Chlorofluorocarbons exposure

Fig. 9. Ethylene oxide sterilisation 4-h cycle, 12/88 12 wt % ethylene oxide/88 wt % chlorofluorocarbon (Freon 12), where the horizontal line represents standard barometric pressure A, preconditioning and humidification at 87.8—94.55 kPa, 30—40 min B, exposure for 3/4 h at 55.17—68.95 kPa above standard barometric pressure C, air washes at 81.04—87.8 kPa, 20 min. To convert kPa to psi, multiply by 0.145.

An important effect of air pollution on the atmosphere is change in spectral transmission. The spectral regions of greatest concern are the ultraviolet and the visible. Changes in ultraviolet radiation have demonstrable adverse effects e.g., a decrease in the stratospheric ozone layer permits harmful UV radiation to penetrate to the surface of the earth. Excessive exposure to UV radiation results in increases in skin cancer and cataracts. The worldwide effort to reduce the release of stratospheric ozone-depleting chemicals such as chlorofluorocarbons is directed toward reducing this increased risk of skin cancer and cataracts for future generations. 

Toxicity of Alternatives to Chlorofluorocarbons HFC-134a and HCFC-123 (1996) Permissible Exposure Levels for Selected Military Fuel Vapors (1996)... 

Eight healthy human volunteers, four males and four females, ages 20-24, were exposed individually (whole body) to concentrations at 0 (air), 1,000, 2,000, 4,000, or 8,000 ppm for 1 h in a 13.6 m3 room (Emmen and Hoogendijk 1998 Emmen et al. 2000).2 Each subject was exposed at each concentration in a partially blind ascending order of concentration. With the exception of one 14-d interval, each exposure was separated by a period of 7 d. Chlorofluorocarbon-12 (CFC-12) was used as a reference compound. No mention was made of the ability of the test subjects to recognize the odor of either test chemical. Prior to and during exposures, blood pressure and cardiac rate and rhythm (EKG) were monitored. Pulmonary function, as indi... 

Aside from the actions already initiated by EPA under Section 6 to restrict exposures to polychlorinated biphenyls and to chlorofluorocarbons in certain uses, no other actions have been taken against specific chemical substances, nor has an imminent hazard been identified for appropriate action. Less than a dozen proposed orders have been issued under Section 5(e) requesting further information to assess the risks of as many new substances. Perhaps 80 informal requests for further information on such substances have been made and satisfied voluntarily. Testing programs for a substantial number of existing substances have been started and more are planned. In addition, of course, the monumental task of creating an inventory of some 55,000 existing chemicals was completed. 

Inhalation studies with chloropentafluoroethane in anesthetized dogs, rats, and monkeys showed that exposure to 100,000-2 5 0,000 ppm, under certain conditions, caused an increase in blood pressure, accelerated heart rate, depression of myocardial contractility and sensitized the heart to epinephrine.Compared with other chlorofluorocarbons, it is ranked among the least potent for cardiac sensitization." ... 

Production, import/Export, Use, Reiease, and Disposai. Although the production of carbon tetrachloride has been declining, humans are at risk of exposure to the compound at specific industrial locations where the compound is used or near chemical waste sites where emission to the environment may occur. Available data indicate that most carbon tetrachloride manufactured in this country is consumed in the synthesis of chlorofluorocarbons, but current quantitative data on the amounts of carbon tetrachloride imported and exported into and from the United States are sparse (CEH 1985 HSDB 1992). According the the Emergency Planning and Community Right-to Know Act of 1986, 43 U.S.C. Section 11023, Industries are required to submit substance release and off-site transfer information to the ERA. The Toxic Release Inventory (TRI), which contains this information for 1990, became available in May of 1992. This database is updated yearly and should provide a list of industrial production facilities and emissions. 

The chlorofluorocarbons (CFCs) have very long lifetimes in the troposphere. This is a consequence of the fact that they do not absorb light of wavelengths above 290 nm and do not react at significant rates with 03, OH, or N03. In addition to the lack of chemical sinks, there do not appear to be substantial physical sinks thus they are not very soluble in water and hence are not removed rapidly by rainout. While laboratory studies have shown that some of the CFCs decompose on exposure to visible and near-UV present in the troposphere when the compounds are adsorbed on siliceous materials such as sand (Ausloos et al., 1977 Gab et al., 1977, 1978), the lifetimes for CFC-11 and CFC-12 with respect to these processes have been estimated to be 540 and 1800 years, respectively (National Research Council, 1979). Similarly, an observed thermal decomposition when adsorbed on sand appears to be an insignificant loss process under atmospheric conditions. 

Inhalation (pulmonary route) is the main source of toxic exposures to chlorofluorocarbons. Dermal exposure may also occur. Ingestion would be intentional. 

Loss of CFC-113 from tissues is rapid during the postexposure period with virtually 100% clearance within 24 h of exposure. Freons are eliminated entirely by the respiratory tract. Chlorofluorocarbon compounds partition preferentially into lipid-rich tissues and are poorly metabolized. Significant accumulation occurs in brain, liver, and lung tissues compared to blood levels. 

The main effects observed in animals following exposure to chlorofluorocarbons are CNS depression, respiratory tract irritation, rapid breathing, lung congestion, and microscopic liver changes. Cardiac dysrhythmias and mild chemical conjunctivitis have... 

Chlorofluorocarbons are more acutely toxic to rabbits than to mice via the oral route of exposure. Dogs have demonstrated vomiting, lethargy, nervousness, and tremors following inhalation exposure to chlorofluorocarbons. High-concentration exposures to dogs, monkeys, and rats resulted in cardiac arrhythmias. 

Eye and skin irritations have been observed following exposure to chlorofluorocarbons. No corneal opacity has been noted as a result of exposure to chlorofluorocarbons but frostbite of the eyelids may be severe. 

Chlorofluorocarbons are very toxic when inhaled at high concentrations and/or for extended periods of time. Lower concentrations or brief periods of exposure result in transient eye, nose, and throat irritations. Temporary CNS depression, dizziness, headache, confusion, and incoordination are associated with exposure to high concentrations (>2500 ppm in air). Gross overexposure may lead to abnormal liver function, refractory ventricular dysrhythmias, and sudden death. Intentional sniffing of aerosols has resulted in sudden death. There is significant individual variability in response to chlorofluorocarbons. 

Chlorofluorocarbon compounds are cardiac sensitizing agents. Pulmonary edema, bronchial constriction, and lung irritation may also occur following inhalation exposure to high chlorofluorocarbon concentrations. 

Oral exposures to liquid chlorofluorocarbons are rare but have resulted in severe frostbite to the upper respiratory system and gastrointestinal tract. Necrosis and perforation of the stomach have been reported. Thus, emesis, activated charcoal, and gastric lavage are not recommended. 

Exposure of the eyes to liquid chlorofluorocarbons or significant air concentrations should be treated by irrigating the eyes with tepid water for at least 15 min. Cryogenic dermal injuries should be treated by water bath rewarming until vasodilatory flush has returned. 

Exposure limits have been defined for land, sea and air the National Academy of Sciences gives a 90-day atmospheric limit of 0.05 p.p.m. in submarines, and a Douglas aircraft continuous atmospheric limit of 0.04 p.p.m. [40]. These recommendations exist because of the possibility of producing phosgene as a result of the decomposition of chlorofluorocarbon refrigerants used in air-conditioning systems. 

Exposure to ethylene oxide, admixed with a carrier gas such as carbon dioxide or a chlorofluorocarbon, is the most widely used sterilization process because it has the least damaging effect on materials and devices and is low cost. EtO sterilization is a room-temperature process that affects only the external surfaces of a module. 

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