Gradient

Principals

Ari S. Lewis, M.S.
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Education

M.S., Environmental Toxicology, Cornell University

B.A., Biology/Environmental Sciences, University of Pennsylvania

Expertise

  • Metals Toxicology
  • Molecular Toxicology
  • Human Health Risk Assessment
  • Arsenic Toxicology

Ari S. Lewis, M.S.

Principal

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Ms. Lewis is a Principal with expertise in toxicology and risk assessment.  She has led and contributed to a variety of projects, including product safety evaluations, regulatory comment, green chemistry assessments, and technical support for the utility and mining industry.  She also has particular expertise in risk assessment of arsenic and other metals.  In this capacity, Ms. Lewis has both published and presented extensively on the carcinogenic risks of arsenic and provided direct input to US EPA on arsenic regulatory issues.  Ms. Lewis also has expertise in developing quantitative human health risk criteria for chemicals with limited toxicity data.  Before joining Gradient, Ms. Lewis earned her M.S. at Cornell University; her thesis project investigated the molecular and cellular responses to arsenic exposure during early animal development.

Education

M.S., Environmental Toxicology, Cornell University

B.A., Biology/Environmental Sciences, University of Pennsylvania

Expertise

  • Metals Toxicology
  • Molecular Toxicology
  • Human Health Risk Assessment
  • Arsenic Toxicology

Services

Representative Projects

Risk Assessment of Emerging Chemicals:  Provided technical oversight of a large risk assessment evaluating potential drinking water risks for emerging contaminants, a majority of which did not have established toxicity criteria.  Researched and developed quantitative toxicity information that could be used to estimate potential risks.

Regulatory Comment on Coal Combustion Product Risk Assessment:  Led an evaluation of US EPA’s technical approach for assessing human health and ecological risks associated with the storage of coal combustion products.  Evaluations occurred in 2007 and on an updated version of the risk assessment in 2010.  Our evaluations were provided to US EPA during a public comment period.

Arsenic Content in Dietary Supplement:  Evaluated whether the amount of inorganic arsenic in a dietary supplement product line would constitute an unacceptable inorganic arsenic exposure if products were taken individually or as part of a multi-product program.  Exposure from supplements was estimated and compared to international guidelines for arsenic in food, typical inorganic arsenic exposure in the US diet, and levels known to cause adverse effects in humans.

Inhalation Criteria Development:  Developed a series of health-based inhalation criteria (HBIC) for several different organic compounds present in consumer products.  In some cases, derivation of the HBIC required surrogate selection, route-to-route extrapolation, and animal-to-human pharmacokinetic adjustments.

Toxic Tort Involving Pesticide Exposure:  In the context of litigation, analyzed whether pesticide exposure was the cause of a specific birth defect.  The evaluation involved a review of toxicological and epidemiological literature, as well as a reconstruction of potential dose via complex exposure pathways.

Green Chemistry Assessment: Led toxicology of an alternatives assessment for a product using criteria outlined in US EPA’s Design for the Environment (DfE) program.  Assessment accepted to US EPA DfE under this “green” chemistry program.

Metal Risk Assessment:  Interpreted the results of a metal bioassay and potential regulatory implications.  Proposed an experimental approach to establish chemical mode of action and human relevance of rodent bioassay results.

Selected Publications

Lewis, A; Bittner, AB; Herman, K; Dube, EM; Long, CM; Hensel, BR; Ladwig, KJ.  2015. "Framework for evaluating the relative impacts of surface impoundment closure options." Presented at World of Coal Ash (WOCA) 2015, Nashville, Tennessee, May 5-7, 3p.

Rohr, AC; Campleman, SL; Long, CM; Peterson, MK; Weatherstone, S; Quick, W; Lewis, A.  2015. "Potential occupational exposures and health risks associated with biomass-based power generation." Int. J. Environ. Res. Public Health 12 : 8542-8605.

Cohen, SM; Arnold, LL; Beck, BD; Lewis, AS; Eldan, M.  2013. "Evaluation of the carcinogenicity of inorganic arsenic." Crit. Rev. Toxicol. 43 : 711-752.

Mayfield, DB; Lewis, AS.  2013. "Coal ash: A resource for rare earth and strategic elements." ASH at Work : 17-21.

Lewis, AS; Reid, KR; Pollock, MC; Campleman, SL.  2012. "Speciated arsenic in air: Measurement methodology and risk assessment considerations." J. Air Waste Manag. Assoc. 62 : 2-17.

Lewis, AS; Sax, SN; Wason, SC; Campleman, SL.  2011. "Non-chemical stressors and cumulative risk assessment: An overview of current initiatives and potential air pollutant interactions." Int. J. Environ. Res. Public Health 8 : 2020-2073.

Lewis, AS; Beck, BD.  2010. "Nonlinear low-dose extrapolations." Cancer Risk Assessment: Chemical Carcinogenesis, Hazard Evaluation, and Risk Quantification. (Eds.: Hsu, CH; Stedeford, T), John Wiley & Sons, Inc., Hoboken, NJ, p659-680.