Gradient

Senior Scientists

Mary L. Hixon, Ph.D.
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Education

Ph.D., Toxicology, University of North Carolina at Chapel Hill

M.S., Environmental Health, Case Western Reserve University

B.A., Biology, Hiram College

Expertise

  • Reproductive and Developmental Toxicology
  • Toxicogenomics
  • Mode of Action Analyses
  • Human Exposure

    Mary L. Hixon, Ph.D.

    Senior Toxicologist

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    Dr. Hixon is experienced in reproductive and developmental toxicology.  Her primary responsibilities include environmental and chemical toxicology data analyses and the evaluation of specific environmental chemical exposures to assess potential human health risks.  Before coming to Gradient, Dr. Hixon was an Assistant Professor at Brown University, where she researched the reproductive health effects of endocrine-disrupting chemicals in the male and female reproductive systems.  Utilizing mouse models and toxicogenomic approaches, her research involved elucidating the signaling networks activated and gene expression signatures elicited by endocrine-disrupting chemicals.  She has authored original research articles, review articles, and book chapters on a wide variety of topics, including reproductive biology and toxicology.

    Education

    Ph.D., Toxicology, University of North Carolina at Chapel Hill

    M.S., Environmental Health, Case Western Reserve University

    B.A., Biology, Hiram College

    Expertise

    • Reproductive and Developmental Toxicology
    • Toxicogenomics
    • Mode of Action Analyses
    • Human Exposure

      Representative Projects

      Waiver Assessment for a US EPA-Required Pesticide:  Provided technical expertise to successfully waive the Immunotoxicity Test Guideline (870.7800) requirement for an herbicide.  Utilized a weight-of-evidence approach to evaluate the toxicity of the pesticide, including consideration of its chemical structure, toxicity profile, primary target organs(s), mode of action, and structural analog information.

      Product Safety Assessment:  Provided technical expertise for a comprehensive literature search and review of the ingredients in an energy drink supplement. Prepared toxicity profiles for the ingredients in the energy drink supplement and determined the margin of safety for each constituent in the product under the recommended conditions of use.

      New Zealand Hazard Assessments:  Provided technical expertise for hazard assessments evaluating potential physical, ecological, and human health risks of chemicals under New Zealand Regulatory guidance.  Reviewed literature and toxicology databases to estimate potential health hazards.

      REACH Hazard Assessments:  Provided technical expertise for hazard assessments evaluating potential physical, ecological, and human health risks of chemicals for REACH.  Reviewed literature and toxicology databases to estimate potential health hazards.

      Antioxidants, Oxidative Stress, and Telomere Stability Literature Review:  Conducted a comprehensive literature search and review on antioxidants, oxidative stress, and telomere stability.  Provided a report including tables that provided detailed information on the methods, findings, conclusions, strengths, and weaknesses of the literature on telomeres, oxidative stress, and antioxidants.  Assessed the conclusions reached concerning the role antioxidants play in decreasing oxidative stress and maintaining telomere length.

      Selected Publications

      Hixon, ML.  2015. "Toxic effects on reproduction." In Principles of Toxicology: Environmental and Industrial Applications (Third Edition). (Eds.: Roberts, SM; James, RC; Williams, PL), John Wiley & Sons, Inc., Hoboken, NJ., p211-221.

      Hixon, M; Mayfield, D; Peterson, M; Dube, EM; Beyer, L.  2015. "Development of a Noncancer Toxicity Criterion Using Developmental Toxicity Data as the Most Sensitive Endpoint in Estimating Health Risk(s) from TEG-Contaminated Coffee." Presented at the 55th Teratology Annual Meeting, Montreal, Qubec, June 27-July 1

      Beyer, L; Hixon, ML; Mayfield, DB; Peterson, MK; Dube, EM.  2015. "Risk Assessment of Contaminated Coffee to Determine the Need for a Product Recall." Presented at Institute of Food Technologists (IFT) Annual Meeting, Chicago, IL, July 11-14

      Moyer, B; Hixon, ML.  2012. "Reproductive effects in F1 adult females exposed in utero to moderate to high doses of mono-2-ethylhexylphthalate (MEHP)." Reprod. Toxicol. 34 : 43-50.

      Knudsen, TB; Kavlock, RJ; Daston, GP; Stedman, D; Hixon, M; Kim, JH.  2011. "Developmental toxicity testing for safety assessment: New approaches and technologies." Birth Defects Res. B Dev. Reprod. Toxicol. 92 : 413-420.