Center for Interdisciplinary Research
in Environmental Exposures and Health
Main / Interactions of Chemicals--Research at Boston University School of Public Health

Suppose that the above graph shows the result of experiments using 10 uM of compound B, 10 uM of compound A, and a mixture of 10 uM of A and 10 uM of B. What does this experiment demonstrate?

  • Synergy of A and B
  • Additivity of A and B
  • Antagonism of A and B
  • Don't know

Answer

My research:

  • We are currently examining biologically-based, mathematical models of chemical interactions using kinetic models of receptor-ligand systems. More to come!
  • As part of the BU Superfund Research Program, I collaborate with Dr. Jennifer Schlezinger on experimental studies of chemical mixtures.

News

  • March 2009: Our new paper is in press at Journal of Theoretical Biology.
  • 20 May 2008: Doctoral student Greg Howard defends his dissertation on Assessing the Combined Effects of Similarly-Acting Agents.
  • 21 June 2007: Doctoral student Greg Howard wins best poster award at 2007 Society for Epidemiologic Research Conference. See Howard G, Webster T. Contrasting Theories of Additivity, Synergy, and Antagonism in Epidemiology and Toxicology. American Journal of Epidemiology 2007; 165(11) Suppl: S62.
  • More News & Awards

Publications

  • Webster TF. Mixtures of endocrine disruptors: How similar must mechanisms be for concentration addition to apply? Toxicology 2013; 313: 129 133. [accepted 20 January 2013]. doi:10.1016/j.tox.2013.01.009
  • Howard GJ, Webster TF. Contrasting Theories of Interaction in Epidemiology and Toxicology. Environ Health Perspect 2013; 121:16. [online 26 September 2012]. http://dx.doi.org/10.1289/ehp.1205889
  • Howard GJ, Schlezinger JJ, Hahn ME, Webster TF. Generalized Concentration Addition Predicts Joint Effects of Aryl Hydrocarbon Receptor Agonists with Partial Agonists and Competitive Antagonists.Environ Health Perspect. 2010; 118(5):666-672 [Online 22 December 2009]. The full text is freely available doi:10.1289/ehp.0901312.
  • Howard GJ, Webster TF. Generalized concentration addition: A method for examining mixtures containing partial agonists. Journal of Theoretical Biology 2009; 259:469477. [Online 5 April 2009]. Abstract: doi:10.1016/j.jtbi.2009.03.030.
  • Howard GJ, Schlezinger JJ, Webster TF. Interactions of TCDD with AhR partial agonists and a competitive antagonist: implications for TEFs. Organohalogen Compounds 2007; 69:1065-1068.
  • Schlezinger JJ, Howard GJ, Hurst CH, Emberley JK, Waxman DJ, Webster T, Sherr DH. Environmental and endogenous peroxisome proliferator-activated receptor gamma agonists induce bone marrow B cell growth arrest and apoptosis: interactions between mono(2-ethylhexyl) phthalate, 9-cis-retinoic acid, and 15-deoxy-Delta12,14-prostaglandin J2. J Immunol 2004; 173(5): 3165-77. The full text is freely available here

Presentations

  • Webster, TF. How to add: Perspectives in toxicology & epidemiology. Complex Mixtures and Exposures: Analyzing, Modeling and Predicting Fate and Effects at Multiple Levels of Environmental and Biological Systems. (Woods Hole MA, April 23-24, 2012).
  • Webster, TF. Mixtures of endocrine disruptors: how similar must mechanisms be for concentration addition to apply? Society of Toxicology (San Francisco, 11-15 March 2012).
  • Webster, TF. Mixtures of endocrine disruptors: how similar must mechanisms be for concentration addition to apply? International Toxicology of Mixtures Conference (Arlington VA, 21-23 October 2011).
  • Howard GJ, Schlezinger JJ, Hahn ME, Webster TF. Generalized Concentration Addition (GCA): A method for analyzing mixtures of full and partial agonists. International Toxicology of Mixtures Conference (Arlington VA, 21-23 October 2011).
  • Howard GJ, Webster TF. Epidemiologic analysis of concentration-additive mixture data. International Toxicology of Mixtures Conference (Arlington VA, 21-23 October 2011).
  • Webster, TF. Chair, Group on Reconciling Epidemiological and Toxicological Approaches to Mixtures. NIEHS Conference on Advancing Research on Mixtures: New Perspectives and Approaches for Predicting Adverse Human Health Effects (Chapel Hill, 26-27 September 2011).
  • Howard GJ, Webster TF. Risk difference additivity is an inappropriate test of biological interaction for many combination exposures. International Society for Environmental Epidemiology (Barcelona Spain, 13-16 September 2011).
  • Webster, T. Does 2+2=4? It depends what you mean by +. Society for Risk Analysis, New England. USEPA, Boston. 9 February 2011.
  • Howard GJ, Schlezinger JJ, Webster TF. Method for assessing interactions of full and partial agonists: Application to AhR ligands. Presented at the SETAC Europe 19th Annual Meeting. 31 May-4 June, 2009, Goteborg, Sweden.
  • Howard G, Schlezinger J, Webster TF. Mixtures of AhR Full Agonists, Partial Agonists, and Antagonists: Implications for TEFs. 47th Annual Meeting of the Society of Toxicology. 16-20 March 2008. Seattle, WA.
  • Howard GJ, Schlezinger JJ, Webster TF. Interactions of TCDD with AhR partial agonists and a competitive antagonist: implications for TEFs. Presented at the 27th International Symposium on Halogenated Persistent Organic Pollutants (Dioxin 2007), Tokyo, 2-7 September.
  • Howard GJ, Schlezinger JJ, Webster TF. Modeling Mixtures of Full and Partial Agonists Using Generalized Concentration Addition. Superfund Basic Research Program 20th Anniversary Meeting. Durham, NC. December 3-5, 2007.
  • Howard GJ, Schlezinger JJ, Webster TF. A Generalized Concentration Addition Model Predicts Joint Effects of TCDD and Partial-Agonist PCBs. Presented at the American Chemical Society Annual Meeting, 19-23 August 2007, Boston, MA. ACS 2007
  • Howard G, Webster T. Contrasting Theories of Additivity, Synergy, and Antagonism in Epidemiology and Toxicology. Society for Epidemiologic Research. Boston, 19-22 June 2007. American Journal of Epidemiology 2007; 165(11) Suppl: S62.
  • Howard GJ, Schlezinger JJ, Webster TF. A Generalized Concentration Addition Model Predicts Interactions of TCDD with Partial-Agonist AhR Ligands. Society of Toxicology Annual Meeting. 25-29 March 2007, Charlotte, NC.

Harry Potter and chemical interaction

  • "Golpatt's Third Law states that the antidote for a blended poison will be equal to more than the sum of the antidotes for each of the separate components."--Book VI, pg. 374 [thanks to Greg Howard for pointing this out]

Mixtures group

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