Revised assessment of cancer risk to dichloromethane II. Application of probabilistic methods to cancer risk determinations.

2.50
Hdl Handle:
http://hdl.handle.net/10146/68636
Title:
Revised assessment of cancer risk to dichloromethane II. Application of probabilistic methods to cancer risk determinations.
Authors:
David, Raymond M.; Clewell, Harvey J.; Gentry, P. Robinan; Covington, Tammie R.; Morgott, David A.; Marino, Dale J.
Abstract:
An updated PBPK model of methylene chloride (DCM, dichloromethane) carcinogenicity in mice was recently published using Bayesian statistical methods (Marino et al., 2006). In this work, this model was applied to humans, as recommended by Sweeney et al.(2004). Physiological parameters for input into the MCMC analysis were selected from multiple sources reflecting, in each case, the source that was considered to represent the most current scientific evidence for each parameter. Metabolic data for individual subjects from five human studies were combined into a single data set and population values derived using MCSim. These population values were used for calibration of the human model. The PBPK model using the calibrated metabolic parameters was used to perform a cancer risk assessment for DCM, using the same tumor incidence and exposure concentration data relied upon in the current IRIS entry. Unit risks, i.e., the risk of cancer from exposure to 1 microg/m3 over a lifetime, for DCM were estimated using the calibrated human model. The results indicate skewed distributions for liver and lung tumor risks, alone or in combination, with a mean unit risk (per microg/m3) of 1.05 x 10(-9), considering both liver and lung tumors. Adding the distribution of genetic polymorphisms for metabolism to the ultimate carcinogen, the unit risks range from 0 (which is expected given that approximately 20% of the US population is estimated to be nonconjugators) up to a unit risk of 2.70 x 10(-9) at the 95th percentile. The median, or 50th percentile, is 9.33 x 10(-10), which is approximately a factor of 500 lower than the current EPA unit risk of 4.7 x 10(-7) using a previous PBPK model. These values represent the best estimates to date for DCM cancer risk because all available human data sets were used, and a probabilistic methodology was followed.
Citation:
Regul. Toxicol. Pharmacol. 2006, 45 (1):55-65
Journal:
Regulatory toxicology and pharmacology : RTP
Issue Date:
Jun-2006
URI:
http://hdl.handle.net/10146/68636
DOI:
10.1016/j.yrtph.2005.12.003
PubMed ID:
16439044
Additional Links:
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WPT-4J3WSK2-2&_user=1843694&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000055040&_version=1&_urlVersion=0&_userid=1843694&md5=d898c2cb33cb4a8051bc27025a9d6366
Type:
Article
Language:
en
Description:
KEYWORDS - CLASSIFICATION: analysis;chemically induced;Carcinogens;Dose-Response Relationship,Drug;Environment;genetics;Glutathione;Glutathione Transferase;Humans;Inhalation Exposure;Laboratories;metabolism;methods;Markov Chains;mechanisms of carcinogenesis;Methylene Chloride;Models,Biological;Monte Carlo Method;Neoplasms;pharmacokinetics;Polymorphism,Genetic;Risk Assessment;toxicity.
ISSN:
0273-2300
Appears in Collections:
Articles with annotation

Full metadata record

DC FieldValue Language
dc.contributor.authorDavid, Raymond M.-
dc.contributor.authorClewell, Harvey J.-
dc.contributor.authorGentry, P. Robinan-
dc.contributor.authorCovington, Tammie R.-
dc.contributor.authorMorgott, David A.-
dc.contributor.authorMarino, Dale J.-
dc.date.accessioned2009-05-20T10:24:31Z-
dc.date.available2009-05-20T10:24:31Z-
dc.date.issued2006-06-
dc.identifier.citationRegul. Toxicol. Pharmacol. 2006, 45 (1):55-65en
dc.identifier.issn0273-2300-
dc.identifier.pmid16439044-
dc.identifier.doi10.1016/j.yrtph.2005.12.003-
dc.identifier.urihttp://hdl.handle.net/10146/68636-
dc.descriptionKEYWORDS - CLASSIFICATION: analysis;chemically induced;Carcinogens;Dose-Response Relationship,Drug;Environment;genetics;Glutathione;Glutathione Transferase;Humans;Inhalation Exposure;Laboratories;metabolism;methods;Markov Chains;mechanisms of carcinogenesis;Methylene Chloride;Models,Biological;Monte Carlo Method;Neoplasms;pharmacokinetics;Polymorphism,Genetic;Risk Assessment;toxicity.en
dc.description.abstractAn updated PBPK model of methylene chloride (DCM, dichloromethane) carcinogenicity in mice was recently published using Bayesian statistical methods (Marino et al., 2006). In this work, this model was applied to humans, as recommended by Sweeney et al.(2004). Physiological parameters for input into the MCMC analysis were selected from multiple sources reflecting, in each case, the source that was considered to represent the most current scientific evidence for each parameter. Metabolic data for individual subjects from five human studies were combined into a single data set and population values derived using MCSim. These population values were used for calibration of the human model. The PBPK model using the calibrated metabolic parameters was used to perform a cancer risk assessment for DCM, using the same tumor incidence and exposure concentration data relied upon in the current IRIS entry. Unit risks, i.e., the risk of cancer from exposure to 1 microg/m3 over a lifetime, for DCM were estimated using the calibrated human model. The results indicate skewed distributions for liver and lung tumor risks, alone or in combination, with a mean unit risk (per microg/m3) of 1.05 x 10(-9), considering both liver and lung tumors. Adding the distribution of genetic polymorphisms for metabolism to the ultimate carcinogen, the unit risks range from 0 (which is expected given that approximately 20% of the US population is estimated to be nonconjugators) up to a unit risk of 2.70 x 10(-9) at the 95th percentile. The median, or 50th percentile, is 9.33 x 10(-10), which is approximately a factor of 500 lower than the current EPA unit risk of 4.7 x 10(-7) using a previous PBPK model. These values represent the best estimates to date for DCM cancer risk because all available human data sets were used, and a probabilistic methodology was followed.en
dc.language.isoenen
dc.relation.urlhttp://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WPT-4J3WSK2-2&_user=1843694&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000055040&_version=1&_urlVersion=0&_userid=1843694&md5=d898c2cb33cb4a8051bc27025a9d6366en
dc.subjectMethylene chlorideen
dc.subjectDichloromethaneen
dc.subjectRisk assessmenten
dc.subjectPBPK modelingen
dc.subjectBayesian analysisen
dc.subjectMonte Carlo analysisen
dc.subjectGST polymorphismen
dc.subject.meshCarcinogens-
dc.subject.meshDose-Response Relationship, Drug-
dc.subject.meshGlutathione Transferase-
dc.subject.meshHumans-
dc.subject.meshInhalation Exposure-
dc.subject.meshMarkov Chains-
dc.subject.meshMethylene Chloride-
dc.subject.meshModels, Biological-
dc.subject.meshMonte Carlo Method-
dc.subject.meshNeoplasms-
dc.subject.meshPolymorphism, Genetic-
dc.subject.meshRisk Assessment-
dc.titleRevised assessment of cancer risk to dichloromethane II. Application of probabilistic methods to cancer risk determinations.en
dc.typeArticleen
dc.identifier.journalRegulatory toxicology and pharmacology : RTPen

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