Organic Chemicals
William J. Rea, Kalpana D. Patel in Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
Applications of PERC are similar to those of TCE.132 PERC has been the leading dry cleaning solvent since the 1950s.136 It is also used in textiles manufacturing and as a degreasing agent, and is found in many common household products. PERC persists in air and groundwater for several months or longer and is ubiquitous in human tissues. CCI4 was the first chlorinated solvent used in dry cleaning, predominating from 1930 until the early 1950s. The major use of CCI4 has historically been for the production of chlorofluorocarbon, which is used as a refrigerant. CCI4 has also been used as an anesthetic and antihelminth, and in common household products. Until recently, it was used as a fumigant to kill insects in grain. Due to its toxicity, consumer and fumigant uses were phased out by 2000, but industrial uses remain. CCI4 is a stable chemical that is degraded very slowly, so it has gradually accumulated in the environment, mainly the atmosphere.135
A critical perspective on future developments based on the knowledge we have now
Anthony J. Hickey, Heidi M. Mansour in Inhalation Aerosols, 2019
Although inhalation therapies date back more than 4000 years (1), the first modern systems are much more recent. For example, the first metered-dose devices were the Medihaler Iso™ and Medihaler Epi™ developed by Riker Laboratories beginning in the mid 1950s. With the first inhaler, pressurized metered-dose inhaler (pMDI), a new era of portable, multidose, metered-dose inhalers began and represented a milestone in the field (2,3). A few decades later, propellant gases used in pMDIs underwent a replacement and reformulation due to chlorofluorocarbon (CFC) ozone depletion issues. The CFC phase-out process was completed in the United States in 2013 (4). Early dry powder inhalers (DPIs) were developed before the first pMDIs (Aerohalor®, Abbott in 1944), but their widespread use was only realized later in response to the phase-out of CFC-propelled pMDIs. Today, DPIs are a widely accepted dosage form, and their use increasing steadily (5). Respimat® is the first of a new generation of active metered-dose devices known as Soft Mist™ Inhalers that have been commercialized and that do not require propellants and/or patient inspiratory effect for actuation (6–8).
Environment and health
Liam J. Donaldson, Paul D. Rutter in Donaldsons' Essential Public Health, 2017
The ozone layer constantly passes through natural cycles. At some periods, it thins only then to replenish itself. In the last 30 years, much scientific attention has focused on so-called ozone-depleting substances that destroy the ozone layer to the extent that natural processes cannot heal it. Chief among these are chlorofluorocarbons (CFCs), but there are many others. They had become firmly established in products that were highly successful adjuncts to modern living, such as refrigerator coolants, aerosols and some other solvents. Ultraviolet light interacts with these products and chlorine atoms are released. There is then no natural process to break them down as they drive up into the stratosphere. One chlorine atom destroys 100,000 molecules of ozone. Most concern has been concentrated on the Antarctic, where a so-called ‘hole’ in the ozone layer developed. The low temperatures in this region speed up the conversion of chlorofluorocarbons to chlorine atoms. The hole is not a true gap in the ozone layer, but rather a substantial reduction in its thickness. International agreements, such as the Montreal Protocol, have sought to phase out chlorofluorocarbon-based products. This has been a successful demonstration of collaborative international action – so much so that scientists monitoring the ozone layer report some recovery of the previous damage, but estimate a further 50 years for it to be made good, provided that there is no reversal.
Detrimental effect of UV-B radiation on growth, photosynthetic pigments, metabolites and ultrastructure of some cyanobacteria and freshwater chlorophyta
Published in International Journal of Radiation Biology, 2021
Mostafa M. El-Sheekh, Eman A. Alwaleed, Aml Ibrahim, Hani Saber
Ultraviet radiation (UV) is emitted from the sun and divided to three wavebands; UV-A has wavelengths between 320–400 nm and is not screened out by the molecular oxygen (O2) and the ozone layer, UV-B has wavelengths between 280–320 nm and is usually reflected by ozone layer, and the most harmful, UV-C is entirely screened out by a combination of molecular oxygen and ozone layer (Yongji et al. 2018). So, the ozone layer is vital to natural life in the globe because of their function in absorption of UV radiation. Additional UV radiation has been entered to the earth biosphere due to depletion in this protective layer. The depletion of ozone layer induced by substances such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) (the United States Environmental Protection Agency 2008). Increased UV levels resulted in climate change and is portend to alteration in weather and growth patterns on the earth (Bi and Zhang 2007). Atmosphere pollution as a result of rapid industarlization is the main reason for depletion in this protective ozone layer (Björn 2007). The Antractic ozone hole is the most spectacular example for this depletion (Björn 2007). During 1997 to 2000, at northern multitudes, ozone level depletion was around 6% in relation to 1980 levels, which could cause an increase in UV-B up to 12% (McKenzie et al. 2003; Arróniz-Crespo et al. 2008). So, the influence of UV radiation on life form became a critical affair over the past three decades and could also be vital in the years to come.
Inhalant misuse reported to America’s Poison Centers, 2001–2021
Published in Clinical Toxicology, 2023
Raymond L. Hogge, Henry A. Spiller, Sandhya Kistamgari, Marcel J. Casavant, Natalie Rine, Nichole L. Michaels, Motao Zhu, Gary A. Smith
The reversal in 2010 of the rate of “Freon and other propellants” misuse was abrupt and dramatic, and it coincided with the initiation of a 10-year plan by the US EPA to phase-out refrigerants that contain hydrochlorofluorocarbons through Section 608 of the Clean Air Act [27]. The Clean Air Act was amended in 1990 to establish long-term goals according to the Montreal Protocol, an international environmental agreement aimed at regulating the production and consumption of ozone-depleting substances contributing to climate change [28]. The Montreal Protocol established the goal of completely phasing out hydrochlorofluorocarbons by the year 2030 [28]. To meet this goal, the US EPA banned the production, import, and use of the refrigerants FreonTM (also known as hydrochlorofluorocarbon [HCFC]-22 or R-22) and HCFC-142b starting January 1, 2010, except for continuing servicing needs of existing equipment [27,29]. Although a complete ban on the production and import of these refrigerants (including for servicing of existing equipment) did not occur until January 1, 2020, the 2010 regulation resulted in a sharp decline in the use of FreonTM and HCFC-142b in home refrigerating units [28].
A technology evaluation of CVT-301 (Inbrija): an inhalable therapy for treatment of Parkinson’s disease
Published in Expert Opinion on Drug Delivery, 2021
Michael M. Lipp, Anthony J. Hickey, Robert Langer, Peter A. LeWitt
Nebulizers have been available since the beginning of the twentieth century for pulmonary drug delivery. Most inhaled proteins for clinical development have been developed as liquids for use in nebulizers. Modern inhaler therapy has its origins in treating asthma with pressurized metered-dose inhalers (pMDIs) [15,16]. The commercial dominance of pMDIs was first challenged when chlorofluorocarbon (CFC) propellants were subject to international control and ultimately phase-out through the Montreal Protocol in 1987 [17]. The difficulty of reformulation of inhaled drugs for alternative propellants and the concurrent demand for alternative delivery systems for the products of biotechnology prompted development and use of dry powder inhalers (DPIs) [16].
Related Knowledge Centers
- Ethane
- Fluorine
- Hydrocarbon
- Methane
- Propane
- Volatility
- Halogenation
- Carbon
- Hydrogen
- Chlorine