Monte Carlo mixture model of lifetime cancer incidence risk from radiationexposure on shuttle and international space station

Citation
Le. Peterson et Fa. Cucinotta, Monte Carlo mixture model of lifetime cancer incidence risk from radiationexposure on shuttle and international space station, MUT RES-F M, 430(2), 1999, pp. 327-335
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Molecular Biology & Genetics
Journal title
MUTATION RESEARCH-FUNDAMENTAL AND MOLECULAR MECHANISMS OF MUTAGENESIS
ISSN journal
1386-1964 → ACNP
Volume
430
Issue
2
Year of publication
1999
Pages
327 - 335
Database
ISI
SICI code
1386-1964(199912)430:2<327:MCMMOL>2.0.ZU;2-4
Abstract
Estimating uncertainty in lifetime cancer risk for human exposure to space radiation is a unique challenge. Conventional risk assessment with low-line ar-energy-transfer (LET)-based risk from Japanese atomic bomb survivor stud ies may be inappropriate for relativistic protons and nuclei in space due t o track structure effects. This paper develops a Monte Carlo mixture model (MCMM) for transferring additive, National Institutes of Health multiplicat ive, and multiplicative excess cancer incidence risks based on Japanese ato mic bomb survivor data to determine excess incidence risk for various US as tronaut exposure profiles. The MCMM serves as an anchor point for future ri sk projection methods involving biophysical models of DNA damage from space radiation. Lifetime incidence risks of radiation-induced cancer for the MC MM based on low-LET Japanese data for nonleukemia (all cancers except leuke mia) were 2.77% (90% confidence limit, 0.75-11.34) for males exposed to 1 S v at age 45 and 2.20% (90% confidence limit, 0.59-10.12) for males exposed at age 55. For females, mixture model risks for nonleukemia exposed separat ely to I Sv at ages of 45 and 55 were 2.98% (90% confidence limit, 0.90-11. 70) and 2.44% (90% confidence limit, 0.70-10.30), respectively. Risks for h igh-LET 200 MeV protons (LET = 0.45 keV/mu m), 1 MeV alpha-particles (LET = 100 keV/mu m), and 600 MeV iron particles (LET = 180 keV/mu m) were scored on a per particle basis by determining the particle fluence required for a n average of one particle per cell nucleus of area 100 mu m(2) Lifetime ris k per proton was 2.68 x 10(-2)% (90% confidence limit, 0.79 x 10-3%-0.514 x 10(-2) %). For a-particles, lifetime risk was 14.2% (90% confidence limit, 2.5%-31.2%). Conversely, lifetime risk per iron particle was 23.7% (90% co nfidence limit, 4.5%-53.0%). Uncertainty in the DDREF for high-LET particle s may be less than that for low-LET radiation because typically there is ve ry little dose-rate dependence. Probability density functions for high-LET radiation quality and dose-rate may be preferable to conventional risk asse ssment approaches. Nuclear reactions and track structure effects in tissue may not be properly estimated by existing data using in vitro models for es timating RBEs. The method used here is being extended to estimate uncertain ty in spacecraft shielding effectiveness in various space radiation environ ments. (C) 1999 Elsevier Science B.V. All rights reserved.