THE NAVIGATION GUIDE An Evidence-Based Tool to Bridge the Gap Between Clinical Practice and Environmental Health Science By Patrice Sutton, MPH; Jeanne Conry, MD, PhD; Pablo Rodriguez, MD; Tracey Woodruff, PhD, MPH This article originally appeared in San Francisco Medicine, the journal of the San Francisco Medical Society, www.sfms.org. Rapidly accumulating evidence indicates that ubiquitous exposure to “everyday” levels of environmental chemicals can manifest in a wide range of adverse health outcomes across the human lifespan and generations.1,2 Approximately 87,000 chemical substances were registered for use in U.S. commerce as of 2006, with about 3,000 chemicals manufactured or imported in excess of 1 million pounds each,3 and 700 new industrial chemicals are introduced into commerce each year. Today, these chemicals are distributed throughout patients’ homes, workplaces, and communities, contaminating food, water, air, and consumer products. Everyone in the U.S. has measurable levels of multiple environmental contaminants.4 While many scientific questions remain, the strength of the evidence is sufficiently high that leading health care professionals and scientists have called for timely action to prevent harm.5-7 How have these calls to action reverberated in the trenches of clinical practice? The scientific evidence linking environmental contaminants and adverse human health impacts is voluminous and largely unfamiliar to practicing clinicians. There is no trusted, ready reference, or compendium to consult in order to provide patients with timely, evidencebased advice about their exposure to environmental contaminants (unlike the situation with pharmaceuticals). Hence,
providing evidence-based anticipatory guidance about environmental exposures is far outside the comfort zone and time constraints of most clinicians. Yet patients armed with Internet printouts are clamoring for advice about topics as wideranging as the potential for harm from the chemicals in their babies’ bottles to whether their workplace exposure to toxic chemicals will have an adverse impact on their pregnancies. Many more patients may be unaware of the preventable harms they and their families face from toxic substances in their homes, workplaces, and community environments. Health care providers have a professional and ethical responsibility
In an effort to speed the translation of environmental health science into improved patient outcomes, the University of San Francisco’s Program on Reproductive Health and the Environment undertook an interdisciplinary collaborative effort to develop the Navigation Guide, a systematic and transparent road map for evaluating the relevant scientific evidence. The Navigation Guide is based on contemporary methods of evidence-based medicine (EBM). The purpose of the Navigation Guide is to build a foundation that can be used to provide the practicing clinician with an easy, transparent, and quick way to incorporate the state of the science, patient values and preferences, and other factors into clinical care decisions.
Perhaps the most unfamiliar aspect of environmental health for the practicing physician is the need to advise patients about their exposures in the absence of human experimental data
Perhaps the most unfamiliar aspect of environmental health for the practicing physician is the need to advise patients about their exposures in the absence of human experimental data (i.e., randomized-controlled trials [RCTs]) linking the exposure to a health outcome. When it comes to advising patients regarding their exposure to environmental contaminants, a clinician should not wait for human experimental evidence—it will almost never be available. In the context of preventing adverse exposure to environmental contaminants, clinicians need to take timely action based primarily on scientific evidence from animal (in vivo) and in vitro studies. This can seem counterintuitive, because the use of in vivo and in vitro studies are not routinely part of daily clinical practice and are often misunderstood by clinicians as “weak” evidence.
to provide prevention-oriented guidance in all of these situations. By proactively intervening to protect patients from harmful environmental exposures linked to a myriad of chronic diseases and disabilities, health professionals can improve patient health outcomes more broadly.
However, in vivo and in vitro data are integral to regulatory scrutiny
PAGE 44 | THE BULLETIN | SEPTEMBER / OCTOBER 2010