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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Carcinogens are materials that cause cancer. This information has been obtained by studying populations exposed to materials for long periods, usually in the workplace. The information can also be obtained through tests on laboratory animals. This does not mean that the material will actually cause cancer in humans, but it may be a good indication. Examples of known carcinogens include benzene, asbestos, arsenic, arsenic compounds, vinyl chloride and mustard gas.
Carcinogenic and Mutagenic Substances
Published in Małgorzata Pośniak, Emerging Chemical Risks in the Work Environment, 2020
Most of the carcinogens, by themselves or in combination with others, cause cancer by interacting with the cell’s DNA and disrupting their normal functioning. This ultimately leads to the formation of a tumor (abnormal tissue growth), which has the ability to spread (metastasize) from the location of origin as well as the ability to invade and cause dysfunction of other tissues, which in turn results in organ failure and eventually death. Two basic mechanisms by which carcinogens initiate the formation of such cancers are based on changing the DNA to incite cell division and on taking away the cell’s ability to auto-destruct when stimulated by the usual triggers, such as DNA damage or cell damage (a process known as apoptosis). There are also carcinogens which induce cancer through non-genotoxic mechanisms, such as immunosuppression and the induction of tissue-specific inflammation.
Toxicology
Published in W. David Yates, Safety Professional’s Reference and Study Guide, 2020
Other classifications of chemicals or toxins include carcinogens, cocarcinogens, epigenetic, genotoxic, mutagen, clastogen, and teratogen, which are described in the following. Carcinogen: Any substance or agent known to cause cancer. Carcinogens do not adhere to the dose–response curve.Cocarcinogen: These agents, when applied immediately prior to or with a genotoxic carcinogen, enhance the oncogenic (cancerous) effect of the agent.Epigenetic: Changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the underlying DNA sequence.Genotoxic: These materials are known to be potentially mutagenic and carcinogenic in nature. They act directly by altering the DNA.Mutagen: A physical or chemical agent that changes the genetic material (usually DNA) of an organism and thus increases the frequency of mutagens above the natural background level.Teratogens: Any agent that can disturb the development of an embryo or fetus.
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
Evidence accumulated from molecular epidemiological studies demonstrated that the risk of chemically induced cancer may vary in different individuals as a function of inherited factors such as individual genotype as well as acquired factors such as environmental exposures (Rothman et al. 2001). On the other hand, epidemiological investigations amongst migrant populations showed greater importance of lifestyle as compared with genetics as a cause of cancer. This finding implies that many cancers might be prevented by lifestyle changes that reduce exposure to carcinogens. Risk is also affected by agent-related factors such as exposure conditions including dose, frequency, and duration as well as the health and nutritional status of the host. These variations in risk are most likely mediated by key mechanistic pathways involved in carcinogenesis.
Regulation of cytochrome P450 expression by microRNAs and long noncoding RNAs: Epigenetic mechanisms in environmental toxicology and carcinogenesis
Published in Journal of Environmental Science and Health, Part C, 2019
Dongying Li, William H. Tolleson, Dianke Yu, Si Chen, Lei Guo, Wenming Xiao, Weida Tong, Baitang Ning
A biomarker is defined as an objectively measurable characteristic in biological media (e.g. human tissues, cells, or body fluids) that can indicate biological or pathogenic processes or pharmacological responses.157 Biomarkers have the potential to assist in disease prediction, prevention, diagnosis, prognosis, intervention, and therapeutic efficiency.158 An ideal biomarker features specificity, sensitivity, robustness, validity, actionability, noninvasive detectability, and translatability (from animal models to humans).159 In the era of precision medicine, the development of reliable and robust mechanistic biomarkers will be an important approach to aid clinical practice and regulatory decision-making; their acceptance requires elucidation of underlying mechanisms and advancement of detection technologies. In recent decades, cell free circulating miRNAs have been explored as a new generation of biomarkers for disease, toxicity assessment, and drug development, owing to their conservation, tissue-specificity, stability, and minimally-invasive detectability in human body fluids (e.g. blood, urine, and saliva).69,160–163 miRNAs represent potential biomarkers for detecting exposures to environmental toxicants. Conventional exposure indicators include internal doses of carcinogens and their metabolites, DNA and protein adduct formation, genetic alterations, circulating proteins, and altered gene expression.158,164 The 5-year survival rate for lung cancers overall is only 18%, yet survival increases to 56% when lung tumors are detected before they metastasize; however, only 16% of lung cancer cases are diagnosed at such an early stage.13 The early response of miR-126* in the expression level during lung carcinogenesis indicates miR-126* might be investigated for its potential as an early diagnostic marker for lung cancer.66
Does REACH provide sufficient information to regulate mutagenic and carcinogenic substances?
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Marjolijn Woutersen, Martijn Beekman, Marja E. J. Pronk, Andre Muller, Joop A. de Knecht, Betty C. Hakkert
Substances are classified as carcinogens if they can induce cancer or increase its incidence, see Classification Criteria for Carcinogenicity. The classification can be limited to a certain route of exposure if it can be conclusively proved that no other route exhibits the hazard. The category of the classification reflects the strength of evidence, with a differentiation between sufficient evidence (Category 1B) and limited evidence (Category 2).