Environmental mercury exposure,semen quality and reproductive hormones in Greenlandic Inuit and European men: a cross-sectional study

Several animal studies indicate that mercury is a male reproductive toxicant, but human studies are few and contradictory. We examined semen characteristics and serum levels of reproductive hormones in relation to environmental exposure to mercury. Blood and semen samples were collected from 529 male partners of pregnant women living in Greenland, Poland and Ukraine between May 2002 and February 2004. The median concentration of the total content of mercury in whole blood was 9.2 ng ml⁻¹ in Greenland (0.2–385.8 ng ml⁻¹), 1.0 ng ml⁻¹ in Poland (0.2–6.4 ng ml⁻¹) and 1.0 ng ml⁻¹ in Ukraine (0.2–4.9 ng ml⁻¹). We found a significantly positive association between the blood levels of mercury and serum concentration of inhibin B in men from Greenland (β=0.074, 95% confidence interval (CI)=0.021 to 0.126) and in an analysis including men from all three regions (β=0.067, 95% CI=0.024 to 0.110). The association may be due to beneficial effects of polyunsaturated fatty acids (PUFAs), which are contained in seafood and fish. No significant association (P>0.05) was found between blood concentrations of mercury and any of the other measured semen characteristics (semen volume, total sperm count, sperm concentration, morphology and motility) and reproductive hormones (free androgen index (FAI), follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone and LH×testosterone) in any region. In conclusion, the findings do not provide evidence that environmental mercury exposure in Greenlandic and European men with median whole blood concentration up to 10 ng ml⁻¹ has adverse effects on biomarkers of male reproductive health.     

Short‐term environmental enrichment,in the absence of exercise,improves memory,and increases NGF concentration,early neuronal survival,and synaptogenesis in the dentate gyrus in a time‐dependent manner

Environmental manipulations can enhance neuroplasticity in the brain, with enrichment‐induced cognitive improvements being linked to increased expression of growth factors, such as neurotrophins, and enhanced hippocampal neurogenesis. There is, however, a great deal of variation in environmental enrichment protocols used in the literature, making it difficult to assess the role of particular aspects of enrichment upon memory and the underlying associated mechanisms. This study sought to evaluate the efficacy of environmental enrichment, in the absence of exercise, as a cognitive enhancer and assess the role of Nerve Growth Factor (NGF), neurogenesis and synaptogenesis in this process. We report that rats housed in an enriched environment for 3 and 6 weeks (wk) displayed improved recognition memory, while rats enriched for 6 wk also displayed improved spatial and working memory. Neurochemical analyses revealed significant increases in NGF concentration and subgranular progenitor cell survival (as measured by BrdU+ nuclei) in the dentate gyrus of rats enriched for 6 wk, suggesting that these cellular changes may mediate the enrichment‐induced memory improvements. Further analysis revealed a significant positive correlation between recognition task performance and BrdU+ nuclei. In addition, rats enriched for 6 wk showed a significant increase in expression of synaptophysin and synapsin I in the dentate gyrus, indicating that environmental enrichment can increase synaptogenesis. These data indicate a time‐dependent cognitive‐enhancing effect of environmental enrichment that is independent of physical activity. These data also support a role for increased concentration of NGF in dentate gyrus, synaptogenesis, and neurogenesis in mediating this effect. © 2013 Wiley Periodicals, Inc.     

Toxicological and ecotoxicological properties of gas-to-liquid (GTL) products. 2. Ecotoxicology

Gas-to-liquid (GTL) products are synthetic hydrocarbons produced from natural gas using a catalytic process known as the Fischer–Tropsch process. This process yields a synthetic crude oil that consists of saturated hydrocarbons which can subsequently be refined to a range of products analogous to those obtained from petroleum refining. However, in contrast to their petroleum-derived analogs, GTL products are essentially free of unsaturated or aromatic compounds and do not contain any sulfur-, oxygen-, or nitrogen-containing compounds. Under new chemical substance notification requirements, an extensive testing program covering the entire portfolio of GTL products has been undertaken to assess their hazardous properties to human health and environment. The results of these studies have been summarized in a two-part review. Part 1 provides an overview of the mammalian toxicity hazardous properties of the various GTL products. This second part of the review focuses on the aquatic, sediment, terrestrial, and avian toxicity studies which assess the ecotoxicological hazard profile of the GTL products. Many challenges were encountered during these tests relating to dosing, analysis and interpretation of results. These are discussed with the intent to share experiences to help inform and shape future regulatory mandates for testing of poorly soluble complex substances. As was the case with the mammalian toxicology review, there were a few cases where adverse effects were found, but overall the GTL products were found to exert minimal adverse ecotoxicological effects and these were less severe than effects observed with their conventional, petroleum-derived analogs.     

Naringenin (4,5,7‐trihydroxyflavanone) suppresses the development of precancerous lesions via controlling hyperproliferation and inflammation in the colon of Wistar rats

Colon cancer is a world‐wide health problem and one of the most dangerous type of cancer, affecting both men and women. Naringenin (4, 5, 7‐trihydroxyflavanone) is one of the major flavone glycoside present in citrus fruits. Naringenin has long been used in Chinese's traditional medicine because of its exceptional pharmacological properties and non‐toxic nature. In the present study, we investigated the chemopreventive potential of Naringenin against 1,2‐dimethyhydrazine (DMH)‐induced precancerous lesions, that is, aberrant crypt foci (ACF) and mucin depleted foci (MDF), and its role in regulating the oxidative stress, inflammation and hyperproliferation, in the colon of Wistar rats. Animals were divided into five groups. In groups 3‐5, Naringenin was administered at the dose of 50 mg/kg b. wt. orally while in groups 2‐4, DMH was administered subcutaneously in the groin at the dose of 20 mg/kg b. wt. once a week for first 5 weeks and animals were euthanized after 10 weeks. Administration of Naringenin ameliorated the development of DMH‐induced lipid peroxidation, ROS formation, precancerous lesions (ACF and MDF) and it also reduced the infiltration of mast cells, suppressed the immunostaining of NF‐κB‐p65, COX‐2, i‐NOS PCNA and Ki 67 Naringenin treatment significantly attenuated the level of TNF‐α and it also prevented the depletion of the mucous layer. Our findings suggest that Naringenin has strong chemopreventive potential against DMH‐induced colon carcinogenesis but further studies are warranted to elucidate the precise mechanism of action of Naringenin.     

外环境中布雷图指数和诱蚊诱卵器指数的差异研究

目的 对外环境布雷图指数法和诱蚊诱卵器法的平行对照研究,比较布雷图指数和诱蚊诱卵器指数的差异,以便明确自然积水对诱蚊诱卵器法监测的影响,为蚊虫及蚊媒传染病防控提供科学依据。方法 2020年5—10月期间每月中旬在上海市静安区各街道（镇）居民区外环境中采用布雷图指数法和诱蚊诱卵器法开展相同区域内的平行对照研究,比较不同监测环境中两监测方法的差异。结果 不同月份中,诱蚊诱卵器指数最高为8月6.86,其次为7月6.74;布雷图指数最高为8月16.24,其次为7月14.56。两监测方法在时间趋势上高度相关（r=0.965,P<0.05）,诱蚊诱卵器指数各月均低于布雷图指数,指数月间分布趋于平缓。诱蚊诱卵器指数老旧公房为5.73,商品房为4.91,差异有统计学意义（Z=12.530,P<0.05）;布雷图指数老旧公房为13.58,商品房为7.14,差异有统计学意义（Z=-4.013,P<0.05）。老旧公房布雷图指数和诱蚊诱卵器指数均高于商品房,老旧公房的布雷图指数为13.58,高于同一地区的诱蚊诱卵器指数5.73,差异有统计学意义（Z=-3.608,P<0.05）。两类型居民区积水构成相近,两类型居民区最多的积水种类依次为盆景、水生植物、闲置容器和储水容器,数量上老旧公房自然积水平均66.43处/居民区,商品房平均49.27处/居民区,随自然积水数量增加,布雷图指数上升。结论 布雷图指数和诱蚊诱卵器指数有较高的一致性,诱蚊诱卵器指数相较于布雷图指数更趋于平缓,不同类型居民区中环境积水数是影响诱蚊诱卵器指数的主要因素,在自然积水较多的环境中,布雷图指数法相较于诱蚊诱卵器指数敏感性更高。     

Validity of geographically modeled environmental exposure estimates

Geographic modeling is increasingly being used to estimate long-term environmental exposures in epidemiologic studies of chronic disease outcomes. However, without validation against measured environmental concentrations, personal exposure levels, or biologic doses, these models cannot be assumed a priori to be accurate. This article discusses three examples of epidemiologic associations involving exposures estimated using geographic modeling, and identifies important issues that affect geographically modeled exposure assessment in these areas. In air pollution epidemiology, geographic models of fine particulate matter levels have frequently been validated against measured environmental levels, but comparisons between ambient and personal exposure levels have shown only moderate correlations. Estimating exposure to magnetic fields by using geographically modeled distances is problematic because the error is larger at short distances, where field levels can vary substantially. Geographic models of environmental exposure to pesticides, including paraquat, have seldom been validated against environmental or personal levels, and validation studies have yielded inconsistent and typically modest results. In general, the exposure misclassification resulting from geographic models of environmental exposures can be differential and can result in bias away from the null even if non-differential. Therefore, geographic exposure models must be rigorously constructed and validated if they are to be relied upon to produce credible scientific results to inform epidemiologic research. To our knowledge, such models have not yet successfully predicted an association between an environmental exposure and a chronic disease outcome that has eventually been established as causal, and may not be capable of doing so in the absence of thorough validation.     

Literature on the aetiology of hypospadias in the last 5 years: molecular mechanism and environmental factors

Year‐by‐year, there has been an increasing number of literature on hypospadias, and most of them are mainly focused on two aspects, namely surgical techniques and aetiology, including the molecular mechanism and associated environmental factors. Surgical techniques and nursing levels are being continuously improved. However, in stark contrast, the study of aetiology still lags behind. Up to now, there is still no consensus on the aetiology of hypospadias, including the molecular mechanism and associated environmental factors. To obtain an overall and latest result on the aetiology, we reviewed published literature regarding the aetiology of hypospadias including the molecular mechanism and associated environmental factors in PubMed in the last 5 years. Thirty‐seven studies on the aetiology of hypospadias including molecular mechanism and associated environmental factors were found, of which 25 were about associated environmental factors, and they were described according to the aspects of chemicals, parental characteristics, nutrition and hormones. The remaining studies were about the hormone‐dependent phase of molecular mechanism, namely androgen‐related genes and oestrogen‐related genes. Furthermore, the various points of view were classified and discussed in detail.     

Approaches and considerations for the assessment of immunotoxicity for environmental chemicals: A workshop summary

As experience is gained with toxicology testing and as new assays and technologies are developed, it is critical for stakeholders to discuss opportunities to advance our overall testing strategies. To facilitate these discussions, a workshop on practices for assessing immunotoxicity for environmental chemicals was held with the goal of sharing perspectives on immunotoxicity testing strategies and experiences, developmental immunotoxicity (DIT), and integrated and alternative approaches to immunotoxicity testing. Experiences across the chemical and pharmaceutical industries suggested that standard toxicity studies, combined with triggered-based testing approaches, represent an effective and efficient approach to evaluate immunotoxic potential. Additionally, discussions on study design, critical windows, and new guideline approaches and experiences identified important factors to consider before initiating DIT evaluations including assay choice and timing and the impact of existing adult data. Participants agreed that integrating endpoints into standard repeat-dose studies should be considered for fulfilling any immunotoxicity testing requirements, while also maximizing information and reducing animal use. Participants also acknowledged that in vitro evaluation of immunosuppression is complex and may require the use of multiple assays that are still being developed. These workshop discussions should contribute to developing an effective but more resource and animal efficient approach for evaluating chemical immunotoxicity.