Dr. Melissa Heintz is a toxicologist in ToxStrategies’ Asheville, North Carolina, office. She received her Ph.D. in Environmental Toxicology from Clemson University, where her dissertation research investigated the potential for environmental toxicant inhibition of the detoxification enzyme subfamily, CYP2B, and the subsequent effects on lipid metabolism, allocation, and development of fatty liver disease. Dr. Heintz has experience conducting safety and exposure assessments for various environmental contaminants, especially per- and polyfluoroalkyl substances (PFAS), using methods that include both in vitro and in vivo experimental models, prediction models, systematic literature review and meta-analysis, and whole transcriptome analyses. She has designed and carried out several in vitro and in vivo studies that utilize ‘omic applications to answer either screening-level or specific mechanistic toxicity questions.
Dr. Heintz has experience in both collecting and reviewing mechanistic data to evaluate human health and ecological hazards from exposure to toxic substances. As a mechanistic toxicologist, Dr. Heintz has examined the effects of environmental toxicant exposure on lipid metabolism and gene expression in Daphnia magna. In addition, she used neuron and fibroblast cell lines from patients with autism spectrum disorder (ASD) to study differential gene expression and genomic variants in response to toxic stressors. She has also screened and analyzed numerous clinical drugs, industrial chemicals, and endogenous compounds for induction or inhibition activity in cytochrome p540-transfected baculosomes and HepG2 cell lines using metabolic activity assays. Furthermore, she has used statistical analysis programs, including R and GraphPad Prism, to analyze and create data visualizations of these toxicological data sets.
She has conducted several systematic reviews of the scientific literature to investigate the evidence available on the potential hazards and toxicity of various substances present in foods and consumer products, as well as the environment. Her role in conducting systematic reviews includes initial scoping and problem formulation, development of search strategy, literature screening and full-text review using literature review tools (e.g., SWIFT, DistillerSR), analyzing the reliability and strength of evidence, and reporting findings. She has applied systematic review approaches to the benefit/risk analysis of food ingredients and contaminants, GRAS dossier submissions, and development of adverse outcome pathways (AOPs).
In addition to her expertise in mechanistic toxicology, Dr. Heintz has also conducted ecotoxicology studies on estuarine fish populations to assess transgenerational effects of endocrine-disrupting compounds from anthropogenic sources such as paper mill and wastewater effluents and livestock feedlot runoff. Estrogenic and androgenic chemicals were used singly and in mixtures to identify exposure effects on reproductive success, sex characteristics, and behavioral endpoints in freshwater and estuarine fish models.
Dr. Heintz has presented her research at national and international scientific meetings and reported her results in peer-reviewed scientific journals. She also has more than 10 years of experience in science communication and has disseminated scientific research findings to students at all education levels, including K-12 and college students, as well as the general public.