Retrospective \it{In Utero} Exposure Assessment of PCBs Using Preserved Umbilical Cords and Its Application to Case-Control Comparison

ABSTRACT

Objectives: The aim of this study is to assess preserved umbilical cords as chemical exposure media to investigate in utero chemical exposure. Furthermore, we aim to apply preserved umbilical cords to retrospective studies of the relationship between in utero chemical exposure and neurodevelopment disorders. Methods: Two sets of preserved umbilical cord samples were analyzed for exposure to polychlorinated biphenyls (PCBs) one composed of samples from 20 healthy Japanese subjects and the other set included samples from 17 autistic patients and 7 healthy siblings of theirs. Results: The possibility of external PCBs contamination during storage of preserved umbilical cord samples was found, and due to this problem, the study design should be limited to the comparison between PCBs concentration in preserved cord samples from autistic patients and that in those from their sibling. Total PCBs concentrations in preserved cords from autistic patients and their control siblings were compared and we found no statistically significant difference between them (Wilcoxon signed rank test, p>0.05). Conclusions: The association between autism and in utero PCBs exposure was not clarified in this study; however, retrospective studies such as a case-control study of siblings using preserved umbilical cords can be a method of choice for examining the possible relationship between in utero chemical exposure and childhood disorders.