Significance: The project, an integral part of the PROTECT center from 2010-2020, is significant in seeking to reduce the incidence of preterm birth, a major health problem. Also, the project is significant in advancing technology in general for nontargeted chemical analysis in the area of human exposure to chemicals. Humans are always exposed to mixtures, and nontargeted chemical analysis is a good way to characterize such exposures. This in turn can improve risk assessment for human exposure to chemical exposures.
The long term goal of this project was to discover xenobiotics that contribute to preterm birth, relying on nontargeted chemical analysis by mass spectrometry. The project sought to increase the sensitivity, scope, and qualitative capability of current methods for nontargeted chemical analysis, and applied these improved methods to biological and environmental samples. The project conducted nontargeted analysis of urine samples, and studied the hypothesis that preterm urines in Puerto Rico contain a different exposome (overall in vivo environmental chemical exposure) than term urines. A large volume (0.5 gallon) of urine as an accumulation of early morning voids was collected from participants, which was then extracted with a porous extraction paddle (stirring “reversed tea bag” filled with particulate adsorbents). This novel technique yields a convenient repository sample (the bag of adsorbents) for shipment, storage, and analysis of aliquots. The project also used the technique to identify pollutants in ground and tap water samples in Puerto Rico, and pollutant degradation products formed when these samples were remediated by electrolysis. Other activities in the project involved advances in the analysis of DNA adducts as biomarkers of exposure for testing DNA adducts in human placenta (placental DNA adducts might contribute to preterm birth); improved technology for deconjugation of xenobiotics (to improve the scope of nontargeted chemical analysis); and advances in ionic tagging (also a way to facilitate nontargeted chemical analysis).
Under this project, researchers developed the Porous Extraction Paddle (PEP), pictured above. The device consists of a porous nylon bag filled with solid phase extraction particles, where the bag is rigidified by a metal cage that, in turn, is attached to a stirring motor. This provides a convenient way to extract a large volume of liquid (urine or water) at a remote location, while minimizing contamination. For urine, the large volume as a series of voids enables an integrated measure of exposure, which is more meaningful than data from a spot urine. The PEP promises to become a new tool for sampling by epidemiologists, allowing them to conveniently collect large-volume urine specimens for prospective cohort studies similar to the PROTECT cohort. A patent for this device was issued in 2019.