Effects of mixtures of polychlorinated biphenyls (PCBs) and three organochlorine pesticides on cognitive function differ between older Mohawks at Akwesasne and older adults in NHANES.

BACKGROUND: Akwesasne Mohawks has been exposed to high concentrations of polychlorinated biphenyls (PCBs) and background levels of organochlorine pesticides, hexachlorobenzene (HCB), dichlorodiphenyl dichloroethylene (DDE), and mirex. We have previously reported relative contributions to the mixture of low- and high-chlorinated PCBs, HCB, and DDE on cognitive decrements in Mohawks of various ages. OBJECTIVE: This study examines differences in the mixture effects of PCB congener groups, HCB, DDE, and mirex on cognitive function in older Mohawks and less PCB-exposed older adults from the National Health and Nutrition Examination Survey (NHANES) 1999-2002 cycles. METHODS: We used Bayesian kernel machine regression (BKMR) to evaluate the mixture effects of different PCB congener groups, HCB, DDE, and mirex on cognitive function in both populations. Models were adjusted for age, sex, education levels, and race/ethnicity focusing on individuals 60 years and older. RESULTS: Older Mohawks had 3-fold higher mean total PCB concentrations and 1.8-fold higher mirex, but slightly lower mean DDE and HCB levels than NHANES older adults. Higher mixture concentrations were significantly associated with greater cognitive decline. In older Mohawks, low- and high-chlorinated PCBs, HCB, and DDE contributed to the cognitive score decline. In contrast, score decline in older NHANES adults were primarily from high-chlorinated PCBs and DDE with a threshold dose of approximately 2.08-2.27 ng/g and 2.02-2.40 ng/g, respectively. CONCLUSION: Mixtures of PCBs and organochlorine pesticides increase the risk of cognitive decline in both older Mohawks and NHANES older adults. However, contributions to these mixture effects show significant differences. In older Mohawks, high- and low-chlorinated PCBs, DDE, and HCB are the primary contributors, while high-chlorinated PCBs and DDE are important contributors in NHANES older adults. Due to chronic heavy exposures to PCBs, older Mohawks had a significantly increased risk of cognitive decline compared to general older adults from NHANES.

Cross-sectional associations of persistent organic pollutants measured in adipose tissue and metabolic syndrome in clinically diagnosed middle-aged adults.

INTRODUCTION: Although often overlooked in clinical settings, accumulation of persistent organic pollutants (POPs) in visceral adipose tissue (VAT) is thought to be a relevant risk factor for metabolic syndrome (MetS). METHODS: One hundred and seventeen patients undergoing non-oncological surgery were randomly recruited and classified as MetS + if presented 3 out of the 5 MetS components: waist circumference (WC), systolic and diastolic blood pressure (SBP and DBP, respectively), serum glucose, insulin, triglycerides (TG) and high-density lipoprotein (HDL) cholesterol levels, according International Diabetes Federation (IDF) criteria. Seventeen organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were measured in adipose tissue samples. Linear, logistic and weighted quantile sum (WQS) regression models, adjusted for age and sex, were performed. RESULTS: One third of the participants were males (36.8%) with a median age of 44 years, showing clinical evidences of MetS (35.0%). Adjusted linear regression models showed that WC correlated positively with all OCP concentrations. Higher fasting serum glucose levels were related to higher HCB and γ-HCH concentrations. The remaining OCPs and PCBs were not associated with this MetS component. HCB was inversely associated with HDL cholesterol levels, while PCB-180 was positively associated. HCB and γ-HCH concentrations were also positively correlated with DBP and SBP levels. PCB-138 was also positively associated with SBP. Adjusted logistic models revealed that exposure to HCB and γ-HCH were associated with increased odds of MetS [ORs (95%CI) 1.53 (1.22-1.92) and 1.39 (1.10-1.76) respectively; p < 0.01]. No associations were observed for the remaining POPs. WQS models showed a positive and significant mixture effect of POPs on the odds of MetS (exp [beta] = 2.34; p < 0.001), with γ-HCH (52.9%), o,p'-DDT (26.9%) and HCB (19.7%) driving the association. CONCLUSIONS: Our findings support that POPs accumulated in VAT, specifically HCB and (gamma)-HCH, are associated with both isolated components and clinically diagnosed SMT.

Dithionite promoted microbial dechlorination of hexachlorobenzene while goethite further accelerated abiotic degradation by sulfidation in paddy soil.

It is of great scientific and practical importance to explore the mechanisms of accelerated degradation of Hexachlorobenzene (HCB) in soil. Both iron oxide and dithionite may promote the reductive dechlorination of HCB, but their effects on the microbial community and the biotic and abiotic mechanisms behind it remain unclear. This study investigated the effects of goethite, dithionite, and their interaction on microbial community composition and structure, and their potential contribution to HCB dechlorination in a paddy soil to reveal the underlying mechanism. The results showed that goethite addition alone did not significantly affect HCB dechlorination because the studied soil lacked iron-reducing bacteria. In contrast, dithionite addition significantly decreased the HCB contents by 44.0-54.9%, while the coexistence of dithionite and goethite further decreased the HCB content by 57.9-69.3%. Random Forest analysis suggested that indicator taxa (Paenibacillus, Acidothermus, Haliagium, G12-WMSP1, and Frankia), Pseudomonas, richness and Shannon's index of microbial community, and immobilized Fe content were dominant driving factors for HCB dechlorination. The dithionite addition, either with or without goethite, accelerated HCB anaerobic dechlorination by increasing microbial diversity and richness as well as the relative abundance of the above specific bacterial genera. When goethite and dithionite coexist, sulfidation of goethite with dithionite could remarkably increase FeS formation and then further promote HCB dechlorination rates. Overall, our results suggested that the combined application of goethite and dithionite could be a practicable strategy for the remediation of HCB contaminated soil.

Investigation of obesogenic effects of hexachlorobenzene, DDT and DDE in male rats.

Obesity has become a very important public health problem and is increasing globally. Genetics, individual and environmental factors play roles in the etiology of this complex disorder. Recently, several environmental pollutants have been suggested to have obesogenic activities. Peroxisome proliferator activating receptor gamma (PPARγ), uncoupling protein-1 (UCP1) and their expression in white adipose tissue (WAT) and brown adipose tissue (BAT) play key roles in adipogenesis. UCP3 and irisin were reported to play roles in non-shivering thermogenesis. Our primary aim was to investigate obesogenic effects of hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) in rats. In addition, thermoregulatory effects of HCB, DDT and DDE were also investigated by analyzing the levels of Ucp3 and irisin. Thirty-two adult male Sprague-Dawley rats were randomly divided into four groups as control, HCB, DDT and DDE. Animals were administered with organochlorine pesticides (OCPs; 5 mg/kg bw) by oral gavage every other day for five weeks. At the end of the experimental period, the animals were sacrificed, BAT and WAT samples were collected to analyze Pparγ, Ucp1 and Ucp3 levels. Moreover, skeletal muscle samples were collected to examine Ucp3 and irisin levels. Serum glucose, cholesterol and triglyceride levels were also determined. Body weight and core temperature of the animals were not significantly affected by any of the OCP administration. Serum glucose, cholesterol and triglyceride levels were similar among the experimental groups. Pparγ expression was significantly elevated by HCB administration only in WAT (p < 0.05). On the other hand, both Pparγ and Ucp1 expressions were diminished in WAT and BAT (p < 0.01) by DDT treatment, while in WAT, DDE significantly decreased Pparγ expression without altering its expression in BAT (p < 0.001). Ucp3 and irisin levels in skeletal muscle were not altered. Our findings show that both DDT and DDE reduce the browning of WAT by suppressing white adipocytes and thus may have obesogenic activity in male rats without altering thermoregulation. In addition, HCB, DDT and DDE-induced alterations in expression of Pparγ and Ucp1 in WAT implicates differential regulation of adipogenic processes.

Fenchone Derivatives as a Novel Class of CB2 Selective Ligands: Design, Synthesis, X-ray Structure and Therapeutic Potential.

A series of novel cannabinoid-type derivatives were synthesized by the coupling of (1S,4R)-(+) and (1R,4S)-(-)-fenchones with various resorcinols/phenols. The fenchone-resorcinol derivatives were fluorinated using Selectfluor and demethylated using sodium ethanethiolate in dimethylformamide (DMF). The absolute configurations of four compounds were determined by X-ray single crystal diffraction. The fenchone-resorcinol analogs possessed high affinity and selectivity for the CB2 cannabinoid receptor. One of the analogues synthesized, 2-(2',6'-dimethoxy-4'-(2″-methyloctan-2″-yl)phenyl)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol (1d), had a high affinity (Ki = 3.51 nM) and selectivity for the human CB2 receptor (hCB2). In the [35S]GTPγS binding assay, our lead compound was found to be a highly potent and efficacious hCB2 receptor agonist (EC50 = 2.59 nM, E(max) = 89.6%). Two of the fenchone derivatives were found to possess anti-inflammatory and analgesic properties. Molecular-modeling studies elucidated the binding interactions of 1d within the CB2 binding site.

Three for the Price of One: Concomitant I⋯N, I⋯O, and I⋯π Halogen Bonds in the Same Crystal Structure.

The ditopic molecule 3-(1,3,5-trimethyl-1H-4-pyrazolyl)pentane-2,4-dione (HacacMePz) combines two different Lewis basic sites. It forms a crystalline adduct with the popular halogen bond (XB) donor 2,3,5,6-tetrafluoro-1,4-diiodobenzene (TFDIB) with a HacacMePz:TFDIB ratio of 2:3. In a simplified picture, the topology of the adduct corresponds to a hcb net. In addition to the expected acetylacetone keto O and pyrazole N acceptor sites, a third and less common short contact to a TFDIB iodine is observed: The acceptor site is again the most electron-rich site of the pyrazole π-system. This iminic N atom is thus engaged as the acceptor in two orthogonal halogen bonds. Evaluation of the geometric results and of a single-point calculation agree with respect to the strength of the intermolecular contacts: The conventional N⋯I XB is the shortest (2.909(4) Å) and associated with the highest electron density (0.150 eÅ-3) in the bond critical point (BCP), followed by the O⋯I contact (2.929(3) Å, 0.109 eÅ-3), and the π contact (3.2157(3) Å, 0.075 eÅ-3). If one accepts the idea of deducing interaction energies from energy densities at the BCP, the short contacts also follow this sequence. Two more criteria identify the short N⋯I contact as the most relevant: The associated C-I bond is significantly longer than the database average, and it is the only intermolecular interaction with a negative total energy density in the BCP.

N-[1,3-Dialkyl(aryl)-2-oxoimidazolidin-4-ylidene]-aryl(alkyl)sulphonamides as Novel Selective Human Cannabinoid Type 2 Receptor (hCB2R) Ligands; Insights into the Mechanism of Receptor Activation/Deactivation.

Cannabinoid type 1 (hCB1) and type 2 (hCB2) receptors are pleiotropic and crucial targets whose signaling contributes to physiological homeostasis and its restoration after injury. Being predominantly expressed in peripheral tissues, hCB2R represents a safer therapeutic target than hCB1R, which is highly expressed in the brain, where it regulates processes related to cognition, memory, and motor control. The development of hCB2R ligands represents a therapeutic opportunity for treating diseases such as pain, inflammation and cancer. Identifying new selective scaffolds for cannabinoids and determining the structural determinants responsible for agonism and antagonism are priorities in drug design. In this work, a series of N-[1,3-dialkyl(aryl)-2-oxoimidazolidin-4-ylidene]-aryl(alkyl)sulfonamides is designed and synthesized and their affinity for human hCB1R and hCB2R is determined. Starting with a scaffold selected from the NIH Psychoactive Drug Screening Program Repository, through a combination of molecular modeling and structure-activity relationship studies, we were able to identify the chemical features leading to finely tuned hCB2R selectivity. In addition, an in silico model capable of predicting the functional activity of hCB2R ligands was proposed and validated. The proposed receptor activation/deactivation model enabled the identification of four pure hCB2R-selective agonists that can be used as a starting point for the development of more potent ligands.

Interactions among thyroid hormones and serum lipid levels in association with PCB exposure in the Mohawk Akwesasne population.

Alterations in thyroid function and serum lipid levels were assessed in relation to exposure to polychlorinated biphenyls (PCBs) and three chlorinated pesticides (DDE, hexachorobenzene and mirex) in a sample of Akwesasne Mohawk adults. This population is highly exposed to PCBs because of living in close proximity to three aluminum foundries that used PCBs as hydraulic fluids, which then contaminated local fish, wildlife, water, air and soils. The goal was to assess interactions between thyroid function (TSH, T3, T4 and fT4) and serum lipids (cholesterol, triglycerides and total serum lipids) in relation to concentrations of 101 PCB congeners and three chlorinated pesticides. Previous studies in this population have shown that elevated concentrations of PCBs resulted in suppression of thyroid function in adolescents, and increased risk of clinical hypothyroidism in adults, as well as an elevation in serum lipids. However in adjusted analyses of PCB concentrations of 703 adults we find only small and inconsistent associations between serum PCB levels and thyroid function. The most striking observations were strong significant positive associations between TSH and T3 with serum lipids and a negative association with fT4 in women. Because elevated serum lipids increase risks of other diseases the respective roles of thyroid hormones and PCBs in regulation of serum lipids requires additional study.

Neurobehavioural and cognitive effects of prenatal exposure to organochlorine compounds in three year old children.

BACKGROUND: We report data of a Belgian observational prospective cohort study regarding cognitive and behavioural development until the age of 36 months in relation to internal exposure to organochlorine pollutants [sum of polychlorinated biphenyls (sum PCB), dioxin-like activity, PCB118, PCB170, hexachlorobenzene (HCB) and p,p'-dichlorodiphenyldichloroethylene (DDE)] measured in cord blood. METHODS: Participants were recruited as part of an Flemish Environmental Health Survey (2002-2006). Two hundred and six mother-child pairs were recruited. Hundred twenty five toddlers [Reynell Taal Ontwikkelings Schalen (language development, RTOS), Snijders-Oomen Niet-verbale intelligentietest (non-verbal intelligence, SON), Bayley Scales, milestones, Infant Behaviour Questionnaire (IBQ), gender specific play behaviour, Neurobehavioral Evaluation System (NES)-attentional task] and their mothers [Home Observation Measurement of the Environment (HOME), Wechsler Abbreviated Scale of Intelligence (WASI), State-Trait Anxiety Inventory (STAI), general questionnaires] were tested. Statistical analysis was performed with the SPSS program. Much attention was paid to confounding factors. RESULTS: In the first years of development, higher organochlorine pollutants were associated with less active children (delayed crawling: sum PCB*HCB (p < 0.05), sumPCB*DDE (p < 0.1); delayed first steps alone: sum PCB (p < 0.5), PCB118 (p < 0.01), PCB170 (p < 0.01), HCB (p < 0.01); less switching between toys: sum PCB (p < 0.01); less switching between toys in boys: PCB118 (p < 0.01), sum PCB(p < 0.01)). At 12 months children with higher dioxin-like activity tended to show less fear responses(p < 0.1) (IBQ 12 months). At 36 months, a slower development of language comprehension (RTOS) was related to all organochlorine exposure parameters(p < 0.1 or p < 0.05) except DDE. Lower nonverbal IQ scores (SON) were related to PCB118 in boys only(p < 0.05 or p < 0.01). Less masculine and more non-gender specific play behaviour was associated with sum PCB in boys and girls at 36 months(p < 0.1). Moreover, PCB118 (p < 0.05), PCB170 (p < 0.1), HCB(p < 0.05) and DDE(p < 0.05) were associated with diminished masculine play behaviour in boys. CONCLUSION: Our data confirm the observations that neurobehavioral development of young children is adversely influenced by environmental concentrations of PCBs, especially in boys. In this context, observation of play behaviour seems to be a reliable, easy to perform and sensitive test to detect neurotoxic effects of chemicals like PCB's and dioxin-like compounds in very young children. On the basis of our results, we hypothesize that an underarrousal pattern may play a role in the spectrum of effects measured in toddlers prenatally exposed to PCBs and dioxin-like compounds.

Multi-Person Tracking and Crowd Behavior Detection via Particles Gradient Motion Descriptor and Improved Entropy Classifier.

To prevent disasters and to control and supervise crowds, automated video surveillance has become indispensable. In today's complex and crowded environments, manual surveillance and monitoring systems are inefficient, labor intensive, and unwieldy. Automated video surveillance systems offer promising solutions, but challenges remain. One of the major challenges is the extraction of true foregrounds of pixels representing humans only. Furthermore, to accurately understand and interpret crowd behavior, human crowd behavior (HCB) systems require robust feature extraction methods, along with powerful and reliable decision-making classifiers. In this paper, we describe our approach to these issues by presenting a novel Particles Force Model for multi-person tracking, a vigorous fusion of global and local descriptors, along with a robust improved entropy classifier for detecting and interpreting crowd behavior. In the proposed model, necessary preprocessing steps are followed by the application of a first distance algorithm for the removal of background clutter; true-foreground elements are then extracted via a Particles Force Model. The detected human forms are then counted by labeling and performing cluster estimation, using a K-nearest neighbors search algorithm. After that, the location of all the human silhouettes is fixed and, using the Jaccard similarity index and normalized cross-correlation as a cost function, multi-person tracking is performed. For HCB detection, we introduced human crowd contour extraction as a global feature and a particles gradient motion (PGD) descriptor, along with geometrical and speeded up robust features (SURF) for local features. After features were extracted, we applied bat optimization for optimal features, which also works as a pre-classifier. Finally, we introduced a robust improved entropy classifier for decision making and automated crowd behavior detection in smart surveillance systems. We evaluated the performance of our proposed system on a publicly available benchmark PETS2009 and UMN dataset. Experimental results show that our system performed better compared to existing well-known state-of-the-art methods by achieving higher accuracy rates. The proposed system can be deployed to great benefit in numerous public places, such as airports, shopping malls, city centers, and train stations to control, supervise, and protect crowds.

Hepatoprotective effects of vitamin E against hexachlorobenzene-induced hepatotoxicity and oxidative stress in rats: histological, biochimical and antioxidant status changes.

The protective effects of α-Tocopherol (vitamin E) on liver injury induced by hexachlorobenzene (HCB) were investigated in adult male rats of Wistar strain. Animals were randomly divided into six groups of eight rats each. Group 1 and 2 have received HCB, dissolved in olive oil, at a dose of 4 mg or 16 mg/kg b.w., respectively. Group 3 and 4 were treated by the same doses of HCB (4 mg and 16 mg/kg b.w.) after 1 h of pretreatment with α-tocopherol at a dose of 100 mg kg-1 b.w. The other two groups served as controls; which received either olive oil only, a solvent of HCB, or α-tocopherol. A significant increase in hepatic lipid peroxidation (LPO) and GSH activity were observed following HCB administration. The activities of antioxidant enzymes like superoxide dismutase and catalase were significantly decreased while glutathione peroxidase was significantly increased following HCB administration. Similarly, a significant increase in plasma levels of various marker enzymes [aminotransferase (aspartate aminotransférase (AST) and alanine aminotransferase (ALT)), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH)] and a decrease of total protein level were observed. Pretreatment with vitamin E of HCB treated rats ameliorated all biochemical parameters to near normal values. Liver histological study confirmed biochemical parameters and the beneficial role of vitamin E.

Persistent organic pollutants as predictors of increased FSH:LH ratio in naturally cycling, reproductive age women.

Although several recent studies suggest endocrine disrupting compounds, such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p', DDE), and hexachlorobenzene (HCB), target different organs and systems in the body, their impact on female reproductive function in humans is not well characterized. We seek to determine the relationship between several known endocrine disrupting compounds and a marker of ovarian responsivity, the FSH:LH ratio (higher ratio indicates less ovarian responsivity). For this analysis, 169 naturally cycling women between 21 and 38 years of age completed interviews and had their blood drawn on day 3 of their menstrual cycle for analyses of toxicants, gonadal sex hormones (E2 and P4), and gonadotropins (FSH and LH). PCB congeners were classified into five groups based on their environmental persistence, distribution in human tissue, and toxicological action, reflecting the structure, mechanism, and known biological activity of individual PCB congeners. For every unit (ppb) increase in the level of the estrogenic PCB group, there was a 5-fold greater risk of a FSH:LH ratio ≥ 2, controlling for individual differences in age, percent body fat, cycle day 3 estradiol levels, parity, alcohol use and cigarette smoking in the past year (exp[ß] = 5; p = ≤0.01). PCB congeners identified as estrogenic were analyzed individually, and, of the 19 potentially estrogenic congeners, five were significantly, and positively related to an increased FSH:LH ratio. Four of these congeners are non-persistent, easily volatilize in the environment, and are easily metabolized, and hence, are indicative of very recent or current exposure. p,p'-DDE and HCB were not associated with FSH:LH ratio. We find a clinical indicator of ovarian responsivity, FSH:LH ratio, is associated with a specific group of estrogenic PCBs. These congeners may become airborne when they volatilize from dredged PCB-contaminated soil or from indoor PCB-containing window caulk and sealants in older buildings leading to inhalation exposure. PCB exposure, particularly to non-persistent, estrogenic congeners, may pose an unrecognized threat to female fecundity within the general population.

Identification of the hcb Gene Operon Involved in Catalyzing Aerobic Hexachlorobenzene Dechlorination in Nocardioides sp. Strain PD653.

Nocardioides sp. strain PD653 was the first identified aerobic bacterium capable of mineralizing hexachlorobenzene (HCB). In this study, strain PD653-B2, which was unexpectedly isolated from a subculture of strain PD653, was found to lack the ability to transform HCB or pentachloronitrobenzene into pentachlorophenol. Comparative genome analysis of the two strains revealed that genetic rearrangement had occurred in strain PD653-B2, with a genomic region present in strain PD653 being deleted. In silico analysis allowed three open reading frames within this region to be identified as candidate genes involved in HCB dechlorination. Assays using recombinant Escherichia coli cells revealed that an operon is responsible for both oxidative HCB dechlorination and pentachloronitrobenzene denitration. The metabolite pentachlorophenol was detected in the cultures produced in the E. coli assays. Significantly less HCB-degrading activity occurred in assays under oxygen-limited conditions ([O2] < 0.5 mg liter-1) than under aerobic assays, suggesting that monooxygenase is involved in the reaction. In this operon, hcbA1 was found to encode a monooxygenase involved in HCB dechlorination. This monooxygenase may form a complex with the flavin reductase encoded by hcbA3, increasing the HCB-degrading activity of PD653.IMPORTANCE The organochlorine fungicide HCB is widely distributed in the environment. Bioremediation can effectively remove HCB from contaminated sites, but HCB-degrading microorganisms have been isolated in few studies and the genes involved in HCB degradation have not been identified. In this study, possible genes involved in the initial step of the mineralization of HCB by Nocardioides sp. strain PD653 were identified. The results improve our understanding of the protein families involved in the dechlorination of HCB to give pentachlorophenol.

Prediagnostic plasma concentrations of organochlorines and risk of B-cell non-Hodgkin lymphoma in envirogenomarkers: a nested case-control study.

BACKGROUND: Evidence suggests a largely environmental component to non-Hodgkin's lymphoma (NHL). Persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs), DDE and HCB have been repeatedly implicated, but the literature is inconsistent and a causal relationship remains to be determined. METHODS: The EnviroGenoMarkers study is nested within two prospective cohorts EPIC-Italy and the Northern Sweden Health and Disease Study. Six PCB congeners, DDE and HCB were measured in blood plasma samples provided at recruitment using gas-chromatography mass spectrometry. During 16 years follow-up 270 incident cases of B-cell NHL (including 76 cases of multiple myeloma) were diagnosed. Cases were matched to 270 healthy controls by centre, age, gender and date of blood collection. Cases were categorised into ordered quartiles of exposure for each POP based on the distribution of exposure in the control population. Logistic regression was applied to assess the association with risk, multivariate and stratified analyses were performed to identify confounders or effect modifiers. RESULTS: The exposures displayed a strong degree of correlation, particularly amongst those PCBs with similar degrees of chlorination. There was no significant difference (p < 0.05) in median exposure levels between cases and controls for any of the investigated exposures. However under a multivariate model PCB138, PCB153, HCB and DDE displayed significant inverse trends (Wald test p-value <0.05). Under stratified analyses these were determined to be driven by males and by the Diffuse Large B-Cell Lymphoma subtype. When considering those in the highest levels of exposure (>90th percentile) the association was null for all POPs CONCLUSION: We report no evidence that a higher body burden of PCBs, DDE or HCB increased the risk of subsequent NHL diagnosis. Significantly inverse associations were noted for males with a number of the investigated POPs. We hypothesize these unexpected relationships may relate to the subtype composition of our population, effect modification by BMI or other unmeasured confounding. This study provides no additional support for the previously observed role of PCBs, DDE and HCB as risk factors for NHL.

Endocrine disrupting chemicals and ovulation: Is there a relationship?

Although the potential for endocrine disrupting chemicals (EDCs) to disrupt female fecundity is great, few studies have assessed the threat to human reproduction. This study investigates levels of organochlorines in relation to their impact on women's menstrual cycles and ovulatory status. To address concerns of the Akwesasne Mohawk community in upstate New York regarding well-established exposure to EDCs, women's fertility and reproductive health endpoints, we recruited 215 women between the ages of 21 and 38 years to measure menstrual cycle characteristics and levels of local pollutants. Of these, 155 women collected saliva over the course of their menstrual cycle allowing for analysis of estradiol and progesterone levels and the determination of ovulatory status in relationship to their serum pollutant levels. A subset of participants (15) who did not commence cycling within a month of their enrollment were not included in the analysis, hence reducing the sample size to 140 participants. Additionally, a lipid panel, estradiol and progesterone were assessed in serum on Day 3 of the menstrual cycle. Median cycle length for women in the sample was 29 days. After aligning the cycles, 110 women were considered ovulatory and 45 (29%) anovulatory. Concentrations of groups of more persistent PCBs congeners, HCB, and p,p'-DDE did not differ significantly with ovulatory status. However, a sub-group of low-chlorinated PCB congeners, considered to be estrogenic were significantly higher among anovulatory women. These findings suggest that certain EDC's, ubiquitous in our environment, may adversely affect menstrual cycles and thus have the capacity to impair reproductive function, including likelihood of conception.

Bioaccumulation of organohalogenated compounds in sharks and rays from the southeastern USA.

Organohalogenated compounds are widespread in the marine environment and can be a serious threat to organisms in all levels of aquatic food webs, including elasmobranch species. Information about the concentrations of POPs (persistent organic pollutants) and of MeO-PBDEs (methoxylated polybrominated diphenyl ethers) in elasmobranchs is scarce and potential toxic effects are poorly understood. The aims of the present study were therefore to investigate the occurrence of multiple POP classes (PCBs, PBDEs, DDXs, HCB, CHLs) and of MeO-PBDEs in various elasmobranch species from different trophic levels in estuarine and marine waters of the southeastern United States. Overall, levels and patterns of PCBs, PBDEs, DDXs, HCB, CHLs and of MeO-PBDEs varied according to the species, maturity stage, gender and habitat type. The lowest levels of POPs were found in Atlantic stingrays and the highest levels were found in bull sharks. As both species are respectively near the bottom and at top of the trophic web, with juvenile bull sharks frequently feeding on Atlantic stingrays, these findings further suggest a bioaccumulation and biomagnification process with trophic position. MeO-PBDEs were not detected in Atlantic stingrays, but were found in all shark species. HCB was not found in Atlantic stingrays, bonnetheads or lemon sharks, but was detected in the majority of bull sharks examined. Comparison with previous studies suggests that Atlantic stingrays may be experiencing toxic effects of PCBs and DDXs on their immune system. However, the effect of these compounds on the health of shark species remains unclear.

Changes in persistent organic pollutant levels from adolescence to young adulthood.

Elimination rates and their corresponding half-lives are conceptually important and intuitively accessible pharmacokinetic measures of toxicant elimination, but regression-based estimates are biased proportional to the degree of continuing (background) exposure. We propose an alternative estimator, the censored normal regression model, which uses all observations, but treats individuals whose initial level failed to exceed their follow-up level as censored observations to weight the regression estimates from those that declined between blood draws. In this manner, we derive the intrinsic elimination rate, the elimination rate free from ongoing exposure, as a parameter in a regression with an unobserved, latent dependent variable. We utilize sequential measurements of persistent organic pollutants (POPs) levels from adolescence to adulthood, a period of intense change in size and body composition, to quantify individual-level change within a community exposed to significant quantities of contaminants over an extended period of time. Although much research has been conducted on effects of POPs, far less attention has been given to vectors of intake and changes in toxicant levels during the life course. We apply exploratory factor analysis (EFA) to types and timing of consumption, along with physical behavioral characteristics, to identify a structure of seven underlying factors. Although several variables show factorial complexity, the latent constructs included an age/maturation and period-related factor, a nutritional composite, consumption prior to pregnancy, fish and fowl consumed during pregnancy, factors distinguishing body mass and weight from height, and bottom-feeding fish consumption. Unadjusted and adjusted half-lives using the censored normal regression estimator, as well as estimated half-lives from conventional log concentration regressions, are reported for PCB groupings, specific congeners, p,p'-DDE, and HCB.

Hexachlorobenzene and omega-3 fatty acid intake from traditional foods in the northern Yukon: A risk and benefit analysis.

A human biomonitoring study was conducted in the community of Old Crow, Yukon, in 2019, finding that levels of hexachlorobenzene (HCB) in plasma were elevated in the community relative to the general Canadian population. The aim of this study was to estimate dietary intake of both hexachlorobenzene, and the nutrient omega-3 fatty acids from locally harvested traditional foods in Old Crow, with the aim of identifying possible regional sources of exposure. A stochastic model was constructed to estimate intake of both hexachlorobenzene and the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Average predicted hexachlorobenzene exposure levels from traditional food consumption in Old Crow were below the tolerable daily intake of 1600-1700 ng/kg body weight/day in both average (18 ng/kg body weight/day) and short-term maximum (27 ng/kg body weight/day) exposure models. The primary contributors to average hexachlorobenzene intake were caribou fat, bone marrow, ribs, and kidneys, and Chinook salmon muscle. Average estimated dietary EPA + DHA intake levels from traditional foods were below the recommendation of 2.1 to 3.2 g of EPA + DHA per week in the average (1.6 g/week) exposure model, but above this recommendation in the short-term maximum model (3.3 g/week). The primary contributors to average EPA + DHA intake were the meat of Chinook, coho, and, chum salmon muscle, and whitefish muscle and eggs. The results of this study support the message that traditional foods continue to be an important source of nutrients and other health benefits and that the health benefits of traditional foods generally outweigh contaminant risks.

Back on top: Resuspended by dredging and other environmental disturbances, organochlorine compounds may affect the health of a dolphin population in a tropical estuary, Sepetiba Bay.

Organochlorine compounds (OCs) are persistent organic pollutants linked to damaging the immune and endocrine systems, leading to a greater susceptibility to infectious diseases at high concentrations. Sepetiba Bay, in the Southeastern Brazilian coast, historically presents anthropogenic activities and environmental contamination that could negatively impact resident populations. In this context, this study aimed to investigate the temporal trends in the accumulation of organochlorine compounds over a 12-year database in the Guiana dolphins' (Sotalia guianensis) resident population from Sepetiba Bay, including individuals collected before, during, and after an unusual mortality event triggered by morbillivirus (n = 85). The influence of biological parameters was also evaluated. The OCs concentrations in the blubber ranged from 0.98 to 739 µg/g of ΣPCB; 0.08-130 µg/g of ΣDDT; <0.002-4.56 µg/g of mirex; <0.002-1.84 µg/g of ΣHCH and <0.001-0.16 µg/g of HCB in lipid weight. Increased temporal trends were found for OCs in Guiana dolphins coinciding with periods of large events of dredging in the region. In this way, our findings suggest that the constant high OCs concentrations throughout the years in this Guiana dolphin population are a result of the constant environmental disturbance in the area, such as dredging. These elevated OCs levels, e.g., ΣPCB concentrations found above the known thresholds, may impair the response of the immune system during outbreak periods, which could lead the population to a progressive decline.

Nanoparticles for Mitigation of Harmful Cyanobacterial Blooms.

With the rapid advancement of nanotechnology and its widespread applications, increasing amounts of manufactured and natural nanoparticles (NPs) have been tested for their potential utilization in treating harmful cyanobacterial blooms (HCBs). NPs can be used as a photocatalyst, algaecide, adsorbent, flocculant, or coagulant. The primary mechanisms explored for NPs to mitigate HCBs include photocatalysis, metal ion-induced cytotoxicity, physical disruption of the cell membrane, light-shielding, flocculation/coagulation/sedimentation of cyanobacterial cells, and the removal of phosphorus (P) and cyanotoxins from bloom water by adsorption. As an emerging and promising chemical/physical approach for HCB mitigation, versatile NP-based technologies offer great advantages, such as being environmentally benign, cost-effective, highly efficient, recyclable, and adaptable. The challenges we face include cost reduction, scalability, and impacts on non-target species co-inhabiting in the same environment. Further efforts are required to scale up to real-world operations through developing more efficient, recoverable, reusable, and deployable NP-based lattices or materials that are adaptable to bloom events in different water bodies of different sizes, such as reservoirs, lakes, rivers, and marine environments.