L. Mark Hewitt

Research Scientist - Study Leader, Analytical Toxicology of Complex Mixtures
Environment and Climate Change Canada

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 Programme
  • 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

Organizing Committee for the 8th International Fate and Effects of Pulp and Paper Mill Effluents Conference, Concepcion, Chile, 2012 

Currently supervising two technicians, two Postdoctoral Fellows.

Education and awards

Co-recipient of 2005 NSERC Synergy Award with the University of New Brunswick, and Irving Pulp and Paper Ltd.

NSERC Visiting Fellow in a Canadian Government Laboratory

Key publications

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.

Gagné, F., C. André, M. Douville, A. Talbot, J. Parrott, M. McMaster, and M. Hewitt. 2011. An examination of the toxic properties of water extracts in the vicinity of an oil sand extraction site. J. Environ. Monit. 13(11): 3075-3086.

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.

Kovacs, T., P. Martel, B. O’Connor, J. Parrott, M. McMaster, G. Van Der Kraak, D. MacLatchy, M. van den Heuvel and L.M. Hewitt. 2011. Kraft mill effluent survey: Progress toward best management practices for reducing effects on fish reproduction. Environ. Toxicol. Chem. 30(6):1421-1429.

Basu, N., C.A. Ta, A. Waye, J. Mao, M. Hewitt, J.T. Arnason and V.L. Trudeau. 2009. Pulp and paper mill effluents contain neuroactive substances that potentially disrupt neuroendocrine control of fish reproduction. Environ. Sci. Technol. 43(5): 1635-1641.

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.

Hewitt, L.M. and C.H. Marvin. 2005. Analytical methods in environmental effects-directed investigations of effluents. Mut. Res. 589:208-232.


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)