. No clinical signs were noted 

following exposure. No compound-related gross pathology changes 

were observed. 

Test substance : HFC-152a, purity 99.9 % 

Reliability : (1) valid without restriction 

 1d. Test procedure in accordance with generally accepted scientific 

standards and described in sufficient detail. 

Flag : Critical study for SIDS endpoint 

09.01.2006 (18)

Type : other: Cardiac Sensitization 

Value : 150,000 ppm 

Species : dog 

Strain : Beagle 

Sex : male 

Number of animals : 24 

Vehicle : 

Doses : 50,000, 150,000 ppm 

Exposure time : 5 minute(s) 

Method : other 

Year : 1969 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : Beagle dogs (12/group) were exposed to 50,000 or 150,000 ppm for 5 

minutes. The age of the dogs was not specified. The dogs received a 

control injection of epinephrine (0.008 mg/kg) intravenously, prior to 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

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 UNEP PUBLICATIONS 49

exposure and a challenge injection (same dosage) after breathing the 

test material for 5 minutes. The desired concentrations (calculated) 

were achieved by delivering a metered volume of the vapor or gas 

from the pressured cylinder containing the test substance and diluting 

it with a known volume of air. The flow meter used for monitoring 

the test compound had been previously calibrated with the compound 

by a dry gas test meter. 

The dogs were trained to maintain a standing position while lightly 

supported by a cloth sling with a hole for each leg, to wear a mask 

over their snout, and to accept a venupuncture. An electrocardiogram 

was recorded continuously during the experimental procedure. 

Result : Marked responses (a cardiac arrhythmia which was considered to 

pose a serious threat to life) were observed in 3 of the 12 dogs at the 

150,000 ppm level. No response was seen at the 50,000 ppm level. 

Test substance : HFC-152a, purity 99.99 % 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

Flag : Critical study for SIDS endpoint 

24.03.2006 (17) (56)

Type : other 

Value : 

Species : rat 

Strain : other: albino 

Sex : no data 

Number of animals : 

Vehicle : 

Doses : ranged from 100,000 to 550,000 ppm 

Exposure time : 30 minute(s) 

Method : other 

Year : 1950 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : Rats were exposed for a maximum of 30 minutes to concentrations 

ranging from 100,000 to 550,000 ppm. 

Result : The postural reflex was lost at 200,000 ppm, righting reflex was lost 

at 250,000 ppm, and the corneal reflex was lost at 450,000 ppm. 

Exposure to concentrations > 500,000 ppm was lethal in 10 - 25 

minutes. At concentrations of 400,000 ppm or higher, there was 

considerable effusion of fluid from the respiratory tract, indicative of 

acute irritation of the lungs. 

Test substance : HFC-152a, purity not reported 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

04.04.2006 (46)

Type : other 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 50

Value : 

Species : rat 

Strain : no data 

Sex : no data 

Number of animals : 2 

Vehicle : 

Doses : 74,000, 100,000, or 200,000 ppm 

Exposure time : 2 hour(s) 

Method : other 

Year : 1952 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Result : Occasional trembling and incoordination were observed during the 

exposure. No gross or pathological changes were found in the rats 4 

– 7 days post-exposure. 

Test substance : HFC-152, purity not specified 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

11.01.2006 (15)

Type : other: Approximate Lethal Concentration (ALC) (Lethality in 2 - 4 of 

6 rats) 

Value : 64,000 ppm 

Species : rat 

Strain : Sherman 

Sex : male/female 

Number of animals : 6 

Vehicle : 

Doses : 

Exposure time : 4 hour(s) 

Method : other 

Year : 1949 

GLP : no 

Test substance : as prescribed by 1.1 – 1.4 

Result : Inhalation of 64,000 ppm HFC-152a for 4 hours killed 2/6, 3/6, or 4/6 

rats. 

Test substance : HFC-152a, purity not reported 

Reliability : (2) valid with restrictions 

 3a. Documentation insufficient for assessment. 

04.04.2006 (9)

Type : LC50

Value : 977,200 ppm 

Species : mouse 

Strain : no data 

Sex : no data 

Number of animals : 

Vehicle : 

Doses : 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

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 UNEP PUBLICATIONS 51

Exposure time : 2 hour(s) 

Method : other 

Year : 1982 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Result : The LC50 was 977,200 ppm (896,000 - 1,065,000 ppm). Narcotic 

effects were observed at the LC50. 

Test substance : HFC-152a, purity not reported 

Reliability : (4) not assignable 

 4b. Secondary literature. 

24.03.2006 (42)

Type : other 

Value : 

Species : dog 

Strain : no data 

Sex : no data 

Number of animals : 3 

Vehicle : 

Doses : 500,000 ppm 

Exposure time : 

Method : other 

Year : 1960 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : Three dogs inhaled HFC-152a at a concentration of 500,000 ppm. 

Two dogs also received atropine and succinylcholine intravenously. 

Result : Light surgical anesthesia, with no change in EKG, resulted. 

Test substance : HFC-152a, purity not reported 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

11.01.2006 (65)

Type : other 

Value : 

Species : human 

Strain : 

Sex : 

Number of animals : 

Vehicle : 

Doses : 50,000 ppm 

Exposure time : 

Method : other 

Year : 1960 

GLP : no data 

Test substance : as prescribed by 1.1 – 1.4 

Result : HFC-152a was inhaled briefly by several volunteers, who noted good 

analgesia and impending loss of consciousness. 

Test substance : HFC-152a, purity not reported 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

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Reliability : (3) invalid 

 3a. Documentation insufficient for assessment. 

11.01.2006 (65)

Type : other: Acute Inhalation Toxicity of Pyrolysis Products 

Value : 

Species : rat 

Strain : other: CHR-CD 

Sex : male 

Number of animals : 

Vehicle : 

Doses : various temperatures (1,100, 1,200, and 1,300 °C) 

Exposure time : 15 minute(s) 

Method : 

Year : 1966 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : Rats were exposed for 15 minutes to vapors produced by heating 

HFC-152a to various temperatures (1,100, 1,200, and 1,300 °C). 

Result : No mortality was observed in the study. Clinical signs observed at all 

three temperatures included ptosis, apnea, pale ears followed by 

hyperemia, marked dyspnea followed by rapid irregular respiration, 

lacrimation, chromodacryorrhea, salivation, and moderate 

responsiveness. Rats exposed at 1,300 °C also exhibited gasping and 

mild convulsions. 

Test substance : HFC-152a, purity not reported 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

11.01.2006 (16)

Type : other: Cardiac Sensitization 

Value : 

Species : rat 

Strain : Wistar 

Sex : female 

Number of animals : 50 

Vehicle : 

Doses : 25,000, 50,000, 100,000, 200,000, 400,000 ppm 

Exposure time : 

Method : other 

Year : 1975 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Method : Female rats were anesthetized. 

Result : Administration of 100,000 ppm HFC-152a caused slowing of the 

heart rate whereas 50,000 ppm provoked abnormalities of the 

electrocardiographic patterns (prolongation of the P-R interval, 

elevation of the S-T segment, and widening of the T-wave). 

Test substance : HFC-152a, purity not reported 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 53

Reliability : (3) invalid 

 3b. Significant methodological deficiencies. 

24.03.2006 (13)

Type : other: Cardiac Sensitization 

Value : 

Species : mouse 

Strain : Swiss 

Sex : male 

Number of animals : 

Vehicle : 

Doses : 200,000, 400,000 ppm 

Exposure time : 6 minute(s) 

Method : other 

Year : 1974 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Method : Exposure was to anesthetized mice 

Result : Exposure did not sensitize the heart to epinephrine. No cardiac 

arrythmias were observed. 

Test substance : HFC-152a, purity not reported 

Reliability : (3) invalid 

 3b. Significant methodological deficiencies. 

11.01.2006 (3)

Type : other: Cardiac Sensitization 

Value : 

Species : mouse 

Strain : Swiss 

Sex : male 

Number of animals : 

Vehicle : 

Doses : up to 400,000 ppm 

Exposure time : 4 minute(s) 

Method : other 

Year : 1974 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Method : Male mice were anesthetized. 

Result : Mice exhibited reduction in respiratory rate, tidal volume, respiratory 

minute volume, decreased pulmonary compliance, and increased 

pulmonary resistance. HFC-152a did not produce arrhythmias nor did 

it sensitize the heart to epinephrine. Inhalation of HFC-152a caused 

sensitization of the heart to epinephrine in mice that had 

experimentally induced bronchopulmonary lesions following 

intratracheal injection of papain. 

Test substance : HFC-152a, purity not reported 

Reliability : (3) invalid 

 3b. Significant methodological deficiencies. 

11.01.2006 (8)
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

 DATE: 29.06.2006 

 UNEP PUBLICATIONS 54

Type : other: Cardiotoxicity 

Value : 

Species : rat 

Strain : Wistar 

Sex : male 

Number of animals : 

Vehicle : 

Doses : 2.5, 5, 10, 20, 40 % 

Exposure time : 

Method : other 

Year : 1975 

GLP : no data 

Test substance : as prescribed by 1.1 – 1.4 

Result : There were no observations relating to the effect of HFC-152a on the 

respiratory system. In anesthetized rat, abnormalities in the 

electrocardiogram were produced at 40 % HFC-152a. 

Test substance : HFC-152a, purity not specified 

Reliability : (3) invalid 

 3b. Significant methodological deficiencies. 

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Type : other: Cardiotoxicity 

Value : 

Species : dog 

Strain : other: Mongrel 

Sex : male/female 

Number of animals : 13 

Vehicle : 

Doses : 20 % 

Exposure time : 5 minute(s) 

Method : other 

Year : 1975 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Method : Hemodyanamic effects of fluorocarbon propellants on the systemic 

and pulmonary components of the cardiovascular system were 

studied, with special attention to effects on cardiac output as reflected 

by mean pulmonary arterial flow, total systemic vascular resistance, 

and pulmonary vascular resistance. 

Result : HFC-152a administered at a maximal concentration of 20 %, except 

for a decrease in mean pulmonary arterial flow of 7 %, was without 

effect on the studied parameters. 

Test substance : HFC-152a, purity not specified 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

24.03.2006 (59)

Type : other: Cardiotoxicity 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

5. TOXICITY ID: 75-37-6 

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 UNEP PUBLICATIONS 55

Value : 

Species : dog 

Strain : 

Sex : 

Number of animals : 

Vehicle : 

Doses : 2.5, 5, 10, 20 % 

Exposure time : 

Method : other 

Year : 1975 

GLP : no data 

Test substance : as prescribed by 1.1 – 1.4 

Result : HFC-152a administered in 10 or 20 % concentration caused 

depression of the force of contraction and a displacement of the 

ventricular function curve. 

Test substance : HFC-152a, purity not specified 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

24.03.2006 (4)

Type : other: Cardiotoxicity 

Value : 

Species : dog 

Strain : other: Mogrel 

Sex : 

Number of animals : 

Vehicle : 

Doses : up to 20 % 

Exposure time : 5 minute(s) 

Method : other 

Year : 1975 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Result : HFC-152a did not influence the cardiovascular system when inhaled 

at a concentration of 20 %. However, at a concentration of 10 %, 

there was a stimulation of respiration and an increase in pulmonary 

resistance. 

Test substance : HFC-152a, purity not specified 

Reliability : (3) invalid 

 3b. Significant methodological deficiencies. 

24.03.2006 (6)

Type : other: Cardiotoxicity 

Value : 

Species : monkey 

Strain : other: Macaca mulatta 

Sex : 

Number of animals : 30 

Vehicle : 
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Doses : 2.5, 5, 10, 20 % 

Exposure time : 5 minute(s) 

Method : other 

Year : 1974 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Result : HFC-152a did not influence cardiac rhythm, heart rate, contracility, 

aortic blood pressure, left atrial pressure, or pulmonary arterial 

pressure. In concentrations as high as 20 %, HFC-152a can be 

regarded as inactive in the cardiovascular system. 

Test substance : HFC-152a, purity not specified 

Reliability : (3) invalid 

 3b. Significant methodological deficiencies. 

24.03.2006 (7)

Type : other: Cardiotoxicity 

Value : 

Species : monkey 

Strain : other: Rhesus 

Sex : 

Number of animals : 

Vehicle : 

Doses : up to 20 % 

Exposure time : 

Method : other 

Year : 1975 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Result : HFC-152a did not influence respiration or circulation, even when 

inhaled in levels up to 20 % concentration. 

Test substance : HFC-152a, purity not specified 

Reliability : (3) invalid 

 3b. Significant methodological deficiencies. 

24.03.2006 (5)

5.1.3 ACUTE DERMAL TOXICITY 

5.1.4 ACUTE TOXICITY, OTHER ROUTES 

5.2.1 SKIN IRRITATION 

5.2.2 EYE IRRITATION 
OECD SIDS 1,1-DIFLUOROETHANE (HFC-152A) 

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5.3 SENSITIZATION 

5.4 REPEATED DOSE TOXICITY 

Type : Sub-acute 

Species : rat 

Sex : male 

Strain : other: ChR-CD 

Route of admin. : inhalation 

Exposure period : 2 weeks 

Frequency of treatm. : 6 hours/day, 5 days/week 

Post exposure period : 14-day recovery period 

Doses : 100,000 ppm 

Control group : yes 

Method : other 

Year : 1976 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : Ten rats/concentration were exposed. Control animals were exposed 

to house-line air. Five rats/group were sacrificed for gross and 

histopathologic examination after the last exposure. The remaining 

rats were sacrificed after a 14-day recovery period. At both sacrifice 

intervals, hematological, urine analytical, and biochemical indices 

were also measured in all rats. 

Result : No clinical, hematological, blood chemistry or histopathological 

evidence of effect was seen. There was a slight increase in urinary 

fluoride following the last exposure. During the exposure the rats 

appeared to be anesthetized as indicated by sleeping and 

unresponsiveness to sound. 

Test substance : HFC-152a, purity 99.9+% 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

04.04.2006 (19)

Type : 

Species : rat 

Sex : no data 

Strain : other: albino 

Route of admin. : inhalation 

Exposure period : 2 months 

Frequency of treatm. : 16 hours/day 

Post exposure period : 

Doses : 100,000 ppm 

Control group : 

Method : other 

Year : 1950 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 
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Method : Eight rats were exposed to 10 % HFC-152a for 16 hours per day for 2 

months. At the conclusion of the repeated exposures, surviving 

animals were sacrificed and examined for gross pathological changes. 

Sections of lung and liver were examined microscopically. 

Result : No signs of ill health were apparent at any time. Gross examination at 

autopsy revealed no changes. Microscopic examination revealed a 

mild diffuse infiltration of small and large round cells in the lung 

suggestive of mild chronic irritation. 

Test substance : HFC-152a, purity not reported 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

04.04.2006 (46)

5.5 GENETIC TOXICITY ‘IN VITRO‘ 

Type : Bacterial reverse mutation assay 

System of testing : Salmonella typhimurium strains TA97a, TA98, TA100, and TA1535 

and Escherichia coli strain WP2uvrA (pKM101) 

Test concentration : 0, 20, 30, 40, 50, 75 % 

Cycotoxic concentr. : 

Metabolic activation : with and without 

Result : negative 

Method : OECD Guide-line 471 

Year : 2000 

GLP : yes 

Test substance : as prescribed by 1.1 - 1.4 

Method : This study also followed the U.S. EPA Health Effects Test Guideline 

OPPTS 799.9510 (1989) and Commission Directive 92/69/EEC, EEC 

Method B.12. 

The study consisted of 2 independent trials with and without a 

metabolic activation system (Aroclor®-induced rat liver S-9). Three 

replicates were plated for each tester strain, test concentration, and 

condition. Positive and negative controls were included in all assays. 

The reaction mixture (S-9 mix) contained glucose 6-phosphate, 

NADP, NaH2PO4, KCl, MgCl2, distilled water, and S-9. Treatments 

with activation were conducted by adding 0.5 mL of S-9 mix, and 0.1 

mL of an overnight culture to 2 mL of top agar. These components 

were briefly mixed and poured onto a minimal glucose agar plate. 

Treatments in the absence of the metabolic activation system were 

identical to those with activation with the exception that 0.5 mL of 

sterile buffer was used as a replacement for the S-9. 

Plates were exposed to dilutions of the test gas in 6-L glass chambers. 

The test substance and filtered air flows were regulated using 

individual rotameters, and mixed prior to entry into the chambers. 

Chambers were placed into an incubator at 37 oC for approximately 

48 hours. Gas chromatographic analysis was used to confirm the 
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5. TOXICITY ID: 75-37-6 

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concentration of test atmospheres. 

Bacterial background lawns were evaluated for evidence of test 

substance toxicity and precipitation. Revertant colonies for a given 

tester strain and condition were counted by an automated colony 

counter. 

Positive control substances tested in this study included 2-

nitrofluorene, N-ethyl-N-nitro-N-nitroguanidine, sodium azide, ICR 

191 acridine mutagen, 9,10-dimethyl-1,2-benzanthracene, and 2-

aminoanthracene. 

Filtered house-line air was the test substance diluent and negative 

control. 

A test substance was classified as positive if the mean number of 

revertants in any strain (except S. typhimurium TA1535) at any 

concentration was at least 2 times greater than the mean number of 

revertants of the concurrent negative control, and there was a 

concentration-related increase in the mean number of revertants per 

plate in that same strain. For S. typhimurium TA1535, there must be 

no test substance concentration with a mean number of revertants that 

is at least 3 times greater than the mean number of revertants of its 

concurrent negative control and a concentration-related increase in 

the mean number of revertants per plate. A test substance was 

classified as negative if all positive classification criteria for all 

strains were not met. 

Data for each tester strain were evaluated independently. For each 

tester strain, the mean number of revertants and the standard 

deviation at each concentration in the presence and absence of the 

exogenous metabolic system were calculated. 

Result : The actual concentrations for the first trial were 0, 20.4, 33.5, 42.0, 

55.5, and 82.7 % in the absence of S-9 and 0, 21.7, 33.4, 43.6, 56.1, 

and 84.4 % in the presence of S-9. No test substance-related 

precipitate was observed at any concentration level. Test substancerelated toxicity, evidenced by the concentration-dependent reduction 

in the mean number of revertants per plate, was observed in the first 

trial in S. typhimurium strains TA97a (-S-9) and TA1535 (+S-9), and 

in the E. coli strain (+S-9, -S-9). 

The actual concentrations for the second trial were 0, 20.5, 30.9, 41.4, 

53.9, and 85.1 % in the absence of S-9 and 0, 20.8, 31.7, 41.9, 55.3, 

and 81.4 % in the presence of S-9. Test substance-related toxicity, 

evidenced by the concentration-dependent reduction in the mean 

number of revertants per plate, was observed in the first second in S. 

typhimurium strains TA97a (-S-9) and TA98 (+S-9, -S-9), and in the 

E. coli strain (+S-9, -S-9). 

All acceptability criteria were met in this test. All tester strains 
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exhibited appropriate phenotypic characteristics. No test substancerelated precipitate was observed. The mean number of revertants in 

the negative control for each strain was within the prescribed 

acceptable historical control range. Mean positive control values for 

the tester strains exhibited greater than a 3-fold increase over the 

means of the respective negative controls in both trials. Differences 

between targeted and actual doses in both analyses were acceptable 

for the purposes of this assay and in no way impacted the integrity or 

validity of this study. 

Test substance : HFC-152a, purity 99.99 % 

Reliability : (1) valid without restriction 

 1a. GLP guideline study. 

Flag : Critical study for SIDS endpoint 

09.01.2006 (28)

Type : Chromosomal aberration test 

System of testing : Human lymphocytes 

Test concentration : Test 1 (3-hour exposure with and without S-9): 0, 35, 50, 70 % 

Test 2 (3-hour exposure with S-9): 0, 35, 50, 70 % 

Test 2 (19-hour exposure without S-9): 0, 35, 50, 70 % 

Test 3 (19-hour exposure without S-9): 0, 50, 60, 70 % 

Cycotoxic concentr. : 

Metabolic activation : with and without 

Result : 

Method : OECD Guide-line 473 

Year : 2000 

GLP : yes 

Test substance : as prescribed by 1.1 - 1.4 

Method : This study also followed the U.S. EPA Health Effects Test 

Guidelines OPPTS 870.5375 (1998). 

Human lymphocytes, in whole blood culture, were stimulated to 

divide by addition of phytohaemagglutinin, and duplicate cultures 

were exposed to the test substance. Treatment atmospheres of the test 

substance were prepared in sterile glass bottles with septum caps. 

Negative and positive control cultures were also prepared. Mitomycin 

C and cyclophosphamide were used as positive control substances. 

Air was used as the negative control substance. 

The test substance was sampled from the cylinder into a gas-sampling 

bag. Air was withdrawn from each pre-warmed (37 °C) bottle and 

then an appropriate volume of test substance gas was introduced from 

the sampling bag, inserted through the septum cap, and the 

atmosphere was equilibrated at 37 °C. After injection of the 

lymphocyte culture, air was allowed to enter each bottle through a 

hollow needle to produce the required concentration at atmospheric 

pressure. After approximately 48 hours, the cultures in duplicate were 

injected into the sterile glass bottles. The culture bottles were 

incubated on their sides at 37 °C in a roller apparatus which rotated 

the bottles once every 8 minutes. 
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Test 1 included a 3-hour treatment with and without S-9 mix and 16 

hours of recovery. Test 2 included a 3-hour treatment with S-9 mix 

and 16 hours of recovery, and a 19-hour continuous treatment without 

S-9. 

Following the results of the second test, a third test was performed for 

a continuous treatment time, in the absence of S-9 only, to 

demonstrate reproducibility. 

Two hours before the end of the incubation period, cell division was 

arrested using Colcemid(R), the cells harvested and slides prepared, 

so that metaphase cells could be examined for numerical (polyploidy) 

and structural chromosomal damage. 

In order to assess the toxicity to cultured lymphocytes, the mitotic 

index was calculated for all cultures treated with the test substance 

and the negative control. The highest dose level scored for 

chromosomal damage was, whenever possible, selected as the dose 

level causing a relative depression in mitotic index of at least 50 %. 

The test substance was considered to cause a positive response if the 

following conditions were met: 

Statistically significant increases (p < 0.01) in the frequency of 

metaphases with aberrant chromosomes (excluding gaps) were 

observed at one or more test concentration. 

The increases exceeded the negative control range of this laboratory, 

taken at the 99 % confidence limit. 

The increases were reproducible between replicate cultures. 

The increases were not associated with large changes in osmolality of 

the treatment medium or extreme toxicity. 

Evidence of a dose-relationship was considered to support the 

conclusion. 

A negative response was claimed if no statistically significant 

increases in the number of aberrant cells above concurrent control 

frequencies were observed, at any dose level. 

The numbers of aberrant and polyploid metaphase figures in each 

treatment group were compared with the negative control value using 

a one-tailed Fisher's test. 

Result : No substantial toxicity (greater than or equal to 50 % mitotic 

inhibition) was observed at any dose level under any testing 

condition. 
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In the first test, after 3-hour exposure in the absence or presence of S9, the test substance caused no biologically relevant statistically 

significant increases in the proportion of cells with chromosomal 

aberrations at any dose level. 

In the second test, after 19-hour exposure in the absence of S-9, the 

test substance caused statistically significant increases in the 

proportion of metaphase figures containing chromosomal aberrations 

at the 70 % dose levels both including and excluding gap-type 

aberrations. A trend test analysis also recorded a statistically 

significant dose-response. The observed increased chromosome 

aberration frequencies were outside the upper 99 % confidence limits 

of the historical control range. In the presence of S-9, the test 

substance caused no statistically significant increase in the proportion 

of metaphase figures containing chromosomal aberrations at any dose 

level. 

In the third test, after a confirmatory 19-hour exposure in the absence 

of S-9, the test substance caused a statistically significant increase in 

the proportion of cells with chromosomal aberrations only at the 60 

% dose level, excluding gap-type aberrations only. There was, 

however, no recording of a statistically significant dose-response. 

Cultures treated with the test substance at 50 and 70 % did not show 

any statistically significant chromosome aberration increases. 

A quantitative analysis for polyploidy was made in cultures treated 

with the negative control and highest dose level. No increases in the 

proportion of polyploid cells were seen in any test. 

All positive control compounds caused large, statistically significant 

increases in the proportion of aberrant cells, demonstrating the 

sensitivity of the test system and the efficacy of the S-9 mix. 

It was concluded that the test substance showed statistically 

significant evidence of clastogenic activity in this test system only 

after continuous 19-hour treatment in the absence of S-9. However, 

the observed positive responses were weak and considered to be of 

marginal biological relevance. 

Test substance : HFC-152a, purity 99.99 % 

Conclusion : Weakly positive 

Reliability : (1) valid without restriction 

 1a. GLP guideline study. 

Flag : Critical study for SIDS endpoint 

09.01.2006 (27)

Type : Bacterial reverse mutation assay 

System of testing : Salmonella typhimurium strains TA98, TA97, TA100, and TA1537 

or in Escherichia coli WP2 uvrA 

Test concentration : 

Cycotoxic concentr. : 
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Metabolic activation : with and without 

Result : negative 

Method : other 

Year : 1994 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Test substance : HFC-152a, purity not reported 

Reliability : (4) not assignable 

 4a. Abstract. 

23.03.2006 (2)

Type : Bacterial reverse mutation assay 

System of testing : Salmonella typhimurium strains TA1535, TA1537, TA98, and 

TA100 

Test concentration : 0, 20, 35, 50 % 

Cycotoxic concentr. : 

Metabolic activation : with and without 

Result : negative 

Method : other 

Year : 1977 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Test substance : HFC-152a, purity 99.9+% 

Reliability : (4) not assignable 

 4a. Abstract. 

09.01.2006 (20)

Type : Bacterial reverse mutation assay 

System of testing : Salmonella typhimurium strains TA1535 and TA100 

Test concentration : 

Cycotoxic concentr. : 

Metabolic activation : with 

Result : negative 

Method : other 

Year : 1984 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Test substance : HFC-152a, purity not reported 

Reliability : (4) not assignable 

 4a. Abstract. 

09.01.2006 (48)

5.6 GENETIC TOXICITY ‘IN VIVO‘ 

Type : Micronucleus assay 

Species : rat 

Sex : male/female 

Strain : Sprague-Dawley 

Route of admin. : inhalation 
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Exposure period : 6 hours 

Doses : 0, 4875, 9750, 19,500 ppm 

Result : negative 

Method : OECD Guide-line 474 "Genetic Toxicology: Micronucleus Test" 

Year : 2001 

GLP : yes 

Test substance : as prescribed by 1.1 - 1.4 

Method : The procedures used in the test were also based on the 

recommendations of the EC Commission Directive 2000/32/EC 

Annex 4C - B.12. Mutagenicity - In vivo mammalian erythrocyte 

micronucleus test. No. L 136/50 and US EPA (1998) Health Effects 

Test Guidelines; OPPTS 870.5395 Mammalian erythrocyte 

micronucleus test. EPA 712-C-98-226. 

Animals were treated for a single 6-hour period of whole body 

inhalation exposure to nominal concentrations of 4,875, 9,750, and 

19,500 ppm. The negative control group received clean air only. The 

positive control group was dosed, orally, by gastric intubation, with 

cyclophosphamide at 20 mg/kg body weight. Rats weighed between 

140 and 149 grams on dispatch from the supplier. Each group of 

animals was kept, with sexes separate, in cages and maintained in a 

controlled environment. Temperatures recorded throughout the test 

were in the range 21 ± 2 °C. Relative humidity was recorded in the 

range 34 - 56 %. Although the lower limit was outside the normal 

range for this species (55 ± 10 %), no adverse effects were recorded 

for any animal throughout the test and was not considered to have any 

affect on the integrity of the study. The room was illuminated by 

artificial light for 12 hours per day. Animals were provided with food 

and tap water ad libitum except during the period of inhalation 

exposure. 

Animals were exposed in whole-body exposure chambers constructed 

from stainless steel and glass. The internal volume of each chamber 

was approximately 750 litres. Air was introduced into each exposure 

chamber at a total rate of 150 litres per minute. The flow through 

each chamber was approximately 12 air changes an hour; normally 

sufficient to maintain oxygen concentration above 19 % v/v, 

temperature approximately 22 (± 1) °C and relative humidity between 

40 – 60 %. The exposure chamber was maintained 1 - 10 mm H2O 

below ambient pressure. Animals were housed singly in stainless 

steel mesh compartments during exposure. 

The test atmosphere was produced by diluting the gaseous test 

substance with air. Adjustments were made to the gaseous test 

substance supply to each chamber during exposures in order to 

maintain the desired concentrations. The dilutions of gaseous test 

substance with air were determined during preliminary generation 

trials. During exposure the chamber atmosphere was sampled to 

determine the concentration of test vapor on at least six occasions 

during each exposure. The nominal concentration of test substance 
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was calculated by recording the amount of test substance delivered to 

the generation system during the exposure. The usage over the six 

hours exposure was divided by the total airflow through the chamber. 

Any losses during the generation process were quantified and 

included in the calculation of the nominal concentration. Airflow, 

chamber temperature, and humidity were monitored continuously and 

recorded at approximately 30-minute intervals. 

Following dosing, the animals were examined regularly and any 

observed mortality or adverse clinical signs were recorded. Five 

males and five females were sacrificed from the negative control and 

each of the test substance groups 24 hours after completion of the 

exposure period and from the positive control group 24 hours after 

dosing. In addition 5 male and 5 female animals were sacrificed from 

the negative control and high level treatment groups 48 hours after 

completion of the exposure period. 

The animals were killed by cervical dislocation following carbon 

dioxide inhalation and both femurs dissected out from each animal. 

The femurs were cleared of tissue and the proximal epiphysis 

removed from each bone. The bone marrow of both femurs from each 

animal was flushed out and pooled in a total volume of 10 mL Hanks' 

balanced salts solution by aspiration. The resulting cell suspensions 

were centrifuged at 1,000 rpm (150 x g) for 5 minutes and the 

supernatant discarded. Each resulting cell pellet was resuspended in 2 

mL of filtered foetal calf serum before being sedimented by 

centrifugation. The supernatant was discarded and the final cell pellet 

was resuspended in a small volume of foetal calf serum to facilitate 

smearing in the conventional manner on glass microscope slides. 

Several smears were prepared from each femur. 

Due to the presence of mast cell granules in rat bone smears, which 

appear identical to micronuclei when stained using the Romanowsky 

methods, a modified Feulgen staining method was employed. This 

method specifically stains DNA-containing bodies deep purple while 

leaving mast cell granules unstained. The method also allows 

reasonable differentiation of mature and immature erythrocytes and 

produces permanent preparations. The stained smears were examined 

(under code) by light microscopy to determine the incidence of 

micronucleated cells per 2000 immature erythrocytes (polychromatic 

erythrocytes, PCE) per animal. The proportion of PCEs was assessed 

by examination of at least 1000 erythrocytes from each animal. 

The results for each treatment group were compared with the results 

for the concurrent control group using non-parametric statistics. For 

incidences of micronucleated immature erythrocytes, exact one-sided 

P-values were calculated by permutation. Comparison of several dose 

levels was made with the concurrent control using the Linear by 

Linear Association test for trend, in a step-down fashion if 

significance was detected. For individual inter-group comparisons 
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(i.e. the positive control group), this procedure simplified to a 

straightforward permutation test. For assessment of effects on the 

proportion of immature erythrocytes, equivalent permutation tests 

based on rank scores were used, i.e. exact versions of Wilcoxon's sum 

of ranks test and Jonckheere's test for trend. 

Result : The exposure mean concentrations of the test material were 5,031, 

9,413, and 19,030 ppm compared with target levels of 4,875, 9,750, 

and 19,500 ppm, respectively, expressed in terms of volume of test 

substance vapour per unit volume of atmosphere. 

Neither mortality nor adverse clinical signs was observed in the 

micronucleus test for any animal in any dose group over the duration 

of the test. 

No statistically significant increases in the frequency of 

micronucleated PCEs and no substantial decrease in the proportion of 

PCEs were observed in rats treated with the test substance and killed 

24 or 48 hours, compared to negative control values. 

The positive control compound, cyclophosphamide, produced large, 

highly significant increases in the frequency of micronucleated PCEs 

and a decrease in the proportion of PCEs. 

It was concluded that the test substance did not show any evidence of 

causing chromosome damage or bone marrow cell toxicity when 

administered by whole body inhalation exposure in this in vivo test 

procedure. 

Test substance : HFC-152a, purity 99.99 % 

Reliability : (1) valid without restriction 

 1a. GLP guideline study. 

Flag : Critical study for SIDS endpoint 

09.01.2006 (29)

Type : Drosophila SLRL test 

Species : Drosophila melanogaster 

Sex : male/female 

Strain : other: Canton-S 

Route of admin. : 

Exposure period : 5 minutes 

Doses : 100 %; flow rate of 10 mL/min 

Result : positive 

Method : other 

Year : 1974 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : The Canton-Special (Canton-S) strain was obtained from the 

laboratory of Dr. Luolin Browning of Houston Texas. The cultures 

were kept under standard laboratory conditions in an air conditioned 

room at approximately 22 °C. Newly hatched (< 12 hours old) 

unetherized virgin flies were used. 
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A Turner bulb apparatus was used. The gas was passed through a 

cotton trap and from there into a dry gassing chamber that contained 

the flies. From this Turner bulb, tubing connected with the inlet of a 

second Turner bulb, which contained 15 mL of water, into which the 

gas was bubbled. In this way, 100 ± 5 bubbles per minute could 

easily be counted. The rate of gas flow in mL/min, as determined by 

bubble count, was also measured by water displacement. The gassing 

time was 5 minutes with a flow rate of 10 mL/min, with the flies 

remaining in the gaseous atmosphere another 5 minutes. The treated 

flies were then placed in a clean container and observed. Upon 

recovery, the flies were lightly etherized and the males placed in 1/2 

pint culture bottles. The females were discarded. Using the Basc 

technique, untreated Muller-5 virgin females were placed with 

Canton-S treated males. The Basc technique was used for scoring 

sex-linked recessive lethal mutations that arose in the germ line of the 

treated paternal male. The protocol for scoring semilethal (mosaic 

lethal) recessive mutations was to further test any F2 culture having a 

ratio of at least 10 heterozygous females, or 11 Basc males, to 1 

normal male, and if this ratio continued in the F3 generation, to score 

the culture as a semilethal mutation. 

The significance of the mutation rate induced was determined by ttest comparison to the control rate. 

Result : Individual lethal tests of 276 F1 females gave 1 lethal and 8 semilethal, each scored as 0.5 lethal, giving a lethal count of 5/276 

chromosomes. A lethal mutation frequency of 1.5 % was calculated; 

this value was corrected for a spontaneous frequency of 0.23 %. A 

number of developmental type abnormalities were noted among F2 

progeny. One heterozygous female had ocelli in place of proboscis 

and no proboscis was present. Eye color mutants transmitted were 

white, apricot, and a deep orange. 

Test substance : HFC-152a, purity > 98 % 

Reliability : (4) not assignable 

 4e. Documentation insufficient for assessment. 

09.01.2006 (38)

Type : Drosophila SLRL test 

Species : Drosophila melanogaster 

Sex : 

Strain : other: Canton-S and Muller-5 

Route of admin. : 

Exposure period : 6 minutes 

Doses : 

Result : positive 

Method : other 

Year : 1974 

GLP : no data 

Test substance : as prescribed by 1.1 - 1.4 

Result : HFC-152a was mutagenic to Drosophila melanogaster as determined 
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by the Basc technique for the detection of sex-linked lethal recessive 

mutations. Treatment with HFC-152a produced a mutation rate of 

1.31 ± 0.05. 

Test substance : HFC-152a, purity 99.5 - 99.9 % 

Reliability : (2) valid with restrictions 

 2d. Test procedure in accordance with national standard methods with 

acceptable restrictions. 

09.01.2006 (39)

5.7 CARCINOGENICITY 

Species : rat 

Sex : male/female 

Strain : other:Crl:CD(R)Br 

Route of admin. : inhalation 

Exposure period : 2 years 

Frequency of treatm. : 6 hours/day, 5 days/week (excluding holidays) 

Post exposure period : 

Doses : 0, 2,000, 10,000, 25,000 ppm 

Result : negative 

Control group : yes 

Method : other 

Year : 1982 

GLP : yes 

Test substance : as prescribed by 1.1 - 1.4 

Method : Food and water were available to the rats ad libitum except during 

exposures. Thirty rats per sex per concentration (54 days of age at 

the time of the first exposure) were exposed whole-body to the vapor. 

During exposures, chamber temperature and relative humidity were 

maintained at approximately 24 ± 5 °C and 50 ± 10 %, respectively. 

Chamber atmospheres were generated by metering HFC-152a vapors 

from 1-ton cylinders of liquid HFC-152a, maintained at room 

temperature, through rotometers into the chamber air flow. The 

control chamber received dilution air only. Chamber atmospheres 

were quantitatively analyzed for HFC-152a by gas chromotography. 

Body weights were recorded twice monthly for the first 14 weeks, 

and then once monthly for the remainder of the study. All animals 

were observed for abnormal behavior and clinical signs of toxicity 

twice daily during the work week. On weekends and holidays, all 

cages were observed daily for animals that had died. 

Ten rats/sex/group were subjected to clinical pathology evaluation at 

1, 3, 6, 12, 18, and 24 months on test. Twelve hematological and 8 

clinical chemistry parameters were measured or calculated. On the 

day prior to each bleeding time, an overnight urine specimen was 

collected and 12 urine parameters were measured or calculated. 

Ten rats/sex/group were sacrificed and necropsied at 3 and 12 
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months. All surviving rats at 24 months were sacrificed and 

necropsied. Gross examinations were conducted on all rats and 38 

tissues were saved for microscopic examination. Organ weights were 

recorded for 10 of the organs. Histopathological examinations were 

conducted on the control and high-exposure groups and on any 

animals that died or were sacrificed in extremis. In addition, kidneys 

and nasal tissues at the 3-month and 24-month final sacrifices, 

respectively, from all intermediate- and low-exposure rats received 

histological evaluation. 

Clinical measurements were subjected to partially-nested and crossed 

analysis of variance. Organ weight and final body weight data were 

subjected to one-way analysis of variance and Dunnett's test. The 

least significant differences from control values were calculated 

whenever the ratio of variances indicated that differences existed 

among the study groups. Body weight data were subjected to oneway analysis of variance. Significance was judged at the p = 0.05 

level of significance. The results of histopathologic examination were 

analyzed by the Fisher's Exact Test for differences between control 

and exposed groups and by the Mantel-Haenszel Test for a doserelated trend. 

Result : Overall means and standard deviations of the weekly average 

exposure concentrations were 2,000 ± 100, 10,000 ± 500, and 25,000 

± 600 ppm HFC-152a. 

Mean body weights and body weight gains of male and female rats 

were comparable or superior to their respective controls. Ocular/nasal 

discharges (25,000 ppm males and females), wet/stained perinea 

(25,000 ppm males and females), and stained body/face (25,000 

females) were observed. Dose-response trends were apparent for the 

latter two signs. Swollen ears were significantly elevated in the 2000 

ppm male and the 25,000 ppm males and females with a dose-related 

trend apparent in the females. Incidence of the clinical signs noted 

above are presented in the table below: 

Exposure (ppm) 0 2,000 10,000 25,000 

Males 

Ocular/nasal discharges 19a 27 21 31 

Wet/stained perineum 10 4 12 25 

Swollen ears 11 30 16 31 

Females 

Ocular/nasal discharges 13 16 15 24 

Wet/stained perineum 30 18 36 50 

Stained body/face 3 6 9 21 

Swollen ears 4 5 4 16 

a Incidence is the total number of rats affected throughout the study. 
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At the time of final sacrifice, mortality ratios of male rats were 

48/100, 51/100, 49/100, and 51/100 in the 0, 2,000, 10,000 and 

25,000 ppm groups, respectively. Mortality ratios in female rats were 

54/100, 61/100, 47/100, and 47/100 in the 0, 2,000, 10,000 and 

25,000 ppm groups, respectively. 

Over the duration of the study, female rats exhibited increased mean 

corpuscular volumes (10,000 and 25,000 ppm) and increased serum 

bilirubin (all treatment groups), while male rats exhibited increased 

hematocrits (10,000 and 25,000 ppm), increased mean corpuscular 

volumes (10,000 and 25,000 ppm), and increased urobilinogin 

(25,000 ppm). In the absence of any abnormalities in hematopoietic 

tissues or red blood cell counts among either males or females or of 

changes in serum bilirubin in males, the above observations, which 

would be consistent with a hemolytic effect, provide inconclusive 

evidence of such a condition. While significantly lower than control 

values for all treated female groups when analyzed as relative 

numbers, eosinophils were significantly low only for the 10,000 ppm 

female group when analyzed as absolute numbers. Monocytes were 

significantly lower than control values for all treated male groups 

when analyzed as either relative or absolute numbers. The depression 

in monocytes, however, is of unknown clinical or biological 

significance. 

A dose-related increase in urinary fluoride concentration and 

excretion was observed in the 10,000 and 25,000 ppm male and 

female rats and in the 2,000 ppm males when evaluated over the 

entire study. Urine fluoride concentrations (μg) are listed in the tables 

below. 

Months on Test (males) 1 3 6 12 18 24 

Concentration (ppm) Urine Fluoride (ppm) 

0 1.7 1.4 3.7 3.4 10.9 2.5 

2,000 2.9 1.9 6.9 7.1 38.9 4.2 

10,000 6.5 5.6 13.7 16.4 44.8 8.5 

25,000 8.1 11.8 19.2 30.9 88.4 13.0 

Months on Test (females): 1 3 6 12 18 24 

Concentration (ppm) Urine Fluoride (ppm) 

0 4.2 2.3 3.5 2.8 10.8 2.2 

2,000 5.3 2.4 5.3 4.5 17.0 4.1 

10,000 9.4 4.9 11.8 12.5 32.0 13.5 

25,000 9.6 5.3 14.2 14.6 42.8 10.5 

Serum creatinine was significantly elevated in both the 10,000 and 

25,000 ppm female groups. The latter also exhibited increased urine 

volume and a decrease in urine osmolality. 
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At the 3-month sacrifice, statistically significant differences in the 

following organ weights were noted: increased absolute heart, 

stomach, and adrenal weights (2000 ppm males); decreased absolute 

liver and spleen weights (25,000 ppm males); decreased relative liver 

and spleen weights (10,000 and 25,000 ppm males); decreased 

relative lung weights (2,000 and 25,000 ppm males); decreased 

relative testes weights (10,000 ppm males); decreased relative 

pituitary weights (2,000 ppm males); increased absolute stomach 

weights (2,000 ppm females); increased adrenal weights (2,000 and 

10,000 ppm females); decreased absolute brain weights (25,000 

females); decreased relative brain weights (2,000 and 25,000 ppm 

females); decreased absolute heart weight (25,000 females); 

decreased relative heart weights (all treated female groups); 

decreased absolute lung weights (10,000 and 25,000 ppm females); 

decreased absolute spleen weights (25,000 ppm females); decreased 

relative spleen weights (all treated females); increased absolute 

pituitary weights (all treated females); increased relative pituitary 

weights (10,000 and 25,000 ppm females); and decreased relative 

liver weights (25,000 ppm females). Renal tubular changes were 

noted in females at the 3-month sacrifice. The changes consisted of 

slight cytoplasmic vacuolation, luminal dilation, and presence of 

occasional vesiculated nuclei in 4/10 males and 7/10 females in the 

25,000 ppm group. Similar lesions were not seen in rats from the 

2,000 or 10,000 ppm groups. A pathological peer review of the study 

by Pathology Associates revealed no distinct evidence of HFC-152ainduced toxicity or carcinogenicity in any tissue examined. 

Preparation of additional kidney sections indicated that renal tubular 

changes recorded by the original pathologist in female rats sacrificed 

after 3 months exposure were the result of tissue processing artifact 

rather than treatment-related nephrotoxicity. 

At the 12-month sacrifice, no differences in macroscopic lesions were 

detected between the treated and control groups. No compoundrelated neoplastic or non-neoplastic lesions were observed. 

Differences in mean absolute and relative organ weights of animals 

sacrificed at 12 months consisted of: increased absolute lung weights 

(10,000 ppm males); decreased absolute thymus weights (2,000 ppm 

males); decreased relative thymus weights (2,000 and 10,000 ppm 

males); increased relative heart and stomach weights (25,000 ppm 

males); decreased absolute pituitary weights (2,000 and 10,000 ppm 

females); decreased relative pituitary weights (all treated females); 

and decreased relative liver weights (25,000 ppm females). 

No statistically significant difference in mean absolute or relative 

organ weights were noted between treated and control male rats 

sacrificed at 24 months. However, treated female rats presented the 

following differences from control in organ weights: increased 

absolute and relative lung weights (2,000 and 10,000 ppm), increased 

absolute stomach weight (25,000 ppm), increased relative stomach 
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weight (all treated females), increased relative heart weight (2000 

ppm), and increased relative liver weight (25,000 ppm). 

Female Exposure (ppm) 0 2,000 10,000 25,000 

Absolute lung weight (g) 1.9939 2.1244 2.1166 2.0562 

Relative lung weight (g) 0.3870 0.4447 0.4415 0.4115 

Absolute stomach weight (g) 2.5302 2.6428 2.6200 2.7792 

Relative stomach weight (g) 0.4857 0.5494 0.5446 0.5448 

Relative heart weight (g) 0.2570 0.3176 0.2966 0.2917 

Relative liver weight (g) 3.3324 3.4723 3.6701 3.8151 

Atrophy of the nasal olfactory epithelium was noted at the 2-year 

sacrifice in some rats from all but the intermediate-exposure females. 

Incidences of the lesions are provided in the table below. The 

incidence of focal mucosal metaplasia in all treated groups were 

clearly not dose-related. The increased incidence of mucosal atrophy 

was statistically significant in the 2,000 and 25,000 ppm male and 

female groups, although an analysis for dose-related trend was 

significant only in the males. 

Exposure (ppm) 0 2,000 10,000 25,000 

Males 

No. of nasal 

tissues examined 97 87 92 89 

Focal mucosal 

 metaplasia 57 21 21 21 

Mucosal atrophy 0 5 2 8 

Females 

No. of nasal 

 tissues examined 95 88 91 95 

Focal mucosal 

 metaplasia 22 17 6 23 

Mucosal atrophy 0 9 0 17 

Atrophy of the olfactory epithelium was confirmed by the peer 

review to be present in small numbers of females exposed for 2 years. 

These nasal changes, however, usually were unilateral in distribution 

and were entirely consistent with olfactory lesions, which have been 

described as spontaneous alterations in aging rats. Further, group 

incidence trends for olfactory atrophy were inconsistent with 

exposure concentration gradients. Olfactory changes, therefore, were 

not regarded as treatment related. 

A nasal adenoma in 1 male and 1 female from the 25,000 ppm groups 

and osteomas originating from the skull in 3 males from the 25,000 
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ppm group were observed at the final sacrifice. These tumor types did 

not occur in the concurrent controls. The incidence of neither tumor 

was statistically significant and each was considered to be of unclear 

biological significance. 

FC-152a was not carcinogenic and produced no life-shortening toxic 

effects. 

Test substance : HFC-152a, purity > 99.9 % 

Reliability : (1) valid without restriction 

 1b. Comparable to guideline study. 

Flag : Critical study for SIDS endpoint 

04.04.2006 (22) (24)

5.8.1 TOXICITY TO FERTILITY 

5.8.2 DEVELOPMENTAL TOXICITY/TERATOGENICITY 

Species : rat 

Sex : female 

Strain : other: Charles River CD(R) 

Route of admin. : inhalation 

Exposure period : Days 6 - 15 of gestation 

Frequency of treatm. : Daily 

Duration of test : 6 hours/day 

Doses : 0, 5,000, 50,000 ppm 

Control group : yes, concurrent vehicle 

NOAEL maternal 

tox. 

: 50.000 ppm 

NOAEL teratogen. : 50.000 ppm 

Method : other 

Year : 1979 

GLP : no 

Test substance : as prescribed by 1.1 - 1.4 

Method : The rats were bred by the supplier (Charles River). The morning 

when sperm were found in the vaginal smear was counted as Day 1 of 

gestation. Animals (young adults weighing approximately 185 grams) 

were delivered at either 4 or 2 days pregnant. Food and water were 

available ad libitum except during inhalation exposures. 

Pregnant female rats (27 rats/group) were exposed to nominal 

concentrations of 0, 5,000, or 50,000 ppm HFC-152a for 6 hours per 

day on days 6 - 15 of gestation. Desired exposure concentrations were 

generated by metering the vapors of HFC-152a from the cylinder into 

1.4 m3

 stainless steel and glass chambers operating under dynamic 

airflow conditions. Chamber atmospheres were monitored every 30 

minutes via gas chromatograph (GC). The GC was calibrated daily 

with gaseous standards. Control animals were exposed to room air in 
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identical chambers. Animals were observed daily for signs of toxicity 

and weighed periodically throughout the study. Dams were 

euthanized on Day 21 and organs of the thoracic and abdominal 

cavities were examined and the uterine weight was recorded. Corpora 

lutea, implantation sites, live and dead fetuses, resorptions, fetal 

weight, crown-rump length of live fetuses, and a gross external fetal 

examination were recorded. Half of the fetuses from each litter were 

examined for skeletal abnormalities. The remaining fetuses were 

examined for visceral and neural anomalies (via the Wilson method 

with modification described by Barrow and Taylor). 

For statistical evaluation of the data, the litter was considered the 

experimental unit of treatment and observation. The Fisher Exact 

probability test was used to evaluate the incidence of resorptions and 

abnormalities among litters. Maternal and fetal body weights and 

fetal crown-rump measurements were treated statistically by analysis 

of variance and least significant difference (LSD) tests. The number 

of corpora lutea, implantations, and live fetuses per litter were 

analyzed by the Wilcoxon rank sum test. In all cases, two-tailed 

significance tests were performed and significance was judged at the 

0.05 probability level. 

Result : The daily average analytical exposure levels during the entire 10-day 

exposure period were 5,300 ± 1,200 and 45,300 ± 4,900 ppm. 

No compound-related clinical signs of maternal toxicity or body 

weight changes were observed. No gross pathological abnormalities 

were observed in ovaries, uterine horns, vital organs, or tissues of 

treated animals. 

Pregnancy ratios were 22/27, 21/27, and 19/27 at 0, 5,000, and 

50,000 ppm, respectively. A summary of other reproductive 

outcomes (means/litter) are provided in the table below: 

Concentration (ppm) 0 5000 50,000 

Corpora lutea: 11.6 11.3 12.2 

Implantations: 10.0 9.4 10.5 

No. of Resorptions: 1.5 1.4 1.2 

Total No. of Fetuses: 9.3 8.8 9.9 

Total No. of Live 

 Fetuses: 9.3 8.8 9.9 

Mean Fetal Weight (g): 4.3 4.4 4.3 

Sex Ratio: NR NR NR 

NR = Fetal sex was not recorded; therefore, sex ratios could not be 

calculated. 

The number of corpora lutea, implantation sites, and live fetuses per 

litter were similar in all groups. The post-implantation death of 
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fertilized ova in exposed females indicated by early and late 

resorptions and dead fetuses was not different from that of the control 

group. Fetal body measurements, i.e. mean weight and crown-rump 

length in groups were not different from controls. 

The HFC-152a treatment did not affect embryonal development as 

measured by gross external, visceral, and skeletal examinations. 

Petechial hemorrhages and small subcutaneous hematomas on 

various parts of the body and the number of runts among litters and 

fetuses were similar in all groups. Apparent hydronephrosis, 

transposition of the viscera, liver peliosis, and internal hemorrhage 

were detected; however, none of these findings were considered to be 

treatment-related. No statistically significant differences in the 

frequency of minor skeletal anomalies or variants were observed. 

A summary of gross, soft tissue, and skeletal anomalies are provided 

in the table below. Data are presented as number of litters (fetuses) 

affected. 

 

Concentration (ppm) 0 5,000 50,000 

Gross External, 

Number examined: 22(205) 20(184) 19(188) 

Petechial hemorrhages 4(4) 5(5) 3(5) 

Hematoma 10(12) 6(7) 8(14) 

Runts 2(2) 1(1) 1(1) 

Soft Tissue, 

Number examined: 22(105) 20(93) 19(90) 

Hydronephrosis 

 (apparent) 1(1) 3(4) 2(2) 

Situs inversus 0 0 1(1) 

Liver peliosis 0 0 3(3) 

Internal hemorrhage 1(1) 0 0 

Skeletal, 

Number examined: 22(100) 20(91) 19(98) 

14th rudimentary rib 16(51) 16(53) 19(69) 

Wavy ribs 8(17) 6(8) 5(7) 

Sternebrae unossified 10(14) 9(16) 12(23) 

Bipartite centra 3(3) 0 2(2) 

Hyoid unossified 2(3) 0 4(6) 

The NOEL for maternal and developmental toxicity was 50,000 ppm, 

the highest level tested. 

Test substance : HFC-152a, purity > 99.9 % 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 
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principles, acceptable for assessment. 

Flag : Critical study for SIDS endpoint 

30.05.2006 (21)

5.8.3 TOXICITY TO REPRODUCTION, OTHER STUDIES 

Type : other: 2-year Chronic and Carcinogenicity Study 

In vitro/in vivo : In vivo 

Species : rat 

Sex : male/female 

Strain : other: Rats/Crl:CD(R)BR 

Route of admin. : inhalation 

Exposure period : 2 years 

Frequency of treatm. : 6 hours/day, 5 days/week (excluding holidays) 

Duration of test : 

Doses : 0, 2,000, 10,000, 25,000 ppm 

Control group : yes, concurrent vehicle 

Result : No histopathological or weight effects on reproductive organs of 

either male or female rats were observed. 

Method : other 

Year : 1982 

GLP : yes 

Test substance : as prescribed by 1.1 - 1.4 

Method : Refer to 2-year carcinogenicity study in Section 5.7 for methods. 

Result : Additional information can be found in the Carcinogenicity Section 

(Section 5.7). 

Test substance : HFC-152a, purity > 99.9 % 

Reliability : (2) valid with restrictions 

 2e. Study well documented, meets generally accepted scientific 

principles, acceptable for assessment. 

Flag : Critical study for SIDS endpoint 

09.01.2006 (22)

5.9 SPECIFIC INVESTIGATIONS 

5.10 EXPOSURE EXPERIENCE 

5.11 ADDITIONAL REMARKS 
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