Individual Congeners Research Articles

Correlates of plasma concentrations of brominated flame retardants in a cohort of U.S. Black women residing in the Detroit, Michigan metropolitan area

BackgroundPolybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) are brominated flame retardant chemicals detectable in the environment and U.S. population, and are associated with adverse health outcomes over the life course. Correlates of these organic pollutants are understudied among U.S. Black women. MethodsUsing baseline data from a prospective cohort study of U.S. Black women aged 23–35 years from the Detroit area of Michigan (2010−2012), we examined correlates of PBDEs and PBB-153. Non-fasting blood samples were collected from 742 participants at enrollment, a subset of women selected for a case-cohort study of environmental chemicals. Data on socio-demographics, behaviors, diet, medical history, and early-life exposures were collected via self-administered questionnaires, telephone interviews, and in-person clinic visits. We fit linear regression models to calculate percent differences and 95% confidence intervals in lipid adjusted plasma concentrations of 11 individual PBDE congeners and PBB-153 for each baseline predictor. ResultsIn models adjusted for all other correlates, a 5-year increase in age was inversely associated with most PBDE congeners (% differences ranged from 6 to 15% lower), and was positively associated with PBB-153 (52% higher). A 5-kg/m2 increase in BMI was inversely associated with PBDE-153 and PBB-153 (16% lower for both), and 6% higher for PBDE-28. Compared with having never been breastfed in infancy, ≥3 months of breastfeeding in infancy was associated with 69% higher PBB-153 concentrations. Lower education, current smoking, and heavy alcohol use were associated with higher plasma concentrations of most flame retardants. Diet was not an important predictor. ConclusionImportant correlates for elevated body burdens of PBB-153 were increasing age and a history of having been breastfed in infancy. Education, smoking, and heavy alcohol use were important predictors of elevated body burdens of most flame retardants. This study fills an important gap in the environmental health literature by focusing on an understudied population.

Exposure to polycyclic aromatic hydrocarbons and risk for premature ovarian failure and reproductive hormones imbalance

Polycyclic aromatic hydrocarbons (PAHs) are a typical class of persistent organic pollutants that is ubiquitous worldwide. Previous animal studies suggested that PAHs had adverse effects on female reproduction. However, the human data regarding relationship of PAHs exposure with women reproductive health, such as ovarian dysfunction, are scarce. In this case-control study, the associations of serum levels of PAHs with the risk of premature ovarian failure (POF) and reproductive hormones in Chinese women were investigated, with recruiting 157 POF patients and 217 healthy women. The serum levels of 12 types of PAHs, as well as reproductive hormones, including follicle-stimulating hormone, luteinizing hormone and anti-mullerian hormone, were determined. In the logistic regression models, most individual PAH congeners showed significantly positive correlations with the risk of POF (p < 0.05), except for fluorine and pyrene. Benzo(a)pyrene (BaP), as the most carcinogenic PAH congener, was observed to be significantly positively associated with the risk of POF. After adjustment for age, body mass index, educational levels and household income, per one-unit increase in the log-transformed BaP concentration was significantly correlated with 2.191-fold increased risk of POF (OR = 2.191, 95%CI: 1.634–2.938, p < 0.05). To the best of our knowledge, this is the first study to report an association between internal exposure levels of PAHs and the increased risk of POF in women.

Mycophenolate co-administration with quercetin via lipid-polymer hybrid nanoparticles for enhanced breast cancer management

Mycophenolic acid (MPA) has promising anticancer properties; however, it has limited clinical applications in vivo due to hydrophobic nature, high first-pass metabolism, lack of targeting, etc. These associated problems could be addressed by developing a suitable delivery vehicle, inhibiting the first-pass metabolism and additive/synergistic pharmacodynamic effect. Thus, MPA loaded highly stable lipid polymer hybrid nanoparticles (LPNs) were developed and investigated with the combination of quercetin (QC), a CYP 450 inhibitor cum anticancer. LPNs of MPA and QC (size; 136 ± 12 and 176 ± 35 nm, respectively) demonstrated higher cellular uptake and cytotoxicity of combination therapy (MPA-LPN + QC-LPN) compared to individual congeners in MCF-7 cells. In vivo pharmacokinetics demonstrated 2.17 fold higher T1/2 value and significantly higher pharmacodynamic activity in case of combination therapy compared to free MPA. In nutshell, the combinatory therapeutic regimen of MPA and QC could be a promising approach in improved breast cancer management.

Juvenile harbor porpoises in the UK are exposed to a more neurotoxic mixture of polychlorinated biphenyls than adults

Polychlorinated biphenyls (PCBs) are a group of 209 persistent and bio-accumulative toxic pollutants present as complex mixtures in human and animal tissues. Harbor porpoises accumulate some of the highest levels of PCBs because they are long-lived mammals that feed at a high trophic level. Studies typically use the sum of a suite of individual chlorobiphenyl congeners (CBs) to investigate PCBs in wildlife. However, toxic effects and thresholds of CB congeners differ, therefore population health risks of exposure may be under or over-estimated dependent on the congener profiles present. In this study, we found congener profiles varied with age, sex and location, particularly between adult females and juveniles. We found that adult females had the highest proportions of octa-chlorinated congeners whilst juveniles had the highest proportions of tri- and tetra-chlorinated congeners. This is likely to be a consequence of pollutant offloading between mothers and calves during lactation. Analysis of the individual congener toxicities found that juveniles were exposed to a more neurotoxic CB mixture at a time when they were most vulnerable to its effects. These findings are an important contribution towards our understanding of variation in congener profiles and the potential effects and threats of PCB exposure in cetaceans.

Accumulation of polybrominated diphenyl ethers and microbiome response in the great pond snail Lymnaea stagnalis with exposure to nylon (polyamide) microplastics

Microplastics attract widespread attention, including for their potential to transport toxic chemicals in the form of plasticisers and associated hydrophobic organic chemicals, such as polybrominated diphenyl ethers (PBDEs). The aims of this study were to investigate how nylon (polyamide) microplastics may affect PBDE accumulation in snails, and the acute effects of nylon particles and PBDEs on survival, weight change and inherent microbiome diversity and community composition of the pond snail Lymnaea stagnalis. Snails were exposed for 96 h to BDEs-47, 99, 100 and 153 in the presence and absence of 1% w/w nylon microplastics in quartz sand sediment. No mortality was observed over the exposure period. Snails not exposed to microplastics lost significantly more weight compared to those exposed to microplastics. Increasing PBDE concentration in the sediment resulted in an increased PBDE body burden in the snails, however microplastics did not significantly influence total PBDE uptake. Based on individual congeners, uptake of BDE 47 by snails was significantly reduced in the presence of microplastics. The diversity and composition of the snail microbiome was not significantly altered by the presence of PBDEs nor by the microplastics, singly or combined. Significant effects on a few individual operational taxonomic units (OTUs) occurred when comparing the highest PBDE concentration with the control treatment, but in the absence of microplastics only. Overall within these acute experiments, only subtle effects on weight loss and slight microbiome alterations occurred. These results therefore highlight that L. stagnalis are resilient to acute exposures to microplastics and PBDEs, and that microplastics are unlikely to influence HOC accumulation or the microbiome of this species over short timescales.

Serum concentrations of legacy and emerging halogenated flame retardants in a Norwegian cohort: Relationship to external exposure

Sixty-one serum samples from a Norwegian cohort were analyzed for 43 emerging and legacy halogenated flame retardants (HFRs). BDE-47, -153, −197 and −209 were detected in >56% of the samples with median concentrations of 0.23, 1.0, 0.64 and 1.5 ng/g lipid, respectively. BDE-49, -85, −99, −100, −154, −206, −207, −208 as well as HBB, syn- and anti-DDC-CO, OBTMPI, DBDPE, α-HBCDD and TBBPA were also detected in some serum samples (detection frequencies of 2–36%). Other tri-octaBDEs, TBP-AE, α- and β-DBE-DBCH, BATE, pTBX, αβ-TBCO, PBBz, TBCT, PBT, PBEB, DPTE, EH-TBB, BTBPE, BEH-TEBP, HCDBCO, β- and γ-HBCDD were below the limits of detection (mLOD). Concentrations of individual BDE congeners detected in this study were within the range from previous European studies. Positive correlations were seen between concentrations of BDE-47 in dust and BDE-153 in serum, between BDE-153 in dust and BDE-153 in serum, and between BDE-153 masses in handwipes and BDE-47 concentrations in serum (Spearman’s rank, 0.29 < r < 0.43). Associations between the number of phones/mobiles, numbers of electronic equipment per person in the home and the consumption of specific food categories (such as soups/spices/sauces and alcoholic beverages) with BDE-47 and -153 serum levels were confirmed by multivariate linear regression analyses. The measured median serum level of BDE-47 was slightly over-predicted by a factor of 5.5 whereas other BDE congeners were under-predicted by factors of 13–6000 when compared to serum concentrations predicted from external exposure media (inhalation, dermal uptake, dietary intake from duplicate diet and dust ingestion) using a simple one compartment pharmacokinetic (PK) model. BDE-153 was not detected and BDE-197 not analyzed in food so no dietary intake assessments for these could be made, which may partially explain the discrepancies between their measured and predicted serum concentrations. Overall, our results suggest that exposure via diet is the most important exposure pathway for BDE-47 and -209, with diet being responsible for more than 96% of the total daily intake of these two BDEs in the Norwegian cohort.

Understanding possible causes of exceeding dioxin levels in palm oil by-products: An explorative study

The Rapid Alert System for Food and Feed (period 1999–2014) reported exceeding levels of dioxins (polychlorinated dibenzo-p-dioxinsand dibenzofurans (PCDD/Fs)) in palm oil by-products, such as palm fatty acid distillate (PFAD) and hydrogenated palm fatty acid distillate (HPFAD), but not in crude and refined palm oil. The aim of the present study was to gain insight into the occurrence and congener profiles of dioxin contamination during industrial processing of crude palm oil into refined oil and its by-products PFAD and HPFAD via analysis of individual congener concentrations. In total, 1217 samples from an industrial process were collected at four different points, crude palm oil at delivery (N = 202), fresh bleaching earth before bleaching (N = 84), PFAD after deodorising palm oil (N = 553), and HPFAD after hydrogenation of PFAD (N = 378). Congener profiles were analysed by GC-HRMS, and toxic equivalent (TEQ) levels were calculated using toxic equivalence factors (TEF) of WHO2005 to assess non-compliance to legal limits. All dioxin levels in crude palm oil samples were far below the action limit. All dioxin levels in fresh bleaching earth were in compliance with the maximum level. For the by-product samples, such as PFAD, 0.6% exceeded the action level, but all were below the maximum level (ML). However, for 1.3% of the HPFAD samples, the TEQ level exceeded the ML.In-depth analysis of the congener profiles revealed that after the hydrogenation step, the concentration of the lower chlorinated congeners in the HPFAD samples was higher than in the PFAD samples. The hydrogen atoms possibly replaced the chlorine atoms during hydrogenation. As these lower chlorinated congeners have a higher TEF, when they are regulated, their contribution to the calculated TEQ is higher, which resulted in some HPFAD samples exceeding the legal limit. Further research is needed to obtain insight into the changes in PCDD/F congener profiles during the hydrogenation of palm oil products.

Trophic Dilution of Short-Chain Chlorinated Paraffins in a Plant-Plateau Pika-Eagle Food Chain from the Tibetan Plateau.

Little is currently known about the trophic transfer behavior of short-chain chlorinated paraffins (SCCPs) in terrestrial ecosystems. The trophodynamics of SCCPs were investigated in a typical terrestrial food chain (plant-plateau pika-eagle) from the interior of the Tibetan Plateau with an altitude of 4730 m. Pervasive contamination by SCCPs was found in the Tibetan Plateau samples, and the average concentrations of SCCPs in soil, plant, plateau pika, eagle, and gut content of eagle samples were 81.6 ± 31.1, 173 ± 70.3, 258 ± 126, 108 ± 59.6, and 268 ± 93.9 ng/g (average ± standard deviation, dry weight, dw), respectively. The trophic magnification factor (TMF) of SCCPs was 0.37, implying the trophic dilution of SCCPs in this terrestrial food chain. The TMF values of individual congener groups were positively correlated with the values of log Kow, log Koa and biotransformation half-life. As a result of long-range transport, SCCPs congeners with low molecular weight dominated in Tibetan Plateau species (C10+11 congeners = 76.9%, Cl5+6+7 congeners = 71.5%), which could partly explain the low biomagnification factors (BMFs) of SCCPs in the Tibetan Plateau.

Evaluating putative ecological drivers of microcystin spatiotemporal dynamics using metabarcoding and environmental data

Microcystin is a cyanobacterial hepatotoxin of global concern. Understanding the environmental factors that cause high concentrations of microcystin is crucial to the development of lake management strategies that minimize harmful exposures. While the literature is replete with studies linking cyanobacterial production of microcystin to changes in various nutrients, abiotic stressors, grazers, and competitors, no single biotic or abiotic factor has been shown to be reliably predictive of microcystin concentrations in complex ecosystems. We performed random forest regression analyses with 16S and 18S rRNA gene sequencing data and environmental data to determine which putative ecological drivers best explained spatiotemporal variation in total microcystin and several individual congeners in a eutrophic freshwater reservoir. Model performance was best for predicting concentrations of the congener MC-LR, with ca. 88% of spatiotemporal variance explained. Most of the variance was associated with changes in the relative abundance of the cyanobacterial genus Microcystis. Follow-up RF regression analyses revealed that factors that were the most important in predicting MC-LR were also the most important in predicting Microcystis population dynamics. We discuss how these results relate to prevailing ecological hypotheses regarding the function of microcystin.

Relative Effect Potency Estimates for Dioxin-Like Compounds in Pregnant Women with Gestational Diabetes Mellitus and Blood Glucose Outcomes Based on a Nested Case-control Study.

To improve the applicability of the toxic equivalents principle for human health risk assessment, systemic relative effect potencies (REPs) for dioxin-like compounds (DLCs) deriving from human in vivo data are required. A prospective nested case-control study was performed to determine REPs from the human serum concentration of DLCs using gestational diabetes mellitus (GDM) and fasting blood glucose (FBG) as the end points of concern. Serum concentration of 29 DLCs from 77 cases and 154 controls were measured. Logistic and linear regression were used to estimate the effects of individual congeners on GDM and FBG, respectively. The REPs based on GDM and FBG were calculated from the ratios of regression coefficients, βi(DLCs)/βTCDD. Two sets of consistent human serum-based REPs, that is, GDM-REP and FBG-REP, were established and largely agree with REPs from other human studies. These human-serum REPs show much smaller variation compared to the 4 to 5 orders of magnitude span in REPs database for the present WHO-TEF determination. Moreover, the established REPs fitted well with WHO-TEFs, especially for polychlorinated dibenzo- p-dioxins, furans. These REPs reflecting real human exposure scenarios exhibited validity and could be used to improve health risk assessment of human body burden of DLCs.

PBDE serum concentration and preschool maturity of children from Slovakia

Polybrominated diphenylethers (PBDEs) are persistent organic pollutants (POPs), they are considered endocrine disruptors and can bioaccumulate in nature, and in living tissue. Human exposure to and the presence of PBDEs in human samples is of concern due to their potential health risks. Young children are one of the most vulnerable populations to PBDE's potential health effects.Ninety-one serum samples of 6-year-old children, residing in a contaminated location, due to former production of polychlorinated biphenyls (PCBs), were analysed to examine children's exposure to PBDEs in Slovakia. Median serum concentrations found for individual PBDE congeners BDE-28+33, −47, −99, −100, −153, −154 and −183 were 0.015, 0.184, 0.079, 0.046, 0.176, 0.014, and 0.097 ng g−1 lipid weight, respectively.Children's preschool maturity was measured using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) test. In multivariate analyses BDE-153 serum concentrations were significantly inversely associated with WPPSI-III composite score (p = 0.011, β = −23.6), while adjusting for PCB-153 and sex. Significant negative associations were observed for BDE-153 serum concentrations (p = 0.002, β = −29.8) and WPPSI-III composite score, after controlling for PCB-118 and sex. Negative associations were also observed for BDE-47, BDE-100 and BDE-153, with different individual WPPSI subtest scores, after adjustment with PCB-153 and/or PCB-118 and sex. Serum concentrations of PCB-153 and PCB-118 were not statistically significantly associated with WPPSI-III composite score and individual subtest scores. These findings demonstrate adverse effects of PBDE serum exposure on preschool maturity of children, and PBDEs potentially negative impact on child neuropsychological development.

Lactational exposure to dioxin-like polychlorinated biphenyl 169 and nondioxin-like polychlorinated biphenyl 155: Effects on rat femur growth, biomechanics and mineral composition

Exposure to polychlorinated biphenyls (PCBs), which are persistent lipophilic environmental pollutants, has a variety of adverse effects on wildlife and human health, including bone mineralization, growth and mechanical strength. The present study evaluated the effects of lactational exposure to nondioxin-like PCB-155 and dioxin-like PCB-169, individually and in combination, on pubertal rat femur development and its biomechanics. After offspring delivery, Wistar rat mothers were divided into four groups, i.e., PCB-169, PCB-155, PCB-155+169 and control, and were administered PCBs intraperitoneally. Data on bone geometry, biomechanics and mineral composition were obtained by analysis of femurs from 42-day-old offspring by microCT scanning, three-point bending test and inductively coupled plasma mass spectrometry. Decreased somatic mass and femur size, i.e., mass, periosteal circumference and cross sectional area, were observed in the PCB-169 and PCB-155 groups. Additionally, lactational exposure to planar PCB-169 resulted in harder and more brittle bones containing higher amounts of minerals. Combined exposure to structurally and functionally different PCBs demonstrated only mild alterations in bone width and mineralization. To conclude, our results demonstrated that alterations, observed on postnatal day 42, were primarily induced by PCB-169, while toxicity from both of the individual congeners may have been reduced in the combined group.

Biodegradation of Polychlorinated Biphenyls by Lysinibacillus macrolides and Bacillus firmus Isolated from Contaminated Soil

Polychlorinated biphenyls (PCBs) cause many significant ecological problems because of their low degradability, high harmfulness, and solid bioaccumulation.Two bacterial strains were isolated from soil that had been polluted with electrical transformer liquid for more than 40 years. The isolates were distinguished as Lysinibacillus macrolides DSM54Tand Bacillus firmus NBRC15306Tthrough 16S rRNA sequencing analysis.This is the primary report of an agent of the genus Bacillus firmus equipped for the removal of PCBs. The strains could develop broadly on 2-Chlorobiphenyl and 2,4-dichlorobiphenyl. GC/MS analysis of individual congeners revealed up to 80% degradation of the xenobiotics in 96h, attendant with cell proliferation of up to two orders of extent. More extensive investigation of the isolates may be helpful in surveying detoxification forms and in planning bioremediation and bioaugmentation strategies.

Comparative Analyses of the 12 Most Abundant PCB Congeners Detected in Human Maternal Serum for Activity at the Thyroid Hormone Receptor and Ryanodine Receptor.

Polychlorinated biphenyls (PCBs) pose significant risk to the developing human brain; however, mechanisms of PCB developmental neurotoxicity (DNT) remain controversial. Two widely posited mechanisms are tested here using PCBs identified in pregnant women in the MARBLES cohort who are at increased risk for having a child with a neurodevelopmental disorder (NDD). As determined by gas chromatography-triple quadruple mass spectrometry, the mean PCB level in maternal serum was 2.22 ng/mL. The 12 most abundant PCBs were tested singly and as a mixture mimicking the congener profile in maternal serum for activity at the thyroid hormone receptor (THR) and ryanodine receptor (RyR). Neither the mixture nor the individual congeners (2 fM to 2 μM) exhibited agonistic or antagonistic activity in a THR reporter cell line. However, as determined by equilibrium binding of [3H]ryanodine to RyR1-enriched microsomes, the mixture and the individual congeners (50 nM to 50 μM) increased RyR activity by 2.4-19.2-fold. 4-Hydroxy (OH) and 4-sulfate metabolites of PCBs 11 and 52 had no TH activity; but 4-OH PCB 52 had higher potency than the parent congener toward RyR. These data support evidence implicating RyRs as targets in environmentally triggered NDDs and suggest that PCB effects on the THR are not a predominant mechanism driving PCB DNT. These findings provide scientific rationale regarding a point of departure for quantitative risk assessment of PCB DNT, and identify in vitro assays for screening other environmental pollutants for DNT potential.

Association study between plasma levels of polychlorinated biphenyls and risk of cutaneous malignant melanoma

Cutaneous malignant melanoma (CMM) ranks the most lethal skin cancer worldwide. However, other risk factors have been hardly explored, aside from ultraviolet radiation (UVR). Polychlorinated biphenyls (PCBs) were implied to be potential risk factors for CMM, although all the evidence was obtained from the western countries. This study examined the relationships between plasma levels of PCBs and CMM risk adjusting for sun sensitivity and sun exposure in a Chinese population, using a case-control study, including 450 CMM cases and 500 healthy controls. Plasma levels of a total of 33 PCB congeners were assayed in both cases and controls. Our results showed that there was a significant association between total summed PCB level and CMM risk, with a 1.44-fold increased risk for those in the highest quartile compared to those in the lowest quartile (OR = 1.44, 95% CI: 1.02–2.03, P for trend = 0.031). Significantly increased ORs were also observed for individual PCB congeners (PCB52, PCB170 and PCB180). These associations persisted after control for sun sensitivity and sun exposure. Our study represents the first evidence conducted in Asians, and does support the hypothesis that PCB exposure increases CMM risk.

Using Spectrometric Colour Measurement for the Prediction of Soil PCBs in a Contaminated Site of Southern Italy

Soil contamination with polychlorinated biphenyls (PCBs) is one the most relevant environmental problem in the SIN (Site of National Interest) of Taranto (Apulia Region, Southern Italy) and the surrounding area. Evaluation of PCB contents and their spatial distribution is an essential pre-requisite for soil remediation. Conventional laboratory analyses, although useful and irreplaceable for a precise and detailed evaluation of these contaminants, are costly and time-consuming, thus not very suitable for investigation over large areas. Then, there is a need to develop/validate alternative, rapid and cost-effective techniques, to use as substitutive of integrative to conventional analytical approaches. In this study, the usefulness of soil colour, based on spectrometric measurements, coupled with regression analysis, was assessed. Until now, never an analogous investigation has been realised. Twenty-eight soil samples, previously collected within an area (the ex-MATRA) highly contaminated by the disposal of oil used as dielectric fluid, composed by a mixture of PCB congeners, were used in the investigation. Colour coordinates in different colour systems were calculated from spectroradiometric measurements over the soil samples. Eighteen PCB congeners (i.e. 12 dioxin-like PCBs and six non-dioxin-like “indicator” PCBs), their sum (PCBs18) and the extractable organic halogen content (EOX)—which is an expression of the total content of halogen in organochlorine compounds, including the PCBs—were determined through conventional laboratory analysis. Simple linear regression analysis was carried out to predict the values of PCBs and EOX on the basis of colour variables. Excellent predictive models (R2 > 0.80) for PCBs18 and EOX, as well as for some of the individual PCB congener, resulted from the regression analysis. Thus, spectroscopic determination of soil colour can be considered as a promising tool for a rapid screening of PCBs in contaminated soils.

Plasma levels of polychlorinated biphenyls (PCB) and the risk of soft tissue sarcoma.

Background::Soft tissue sarcoma (STS) is a heterogeneous group of rare neoplasms whose aetiology is largely unknown. Dioxin and dioxin-like compounds, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and polychlorinated biphenyls (PCBs), are potential risk factors for STS.Objectives:To investigate the relation of 17 PCBs congeners, assessed in human plasma, with STS risk.Methods:We conducted a case-control study in Italy, including 52 STS cases and 99 hospital-based controls. Selected PCB were extracted by high-performance liquid chromatography (HPLC) and measured with gas chromatography-mass spectrometry (GC-MS). Odds ratios (OR), and the corresponding 95% confidence intervals (CI), were estimated through multivariate logistic regression models.Results:The most frequently detected PCB congeners were 138, 170, 180 and 149 (detected in 40-77% of controls). The OR for the sum of all 17 PCB congeners was 1.20 (95% CI 0.50-2.92). In categorical analysis no consistent association was found for individual congeners and for groups based on Wolff’s classification or the degree of chlorination. For continuous estimates, borderline positive associations emerged for Wolff’s groups 2A (OR 1.23, 95% CI 0.97-1.55), 2B (OR 1.34, 95% CI 1.00-1.77, and 3 (OR 1.19, 95% CI 0.96-1.49), for moderately (OR 1.20, 95% CI 0.96-1.51) and highly (OR 1.18, 95% CI 0.99-1.41) chlorinated PCBs, and for congeners 170 (OR 1.26, 95% CI 0.98-1.63), 180 (OR 1.26, 95% CI 0.97-1.64) and 138 (OR 1.45, 95% CI 1.02-2.04).Discussion:Most associations between PCBs and STS risk were not significant, but, given the limited sample size, we cannot exclude moderate associations.

Polycyclic aromatic hydrocarbons in two polluted lagoons, eastern coast of the Red Sea: Levels, probable sources, dry deposition fluxes and air-water exchange

The air-water exchange of polycyclic aromatic hydrocarbons (PAHs) is an important process in determining the fate, transport and chemical loadings of these contaminants in the atmosphere and water bodies. Concentration levels of PAHs in air (gaseous and particulate) and surface water were investigated in the environments of two polluted lagoons along the eastern coast of the Red Sea to study air water exchange and dry deposition fluxes. Nine priority parent PAHs and nine methylated PAHs were identified and quantified by GC-MS. The range of total PAHs in surface water was from 120.29 ng L−1 to 524.45 ng L−1 (average: 308.7 ng L−1, n = 19). The PAHs levels in air recorded significant rise form the previous study. The probable sources of dissolved PAHs in water were found predominantly to be of petrogenic origin in one lagoon and of pyrogenic origin in the other lagoon. The dry deposition fluxes for individual congeners ranged between 0.01 ng m−2d−1 to 2.82 μg m−2d−1. After Henry's law constant corrections for temperature and salinity; the air-water exchange fluxes were found in the range of −9.7 × 104 to 8.6 × 106 ngm−2d−1 with an average of 6.8 × 105 ngm−2d−1. Beside the other sources of PAHs in the studied lagoons, high temperature and wastewater dumping might affect the magnitude and direction of air-water exchange fluxes.

The application of the carcinogenic hazardous property assessment to oil contaminated dredging waste

AbstractThe carcinogenic hazardous property assessment for oil contaminated waste is inappropriate when applied to canal and river dredgings. The presence of polyaromatic hydrocarbons (PAH) derived from non‐oil sources means that Benzo(a)Pyrene concentrations cannot be assumed to be markers for the carcinogenicity of any oil contaminants present. Canal dredgings can be suitable for use in a residential without homegrown produce land use whilst also being classified as ‘carcinogenic’ waste. A revision of the basis on which waste is classified as hazardous or non‐hazardous is needed, at least for canal and river dredgings which may contain PAH from several pyrogenic and petrogenic sources. Such a basis could simply refer to a concentration of PAH or individual congeners reflecting risk‐based assessment criteria.

Seasonal variation, air-water exchange, and multivariate source apportionment of polycyclic aromatic hydrocarbons in the coastal area of Dalian, China

The concentrations and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) in air and seawater dissolved samples from the coastal area of Dalian were investigated, as well as their air-water exchanges. The average concentrations of PAHs were 27.5 ± 14.6 ng/m3 and 49.5 ± 20.5 ng/L in the air and water, respectively. Phenanthrene was the dominant congener in both air and water dissolved phase. Seasonality was discovered in the air with the concentrations higher in winter than in summer, but not in the water dissolved phase. Air-water exchange trends also displayed apparent seasonality with 3–4 ring PAHs generally being volatilization or equilibrium in summer but deposition in winter, which highlighted the important influence of temperature on the air-water exchange direction of PAHs. The air-water exchange fluxes of individual PAH congeners ranged from −24331 to 6541 ng/m2/d, and the highest deposition and volatilization fluxes both appeared at the industrial areas, which emphasized the influence of point source emission to the magnitude of air-water diffusion flux of PAHs. Multivariate source apportionment approaches, including principle component analysis, diagnostic ratios, and positive matrix factorization, were conducted, which suggested that PAHs in water originated from multiple sources. Frequent port transport correlated vehicle/ship emission rather than coal combustion may be the primary contributor of PAHs to the coastal air and water.