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Considerations in the Design and Conduct of Subchronic and Chronic Dermal Exposure Studies with Chemicals
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
Polycarbonate or stainless steel, wire mesh cages are used in large scale toxicology studies. Cages should be chemical specific and destroyed or decontaminated after the study is completed to reduce the potential of cross-chemical contamination between studies. Polycarbonate cages are less drafty and temperature is less variable. Stainless steel, wire mesh cages allow for air to circulate, an important consideration to help reduce an unintentional inhalation exposure if the chemical or vehicle solvent is volatile.
Nonclinical Safety Evaluation of Medical Devices
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Kathleen A. Funk, Victoria A. Hampshire, JoAnn C. L. Schuh
Regarding polymers, the host cell and tissue response (Section 9.5) and the specific chemistry of the polymer can be manipulated to result in resorption or to protect against degradation. Polymers may be biodegradable or stable and the chemistry and response evaluation of each are different. For instance, sutures made of polyesters are designed to resorb. Polyethylene and polypropylene may resorb, particularly if damaged by free radicals, and may be designed with a coating to protect against oxidation. Polyethylene terephthalate (Dacron®) is not designed to resorb and is often used for vascular grafts. The specific chemistry of polyurethane dictates whether it will resorb (Anderson et al. 2008; Thevenot et al. 2008). New generation polyurethanes incorporate antioxidants and anti-adhesion short chain molecules (surface-modifying end groups) to reduce unwanted degradation that may lead to environmental stress cracking of partially degraded and, therefore, brittle device substances. The addition of polycarbonate and polyelastomer segments has improved flexibility and continued stability of some of these polymer materials.
Organic Chemicals
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Polycarbonates are used in containers for many liquids as well as in oxygenators for heart–lung machines and other extracorporeal medical devices. Polycarbonates leach off synthetics, which causes problems in the chemically sensitive; however, polycarbonates are not as toxic as most plastics.
Detection of endocrine and metabolism disrupting xenobiotics in milk-derived fat samples by fluorescent protein-tagged nuclear receptors and live cell imaging
Published in Toxicology Mechanisms and Methods, 2023
Keshav Thakur, Emmagouni Sharath Kumar Goud, Yashika Jawa, Chetan Keswani, Suneel Onteru, Dheer Singh, Surya P. Singh, Partha Roy, Rakesh K. Tyagi
Further experiments were conducted to examine the translocation behavior of GFP-AR with BPA alone and fat extracted from milk spiked with BPA. BPA is reported to be an anti-androgenic and estrogen-mimicking synthetic chemical extensively used to synthesize polycarbonate plastics for containers, food packaging material, electronic gadgets, housewares, water pipes, etc. When tested with our current cell-based assay we observed that BPA alone and BPA in milk-fat extracted from spiked milk efficiently translocated GFP-AR from cytoplasm to nuclear compartment. For the study, COS-1 cells were transiently transfected with GFP-AR. After the transfection period of 12–16 hours, the cells were incubated with experimental ligand in DMEM having 5% steroid-free serum without antibiotics for 24 hours at 37 °C. Cell treatments were performed in two groups i.e. a) solvent group (DHT/BPA in DMSO: EtOH) and b) fat group (DHT/BPA in milk-fat). BPA exhibited a dose-dependent (25–100 µM) increase in receptor translocation. In addition, when compared, milk-fat alone showed marginally higher nuclear translocation than the solvent alone, implying the possible presence of low levels of AR ligand in milk samples (Figure 2).
Protective role of resveratrol and apigenin against toxic effects of bisphenol a in rat salivary gland
Published in Drug and Chemical Toxicology, 2023
Yaser Said Çetin, Fikret Altındağ, Mehmet Berköz
Bisphenol A (BPA), the starting monomer of polycarbonates, is among the most widely produced chemicals worldwide. It is an important chemical since it can leak into the environment and thereby may cause chronic exposure in humans and nature. Today, many people are exposed to BPA chemicals through the use of materials including water bottles, storage containers, sports equipment, detergents, toys, medical supplies, and dental composite resin (Michałowicz, 2014). Moreover, people are exposed to BPA through direct contact or its migration to food products. It is also known that exposure to this chemical occurs through inhalation and its absorption through the skin. Studies in the literature indicate that low doses of BPA adversely affect the endocrine system and also have various effects on the central nervous and immune systems. In addition, BPA exposure has also been shown to have negative effects on the cardiovascular, respiratory, and renal systems and may cause chronic diseases such as birth defects and breast cancer (Geens et al.2012, Rezg et al.2014).
The effects of bisphenols on the cardiovascular system
Published in Critical Reviews in Toxicology, 2022
Patrícia Dias, Václav Tvrdý, Eduard Jirkovský, Marija Sollner Dolenc, Lucija Peterlin Mašič, Přemysl Mladěnka
The general population has been unavoidably exposed to BPA via food and beverages packaged in containers made from materials containing BPA. Data from a European Union assessment (2008) and the Scientific Committee on Food (2002) suggested daily BPA exposure range between 0.48 and 1.45 µg/kg. Except of classical oral exposure, there are other ways of exposure to BPA and its derivatives, like sublingual, transdermal, and inhalation exposures (Gayrard et al. 2013; vom Saal and Welshons 2014). Furthermore, a potentially important source of exposition to bisphenols is represented by medical devices and tubing as documented for BPA in cases of exposition of neonates at intensive care units (Calafat et al. 2009; Duty et al. 2013). In addition, there have also been cases of occupational exposure-related to BPA due to polycarbonate or epoxy resin handling procedures (Gray et al. 2004; Joint Research Centre Institute for Health and Consumer Protection 2010).