George R. Hoffmann


Biology Department

Distinguished Professor of Science Emeritus
Ph.D., University of Tennessee


Fields: Genetics, Toxicology, and Botany


PO Box: B


Past Courses Taught

  • Toxicology
  • Genetics
  • Introductory Biology / Botany


Teaching & Research

I retired from the faculty in May, 2014, after 33 years of teaching and research at Holy Cross.  As an emeritus faculty member, I continued to teach Toxicology as needed.  My primary research interests are in mutation research and genetic toxicology, including the induction of point mutations, genetic recombination and chromosomal damage.  Related interests include relationships between chemical structure and biological activity, the analysis of dose-response relationships, additivity and synergy among chemical treatments, and applications of microbial and cytogenetic assays as models for predicting and interpreting genotoxic effects.


Selected Publications

Hoffmann, G.R.  2019.  Twenty Years of Reflections in Mutation ResearchMutat. Res. / Reviews in Mutation Research 780: 106-120.

Hoffmann, G.R. (Editor). “Reflections in Mutation Research: 1999-2019” (e-book:, Elsevier, 2019, 458 pp.

Chapman, K.E., G.R. Hoffmann, S.H. Doak and G.J.S. Jenkins.  2017.  Investigation of J-shaped dose-responses induced by exposure to the alkylating agent N-methyl-N-nitrosourea.  Mutat. Res. 819: 38-46

Hoffmann, G.R., C.L. Gray, P.B. Lange and C.I. Marando.  2015.  A source of artifact in the lacZ reversion assay in Escherichia coli.  Mutat. Res., 784-785: 23-30. get PDF

Preston, R.J. and G.R. Hoffmann. 2015. Genetic Toxicology. In “Casarett and Doull's Essentials of Toxicology,” Third Edition. C.D. Klaassen and J.B. Watkins III, eds., McGraw-Hill, New York, Chapter 9, pp. 135-147.

Hoffmann, G.R. 2014.  Relating Hormesis to Ethics and Policy: Conceptual Issues and Scientific Uncertainty. In "Hormesis in Health and Disease," Suresh I. S. Rattan and Éric Le Bourg, eds., CRC Press, Boca Raton, FL, USA, Chapter 15, pp. 307-337.  get PDF

Hoffmann, G.R., A.V. Moczula, A.M. Laterza, L.K. MacNeil and J.P. Tartaglione. 2013. Adaptive response to hydrogen peroxide in yeast: Induction, time course, and relationship to dose-response models. Environ. Mol. Mutagen., 54:384-396.  get PDF

Preston, R.J. and G.R. Hoffmann. 2013. Genetic Toxicology. In “Casarett and Doull's Toxicology: The Basic Science of Poisons,” C.D. Klaassen, ed., McGraw-Hill, New York, Eighth Edition, Chapter 9, pp. 445-480.

Zeiger, E. and G.R. Hoffmann. 2012. An illusion of hormesis in the Ames test: Statistical significance is not equivalent to biological significance. Mutat. Res., 746: 89-93.

Hoffmann, G.R., A.M. Laterza, K.E. Sylvia, and J.P. Tartaglione.  2011. Potentiation of the mutagenicity and recombinagenicity of bleomycin in yeast by unconventional intercalating agents.  Environ. Mol. Mutagen., 52: 130-144. get PDF

Hoffmann, G.R., M.V. Ronan, K.E. Sylvia and J.P. Tartaglione. 2009. Enhancement of the recombinagenic and mutagenic activities of bleomycin in yeast by intercalation of acridine compounds into DNA. Mutagenesis 24:317-329. get PDF

Hoffmann, G.R. 2009. A perspective on the scientific, philosophical, and policy dimensions of hormesis. Dose-Response: 7:1–51. get PDF

Hoffmann, G.R. and W.E. Stempsey. 2008. The Hormesis concept and risk assessment: Are there unique ethical and policy considerations? Hum. Exper. Toxicol. 27:613-620 (

Hoffmann, G.R., Gessner, G.S., Hughes, J. F., Ronan, M.V., Sylvia, K.E., & Willett, C.J. 2007. Modulation of the genotoxicity of bleomycin by amines through noncovalent DNA interactions and alteration of physiological conditions in yeast. Mut. Res. 623: 41–52. get PDF

Freeman, K.M. & Hoffmann, G.R. 2007. Frequencies of mutagen-induced coincident mitotic recombination at unlinked loci in Saccharomyces cerevisiae. Mut. Res. 616: 119-132. get PDF

Hoffmann, G.R., Yin, C.C., Terry, C.E., Ferguson, L.R. & Denny, W.A. 2006. Frameshift Mutations Induced by Four Isomeric Nitroacridines and Their des-Nitro Counterpart in the lacZ Reversion Assay in Escherichia coli. Environmental and Molecular Mutagenesis 47:82-94. get PDF

Calabrese, E.J., J.W. Staudenmayer, E.J. Stanek III, and G.R. Hoffmann. 2006. Hormesis outperforms threshold model in NCI anti-tumor drug screening database. Toxicol. Sci., 94: 368-378. get PDF

Hoffmann, G.R., M.A. Calciano, B.M. Lawless, and K.M. Mahoney. 2003. Frameshift mutations induced by three classes of acridines in the lacZ reversion assay in Escherichia coli: Potency of responses and relationship to slipped mispairing models. Environ. Mol. Mutagen., 42:111-121. get PDF

Hoffmann, G.R., D. J. Crowley, and P. J. Theophiles. 2002. Comparative potencies of induction of point mutations and genetic duplications by the methylating agents methylazoxymethanol and dimethyl sulfate in bacteria. Mutagenesis, 17:439-444. get PDF

Hoffmann, G.R., A.M. Sayer, and L.G. Littlefield. 2002. Higher frequency of chromosome aberrations in late-arising first-division metaphases than in early-arising metaphases after exposure of human lymphocytes to X-rays in G0. Int. J. Radiat. Biol., 78:765-772. get PDF

Hoffmann, G.R., J. Buccola, M.S. Merz, and L.G. Littlefield. 2001. Structure-activity analysis of the potentiation by aminothiols of the chromosome-damaging effect of bleomycin in G0 human lymphocytes. Environ. Mol. Mutagen., 37:117-127. get PDF

Hoffmann, G. R., R. Janel-Bintz, and R.P.P. Fuchs. 2001. Induction of-2 frameshift mutations by 2-nitrofluorene, N-hydroxyacetylaminofluorene, and N-2-acetylaminofluorene in reversion assays in Escherichia coli strains differing in permeability and acetyltransferase activity. Mut. Res 493: 127-137. get PDF

Hoffmann, G.R., A.M. Sayer, E.E. Joiner, A.F. McFee, and L.G. Littlefield. 1999. Analysis by FISH of the spectrum of chromosome aberrations induced by x rays in human lymphocytes and their fate through mitotic divisions in culture. Environ. Molec. Mutagen., 33:94-110. get PDF

Hoffmann, G.R., R.A. Shorter, J.L. Quaranta, and P.D. McMaster. 1999. Two mechanisms of antimutagenicity of the aminothiols cysteamine and WR-1065 in Saccharomyces cerevisiae. Toxicol. In Vitro., 13:1-9. get PDF

Hoffmann, G.R., and R.P.P. Fuchs. 1997. Mechanisms of frameshift mutations: Insight from aromatic amines. Chem. Res. Toxicol., 10:347-359. get PDF

Hoffmann, G.R., S.M. Deschênes, T. Manyin, and R.P.P. Fuchs. 1996. Mutagenicity of acridines in a reversion assay based on tetracycline resistance in plasmid pBR322 in Escherichia coli. Mutation Res., 351:33-43. get PDF

Hoffmann, G.R., J.L. Quaranta, R.A. Shorter, and L.G. Littlefield. 1995. Modulation of bleomycin-induced mitotic recombination in yeast by the aminothiols cysteamine and WR-1065. Molec. Gen. Genet., 249:366-374. get PDF

Hoffmann, G.R., and L.G. Littlefield. 1995. Enhancement of the activity of bleomycin by cysteamine in a micronucleus assay in G0 human lymphocytes. Toxicol. Lett., 78:147-151. get PDF

Hoffmann, G.R., A.M. Sayer, and L.G. Littlefield. 1994. Potentiation of bleomycin by the aminothiol WR-1065 in assays for chromosomal damage in G0 human lymphocytes. Mutation Res., 307:273-283. get PDF

Hoffmann, G.R. 1992. Bacterial assays for recombinagens. Mutation Res., 284:125-146. get PDF

Hoffmann, G.R. and R.P.P. Fuchs.  1990.  DNA sequence analysis of mutations induced by N–2-acetylamino-7-iodofluorene in plasmid pBR322 in Escherichia coli. J. Molec. Biol., 213:239-246.

Hoffmann, G.R., C.S. Freemer, and L.A. Parente. 1989. Induction of genetic duplications and frameshift mutations in Salmonella typhimurium by acridines and acridine mustards: Dependence on covalent binding of the mutagen to DNA.  Molec. Gen. Genet., 218:377-383.

Hoffmann, G.R., K.M. Sprague, J.A. Wrobel, and D.H. Wroblewski.  1987.  A recombinagenic effect of strychnine in Salmonella typhimurium. Environ. Mol. Mutagen., 10:27-33.

Hoffmann, G.R., J.F. Boyle, and C.S. Freemer. 1988. Induction of genetic duplications in Salmonella typhimurium by dialkyl sulfates. Environ. Mol. Mutagen. 11:545-551.

Hoffmann, G.R.  1985.  Genetic duplications in bacteria and their relevance for genetic toxicology.  Mutation Res., 150:107-117.

Hoffmann, G.R., L.S. Catuogno, J.F. Linnane, and L.A. Parente.  1985.  Effects of DNA repair processes on the induction of genetic duplications in bacteria by ultraviolet light.  Mutation Res., 151:25-33.

Hoffmann, G.R., and R.W. Morgan.  1984.  Putative mutagens and carcinogens in foods:  V. Cycad azoxyglycosides.  Environ. Mutagen., 6:103-116.

Morgan, R.W. and G.R. Hoffmann.  1983.  Cycasin and its mutagenic metabolites.  Mutation Res. 114:19-58.

Hoffmann, G.R., M.J. Walkowicz, J.M. Mason, and J.F. Atkins.  1983.  Genetic instability associated with the aroC321 allele in Salmonella typhimurium involves genetic duplication.  Molec. Gen. Genet. 190:183-188. 

Hoffmann, G.R.  1983.  Detection of effects of mutagens in human populations.  In “Chemical Mutagens:  Principles and Methods for their Detection,”  F.J. deSerres, ed., Plenum Press, New York, Volume 8, pp. 1-53.

Hoffmann, G.R. 1982.  Mutagenicity testing in environmental toxicology.  Environ. Sci. Technol. 16:560A-574A and ES&T 17:112A, 1983.)

Hoffmann, G.R. 1980.  Genetic effects of dimethylsulfate, diethylsulfate, and related compounds.  Mutation Res. 75:63-129.

Hoffmann, G.R., R.W. Morgan, and R.C. Harvey.  1978.  Effects of chemical and physical mutagens on the frequency of a large genetic duplication in Salmonella typhimurium.  I. Induction of duplications.  Mutation Res. 52:73-80.

Hoffmann, G.R., R.W. Morgan, and R. Kirven. 1978.  Effects of chemical and physical mutagens on the frequency of a large genetic duplication in Salmonella typhimurium.  II. Stimulation of duplication loss from merodiploids.  Mutation Res. 52:81-86.

Hoffmann, G.R. and R.W. Morgan.  1976.  The effect of ultraviolet light on the frequency of a genetic duplication in Salmonella typhimurium.  Radiation Res. 67:114-119.

Hoffmann, G.R. and H.V. Malling. 1975. Azaguanine resistant mutants induced by several mutagens in a Neurospora heterokaryon.  Mutation Res. 27:307-318.

Straus, D.S. and George R. Hoffmann. 1975.  Selection for a large genetic duplication in Salmonella typhimurium.  Genetics 80:227-237.

Hoffmann, G.R. and H.V. Malling.  1974.  Mutants of Neurospora crassa resistant to 8–azaguanine.  J. Gen. Microbiol. 83:319-326.

Hoffmann, G.R., H.V. Malling, and T.J. Mitchell.  1973.  Genetics of 5-fluorodeoxyuridine resistant mutants of Neurospora crassa.  Can. J. Genet. Cytol. 15:831-844.

Hoffmann, G.R. 1970.  Studies on the reversal of 5-fluorodeoxyuridine-induced mitotic inhibition by thymidine and thymidine analogues.  Can. J. Genet. Cytol. 12:230-240.