Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs), are widely distributed in the environment. Several studies have demonstrated that these pollutants will cause potential impacts such as carcinogenic and mutagenic for human health. In this study, four different types of sampling stations were chosen. Two of the sampling sites are located in Kaohsiung city, which is an industrialized city with densely population in southern Taiwan (KHU and KHC). The other sampling sites are in a rural coastal area (KT) and an offshore island (LY), respectively. We determined the concentrations of PCBs and PBDEs in the atmosphere to identify the spatial and temporal distributions of PCBs and PBDEs in southern Taiwan. Hierarchical cluster analysis (HCA) and principal components analysis (PCA) of congener-specific composition of PCBs and PBDEs were performed with the commercial products to investigate the relationship of regional signatures and possible pollution sources. Finally, back trajectory analysis was undertaken to gain a better understanding of long-distance transport contribution to the studied area. The concentrations of £UPCBs in the ambient air ranged from 9.51 to 482 pg m-3, with an average concentration of 162¡Ó155 pg m-3. The mean PCB concentrations in gas and particle phase were 159¡Ó153 pg m-3 and 3.04¡Ó2.38 pg m-3, respectively. The concentrations of £UPBDEs in the ambient air ranged from 3.42 to 166 pg m-3, with an average concentration of 31.7¡Ó37.3 pg m-3. The average PBDE concentrations in gas and particle phase were 7.22¡Ó6.50 pg m-3 and 23.7¡Ó33.4 pg m-3, respectively. Comparison of the total PCB and PBDE concentrations from the four sampling sites showed that the total PCB and PBDE concentrations at the Kaohsiung urban site (KHU) and Kaohsiung coastal site (KHC) were higher than those at a rural coastal site (Kenting, KT) and an offshore island site (Lanyu, LY), suggesting that densely population and heavy industrial park may be the major contributor of PCBs and PBDEs . Results from HCA, PCA and compositional patterns of PCBs indicate that offshore island site (Lanyu, LY) was different from KHU, KHC and KT. Lower chlorinated congeners (dichlorobiphenyls to hexachlorobiphenyls) were predominant in the gas phase. Since most of the lower molecular weight congeners were below the detection limit, the total PCB concentrations were found at much lower level in LY sampling sites. In addition, a significantly higher proportion of high-chlorinated congeners, was observed at LY, suggesting that there may be local pollution sources in this area. Results from HCA, PCA and compositional patterns of PBDEs indicate that the samples from February and October were dominated by BDE-209, while the samples from July were dominated by BDE-71, BDE-47 and BDE-99, suggesting that this might be due to the significantly low concentrations of suspended particles (PM10) in July. Since much higher temperature was observed in July, these lower brominated congeners may be released much easier from the sediment, water, and brominated-containing products due to smaller molecular size and higher vapor pressure. Moreover, debromination of the deca-BDEs had been observed in the environment. Several studies have shown that photolytic debromination of BDE-209 is possible pathway for the formation of lower brominated-BDEs. TEQ was used to determine the level of pollution for environment and human health. In this study area, the TEQ ranged from 0.145 to 0.878 pg-TEQ m-3, with an average TEQ of 0.0004¡Ó0.0003 pg-TEQ m-3 in gas-phase of ambient air. PCB114 was observed to be the predominant congener in this study.

PCBs are known to cause thyroid disruption in laboratory rats and are thought to be the causal agent in thyroid gland alterations in herring gulls in the Great Lakes. This study examined the regulation of thyroid hormone supply during development in (1) domestic chicken embryos (Gallus domesticus) exposed to a specific dioxin-like PCB congener (PCB-126) and (2) herring gull (Larus argentatus) embryos and pre-fledglings from Great Lakes sites with different chemical pollutant exposures. Specifically, PCB effects on thyroid status were evaluated by measuring plasma thyroid hormone concentrations and brain type II 5'D activity (to determine if PCB exposure was associated with alteration in brain 5'D type II activity that could maintain local T3 supply to the brain). If PCB-126 and PCB mixtures altered thyroid function, we expected to see decreased plasma thyroid hormone concentrations and subsequent increases in 5'D-II activity. Chicken eggs were injected (into the air cell) before incubation with five dose levels (0.0512, 0.128, 0.32, 0.64, 0.8 ng/g) of PCB-126 (3,3, 4,4',5-pentachlorobiphenyl), or vehicle (sunflower oil); sampling was on day 20 of the 21-day incubation period. Studies on PCB-treated embryos included a preliminary study and a larger study encompassing a serious of smaller studies. Herring gull embryos (at pipping, on day 25 of the 26 day incubation), and 28-day pre-fledgling chicks were sampled (for two field seasons) at several Great Lakes sites with different contaminant exposures (with Kent Island being the reference site). In PCB-treated chicken embryos, there were no statistically significant decreases in plasma T4 or T3 concentrations and no significant increases in brain 5'D-II activity in either the preliminary or the larger study. We found no clear pattern of altered thyroid function in herring gulls from polluted Great Lakes' sites. Plasma TH concentrations were not significantly decreased and 5'D-II activity did not significantly increase in birds from more contaminated sites in comparison to birds from Kent Island or sites with less contamination. Although pipped embryos from Strachnan Island had a significant increase in 5'D-II activity when compared to Kent Island, there were no differences in plasma TH concentrations, and brain 5'D-II activity was not significantly increased in birds from sites with greater PCB loads than Strachnan Island. Plasma T4 and T3 concentrations were significantly decreased in prefledglings from West Sister Island and Detroit Edison in comparison to Kent Island, but there was no subsequent increase in brain 5'D-II activity. The present study is the first to evaluate the potential effects of PCBs, alone and in a mixed environmental exposure, on circulating THs and brain 5'D-II activity in developing birds. Although thyroid function was not altered by the specific PCB congener used in my study or by exposure to environmental pollutants, more complete evaluations are needed before determining whether PCBs alter thyroid function in birds. / Master of Science

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Polychlorniated Biphenyls (PCBs), a group of 209 individual congeners, are ubiquitous environmental pollutants and classified as probable human carcinogens. Hallmarks of aging and carcinogenesis are changes in telomerase activity and telomere length. I hypothesize that PCBs modulate telomerase activity and telomeres via interference in gene regulation and generation of reactive oxygen species (ROS) resulting in the dysregulation of cell growth. To explore this possibility, I exposed human skin keratinocytes (HaCaT) to a synthetic airborne PCB mixture (CAM) and individual congeners, i.e. PCB28, PCB52, PCB126 and PCB153. To mimic the chronic human exposure to PCBs and the slow process of carcinogenesis, a long term exposure period of 48 days and beyond was employed. All PCB congeners and CAM reduced telomerase activity, telomere length and cell growth. Among all PCBs, PCB126 had the most pronounced effect with reduction in telomerase activity, telomere length, hTERT and hTR gene expression and cell growth, while increasing TRF1 & TRF2 gene expression. PCB126 elicited an increase in CYP1A1 mRNA, CYP1A1 activity, DHE and DCFH oxidation levels from days 6 to 48, suggesting that increased ROS might be a causative factor for the reduction in telomerase activity and telomere length. However, transduction with hTERT and hTR subunits partly rescued telomerase activity, while treatment with PEG-catalase did not rescue telomerase activity suggesting that telomerase subunits play an important role on PCB126 induced effects on telomerase activity and telomere length. Since cells with shortened telomeres may escape crisis through telomerase reactivation, PCB126 treatment was continued until day 90. A change in growth behavior was observed from day 54 to 90, with cells recovering the proliferation rate, and increasing c-Myc, hTERT, and hTR gene expression level, re-activating telomerase activity and re-elongating telomere length. TRF1 & 2 gene expression started to decrease after day 66. From day 78, no increase in CYP1A1mRNA and its activity as well as CYP1B1, ALDH3A1, UGT1A1 and AhRRmRNA was observed suggesting that the AhR response pathway may have been altered. This study shows for the first time that PCBs initially reduce telomerase activity, telomere length, and cell growth, and can later lead to telomerase re-activation, telomere lengthening and increased cell growth with modulation of the AhR receptor pathway. This observation has broad implications for chronic PCB exposure scenarios.

Persistent organic pollutants (POPs), which include polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), are widely distributed in the environment. Some investigations have demonstrated that these pollutants will cause potential impacts such as carcinogenic and mutagenic for human health. In this study, we analyzed the concentrations and distributions of PAHs and PCBs in sediments of the Er-ren River, as well as the relations with total organic carbon (TOC) and particle sizes. Several molecular ratios were utilized to distinguish the major sources in this study. Results showed that PAH and PCB concentrations in Er-ren River ranged from 12.1 to 1460 and 0.45-591 (ng/g dw), respectively. The maximum concentrations of PAHs and PCBs were mostly found in sediments from Sanyegong River. In comparison with other studies all over the world, the concentrations of PAHs in this study were between low and mid-low levels. PCB concentrations in sediments of the Er-ren River were lower than those reported from previous studies. PAH and PCB concentrations showed no significant correlation between TOC and particle size. Petrogenic and petroleum combustion origin were the main sources of PAHs in sediments of Er-ren River In addition, perylene was the most dominant compound in Er-ren River, suggesting that it could be a useful indicator to differentiate various PAH sources in sediments. The results of hierarchical cluster analysis (HCA) and principal components analysis (PCA) indicated that PAH groups were clustered based on the loading of perylene, while PCB groups were clustered by the compositional homologues of PCBs. Comparing with sediments quality guidelines (SQGs), the PAH concentrations in all the sampling sites were below ERL value, suggesting that few adverse ecological effects would arise from the PAHs. However, the PCB concentrations in 14 sampling sites ranged between TEL and PEL values, indicating that adverse effects could arise for benthic organisms. The £UESBTUFCV of PAHs and the toxic equivalents (TEQ) of PCBs were both lower than quality values reported, suggesting that adverse ecological effects might be not expected.

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are persistent, ubiquitous, and toxic organic contaminants in coastal sediments. Being hydrophobic in water column, PAHs and PCBs tend to sorb rapidly on particles and eventually accumulate in sediments. Re-suspension of fine or low-density particles from the surface sediment would lead to release of the pollutants bound in sediment particles into water column. This study was to evaluate the potential of remobilization of sediment-bound pollutants into harbor water column by measuring the concentrations and compositions of PAHs and PCBs in different particle size (size fraction: 1000, 500, 250, 125 and 63 £gm) and the different density fractions (density: > 2.15, < 2.15 g/cm3) in the Kaohsiung Harbor area. The total PAH concentrations obtained from the sediments of Kaohsiung sub-channel (KH1) is higher than those of Shang-Zhu-Li fishing ferry (KH2), but it presents the opposite situation in total PCB concentrations. Total PAH concentrations are 3400 and 1700 (ng/g dw) and total PCB concentrations are 103 and 141 (ng/g dw) at sites of KH1 and KH2. PAH and PCB concentrations in the low-density fraction sediment made up more than 91% and 87% of the total concentration of the bulk sediment, respectively; while low-density fraction sediment made up only 4.3 to 7.7% of the bulk sediment in dry weight. According to the chemical fingerprinting, PAH source of Kaohsiung sub-channel (KH1) is from pyrogenic which might be from the diesel oil burning of shipping activities and containerized traffic. But the PAH sources in Shang-Zhu-Li fishing ferry (KH2) were from the combustion of coal and petroleum, which is possibly from iron and steel plant and the power plant nearby. The Toxic equivalents (TEQ) of dioxin-like PCBs in low and high-density fraction sediments were ranged from 1.1-7.6 pg-TEQ/g and 8.9-1500 pg-TEQ/g, respectively. Based on the Sediment Quality Guidelines (SQGs), only few PAH concentrations in the high-density fraction sediments were higher than the TEL value, while most of PAH concentrations in the low-density fraction sediments ranged between ERL and ERM values. This suggests the low-density sediment particles possessed higher potential of adverse effects to organisms in the aquatic environment.

The aldolase-dehydrogenase complex catalyzes the last two steps in the microbial meta-cleavage pathway of various aromatic compounds including polychlorinated biphenyls (bph pathway) and cholesterol (hsa pathway). The aldolase, BphI, cleaves 4-hydroxy-2-oxoacids to produce pyruvate and an aldehyde. Linear aldehydes of up to six carbons long and branched isobutyraldehyde were directly channeled to the aldehyde dehydrogenase BphJ, via a molecular tunnel, with greater than 80% efficiency. The molecular tunnel is narrow in positions lined by Gly-322 and Gly-323 in the aldolase. BphI variants G322F, G322L and G323F were found to block aldehyde channeling. The replacement of Asn-170 in BphJ with alanine and aspartate did not substantially alter aldehyde channeling efficiencies, thus disproving a previous hypothesis that hydrogen bonding between the Asn-170 and the nicotinamide cofactor induces the opening of the exit of the tunnel. The H20A and Y290F BphI variants displayed significantly reduced aldehyde channeling efficiencies indicating that these residues control the entry and exit of substrates and products from the aldolase reaction. The BphI reaction was activated by NADH binding to BphJ in the wild-type enzyme and channel blocked variants. Activation of BphI by BphJ N170A, N170D and I171A was decreased by ≥ 3-fold in the presence of NADH and ≥ 4.5-fold when BphJ was undergoing turnover. These results demonstrate that the dehydrogenase coordinates catalytic activity of BphI through allostery rather than through faster aldehyde release from substrate channeling. HsaF, an ortholog of BphI from Mycobacterium tuberculosis could be expressed as a soluble dimer, however HsaF was inactive in the absence of HsaG, a BphJ ortholog. Acetaldehyde and propionaldehyde were channeled directly to HsaG with similar efficiencies as in the BphI-BphJ system. The HsaF-HsaG complex was crystallized and its structure solved to a resolution of 1.93 Å. Substitution of Ser-41 in HsaG with isoleucine or aspartate resulted in about 35-fold increase in Km for CoA but only 4-fold increase in Km for dephospho-CoA, confirming its importance in interacting with the 3’- ribose phosphate of CoA. A second gene annotated as 4-hydroxy-2-oxopentanoic acid aldolase (Rv3469c) from M. tuberculosis was expressed, purified and found to possess oxaloacetate decarboxylase and not aldolase activity.

Concern about the possible contamination by metals, hydrocarbons and PCBs of Tees Bay and the Tees estuary, and potential sources of such materials has led to this study of surficial sediments. Surface sediment samples were collected from the Tees estuary and Tees Bay and were analysed for grain size, organic carbon content, metals, hydrocarbons (aliphatic and polyaromatic) and polychiorinated biphenyls (PCB5). The Tees estuary sediments are largely organic-rich clayey-silts, while the Bay sediments are organic-poor sands. All of the metals measured (Cd, Co, Cr, Cu, Ni, Pb and Zn) have significantly higher concentrations in the sediments of the Tees estuary than in those of Tees Bay (F<0.01), and the mean averages decrease in the order Zn > Pb> Cr> Cu > Ni > Co> Cd. These significantly higher concentrations remain apparent when the data are normalized to remove the effect of grain size variation, suggesting that the sediments of the Tees estuary are enriched in metals in comparison with the sediments of Tees Bay and that these differences are not the result of the different grain size distributions. Metal partitioning was determined by sequential extraction, using the scheme of Tessier et al. (1979) as recently modified by Ajayi and Van Loon (1989), in order to assess the likely behaviour of metals in the sediments studied. The results of the sequential extraction showed that the partitioning patterns of Cd, Cr, Cu and Zn differed between the marine and estuarine sediments. In the Tees Bay sediments the residual fraction hosted >50% of all of the metals, except Cd and Pb. In the Tees estuary, however, this fraction only accounted for >50% of the Cd, Co and Ni. Significant portions of Cd are contained in fractions 1 and 2 in both the Tees estuary sediments and those from Tees Bay. Because of the toxicity and availability of Cd this may pose a serious problem to the ecosystem. The total Pb in the sediments is also quite high, particularly in the Tees estuary, and even the small proportion in fraction 2 could cause deleterious effects. High concentrations of Cd and Pd, in Tees Bay and the Tees estuary sediments, and Cr and Zn, in Tees estuary sediments, were associated with fraction 3. Concern is directed to heavy metals associated with fraction 3 because changing environmental conditions can transfer these elements from the sediments into the aqueous phase. Cu was the only metal significantly associated with fraction 4. This fraction is likely to have an important role as a sink for trace metals, particularly for Cu and to a lesser extent Cr and Zn. Petroleum hydrocarbons, both aliphatic and polyaromatic (PAHs), were detected and quantified in all samples. The distributions of the n-alkanes, acyclic isoprenoids (especially pristane from coal), triterpanes and steranes, in most sediments from both areas, were indicative of pollution by fossil fuels. On the other hand, a few sediments from the estuary contain hydrocarbons from both biogenic and anthropogenic sources. Polyaromatic hydrocarbon assemblages observed in the samples were relatively rich in hydrocarbons having petrogenic origins. However, the presence of pyrolytic derived components was also indicated by several characteristic component composition ratios. Single PCB congeners were determined in the sediments studied. The PCB profile is fairly constant in sediments from both areas and similar to that of Aroclor 1260 and 1254. The similarity to the commercial mixtures, with only a slight enrichment of the lighter congeners, indicates that sources responsible for PCB pollution are located in the Tees area. The sediments of the Tees estuary tend to be more highly polluted, by metals, hydrocarbons and PCBs, than those of the Bay, particularly in the middle section of the estuary. However, there is a general decrease in the concentrations of these compounds from the middle to the mouth of the estuary, while within the Bay area offshore sites showed higher concentrations. Distributions of inorganic and organic constituents in the Tees Bay were significantly influenced by the organic carbon content and particle size of sediments.

The indoor environment is a potentially dominant source of exposure for polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). This thesis describes a study on levels, sources, emissions, and fate of PBDEs and PCBs indoors. PBDEs and PCBs air levels in 20 indoor environments in Toronto were sampled and measured. The geometric means of PBDE (Σ10BDE) and PCB (Σ35PCB) concentrations were 0.072 and 7.2 ng m-3 respectively. Statistical analysis on chemical profiles distinguished the chemical sources in the 20 environments. A multimedia indoor environmental model was applied on two test rooms. Estimated PBDE and PCB emission rates were 5.4-550 ng h-1 and 280-5870 ng h-1 respectively. Particle movement dominates within-room transport processes, and dust removal and air advection are the main chemical loss processes. Temperature, particle concentration and deposition velocity, and air exchange rate are the most influential parameters, which can alter source or sink behaviors of household products for the chemicals.