Use of Targeted and Non-Targeted Analysis to Study Complex PAH Environmental Mixtures

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants formed from the incomplete combustion of organic material. These contaminants are of concern because of their widespread presence in the environment and toxic properties. In addition, PAHs encompass a class of diverse compounds with varying physicochemical properties and exist in the environment as complex mixtures. Research has primarily focused on parent (or unsubstituted) PAHs, mainly the 16 U.S. Environmental Protection Agency priority PAHs. However, many other PAH derivatives, such as oxygen containing PAHs, co-occur in these complex mixtures and may be equally, if not more, toxic than parent PAHs. This dissertation investigates PAHs in complex soil and house dust environmental mixtures. Previous studies have suggested that the partial degradation of PAHs during bioremediation may result in increased toxicity postbioremediation. However, there is limited information on these transformation products in soil. An effects-directed analysis approach, incorporating targeted gas chromatography mass spectrometry (GC/MS), the DT40 genotoxicity and zebrafish developmental toxicity assays demonstrated increased toxicity postbioremediation in four soil extract fractions (C, D, E and F). Non-targeted analysis, combing comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS) and liquid chromatography quadrupole time-of-flight mass spectrometry (LC/QTOF-MS), was subsequently used to characterize the toxic soil extract fractions postbioremediation. Several of the tentatively identified compounds contained an oxygen and/or nitrogen in their elemental compositions, suggesting they would be relatively polar. Additionally, targeted GC/MS analysis of high molecular weight 302 PAHs (MW302-PAHs, PAHs with molecular weight ≥ 302 a.m.u), which are highly mutagenic, showed no degradation postbioremediation. The data suggest that monitoring the disappearance of a subset of parent PAH compounds may potentially overestimate the efficiency of bioremediation. In the second part of the dissertation, a targeted approach, using GC×GC/TOF-MS, was used to investigate the long-term associations between parent PAHs, methylated PAHs, selected oxygenated PAHs, and thirdhand smoke (THS) in house dust. THS contains a complex mixture of toxic chemicals, and was recently shown to be a significant contributor of PAHs in settled house dust in smoker and non-smoker homes. However, less is known about how PAHs, more specifically other PAH derivatives, may associate with THS. In a pilot study, five homes were evaluated for the different PAH classes, tobacco-specific nitrosamines (TSNAs) and nicotine, up to six months after smoking had ended. Individual PAHs, 2+1 methylphenanthrene (2+1MPHE), 2-methylanthracene (2MANT), retene (RET), dibenz[a,h]anthracene (DBahA), 9,10-anthraquinone (9,10AQ), 2-methylanthraquinone (2MAQ), benzanthrone (BZ), benzo[cd]pyrenone (BcdP), 5,12-naphthacenequinone (5,12NQ) and 9-fluorenone (9FLO) dust loadings were significantly correlated with nicotine and TSNA dust loadings over time (R²: 0.47-0.72, p < 0.05). This suggests that these compounds may strongly associate with THS and should potentially be considered when assessing the long-term risks associated with THS exposure. This dissertation demonstrates that PAHs exist in complex mixtures, and uses various tools (i.e. targeted and/or non-targeted methods, toxicity testing, complementary instrumental techniques) to investigate PAH compounds beyond those routinely monitored. Many of these compounds, such as transformation products, may be of ecological and toxicological significance

Automating Data Analysis for Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry Non-Targeted Analysis of Comparative Samples

Non-targeted analysis of environmental samples, using comprehensive two‐dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC/ToF-MS), poses significant data analysis challenges due to the large number of possible analytes. Non-targeted data analysis of complex mixtures is prone to human bias and is laborious, particularly for comparative environmental samples such as contaminated soil pre- and post-bioremediation. To address this research bottleneck, we developed OCTpy, a Python™ script that acts as a data reduction filter to automate GC × GC/ToF-MS data analysis from LECO® ChromaTOF® software and facilitates selection of analytes of interest based on peak area comparison between comparative samples. We used data from polycyclic aromatic hydrocarbon (PAH) contaminated soil, pre- and post‐bioremediation, to assess the effectiveness of OCTpy in facilitating the selection of analytes that have formed or degraded following treatment. Using datasets from the soil extracts pre- and post‐bioremediation, OCTpy selected, on average, 18% of the initial suggested analytes generated by the LECO® ChromaTOF® software Statistical Compare feature. Based on this list, 63–100% of the candidate analytes identified by a highly trained individual were also selected by OCTpy. This process was accomplished in several minutes per sample, whereas manual data analysis took several hours per sample. OCTpy automates the analysis of complex mixtures of comparative samples, reduces the potential for human error during heavy data handling and decreases data analysis time by at least tenfold

Organic contaminants in western pond turtles in remote habitat in California

Remote aquatic ecosystems are exposed to an assortment of semivolatile organic compounds (SOCs) originating from current and historic uses, of local and global origin. Here, a representative suite of 57 current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons were surveyed in the plasma of the western pond turtle (Emys marmorata) and their potential prey items and habitat. California study sites included Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest. Each was downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources. SOCs were detected frequently in all sites with more found in turtle plasma and aquatic macroinvertebrates in the two sites closest to agricultural and urban sources. Summed PCBs were highest in Whiskeytown National Recreation Area turtle plasma (mean; 1.56 ng/g ww) compared to plasma from Sequoia National Park (0.16 ng/g ww; p = 0.002) and Six Rivers National Forest (0.07 ng/g ww; p = 0.001). While no current-use pesticides were detected in turtle plasma at any site, both current- and historic-use pesticides were found prominently in sediment and macroinvertebrates at the Sequoia National Park site, which is immediately downwind of Central Valley agriculture. SOC classes associated with urban and industrial pollution were found more often and at higher concentrations at Whiskeytown National Recreation Area. These findings demonstrate a range of SOC exposure in a turtle species with current and proposed conservation status and shed additional light on the fate of environmental contaminants in remote watersheds.Keywords: Emys marmorata, Pollutant monitoring, Persistent organic pollutants (POPs), Pesticide

Aerobic Bioremediation of PAH Contaminated Soil Results in Increased Genotoxicity and Developmental Toxicity

This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the American Chemical Society and can be found at: https://doi.org/10.1021/acs.est.5b00499The formation of more polar and toxic polycyclic aromatic hydrocarbon (PAH) transformation products is one of the concerns associated with the bioremediation of PAH-contaminated soils. Soil contaminated with coal tar (pre-bioremediation) from a former manufactured gas plant (MGP) site was treated in a laboratory scale bioreactor (post-bioremediation) and extracted using pressurized liquid extraction. The soil extracts were fractionated, based on polarity, and analyzed for 88 PAHs (unsubstituted, oxygenated, nitrated, and heterocyclic PAHs). The PAH concentrations in the soil tested, post-bioremediation, were lower than their regulatory maximum allowable concentrations (MACs), with the exception of the higher molecular weight PAHs (BaA, BkF, BbF, BaP, and IcdP), most of which did not undergo significant biodegradation. The soil extract fractions were tested for genotoxicity using the DT40 chicken lymphocyte bioassay and developmental toxicity using the embryonic zebrafish (Danio rerio) bioassay. A statistically significant increase in genotoxicity was measured in the unfractionated soil extract, as well as in four polar soil extract fractions, post-bioremediation (p < 0.05). In addition, a statistically significant increase in developmental toxicity was measured in one polar soil extract fraction, post-bioremediation (p < 0.05). A series of morphological abnormalities, including peculiar caudal fin malformations and hyperpigmentation in the tail, were measured in several soil extract fractions in embryonic zebrafish, both pre- and post-bioremediation. The increased toxicity measured post-bioremediation is not likely due to the 88 PAHs measured in this study (including quinones), because most were not present in the toxic polar fractions and/or because their concentrations did not increase post-bioremediation. However, the increased toxicity measured post-bioremediation is likely due to hydroxylated and carboxylated transformation products of the 3- and 4-ring PAHs (PHE, 1MPHE, 2MPHE, PRY, BaA, and FLA) that were most degraded

The landscape for HIV pre-exposure prophylaxis during pregnancy and breastfeeding in Malawi and Zambia: A qualitative study.

High HIV incidence rates have been observed among pregnant and breastfeeding women in sub-Saharan Africa. Oral pre-exposure prophylaxis (PrEP) can effectively reduce HIV acquisition in women during these periods; however, understanding of its acceptability and feasibility in antenatal and postpartum populations remains limited. To address this gap, we conducted in-depth interviews with 90 study participants in Malawi and Zambia: 39 HIV-negative pregnant/breastfeeding women, 14 male partners, 19 healthcare workers, and 18 policymakers. Inductive and deductive approaches were used to identify themes related to PrEP. As a public health intervention, PrEP was not well-known among patients and healthcare workers; however, when it was described to participants, most expressed positive views. Concerns about safety and adherence were raised, highlighting two critical areas for community outreach. The feasibility of introducing PrEP into antenatal services was also a concern, especially if introduced within already strained health systems. Support for PrEP varied among policymakers in Malawi and Zambia, reflecting the ongoing policy discussions in their respective countries. Implementing PrEP during the pregnancy and breastfeeding periods will require addressing barriers at the individual, facility, and policy levels. Multi- level approaches should be considered in the design of new PrEP programs for antenatal and postpartum populations

Organic contaminants in western pond turtles in remote habitat in California

Remote aquatic ecosystems are exposed to an assortment of semivolatile organic compounds (SOCs) originating from current and historic uses, of local and global origin. Here, a representative suite of 57 current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons were surveyed in the plasma of the western pond turtle (Emys marmorata) and their potential prey items and habitat. California study sites included Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest. Each was downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources. SOCs were detected frequently in all sites with more found in turtle plasma and aquatic macroinvertebrates in the two sites closest to agricultural and urban sources. Summed PCBs were highest in Whiskeytown National Recreation Area turtle plasma (mean; 1.56&nbsp;ng/g ww) compared to plasma from Sequoia National Park (0.16&nbsp;ng/g&nbsp;ww; p&nbsp;=&nbsp;0.002) and Six Rivers National Forest (0.07&nbsp;ng/g ww; p&nbsp;=&nbsp;0.001). While no current-use pesticides were detected in turtle plasma at any site, both current- and historic-use pesticides were found prominently in sediment and macroinvertebrates at the Sequoia National Park site, which is immediately downwind of Central Valley agriculture. SOC classes associated with urban and industrial pollution were found more often and at higher concentrations at Whiskeytown National Recreation Area. These findings demonstrate a range of SOC exposure in a turtle species with current and proposed conservation status and shed additional light on the fate of environmental contaminants in remote watersheds

Organic contaminants in western pond turtles in remote habitat in California.

Remote aquatic ecosystems are exposed to an assortment of semivolatile organic compounds (SOCs) originating from current and historic uses, of local and global origin. Here, a representative suite of 57 current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons were surveyed in the plasma of the western pond turtle (Emys marmorata) and their potential prey items and habitat. California study sites included Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest. Each was downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources. SOCs were detected frequently in all sites with more found in turtle plasma and aquatic macroinvertebrates in the two sites closest to agricultural and urban sources. Summed PCBs were highest in Whiskeytown National Recreation Area turtle plasma (mean; 1.56&nbsp;ng/g ww) compared to plasma from Sequoia National Park (0.16&nbsp;ng/g&nbsp;ww; p&nbsp;=&nbsp;0.002) and Six Rivers National Forest (0.07&nbsp;ng/g ww; p&nbsp;=&nbsp;0.001). While no current-use pesticides were detected in turtle plasma at any site, both current- and historic-use pesticides were found prominently in sediment and macroinvertebrates at the Sequoia National Park site, which is immediately downwind of Central Valley agriculture. SOC classes associated with urban and industrial pollution were found more often and at higher concentrations at Whiskeytown National Recreation Area. These findings demonstrate a range of SOC exposure in a turtle species with current and proposed conservation status and shed additional light on the fate of environmental contaminants in remote watersheds

Organic contaminants in western pond turtles in remote habitat in California.

Remote aquatic ecosystems are exposed to an assortment of semivolatile organic compounds (SOCs) originating from current and historic uses, of local and global origin. Here, a representative suite of 57 current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons were surveyed in the plasma of the western pond turtle (Emys marmorata) and their potential prey items and habitat. California study sites included Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest. Each was downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources. SOCs were detected frequently in all sites with more found in turtle plasma and aquatic macroinvertebrates in the two sites closest to agricultural and urban sources. Summed PCBs were highest in Whiskeytown National Recreation Area turtle plasma (mean; 1.56 ng/g ww) compared to plasma from Sequoia National Park (0.16 ng/g ww; p = 0.002) and Six Rivers National Forest (0.07 ng/g ww; p = 0.001). While no current-use pesticides were detected in turtle plasma at any site, both current- and historic-use pesticides were found prominently in sediment and macroinvertebrates at the Sequoia National Park site, which is immediately downwind of Central Valley agriculture. SOC classes associated with urban and industrial pollution were found more often and at higher concentrations at Whiskeytown National Recreation Area. These findings demonstrate a range of SOC exposure in a turtle species with current and proposed conservation status and shed additional light on the fate of environmental contaminants in remote watersheds

MeyerOrganicContaminantsWesternTableS3.xlsx

Remote aquatic ecosystems are exposed to an assortment of semivolatile organic compounds (SOCs) originating from current and historic uses, of local and global origin. Here, a representative suite of 57 current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons were surveyed in the plasma of the western pond turtle (Emys marmorata) and their potential prey items and habitat. California study sites included Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest. Each was downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources. SOCs were detected frequently in all sites with more found in turtle plasma and aquatic macroinvertebrates in the two sites closest to agricultural and urban sources. Summed PCBs were highest in Whiskeytown National Recreation Area turtle plasma (mean; 1.56 ng/g ww) compared to plasma from Sequoia National Park (0.16 ng/g ww; p = 0.002) and Six Rivers National Forest (0.07 ng/g ww; p = 0.001). While no current-use pesticides were detected in turtle plasma at any site, both current- and historic-use pesticides were found prominently in sediment and macroinvertebrates at the Sequoia National Park site, which is immediately downwind of Central Valley agriculture. SOC classes associated with urban and industrial pollution were found more often and at higher concentrations at Whiskeytown National Recreation Area. These findings demonstrate a range of SOC exposure in a turtle species with current and proposed conservation status and shed additional light on the fate of environmental contaminants in remote watersheds.Keywords: Persistent organic pollutants (POPs), Pesticides, Emys marmorata, Pollutant monitoringKeywords: Persistent organic pollutants (POPs), Pesticides, Emys marmorata, Pollutant monitorin

MeyerOrganicContaminantsWesternTableS1.xlsx

Remote aquatic ecosystems are exposed to an assortment of semivolatile organic compounds (SOCs) originating from current and historic uses, of local and global origin. Here, a representative suite of 57 current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons were surveyed in the plasma of the western pond turtle (Emys marmorata) and their potential prey items and habitat. California study sites included Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest. Each was downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources. SOCs were detected frequently in all sites with more found in turtle plasma and aquatic macroinvertebrates in the two sites closest to agricultural and urban sources. Summed PCBs were highest in Whiskeytown National Recreation Area turtle plasma (mean; 1.56 ng/g ww) compared to plasma from Sequoia National Park (0.16 ng/g ww; p = 0.002) and Six Rivers National Forest (0.07 ng/g ww; p = 0.001). While no current-use pesticides were detected in turtle plasma at any site, both current- and historic-use pesticides were found prominently in sediment and macroinvertebrates at the Sequoia National Park site, which is immediately downwind of Central Valley agriculture. SOC classes associated with urban and industrial pollution were found more often and at higher concentrations at Whiskeytown National Recreation Area. These findings demonstrate a range of SOC exposure in a turtle species with current and proposed conservation status and shed additional light on the fate of environmental contaminants in remote watersheds.Keywords: Pesticides, Pollutant monitoring, Emys marmorata, Persistent organic pollutants (POPs