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Strategies for Exposure Monitoring and Instrumentation
Published in Frances Alston, Emily J. Millikin, Willie Piispanen, Industrial Hygiene, 2018
Frances Alston, Emily J. Millikin, Willie Piispanen
Ionizing radiation is a Group 1 carcinogen as defined by the International Agency for Research on Cancer (IARC). By definition, Group 1 carcinogens are contaminants that have shown sufficient evidence of carcinogenicity in humans. In addition to ionizing radiation, other examples of Group 1 carcinogens include asbestos, benzene, cadmium, and polychlorinated biphenyls (PCBs). Predominantly, the exposure model applied to ionizing radiation, and still in existence today for many carcinogens, is the LNT model.
Lung Cancer Risk of a Population Exposed to Airborne Particles: The Contribution of Different Activities and Microenvironments
Published in Ayman El-Baz, Jasjit S. Suri, Lung Imaging and CADx, 2019
The toxicity of aerosols is clearly related to the compounds carried by the particles; some of these compounds are listed by the International Agency for Research on Cancer as group 1 carcinogens (i.e., characterized by an evident carcinogenetic effect on humans), and a causal relationship was established between exposure to these agents and human cancer. Among these, polycyclic aromatic hydrocarbons (PAHs) and some heavy metals could be considered major contributors to human exposure through the respiratory tract. PAHs are organic compounds with two or more fused aromatic rings formed during incomplete combustion. In general, the carcinogenic properties of PAHs increase with the number of aromatic rings [59]. The PAHs emitted by combustion sources are present in the gaseous phase (semivolatile) and are associated with particles (particle bound). Baek et al. [60] found that two- and three-ring PAHs were mainly in the gas phase, while four-ringed PAHs were in both the gas phase and the particle phase and five- and six-ringed PAHs were mainly attached to particles. Benzo[a]pyrene (BaP) is the most extensively studied PAH and is the usual marker for carcinogenic levels of PAHs in epidemiology and environmental studies. The World Health Organization International Program on Chemical Safety [61] represents a source of information on the relative carcinogenic potency of PAHs, and the European Union developed an extensive body of legislation establishing health-based standards for PAHs and heavy metals in the air. In particular, the annual mean concentration of BaP, as a representative for PAHs (1 ng m−3), As (6 ng m−3), Cd (5 ng m−3), and Ni (20 ng m−3), was established by Directive 2004/107/EC [62]. The corresponding estimated lifetime lung cancer risk due to PAHs is 8.7 cases per 100,000 people with chronic inhalational exposure to 1 ng m−3 of BaP over a lifetime of 70 years. Based on this information, the U.K. government's Expert Panel on Air Quality Standards recommended a U.K. standard for BaP of 0.25 ng m−3 [63], and when proposing an action plan to reduce environmental health risks in Sweden, the Swedish Governmental Commission on Environmental Health [64] proposed a value of 0.1 ng m−3 as the long-term average limit for BaP. This level corresponds to a theoretical lifetime cancer risk of 1 × 10−5 [65].
Development of a database on key characteristics of human carcinogens
Published in Journal of Toxicology and Environmental Health, Part B, 2019
Mustafa Al-Zoughool, Michael Bird, Jerry Rice, Robert A. Baan, Mélissa Billard, Nicholas Birkett, Daniel Krewski, Jan M Zielinski
Similarly, some of the mechanistic characteristics of carcinogenic agents may correlate better with cancer risk than others. Agents that react directly with DNA may form adducts or induce single- or double-strand breaks, such genotoxic effects are common to many Group-1 carcinogens. Several lines of evidence from epidemiological investigations, from studies with experimental animals, and from experimental in vitro systems demonstrated that DNA-adduct induction is strongly associated with cancer (Kriek et al. 1998; Phillips et al. 2015; Wiencke 2002). Genotoxic effects might lead to mutations. As noted above, gene mutation represents an important event in the pathway towards carcinogenesis, especially if it involves oncogenes or tumor-suppressor genes. RAS mutations that result from exposure to PAH are involved in the etiology of tumors (Ross and Nesnow 1999), and mutations in TP53 from other chemical exposures are linked to human cancers (Hussain and Harris 1999). Chromosomal changes are another type of genetic alteration frequently seen in many tumors. Consequently, agents that induce genomic instability such as benzene need to be regarded as potential carcinogens.
Volatile organic compound concentrations and their health risks in various workplace microenvironments
Published in Human and Ecological Risk Assessment: An International Journal, 2020
Simge Çankaya, Hakan Pekey, Beyhan Pekey, Burcu Özerkan Aydın
Volatile organic compounds (VOCs) are major air pollutants such as benzene, toluene, xylene, hexane, heptane, trichloroethane, perchloroethane, and cyclohexane in the indoor environment, and their concentration levels are frequently elevated indoors (Walgraeve et al. 2011; Colman Lerner et al. 2012). Because some VOCs are known to have carcinogenic and teratogenic effects, it is important to evaluate and manage their concentrations in indoor air (Srivastava and Devotta 2007). Various indoor microenvironments, such as homes, offices, restaurants, pubs, stores, cinemas, libraries, and train stations, are impacted by one or more potential sources of VOCs, including the following: solvent usage, consumer and commercial products (Guo et al.2004; Yuan et al. 2010), building or furnishing materials (Schlink et al. 2016), combustion materials such as heating and cooking equipment (Kabir et al. 2010; Evtyugina et al. 2014), and infiltration of outdoor VOCs (Kim et al.2001). Benzene, toluene, ethylbenzene, and xylenes (BTEXs) are the most significant compounds because of their large potentials to exert carcinogenic effects and occur in relatively high abundance in ambient air (Miri et al. 2016). Benzene, the most abundant and hazardous BTEX compound, is detected in almost all indoor environments, and the most important indoor sources of benzene are smoking, incense burning, and emissions from consumer products (Sarigiannis et al. 2011; Miri et al.2016). It is classified as a Group 1 carcinogen in an International Agency for Research of Cancer (IARC) monograph (IARC 1987). Chlorinated VOCs, such as dichloromethane, 1,1,1-trichloroethane, carbon tetrachloride (CTC), 1,2-dichloroethane, and 1,1-dichloroethylene, are common contaminants that have also been detected in various microenvironments in recent years (Huang et al. 2014). In particular, the atmospheric lifetime of CTC could reach as high as 100 years (ATSDR 2005), and it transports over long distances. Because chlorinated VOCs could remain stable in the environment for such long periods, they can cause severe effects on both the environment and human health. Thus, it is crucial to detect and take precautions against chlorinated VOCs (Huang et al. 2014).