This case study explores the recent (2010 - 2016) outbreak of neural tube defects, specifically anencephaly, in a rural three-county region of Washington state, particularly Yakima, WA. The case study focuses on the biological aspects of teratogens that may cause birth defects as well as epidemiological investigations of disease outbreaks. By the end of the case, students will have explored how our environment may have severe biological consequences on the human body during pregnancy and will have evaluated governmental and scientific investigations of a rare outbreak of birth defects. This clicker case study was developed for a non-majors biology course entitled "Human Development: Conception to Birth," although it could be taught in any introductory biology course for majors or non-majors during a unit on human reproductive biology or developmental biology. The case assumes that students have no prior knowledge of developmental biology or birth defects. The case study could also be adapted for upper-division courses by getting more in-depth on the specifics of teratogen mechanisms, the developmental biology and physiology of neural tube defects, or more complex epidemiological analyses.