Aerosols, CFC

CFCs. All "nonessential" uses of CFCs in aerosol propellents were banned in 1978—the first and only major control action under TSCA not specifically mandated by the statute. This action may have helped to reduce the future incidence of skin cancer by diminishing CFCs destructive effects on stratospheric ozone. Making appropriate assumptions about rates of ozone depletion and extrapolating from current disease rates, one could estimate a range of cancers avoided because of this prohibition. However, any health benefit due to the ban on aerosol CFC uses may be masked by the continued increase in non-aerosol uses. 

Chlorofluorocarbons (CFCs). Prior to 1978 most aerosol products contained chlorofluorocarbon propeUants. Since that time, the use of chlorinated fluorocarbons for aerosols has been seriously curtailed. These compounds have been impHcated in the depeletion of the ozone (qv) layer and are considered to be greenhouse gases (see Airpollution Atmospheric modeling). 

Hydrocarbons have, for the most part, replaced CFCs as propellants. Most personal products such as hair sprays, deodorants, and antiperspirants, as well as household aerosols, are formulated using hydrocarbons or some form of hydro-carbon—halocarbon blend. Blends provide customized vapor pressures and, if halocarbons are utilized, a decrease in flammabiUty. Some blends form azeotropes which have a constant vapor pressure and do not fractionate as the contents of the container are used. 

In 1976 the United States banned the use of CFCs as aerosol propellants. No further steps were taken until 1987 when the United States and some 50 other countries adopted the Montreal Protocol, specifing a 50% reduction of fully halogenated CFCs by 1999. In 1990, an agreement was reached among 93 nations to accelerate the discontinuation of CFCs and completely eliminate production by the year 2000. The 1990 Clean Air Act Amendments contain a phaseout schedule for CFCs, halons, carbon tetrachloride, and methylchloroform. Such steps should stop the iacrease of CFCs ia the atmosphere but, because of the long lifetimes, CFCs will remain ia the atmosphere for centuries. 

The products are available as tablets, capsules, liquids (in the form of solutions, suspensions, emulsions, gels, or injectables), creams (usually oil-in-water emulsions), ointments (usually water-in-oil emulsions), and aerosols, which contain inhalable products or products suitable for external use. Propellants used in aerosols include chlorofluorocarbons (CFCs), which are being phased out. Recently, butane has been used as a propellant in externally applied products. The major manufactured groups include ... 

During the 1980s, it became recognized that chlorofluorocarbons (CFCs), widely used as aerosol propellants, are damaging the ozone layer, and aerosol manufacturers were asked to use other propellants. Some... 

It is clear that human action can affect seven of eight of the major gi eenhouse forcings carbon dioxide, methane, nitrous oxide, ozone, CFCs, aerosols, and water vapor. As studies of solar variation have shown, it is also clear that human action is not the only factor involved in determining the impact of these forcings. There is still substantial uncertainty regarding the actual climate impact of the climate forcings. 

The formed mixture is composed of trichlorofluoromethane (Freon-11) and dichlorodifluoromethane (Freon-12). These compounds are used as aerosols and as refrigerants. Due to the depleting effect of chlorofluorocarbons (CFCs) on the ozone layer, the production of these compounds may be reduced appreciably. 

Much research is being conducted to find alternatives to CFCs with little or no effect on the ozone layer. Among these are HCFC-123 (HCCI2CF3) to replace Freon-11 and HCFC-22 (CHCIF2) to replace Freon-12 in such uses as air conditioning, refrigeration, aerosol, and foam. These compounds have a much lower ozone depletion value compared to Freon-11, which was assigned a value of 1. Ozone depletion values for HCFC-123 and HCFC-22 relative to Freon-11 equals 0.02 and 0.055, respectively. ... 

It should be noted that prior to 1987, total CFC emissions were made up from aerosol sprays, solvents and foam insulation, and that refrigerant emissions were about 10% of the total. However, all the different users have replaced CFCs with alternatives. 

A typical example of the interaction between hypothesis and experiment is the story of the work that resulted in worldwide concern over the depletion of the ozone layer in the stratosphere. These studies led to the awarding of the 1995 Nobel Prize for Chemistry to Paul Crutzen, Mario Molina, and F. Sherwood Rowland. Figure FT provides a schematic view of how this prize-winning research advanced. It began in 1971 when experiments revealed that chlorofluorocarbons, or CFCs, had appeared in the Earth s atmosphere. At the time, these CFCs were widely used as refrigerants and as aerosol propellants. Rowland wondered what eventually would happen to these gaseous compounds. He carried out a theoretical analysis, from which he concluded that CFCs are very durable and could persist in the atmosphere for many years. 

C Vervaet, PR Byron. Polystyrene microsphere spray standards based on CFC-free inhaler technology. J Aerosol Med 13 105-115, 2000. 

CFCs substitute for ozone destroyers dangerous refrigerants no hospital refrigerators something spectacular needed Midgley group discovers other CFCs and halons lion s share uses for CFCs aerosols and halons in World War II. 

Seth Cagin and Philip Dray. Between Earth and Sky How CFCs Changed Our World and Endangered the Ozone Layer. New York Pantheon Books, 1993. Source for aerosol sprays and Midgley. 

Although deaths from exposure to CFCs have occurred during refrigeration repair, its use as solvents, and its use and abuse as aerosol propellant (Aviado 1994), no data specific to HFCs were located. 

Engle, T. 1991. Patient-related side effects of CFC propellants. J. Aerosol Med. 4 163-168. 

Graepel, P. and D.J.Alexander. 1991. CFC replacements safety testing, approval for use in metered dose inhalers. J. Aerosol Med. 4 193-200. 

Measurement or estimation of health impacts under TSCA would be premature, since relatively little has been done to regulate new or existing chemicals that could result in health benefits. The principal exception to this generalization is the ban on aerosol uses of CFCs, whose chronic effects on human health derive from their environmental impact rather than direct biological toxicity. Compared with other environmental laws, such as the Clean Air Act, the regulatory accomplishments of TSCA are somewhat insubstantial. 

OTS has focused its control efforts on two other chemicals in addition to PCBs. Working in conjunction with the Food and Drug Administration, EPA used TSCA s Section 6 to prohibit the use of chlorofluorocarbons (CFCs) as propellants in nonessential aerosol products. An advanced notice of proposed rulemaking under TSCA outlined approaches for restricting other uses of CFCs, but the attempt to deal with other CFC uses has been abandoned by the Reagan Administration. 

Ban on chlorofluorocarbons (CFCs) as aerosol propellants react with ozone in the stratosphere, causing an increase in the penetration of ultraviolet sunhght and increase the risk of skin cancer. 

Simple hydrocarbons can also be used as CFC substitutes. Hydrocarbons such as propane, 2-methylpropane (common name isobutane), and butane are efficient aerosol propellants. These hydrocarbons are stable and inexpensive, but they are extremely flammable. 

When a vehicle is parked in the sunlight on a hot summer day, the temperature inside can approach 55°C. One company has patented a non-CFC propelled aerosol that can be sprayed inside a vehicle to reduce the temperature to 25°C within seconds. The spray contains a mixture of two liquids 10% ethanol, C2H5OH, and 90% water by mass. 

Several dosage forms carry an increased risk of degradation or adjunct formation. Products such as injections and aerosols are more likely to interact with volatiles or extractables from packaging and closure systems. Tablets have the potential to form adjuncts with excipients (specifically, lactose has been shown to form adjuncts in tablets). Non-CFC propellants in aerosols have a large number of impurities that typically do not interact with drug substances, but the potential for these interactions does still exist. Creams, ointments, lotions, and other such products will each have specific interactions that should be considered while evaluating the impurity profile of a drug product. 

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