RESUMO
A meeting was held within the International Agency for Research on Cancer (IARC) Programme on the Evaluation of Carcinogenic Risks to Humans of surgical implants and other foreign bodies. This meeting report summarises the types of materials considered, their wear and degradation, their cancer epidemiology in both humans and other animals, the published experimental carcinogenicity data and selected data on their toxic, including genotoxic, effects. Evaluations resulting in a classification of Group 2B (possibly carcinogenic to humans) were reached for: (1) polymeric implants prepared as thin smooth films [with the exception of poly(glycolic acid)]; (2) metallic implants prepared as thin smooth films; and (3) implanted foreign bodies consisting of metallic cobalt, metallic nickel and a particular alloy powder consisting of 66-67% nickel, 13-16% chromium and 7% iron. Group 3 classifications (not classifiable as to their carcinogenicity to humans) were made for: (1) organic polymeric materials as a group; (2) orthopaedic implants of complex composition and cardiac pacemakers; (3) silicone breast implants; (4) dental materials; and (5) ceramic implants.
Assuntos
Corpos Estranhos/complicações , Neoplasias/etiologia , Próteses e Implantes/efeitos adversos , Animais , Biodegradação Ambiental , Carcinógenos/efeitos adversos , Humanos , Metais , Neoplasias Experimentais/etiologia , Pesquisa , Medição de RiscoRESUMO
In the absence of adequate data on humans, it is biologically plausible and prudent to regard agents and mixtures for which there is sufficient evidence of carcinogenicity in experimental animals, usually rats and mice, as if they presented a carcinogenic risk to humans. Prediction of cancer sites in humans from bioassay data in rodents is much less certain, however, regardless of organ or tissue. For tumors of the nervous system, there is practically no basis for judging the validity of such predictions, as only ionizing radiation is known to cause tumors of the central nervous system (CNS) in humans. Brain tumors are relatively uncommon findings in bioassays and are rare in untreated rodents, even in rats, which appear to be the most susceptible species. However, CNS tumors have been readily induced in rodents by systemic exposures to some chemicals, notably N-nitrosoalkylureas and other alkylating agents and certain alkyl hydrazine derivatives. CNS tumors in rodents have played a significant role in carcinogenic hazard evaluations of several other chemicals, including acrylonitrile, ethylene oxide, and acrylamide, and have been implicated as part of the tumor spectrum induced by vinyl chloride and certain inorganic lead compounds. In some of these evaluations, it is not certain that all tumors diagnosed as primary brain tumors were correctly identified. Diagnostic difficulties have been presented by undifferentiated small-cell tumors that may invade the brain, including carcinomas of the nasal cavity and undifferentiated schwannomas arising in cranial nerve ganglia, and by the difficulty of reliably distinguishing between focal reactive gliosis and early glial neoplasms. The most striking experimental finding regarding the induction by chemicals of tumors of the nervous system is the dramatically greater susceptibility of the fetal and neonatal nervous system to some carcinogens, as compared with the susceptibility of the nervous system in adults of the same species.
Assuntos
Testes de Carcinogenicidade , Carcinógenos/toxicidade , Neoplasias do Sistema Nervoso/induzido quimicamente , Neoplasias do Sistema Nervoso/patologia , Animais , Humanos , Camundongos , RatosAssuntos
Carcinógenos/efeitos adversos , Córtex Renal/efeitos dos fármacos , Neoplasias Renais/induzido quimicamente , Neoplasias Epiteliais e Glandulares/induzido quimicamente , Neoplasias da Glândula Tireoide/induzido quimicamente , Neoplasias da Bexiga Urinária/induzido quimicamente , Animais , Humanos , Fatores de RiscoAssuntos
Carcinógenos Ambientais/normas , Exposição Ambiental/normas , Dióxido de Silício , Carcinógenos Ambientais/classificação , Carvão Mineral/efeitos adversos , Carvão Mineral/normas , França , Humanos , Nylons/efeitos adversos , Nylons/normas , Exposição Ocupacional/normas , Silicatos/efeitos adversos , Silicatos/normas , Dióxido de Silício/efeitos adversos , Dióxido de Silício/normasRESUMO
For more than twenty years, the IARC has been evaluating the carcinogenic risk to humans of chemicals, groups of chemicals, complex mixtures, occupational exposures, behavioral and life-style exposures, biological agents, such as bacteria and viruses, and physical agents, such as radiation, on the basis of published studies of carcinogenicity in humans and laboratory animals. This paper includes the list established by IARC of substances carcinogenic to humans.
Assuntos
Carcinógenos , Neoplasias Experimentais/etiologia , Neoplasias/etiologia , Animais , Testes de Carcinogenicidade/métodos , Carcinógenos/classificação , Carcinógenos/toxicidade , Carcinógenos Ambientais/classificação , Carcinógenos Ambientais/toxicidade , Métodos Epidemiológicos , Estudos de Avaliação como Assunto , Feminino , Humanos , Masculino , Camundongos , Neoplasias/induzido quimicamente , Neoplasias/epidemiologia , Neoplasias Experimentais/induzido quimicamente , Coelhos , Fatores de RiscoAssuntos
Exposição Ambiental , Inseticidas , Neoplasias/induzido quimicamente , Nitrosaminas , Humanos , MétodosRESUMO
Although both the epidemiologic and experimental studies have led to the identification of chemical carcinogens, the limitations in epidemiologic approaches and the need for primary prevention of cancer require a greater reliance on experimental studies. Long-term carcinogenicity studies in experimental animals have been instrumental in identifying chemicals with carcinogenic activity, and, in some cases, the experimental evidence has preceded the epidemiologic evidence (for 4-aminobiphenyl, aflatoxin B1, diethylstilbestrol, melphalan, mustard gas, and vinyl chloride). A better understanding of the multistage process of carcinogenesis and the findings from various short-term tests available more recently may provide a more solid basis for extrapolating experimental findings to man.