We would like to thank Thomas Erren, Dominique Zeuß, Frank Steffany, and Benno Meyer-Rochow for their thought-provoking comments on our Science and Society article (Wildlife cancer: a conservation perspective. Nature Rev. Cancer 9, 517–526 (2009))1. The information provided by Erren, Zueß, Steffany and Meyer-Rochow (Increase of wildlife cancer: an echo of plastic pollution? Nature Rev. Cancer 09 Oct 2009 (doi:10.1038/nrc2665-c1))2 complements the article's discussion regarding the importance of wild animals as sensitive indicators of anthropogenic factors and the recognition that these factors affect the health of all species and environments around the globe. As Erren and colleagues describe, there are many unanswered questions regarding the short- and long-term effects of environmental toxins, including plastics. Recent reviews examining the environmental threat posed by plastics3, and specifically bisphenol A (BPA)4, support the role of wildlife health monitoring and research in bridging the gap between an in vitro understanding of the mechanisms of action and effects of toxins and the actual health risks of exposure in complicated natural settings. There is, and will continue to be, a tremendous need for immediate conservation interventions that address the global problem of pollution, as well as expanded, focused research in animals and humans. This research is needed to better understand the direct and indirect effects of toxins not only in cancer but also in other diseases.