FORD, D.K.*; HOLLIDAY, C.M.; Ohio University, Athens, OH; Ohio University, Athens, OH: PCB 126 has detrimental effects on bone density in juvenile diamondback terrapins

Synthetic organochlorines, such as polychlorinated biphenyls (PCBs), have been detected in all biological matrices (e.g. air, soil, water, tissue) on every continent. PCB 126 is an endocrine-disrupting toxin with estrogenic effects known to decrease bone density in laboratory rats. However, the effects of this pollutant on reptile skeletal physiology are largely untested. To examine the potential of contamination-induced osteoporosis, forty-four 8-month-old, male, terrapins were divided into two treatment groups (24 control, 20 PCB-exposed) and radiographed using high-resolution X-ray film. Their images were digitized and analyzed for grayscale pixel values of specific anatomical regions (e.g., skull, hand, foot, and plastron) which served as proxies for relative bone density. Initial quantitative analyses suggest PCB exposure results in decreased bone density in Malaclemys juveniles. Turtles in the treatment group exhibited substantial loss in bone density (i.e., element translucency) in skulls, vertebrae, carpals, plastral and hypoplastral elements, and limb midshaft cortices. These data suggest accurate analyses of modern reptilian populations (e.g., wild-caught individuals, museum specimens), which use skeletal criteria, may be hampered due to effects of common anthropogenic pollutants. Moreover, contamination-induced osteoporosis may have over-arching consequences on the interpretation of developmental stages, ontogenetic character states, performance, and overall organismal fitness. These findings warrant further investigation into the effects of persistent organic pollutants on ossification of not only this taxon, but also other turtle and reptilian taxa.