Occupational and environmental medicine focuses on the interactions between work, health and the environment. Doctors who specialize in this field prevent, evaluate, and manage adverse health effects from work and environmental hazards.  Individuals can be exposed to chemicals, sources of traumatic injury, occupational diseases, and hazardous physical agents in their jobs.  Any of these exposures can cause injury or disease, which can occur immediately or even after years or decades. Understanding these issues and their effects constitutes the core of occupational medicine.

Our Staff


David J. Hewitt, MD, MPH, DABT, has more than 25 years of experience in the areas of occupational medicine, environmental epidemiology, and toxicology. A native of South Dakota, he received a Bachelor of Science in chemistry from the South Dakota School of Mines and Technology and a Doctor of Medicine from the University of South Dakota School of Medicine. He received a Master of Public Health degree in epidemiology from the San Diego State University Graduate School of Public Health.  Dr. Hewitt completed a residency in preventive medicine and public health with the California Department of Health Services working with the Environmental Health Investigations Branch.  He also completed a residency in Occupational Medicine with the Midwest Center for Occupational and Environmental Health and the University of Minnesota Graduate School of Public Health.  His previous experience has included work as a medical officer with the Agency for Toxic Substances and Disease Registry (ATSDR) where he provided consultation to both medical providers and the general public throughout the U.S. regarding chemical exposures. He has also worked as a private consultant in toxicology and environmental epidemiology.  Dr. Hewitt specializes in analysis of health effects from chemical and environmental exposures with a special interest in respiratory conditions.  He has worked with numerous clients including Fortune 500 companies, universities, public health agencies, and attorneys nationwide as both a testifying and non-testifying expert regarding a wide range of environmental health topics.  Dr. Hewitt is Board Certified in Occupational Medicine, General Preventive Medicine and Public Health, and Toxicology, and is a Certified Medical Review Officer. 
Contact Dr. Hewitt at djh@reoh.com

Margaret Cook-Shimanek, MD, MPH joined Resources for Environmental and Occupational Health in 2016 and is board certified in Occupational and Environmental Medicine. After completing a Bachelor of the Arts in biology at the University of Montana, Missoula in 2000, she went on to receive a Doctor of Medicine from the University of North Dakota School of Medicine and Health Sciences. Dr. Cook-Shimanek completed Public Health and Preventive Medicine residency training at the University of Colorado and received her Master of Public Health in epidemiology from the Colorado School of Public Health in 2013. Dr. Cook-Shimanek then completed Occupational and Environmental Medicine residency training at the University of Colorado in September of 2015. During residency training, Dr. Cook-Shimanek published on a variety of occupational and prevention focused topics, see the list here.  In 2017, the Montana Department of Labor and Industry contracted with Dr. Cook-Shimanek to perform the functions of the Co-Medical Director position and to update the Montana Utilization and Treatment Guidelines.   She is also a member of the External Advisory Board for the University of Washington Northwest Center for Occupational Health and Safety.  Prior to joining REOH, she worked as a treating occupational medicine physician at Saint Alphonsus Medical Group in Boise, Idaho. Dr. Cook-Shimanek is board certified in Occupational and Environmental Medicine and Public Health and General Preventive Medicine.  She is currently working with the Department of Labor and Industry to update the Montana Utilization and Treatment Guidelines and is a member of the External Advisory Board for the University of Washington Northwest Center for Occupational Health and Safety.
Contact Dr. Cook-Shimanek at mcs@reoh.com

In the office:

Anya Vasquez, Administrator, received a double Bachelor of Psychology and Fine Art from the University of Montana and is currently enrolled in Southern New Hampshire University's MBA program.  Ms. Vasquez oversees all operations of REOH, including human resource management, accounting, marketing, project management, and information organization and dissemination.  Her professional background includes experience in the non-profit and for-profit sectors, where she provided financial and human resource management, grant writing and exhibit creation, and event planning and donor relations.
Contact Ms. Vasquez at akv@reoh.com

Ms Anya Vasquez, Administrator


Kate Petterson, Medical Information Specialist, holds a Bachelor’s of Arts in Philosophy/Political Science from the University of Montana and a Master’s of Science in Psychology from the University of Phoenix.  She provides management of all medical records, editing, and customer service for REOH.  Ms. Petterson has a background in journalism and served as secretary of the Board of Missoula Community Access Television for nine years.  
Contact Ms. Petterson with medical records inquires at kip@reoh.com

Lynn Parenteau, Client Services Specialist, graduated from the University of Montana with an Associate of Applied Sciences degree in Food Service Management and a Certificate in Culinary Arts, and plans on working toward a bachelor's degree in Business.  Her background in customer service and hospitality lends itself well to her position at REOH, where she is the primary point of contact between REOH’s clients and workers compensation claimants. 
Contact Ms. Parenteau to schedule an appointment at ljp@reoh.com

Lynn Parenteau, Client Services Specialist

Ms. Leah Morrow, Communications Specialist

Leah Morrow, Communications Specialist, holds a Bachelor’s of Arts in Philosophy from the University of Montana.  Ms. Morrow brings a wide range of expertise and a background in business to REOH.  Her experience in graphic design, website creation and management, and social media continue to grow REOH’s online presence.  Ms. Morrow also assists in the creation and implementation of REOH’s strategic and marketing plans.
Contact Ms. Morrow at lcm@reoh.com

Marie Osborne, Office and Medical Records Assistant, has a Bachelor of Science degree in Sociology from Western New Mexico University. She has gained office administration experience with nonprofit organizations and for profit businesses over the past  30 years.  Previously, Marie co-founded an Arts in Education Advocacy organization which lobbied for arts funding for public schools. Her experience includes development of Board of Directors, grant writing, budgeting, project management, arts presenting and fundraising. She extended this experience as a project manager and provided administrative support to several additional nonprofits in New Mexico.  In Missoula, Marie has held positions at  First United Methodist Church,  Rocky Mountain School of Photography, and  Western Montana Addiction Services, Inc.  
Contact Ms. Osborne at meo@reoh.com

Marie Osborn

The REOH team

Past Clients:

REOH physicians have  provided services to a diverse range of clients, including small businesses, health care systems, large corporations, educational institutions, attorneys representing both plaintiffs and defendants, and federal and state agencies. 

Contact Us

Physical address:
210 East Pine Street, Suite 100
Missoula, MT 59802

Mailing address:
P.O. Box 8809
Missoula, MT 59807

Phone: 406.549.6520
Fax: 406.549.6797
Email: info@reoh.com