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Urban water supply and water treatment
Published in Sandy Cairncross, Richard Feachem, Environmental Health Engineering in the Tropics, 2018
Sandy Cairncross, Richard Feachem
Slow sand filters improve the microbiological quality of water considerably, but if water completely free of pathogens is required, it is necessary to apply a chemical disinfectant after filtration. In practice, all town water supplies require disinfection. Chlorine is the disinfectant most readily available and suitable for use in most circumstances. It is available in the form of several chlorine compounds, which are safer to use than the poisonous gas.
Our strained relations with environmental agents
Published in Richard Lawson, Jonathon Porritt, Bills of Health, 2018
Richard Lawson, Jonathon Porritt
This longevity of non-biodegradable substances is part of the problem with the notorious ‘ozone-eating’ CFCs which are composed of chlorine, with its more reactive cousin fluorine, locked on to a couple of carbon atoms. The chlorine-carbon bond is chemists’ stock-in-trade. If a drug is promising, but fails to stay long enough in the body, a chlorine atom is attached to a carbon atom on this or that corner, with the result that the body cannot clear it so quickly. To a chemist, this is fundamental practice. In nature, only two chemicals contain the chlorine-carbon bond, and one of them is ricin, the poison in the castor oil bean. This does not mean that all synthetic carbon-chlorine compounds are toxic, merely that they are unusual and unfamiliar to our defence systems. In principle, they may pose a problem for our immune system. Although they are man-made, synthetic chemicals are not human, and do not qualify for human rights. They are not ‘innocent until proved guilty’. They should be treated in a precautionary way, that is the onus of proof should be on the manufacturers to show that they do not harm life, rather than on the victims of the illness they produce to ‘prove’ that they have been harmed by them.
Control of microbial contamination during manufacture
Published in R. M. Baird, S. F. Bloomfield, Microbial quality assurance in cosmetics, toiletries and non-sterile Pharmaceuticals, 2017
The most effective chemical sanitizers are chlorine-releasing compounds or iodophors. Other agents such as quaternary ammonium compounds or amphoterics can be used. Chlorine compounds may be used at a level of 200 to 250 mg l−1 (ppm) of available chlorine in static systems and will achieve sanitation in 30 minutes. If circulation is introduced, it may be possible to use as little as 50 mg l−1, since the relative efficacy is increased. Iodophors are as effective as chlorine compounds, but are more difficult to rinse from the system. They are not, therefore, widely used.
A multidisciplinary approach to the comparison of three contrasting treatments on both lampenflora community and underlying rock surface
Published in Biofouling, 2023
Rosangela Addesso, Daniela Baldantoni, Beatriz Cubero, José Maria De La Rosa, José Antonio González Pérez, Igor Tiago, Ana Teresa Caldeira, Jo De Waele, Ana Z. Miller
The results provided relevant and useful information concerning the efficacy of the most employed physical (UVC) and chemical (NaClO, H2O2) control and removal methods of lampenflora in show caves. This work offers a comprehensive assessment of biofilm physiology, chemical composition, as well as of the potential deterioration processes of the underlying rock substrates in response to their applications. Commercial bleach (NaClO) treatment seemed to be the most efficient method in relation to both surface sterilization and visible cleaning over long time, with unaltered underlying rock substrates. However, the toxicity of chlorine compounds is known and an important drawback, requiring the use of diluted solutions, thus limiting the efficacy of this method. The H2O2 treated surfaces showed a recovery of lampenflora after three months without applications, and evident rock dissolution processes activated on surfaces. Indeed, H2O2 treatment promoted the release of alkyl chemical structures and a visible deterioration of vermiculation deposits. In addition, the organic matter was not eliminated by the application of H2O2, and consequently the remaining organic matrix would need to be removed through brushing or water jets in order to avoid undesirable effects on the ecological balance of the caves. Based on the conditions tested in this work, the UVC irradiation treatment was not an effective method for the removal of lampenflora.
Acute inhalation toxicity of aerosolized electrochemically generated solution of sodium hypochlorite
Published in Inhalation Toxicology, 2022
Bohdan Murashevych, Dmitry Girenko, Hanna Maslak, Dmytro Stepanskyi, Olha Abraimova, Olha Netronina, Petro Zhminko
It is known that active chlorine compounds (primarily hypochlorous acid HOCl and its salts, as well as organic chloramines) are among the most powerful and widespread disinfectants (Al-Abri et al. 2019; Gallandat et al. 2021). Due to pronounced oxidizing properties, they effectively suppress microorganisms (including multi-resistant ones), viruses, and prions (Sassone et al. 2008; Hughson et al. 2016; Köhler et al. 2018; Herruzo and Herruzo 2020; Kampf et al. 2020; Lin et al. 2020). Moreover, such preparations are quite simple in synthesis and inexpensive. Given these advantages, chlorine-active compounds are widely used in water treatment (Wilhelm et al. 2018), for the disinfection of various types of surfaces (Pereira 2015; Gallandat et al. 2017), some food products (Huang et al. 2008; Veasey and Muriana 2016; Simpson and Mitch 2021), and some representatives are also used as antiseptics (Gottardi and Nagl 2010; Anagnostopoulos et al. 2018; Chapman et al. 2018). In medicine, they are included in almost all sanitization protocols (Rutala et al. 2008; Andrade and Pereira 2020). In addition, such compounds are successfully used for the complex aerosol treatment of premises, in particular, in animal husbandry (Clark et al. 2006; Ministry of Agriculture and Food of The Republic of Belarus 2007; Park et al. 2007; Thorn et al. 2013). The creation of polymeric materials with antimicrobial and virucidal activity due to the presence in their structure of functional groups containing active chlorine is also on trend (Hui and Debiemme-Chouvy 2013; Murashevych et al. 2021).
Involvement of PM2.5-bound protein and metals in PM2.5-induced allergic airway inflammation in mice
Published in Inhalation Toxicology, 2018
Keiki Ogino, Kenjiro Nagaoka, Tatsuo Ito, Kei Takemoto, Tomoaki Okuda, Shoji F. Nakayama, Noriyoshi Ogino, Yuka Seki, Hiroki Hamada, Shogo Takashiba, Yoshihisa Fujikura
The other major result of this study was that treating PM2.5 with a strong acid and high-temperature heat treatment changed its constituent trace elements and other unknown acid-soluble chemicals, affecting its ability to induce allergic airway inflammation. This physicochemical treatment of PM2.5 reduced the constituent elements in the order Zn > Cu > Pb > P > S > Mn > Fe > Ca > Ni, with concomitant increases in carbon (C), silicon (Si) and chloride (Cl) because carbon and silicon, which exist in PM2.5 as elemental carbon and silicon dioxide, respectively, are acid-insoluble. As for chloride, the existence of insoluble organic chlorine compounds in PM2.5 and the side chain changes of protein amino acid in PM2.5 by 6 N HCl used for acid was not ruled out. Usually, oxidative stress is associated with Cu, Fe, Ni and Co, which generate OH radicals via Fenton’s reaction in the presence of hydrogen peroxide (H2O2) (Halliwell & Gutteridge, 2015). Thus, reducing the amounts of Cu, Fe and Ni in PM2.5 should reduce oxidative stress in lung airway inflammation. However, in exposed mice, the physicochemically treated PM2.5 augmented levels in lung tissue of 4-OH-2-nonenal, a biomarker of oxidative stress-induced lipid peroxidation (Xiao et al., 2017), when compared with that exposed to untreated PM2.5. This result suggested that oxidative stress only occurred with treated PM2.5 and not with PM2.5, implying that oxidative stress was not a major contributor in PM2.5-induced allergic airway inflammation.