CFCs production

In 1987 an international treaty was signed in Montreal to cut back on the use of CFCs. Production of Freon in the United States ended in 1996. It has been replaced in automobile air conditioners by a related compound with no chlorine atoms, C2H2F4 ... 

Du Pont, the largest producer of CFCs, called for a total CFC production phaseout. A possible arctic ozone hole was studied. The EPA called for a total ban of CFCs. 

CFC use climbed steadily worldwide as it was incorporated in refrigeration and air conditioning, as well as being used as propellants, blowing agents, and solvents. CFC production peaked in the late 1980s, with a worldwide annual production of just over 1.2 million tons (Figure 32.1). 

In summary, it was agreed at Copenhagen that all CFC production and usage in the industrialized world would be phased out by the end of 1995 and provision was made to phase out HCFC production by 2030, although most of it will have been eliminated by 2015. Some countries are already considering the faster elimination of HCFCs and dates as early as 2000 have been mooted. 

Two of the most common CFCs, also known as freons, were CFC-11, trichlorofluo-romethane, and CFC-12, dichlorodifluoro-methane. At the height of CFC production in 1988, some 1.13 million tons were produced worldwide. Because of their inertness, CFCs were once thought to pose little threat to the environment. 

There has been an unprecedented level of international cooperation toward banning ozone-destroying chemicals. The first major step was the signing of the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer, which called for the reduction of CFC production to one-half of 1986 levels by the year 1998. However, only a few years after the protocol was ratified, in 1990, scientists confirmed that the CFC problem was much more serious than they believed in 1987 when the protocol was drafted. The protocol was soon amended to call for cessation of all CFC production by 1996. Even with the protocol in place and the continued cooperation of all signatory nations, however, the ozone-destroying actions of CFCs will be with us for some time. Atmospheric CFC levels are not expected to drop back to the levels found before the ozone hole was formed until sometime in the 22nd century. 

Typically CFC products utilize both the cold-fill and the pressure-fill processes. Whether a product is filled by pressure or cold, is determined by the manufacturing equipment available at a particular company and by the nature of the active drag. For example, since Albuterol is moisture-sensitive, it cannot be filled by the cold process. Hydrofluorocarbon products are typically filled using the pressure-filling method. Figure 3 depicts the process flow, indicating both types of fillings. 

The Montreal Protocol stated that the production and consumption of all substances that deplete the ozone layer would be phased out by the year 2000 in developed countries. (Methyl chloroform would be phased out by 2005.) The chemicals that are named in the agreement include CFCs, halons, carbon tetrachloride, methyl chloroform, and methyl bromide. Once CFC production and consumption are stopped, scientists hope that the ozone layer will recover within 50 or 60 years. The success of the Montreal Protocol depends however, on the co-operation of both developed and developing countries. 

A number of new refrigerants have been proposed during the last several years as candidates to replace R-22 and R-502 in industrial refrigeration systems (73). International accords such as the Montreal Protocol on CFC production and other accords concerning pollution and gas emissions to the atmosphere in particular prompt a review of the refrigerants used in the margarine industry (52, 74). 

If the product under development is transitioning from an existing CFC suspension-based product, it may be difficult to replicate the fine particle mass, the particle size distribution and/or the absorption characteristics. This can lead to problems in providing a seamless transition from the CFC product because of the potential to have to change the dose and because the product can smell and feel different to the original suspension formulation. 

For CFC-based suspension formulations, a surfactant was typically included. A variety of surfactants were used in these systems, e.g., lecithin, oleic acid, sorbitan trioleate. " All these surfactants were freely soluble in the CFC propellants and allowed for a degree of control over the suspension characteristics. Rates of flocculation, sedimentation, and creaming could be controlled and deposition on the internal container components was minimized. The transition to HFA-based MDIs has created significant issues in that none of the surfactants, previously used with the CFC products are soluble in HFA propellants alone. Some formulations have still used these surfactants, but the addition of a cosolvent (ethanol) has been required to solubilize the surfactant. 

CFC s or chlorofluorocarbons are chemicals that cause ozone depletion in the stratosphere as well as the "Greenhouse Effect". They have been typically employed as blowing agent in foams. Since the initial proclamation, the mandate has been revised several times to accelerate the CFC phaseout schedule, with the latest revision resulting from the Copenhagen agreement in November 1992 where 87 nations resolved to move up total CFC phaseout by four years in January 1996. The recent Copenhagen revision induced major CFC manufacturers to accelerate their phaseout time table. DuPont announced recently that it plans to stop CFC production by 1994, almost 2 years ahead of plan. 

Even when CFC production is completely halted, CFCs still will be released to the atmosphere when the equipment in which they were used, such as refrigerators and air conditioners, are junked and the fluid systems are breached. Some municipalities (e.g., the city of Cambridge, Massachusetts) now have ordinances requiring the recovery of CFC refrigerants from appliances and air conditioners before the appliances are discarded. 

The most significant developments in metered-dose inhaler technology to occur since the early 1990s have been the introduction of hydrofluoroalkane (HFA) systems as alternatives to chlorofluorocarbon (CFC) systems [174]. This has largely been caused by the link between the use of CFC systems and ozone depletion in the upper atmosphere [152,175]. Albuterol and beclomethasone have been reformulated in HFA products, but as yet the CFC products are still subject to an annually renewable medical exemption. The Food and Drug Administration has recently published its position on alternative propellant formulations, which should initiate the phase-out of CFCs [176]. In the meantime, a number of generic CFC products of albuterol have been manufactured. The opportunity for reformulation of products as they come of patent is likely to increase research and development in this area in the near future. New formulation opportunities will also arise from these developments, including solutions [177], micellar [178,179], and microemulsion [180]. 

The main formulation challenge with HFA pMDI has been the poor solubility of the surfactants that were used in CFC products. Most pMDI formulations are suspensions of fine powder in propellant, and in order to obtain acceptable dose uniformity these suspensions usually require surfactants to stabilize them. The inability to use conventional surfactants has therefore led to a range of diverse formulation approaches. These encompass drug solubilization using cosolvents (Qvar is an example), new surfactants, coating particles with surfactant, and particle engineering (Fig. 3). However, as is the case with most... 

REGULATION OF CFCs PRODUCTION Depletion of Ozone Layer... 

Recognizing the serious implications of the loss of ozone in the stratosphere, nations throughout the world have acknowledged the need to drastically curtail or totally stop the production of CFCs. In 1978 the United States was one of the few countries to ban the use of CFCs in hair sprays and other aerosols. An international treaty—the Montreal protocol—was signed by most industrialized nations in 1987, setting targets for cutbacks in CFC production and the complete elimination of these substances by the year 2000. While some progress has been made in this respect, it is doubtful that poorer nations such as China and India can strictly abide by the treaty because of the... 

Over time, CFC production increased dramatically as their uses increased. They were used as propellants in spray cans, as gases to expand plastic foam, and in many other applications. By 1985 production of CFCs reached 850,000 tons. Much of this leaked into the atmosphere and in that year the concentration of CFCs reached 0.6 parts per billion. Another observation was made by groups of concerned scientists as the level of CFCs rose, the ozone level in the upper atmosphere declined. Does this correlation between CFC levels and ozone levels prove a relationship between these two phenomena Explain your reasoning. 

The relationship between UV-B radiation and skin cancer is by now well documented and accepted. The US EPA has estimated that each 1 % decrease in stratospheric ozone concentration will result world wide in a 2% rise in cutaneous malignant melanoma. Among the Asian and Pacific region, people of many countries, such as Australia, New Zealand, South Pacific Islands, Indonesia, Malaysia, Philippines, Thailand, etc, are the most vulnerable to the exposure of UV-B radiation. For example, between 1980 and 1991, when the growth of CFCs production was the maximum, melanoma cancer registration rates in New Zealand increased by 22% (ESC AP, 1995). 

Awareness of the ozone depletion problem was reflected by signing in 1987 of the Montreal Protocol on substances that deplete the ozone layer . This international treaty initially set targets for CFC production to be cutback to 1986 baseline levels by mid-1989, cut to 80%ofbaselineby 1993, and to 50% of baseline by 1998. Subsequent information suggested that these cuts in CFC production would be insufficient to prevent substantial loss of stratospheric ozone over the first half of the 2T century. Consequently, amendments have been made to strengthen the original terms of the Montreal Protocol, so that a complete phase-out of the hard CFCs such as CFC-11 and CFC-12 (Figure 6) will be effected. 

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