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Iodotrifluoromethane: Toxicity Review (2004)

Chapter: 2 Physical and Chemical Properties and Efficacy

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Suggested Citation:"2 Physical and Chemical Properties and Efficacy." National Research Council. 2004. Iodotrifluoromethane: Toxicity Review. Washington, DC: The National Academies Press. doi: 10.17226/11090.
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2
Physical and Chemical Properties And Efficacy

PHYSICAL AND CHEMICAL PROPERTIES

The physical and chemical properties of iodotrifluoromethane (CF3I) are presented in the Army’s updated toxicity review (Chaney 2002). The table of physical properties of CF3I from that report is included here (Table 2-1); the entire update is included as Appendix B. The review briefly discusses the degradation of CF3I in air and during a fire and states that no attempt was made by the Army to determine the toxicity of any CF3I degradation products.

The update’s presentation of the physical and chemical properties of CF3I is well written and concise. However, the subcommittee found three points that merit some clarification:

  • The update states on page 6, lines 9-10, in the section “Regulatory Information” that “cardiac sensitization has been demonstrated at relatively low concentrations. . . .” The Army should specify that the statement refers to dogs.

  • On the same page, the Army should also indicate quantitatively what is meant by “relatively low concentrations.”

  • The Army should have added vapor density to the list of physical and chemical properties as halocarbons are usually much heavier than air and can accumulate in “dead spaces” such as tanks. This information has been added to Table 2-1.

Suggested Citation:"2 Physical and Chemical Properties and Efficacy." National Research Council. 2004. Iodotrifluoromethane: Toxicity Review. Washington, DC: The National Academies Press. doi: 10.17226/11090.
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TABLE 2-1 Physical Properties of CF3I

Physical or Chemical Property

Value or Description

Chemical Abstracts Service no. (CAS)

2314-97-8

European Chemical no. (EC)

219-014-5

Molecular weight

195.91

Physical state at 20°C

Gas

Melting point

–110°C (166°F)

Boiling point at 1 atm

–22.5°C (8.5°F)

Liquid density at -32.5°C

2.36 g/mL

Liquid density at 25°C

g/mL

Odor threshold

Odorless

Solubility in water

Slight

Vapor pressure at 25°C

78.4 psia

Pressure-temperature curve

log psia = 5.7411-1146.82/T/K

Critical pressure

586 psia (estimated)

Critical temperature

122°C (estimated)

Critical volume

225 cm3/mole (estimated)

Heat of formation

–141 kcal/mole

Heat of vaporization

5.26 kcal/mole

Electron affinity

150 ± 20 kJ/mole

Refractive index (liquid) at 42°C

1.379

Dipole moment

1.68 debye

Vapor heat capacity

16.9 cal/mole-K

C-I bond disassociation energy

54 kcal/mole

Vapor density (air = 1)

6.9a

aData from PTCL 2003.

Abbreviations: g/mL, gram per milliliter; cm3/mol, cubic meter per mole; kcal/mole, kilocalorie per mole; kJ/mole, kilojoule per mole; cal/mole-K, calorie per mole Kelvin; psia, pounds per square inch absolute.

Source: Adapted from Moore et al. 1994 (see Appendix B).

EFFICACY

The “Efficacy” section of the update indicates that the minimal design concentration—that is, the minimal amount of a chemical required to extinguish an n-heptane fire—of CF3I, 3.2 vol%, is slightly lower than that

Suggested Citation:"2 Physical and Chemical Properties and Efficacy." National Research Council. 2004. Iodotrifluoromethane: Toxicity Review. Washington, DC: The National Academies Press. doi: 10.17226/11090.
×

of Halon 1301, 3.3 vol%. One point in the efficacy section (see Appendix B) should be clarified: The phrase “will be slightly lower” does not have biologic meaning. The term “slightly” should be quantified and the actual amounts given.

Suggested Citation:"2 Physical and Chemical Properties and Efficacy." National Research Council. 2004. Iodotrifluoromethane: Toxicity Review. Washington, DC: The National Academies Press. doi: 10.17226/11090.
×
Page 15
Suggested Citation:"2 Physical and Chemical Properties and Efficacy." National Research Council. 2004. Iodotrifluoromethane: Toxicity Review. Washington, DC: The National Academies Press. doi: 10.17226/11090.
×
Page 16
Suggested Citation:"2 Physical and Chemical Properties and Efficacy." National Research Council. 2004. Iodotrifluoromethane: Toxicity Review. Washington, DC: The National Academies Press. doi: 10.17226/11090.
×
Page 17
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The U.S. military is considering using a compound called iodotrifluoromethane (CF3I) for fire suppression to replace previously-used compounds (halons) that are being phased out because they deplete the ozone layer. This report reviews available toxicological data on CF3I and evaluates the scientific basis of the U.S. Army's proposed exposure limit of 2,000 parts per million (ppm). The report recommends that CF3I be used for fire suppression in normally unoccupied spaces because of its potential to cause cardiac sensitization in test animals. The report also recommends that further genotoxicity testing be conducted (testing for changes in genetic material), and that CF3I be assessed for its potential to cause cancer. Should the Army decide to use CF3I, information should be collected and evaluated on how much of the chemical or any of its degradation products might be released and how often.

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