A Comprehensive Approach for Detecting and Locating Black Carbon in Human Placentae

DENISE IVEY, Amanda Sanko, Barbara Tisdale, Philip Katzman, Thomas O'Connor, Kaye Thomas, Tanzy Love, Rogelio Perez-D'Gregorio, Carolyn Salafia, Ronald Wood, Atsuo Chiu, Richard Miller, Philip K. Hopke, University of Rochester School of Medicine and Dentistry

     Abstract Number: 20
     Working Group: Health-Related Aerosols

Abstract
Molecular passage across the placenta generally serves developmental purposes, but some also can induce harm. Particulate matter affects the pregnancy through the maternal circulation to the placenta. Black Carbon (BC) particles produced by fuel combustion contributes to global air pollution and climate change. Their health impacts likely extend beyond respiratory complications. Thus, studying BC translocation into human tissues provides insights into the mechanisms of observed adverse outcomes. The human placenta is a useful tissue since it provides further understanding of placental transport mechanisms, impacts on the organ and embryo/fetus, and for developing prevention strategies. Having well measured tissue dose metrics provides an epidemiological tool to relate exposures to a variety of health outcomes in the woman, fetus, and resulting child. A microscopy methodology for quantifying BC particles in human placental histology slides utilizing multiphoton microscopy has been developed. A two-photon Olympus FVMPE-RS microscope with an 810 nm laser excitation and four bandpass emission channels with fixed voltage and distinct bandpass filters: 370-410, 425-465, 575-630, and 645-685 nm was used to examine 5 µm thick tissue slides of formalin-fixed placental material. Small (≤300 nm diameter) objects that emitted light observed in all 4 channels were deemed BC. 3-D models were used to ensure that the spots were not above the sample. Artifacts due to formalin precipitation and tissue staining were excluded by using unstained tissue and the multichannel criterion. Using 25 placentae with 4 blocks examined for each placenta and 15 fields per block, the BC counts per field were estimated with a precision of ±0.2. BC densities ranged from 2.9 ± 3.1 x 103 to 2.5 ± 1.4 x 104 mm-3, with a standard error of 2.7 ± 1.4 x103 mm-3. Concentrations declined from maternal blood to fetal tissue to fetal blood. Environmental tissue doses are being measured.