Dr. L. Mark Hewitt

Research Scientist - Study Leader, Analytical Toxicology of Complex Mixtures

Current research and/or projects

Contributing to Environment Canada’s mandate to conduct research on the Impacts of Contaminants and Other Substances of Concern on Aquatic Ecosystems

  • Analytical methods to isolate bioactive compounds in complex mixtures and investigation of mixture interactions.
  • Chemical Fingerprinting Lead on Oil Sands Monitoring Program.
  • Identification of hormonally active substances associated with pulp mill effluents (Canada and South America), pesticide runoff, and Great Lakes Areas of Concern.
  • Analytical methods for quantification of hormones, pesticides and retinoids by liquid chromatography-tandem mass spectrometry (LC-MS-MS); Identification of bio-active unknowns in complex mixtures using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS).
  • Science development for Environmental Effects Monitoring Investigation of Cause.

Professional activities / interests

  • Co-Lead on Environment Canada/FPI-Paprican Investigation of Cause Project, with the Universities of Guelph, Prince Edward Island and Wilfrid Laurier, to find cost-effective solutions to endocrine disruption in fish associated with pulp and paper mill effluents
  • Member of the Environmental Effects Monitoring (EEM) Programs Science Committee (2001-).
  • Board of Directors, Water Science Institute, Wilfrid Laurier University. (2009- ).
  • World Science Council, Society of Environmental Toxicology and Chemistry (2010- ).
  • Stakeholder Board, SOLUTIONS Project. Framework Programme 7 European Commission multi- and interdisciplinary consortium composed of 39 scientific institutions and enterprises from Europe, Brazil, China, and Australia (2013-2018).
  • Steering Committee, Ecotoxicological – Predictive – Information – Connectivity Map (EPIC-map) Project.  University of Liverpool, UK. (2015-2020). http://gtr.rcuk.ac.uk/projects?ref=NE/M01939X/1


Education and awards

  1. Environment Canada Citation of Excellence: Teamwork, Partnering and Collaboration for Oil Sands Monitoring Program Design (2012).
  2. Co-recipient, Synergy Award for Innovation, Natural Sciences and Engineering Research Council of Canada.  Partnership with the University of New Brunswick and Irving Pulp and Paper Ltd., for pollution prevention technology (2005).
  3. Visiting Fellowship in a Canadian Government Laboratory, Natural Sciences and Engineering Research Council of Canada (1997-1998).
  4. Ontario Graduate Scholarship, University of Guelph (1997, $15,000).
  5. Best Student Paper Award, Environmental Toxicology and Chemistry, Vol. 15. (1996).
  6. Inaugural Ulf Ahlborg Best Student Paper Award. Dioxin’96, Amsterdam, Netherlands (1996, $2,000 Guilders).
  7. Best Student Paper Award, International Association of Great Lakes Research, Annual Meeting (1996).
  8. University of Guelph Scholarship (1994, $1,500).
  9. Charles Mott Foundation International Fellowship (1992, $10,000 USD).

Key publications

Martel, P.H., B.I. O’Connor, T.G. Kovacs, D.L. MacLatchy, M.E. McMaster, J.L. Parrott, M.R. van den Heuvel, G.J. Van Der Kraak and L.M. Hewitt. 2017. The relationship between organic loading and effects on fish reproduction for pulp mill effluents across Canada.  Environ. Sci. Technol. 51(6):  3499-3507.

Frank R.A., Milestone C., Kavanagh R.J., Headley J.V., Rowland S.J., Scarlett A.G., West C.E., Peru K.M. and L.M. Hewitt. 2016. Assessing variability of acid extractable organics within two containments of oil sands sprocess-affected water. Chemosphere, 160: 303-313.

Brack, W., S. Ait-Aissac, R.M. Burgess, N. Creusot, C. Di Paolo, E. B.I., L.M. Hewitt, K. Hilscherova, J. Hollender, H. Hollert, W. Jonker, J. Kool, M. Lamoree, M. Muschket, S. Neumann, P. Rostkowski, C. Ruttkies, J. Schollee, E.L. Schymanski, T. Schulze, T.-B. Seiler, A.J. Tindall, G. De Aragão Umbuzeiro, B. Vrana and M. Krauss. 2016. Effect-directed analysis supporting monitoring of aquatic environments – An in-depth overview.  Sci. Tot. Environ. 544: 1017-1118.

Frank, R.A, G. Bickerton, J.W. Roy, S.J. Rowland, J.V. Headley, A.G. Scarlett, C.E. West, K.M. Peru, M. Conly and L.M. Hewitt. 2014. Profiling oil sands mixtures from industrial developments and natural groundwaters for source identification. Environ. Sci. Technol. 48(5): 2660-2670.

Milestone, C.B., R. Orrego, P. Scott, A. Waye, M. Kohli, B.I. O’Connor, B. Smith, H. Engelhardt, D.L. MacLatchy, D.S. Smith, V.L. Trudeau, J.T. Arnason, T. Kovacs, T. Heid Furley, A. Slade, M. Servos, D. Holdway and L.M. Hewitt. 2012. Evaluating the potential of effluents and wood feedstocks from pulp and paper mills in Brazil, Canada, and New Zealand to affect fish reproduction:  Chemical profiling and in vitro assessments.  Environ. Sci. Technol. 46(3): 1849–1858.

Rowland, S.J., C.E. West, D. Jones, A.G. Scarlett, R.A. Frank and L.M. Hewitt. 2011. Steroidal aromatic naphthenic acids in oil sands process-affected water: Structural comparisons with environmental estrogens. Environ. Sci. Technol. 45(22): 9806-9815.


Scott, P.D., C.B. Milestone, S. Smith, D.L. MacLatchy, and L.M. Hewitt. 2011. Isolation and identification of ligands for the goldfish testis androgen receptor in chemical recovery condensates from a Canadian bleached kraft pulp and paper mill. Environ. Sci. Technol. 45(23): 10226-10234.

Headley, J.V., M. P. Barrow, K. M. Peru, B. Fahlman, R. Frank, G. Bickerton, M. McMaster, J. Parrott and L.M. Hewitt. 2011. Preliminary fingerprinting of Athabasca oil sands acids in environmental samples using Fourier transform ion cyclotron resonance mass spectrometry electrospray ionization. Rapid Commun. Mass. Spectrom. 25(13):1899-1909.

Hewitt, M., T. Kovacs, M. Dube, D. MacLatchy, P. Martel, M. McMaster, M. Paice, J. Parrott, M. van den Heuvel and G. Van Der Kraak. 2008. Altered reproduction in fish exposed to pulp and paper mill effluents: Roles of individual compounds and mill operating conditions. Environ. Toxicol. Chem. 27(3):682-697.

Research facility

867 Lakeshore Rd.
Burlington, ON L7S 1A1


Adjunct Professor, Department of Environmental Biology, University of Guelph

Adjunct Professor, Department of Biology, University of New Brunswick, and an Associate of the Canadian Rivers Institute

Adjunct Professor, Department of Chemistry, Wilfrid Laurier University

Associate Professor, Department of Biology, University of Waterloo

Member of the Society of Environmental Toxicology and Chemistry and the American Society of Mass Spectrometry (since 2002)