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Chemical Permeation through Disposable Gloves
Published in Robert N. Phalen, Howard I. Maibach, Protective Gloves for Occupational Use, 2023
The need to test the permeation of isocyanates compounds through disposable gloves has arisen from isocyanates being a skin sensitizer and causative agent for allergic contact dermatitis.37–40 Isocyanate compounds are used in several industries beyond the collision repair industry and construction, as well as in many products and applications, e.g., in foams, bed liners, adhesives, insulation, varnishes, and isocyanate paints.41,42Figure 24.3 shows an example of the PPE worn by a worker using an isocyanate. Isocyanates include diisocyanates both in monomer and polymer forms. Monomer diisocyanates include methylenebis (phenyl isocyanate) (MDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI), followed by less common naphthalene diisocyanate (NDI), methylene bis-cyclohexylisocyanate (HMDI) (hydrogenated MDI), and isophorone diisocyanate (IPDI). Examples of widely used polyisocyanates include HDI biuret and HDI isocyanurate.
The Toxic Environment and Its Medical Implications with Special Emphasis on Smoke Inhalation
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
Jacob Loke, Richard A. Matthay, G. J. Walker. Smith
Various physiological and pulmonary responses have been used to correlate these data from laboratory animals with those of human victims at the industrial plant methyl isocyanate accident in Bhopal, India. In Chapter 3, Alarie and Schaper correlate the obstructive ventilatory pattern in animals with the obstructive airway disease noted among surviving victims in Bhopal. Thus, besides establishing that methyl isocyanate is a potent sensory and pulmonary irritant, these animal studies are valuable in extrapolating “safe” amounts of exposure for humans (Ferguson et al., 1986).
Scientific Rationale for the Use of Single Herb Remedies in Ayurveda
Published in D. Suresh Kumar, Ayurveda in the New Millennium, 2020
S. Ajayan, R. Ajith Kumar, Nirmal Narayanan
Histopathological studies clearly showed the protective effect of extract against toluene diisocyanate-induced asthma. The extract offered significant protection against histamine and acetylcholine aerosol-induced bronchospasm in guinea pigs. A significant decrease in total leukocyte and differential leukocyte count in the broncho-alveolar lavage fluid of the egg albumin-sensitized guinea pigs was observed after administration of the extract. Treatment with the extract for three days inhibited the hypersensitivity reaction. The extract dose dependently protected the mast cell disruption induced by p-Methoxy-N- methylphenethylamine. Alcohol extract of V. negundo therefore offers not only bronchodilation, but also decreases bronchial hyperreactivity, thereby providing protection against asthma (Patel et al. 2010).
Isocyanate induces cytotoxicity via activation of phosphorylated alpha synuclein protein, nitrosative stress, and apoptotic pathway in Parkinson’s Disease model-SHSY-5Y cells
Published in Neurological Research, 2023
Humans are exposed to isocyanates through breathing and physical contact. As powerful irritants, isocyanates irritate the mucous membranes of the eyes, stomach, and lungs. Dyspnea, chest pain, lacrimation, eyelid edema, and unconsciousness are also the symptoms of isocyanate exposure. Over the next 24 to 72 h, these effects may progress to include acute lung injury, cardiac arrest, and death [8]. As low as 1 ppm of isocyanate can cause significant functional changes in humans and inflammation processes in human tissues [9]. Inflammation due to isocyanate includes elevated levels of induced immune cells, especially CD4, CD8 positive T cells, and cytokines such as IL-1 β, IL-4, IL-5, IL-6, IL-15, and TNF-α in biopsies, bronchoalveolar lavage, and sputum of exposed patients [10,11]& [12]. Isocyanates have been extensively used, but their effects, particularly on human neurological functions, are poorly understood.
Microencapsulation of reactive isocyanates for application in self-healing materials: a review
Published in Journal of Microencapsulation, 2021
Amanda N. B. Santos, Demetrio J. dos Santos, Danilo J. Carastan
The term “isocyanate” may refer to the chemical group with formula R-N=C=O, but it is also the generic name of the chemical compounds which have one or more –NCO groups in their structure. The carbon atom in these compounds has an electropositive charge, making it extremely reactive with chemical groups which have an active atom of hydrogen (nucleophilic reagent), such as alcohols, amines and water. The reaction of NCO with the mentioned chemical groups usually forms urethane or urea bonds (Sharmin and Zafar 2012, Cherng et al.2013, Gogoi et al.2014). NCO is available in a large number of chemical compounds with a wide range of reactivity levels. They are usually classified as aliphatic, such as isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), and 4,4′-bis-methylene cyclohexane diisocyanate (HMDI), or aromatic, such as toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI) and polyaryl polymethylene isocyanate (PAPI). The chemical structure of these isocyanates is presented in Figure 2. These compounds are usually combined with other monomers to form polymeric materials covering a vast array of properties, more often based on urethane and urea bonds.
Drug eluting implants in pharmaceutical development and clinical practice
Published in Expert Opinion on Drug Delivery, 2021
Ashley R. Johnson, Seth P. Forster, David White, Graciela Terife, Michael Lowinger, Ryan S. Teller, Stephanie E. Barrett
Poly(urethanes) are notable for their versatility- the wide variety of available isocyanates, polyols, and chain extenders can produce poly(urethanes) with a range of thermal, chemical, and mechanical properties. The choice of isocyanates includes both aromatic isocyanates (such as toluene 2,4-diisocyanate, 4,4-diphenylmethylene diisocyanate, and lysine diisocyanate) and aliphatic isocyanates (such as 1,6-hexamethylene diisocyanate). While aromatic isocyanates produce tougher materials, they can degrade into potentially toxic products [110,111]. While the question of whether these toxic byproducts are present at physiologically relevant levels is hotly debated, there has been a push toward utilizing aliphatic poly(urethanes) for biomedical applications, as these materials carry a significantly lower toxicity risk [110,111].