The Seychelles Child Development Study: two decades of collaboration

The Seychelles Child Development Study represents two decades of collaboration between the Ministry of Health of Seychelles, a small island nation in the middle of the Indian Ocean, and the University of Rochester, a renowned academic and research institution in North America. The study has established itself as a model of strong longitudinal epidemiological studies and collaborative research between institutions in developed and developing countries. It has produced significant scientific findings and a large number of publications on the issue of methyl mercury from fish in the maternal diet and child development. This paper provides a background to the study and describes the key strengths of the collaboration. A brief summary of all the publications is also provided.     

汞相关狒狒综合征一例

患者，女，53岁。5天前因打碎温度计于下腹部、臀部出现红斑，脓疱，后皮疹发展至颈部、肘窝、乳房下、腹股沟。既往有红汞过敏史。接触12、20、30天后血汞测定：0.11 mg/L（参考值＜0.03 mg/L）、0.005 mg/L、0.002 mg/L，诊断：狒狒综合征。给予复方甘草酸、依巴斯汀片、盐酸左西替利嗪、盐酸奥洛他定治疗，1周后红斑消退，脓疱干涸，出现大量脱屑。     

Metabolic and psychological effects of short-term increased consumption of less-processed foods in daily diets: A Pilot Study

AimThis study evaluated whether the consumption of locally produced food without additives might have a positive effect on known risk factors for non-communicable diseases (NCDs) such as hypertension, and levels of fasting glucose and visceral adipose tissue (VAT). Attention was focused on various types of cheese, sausages, fresh pasta, pastries, biscuits and chocolate without additives to make them palatable and durable for transport.MethodsHealthy volunteers were randomized to purchase the foods under study from either local producers not using additives (group 1) or supermarkets (group 2). At baseline and after 6 months, both groups underwent evaluation for weight, blood pressure, VAT, serum sodium, potassium, fasting glucose, insulin, C-peptide and creatinine levels, and also the State-Trait Anxiety Inventory (STAI) and Beck Depression Inventory (BDI-II) by examiners blinded to group allocation. At baseline, the state part of the STAI and Wechsler Adult Intelligence Scale IV were also performed, and body mass index, HOMA index and estimated glomerular filtration rate calculated.ResultsData for 159 subjects (89 in group 1, 70 in group 2) were analyzed. Baseline evaluations did not differ between groups. At 6 months, HOMA scores and fasting glucose levels were lower in group 1 than in group 2 (P < 0.01). Also, in group 1, VAT (P = 0.006), systolic blood pressure (P = 0.001) and BDI-II score (P = 0.0005) were decreased, whereas serum fasting glucose (P = 0.04) and C-peptide (P = 0.03) levels, and diastolic blood pressure (P = 0.02), were increased in group 2.ConclusionConsumption of the locally produced food under study improved some of the major risk factors for NCDs after 6 months.     

Congenital Minamata disease: a description of two cases in Niigata

Minamata disease or methyl mercury poisoning from industrial pollution was first described from Minamata, Japan in the 1950s. Subsequently, a similar poisoning episode occurred at Niigata, Japan in the 1960s. This paper describes the Minamata event and then presents two case reports believed to be prenatal poisoning from consumption of contaminated fish at Niigata. Case number one is of special interest because it is the only subject with congenital Minamata disease for whom exposure was actually measured near the time of birth.     

Mercury–DNA interaction based detection of mercury ions by DNA amplification with high sensitivity and selectivity

An effective and facile approach for mercury detection is essential for environmental protection and human health. In this study, we propose a novel strategy to develop a highly sensitive and selective method for the detection of mercury ions using real-time quantitative polymerase chain reaction (RT-qPCR) technology and the specific binding of Hg²⁺ in thymine–thymine mismatch complexes. The signal for detection of Hg²⁺ was generated using RT-qPCR amplification of a template strand of DNA. The sensor exhibited an excellent linear response between the cycle threshold (Ct) and mercury ion concentration in the range of 0.05–100 nM. Under optimised conditions, the detection limit of this method for aqueous Hg²⁺ was as low as 30 pM. In addition, this system showed good selectivity for Hg²⁺ over other metal ions. This new approach shows significant potential for detection of Hg²⁺ in water and other samples.     

Medico legal aspects of self-injection of metallic mercury in cases of suicide or self-harming

Metallic mercury may be self-injected for suicidal or self-harm purposes or sometimes for superstitious or other inadvisable reasons. Local tissue or systemic consequences such as mercurialism can frequently occur in cases of subcutaneous or deep injection, while death due to pulmonary embolism and cardiac, brain, hepatic or renal toxicity may occur in cases of high dosage intravenous administration.The aim of this review is to focus on the diagnostic difficulties facing coroners and forensic pathologists when the courts require confirmation that evidence of self-injection of metallic mercury is the result of suicide or self-harming. Forensic examination performed on the corpses of victims who died in or out of hospital or on surviving injured or intoxicated victims showing signs of mercurialism, demands the careful evaluation of the death scene, of all related circumstances and of the clinical and autopsy data. Close interaction between forensic pathologists and toxicologists is also needed to identify and quantify mercury levels in blood, urine and tissue.     

Inhalation of mercury vapor can cause the toxic effects on rat kidney

Dental amalgam has been used in dentistry as a filling material. The filler comprises mercury (Hg). It is considered one of the most important and widespread environmental pollutants, which poses a serious potential threat for the humans and animals. However, mercury deposition affects the nervous, cardiovascular, pulmonary, gastrointestinal, and especially renal systems. In most animals’ species and humans, the kidney is one of the main sites of deposition of mercury and target organ for its toxicity. In this study, the effects of mercury intake on kidney in rats were searched. For the this purpose; we used 24 adult female Wistar albino rats (200?g in weight) obtained from Experimental Research and Application Center of Atatürk University with ethical approval. Besides, they were placed into a specially designed glass cage. Along this experiment for 45 days, subjects were exposed to (1?mg/m³/day) mercury vapor. However, no application was used for the control subjects. At the end of the experiment, kidney samples were obtained from all subjects and processed for routine light microscopic level and stereological aspect were assessed. Finally, according to our results, mercury affects the histological features of the kidney. That means, the severe effects of mercury has been shown using stereological approach, which is one of the ideal quantitative methods in the current literature. In this study, it was detected that chronic exposure to mercury vapor may lead to renal damage and diseases in an experimental rat model.     

蒙古族药孟根乌苏（水银）燥“协日乌素”功效的免疫调节机制研究进展

蒙古族药（以下简称蒙药）中燥“协日乌素”药物孟根乌苏（水银）对于自身免疫性疾病，如类风湿性关节炎、牛皮癣等具有显著的疗效。目前，多从镇惊安神功效方面对汞进行药效和毒性研究，对其免疫调节机制研究较少。综述了蒙药孟根乌苏治疗自身免疫性疾病相关报道，并梳理汞对机体的免疫调节作用及汞的形态、摄入剂量对其免疫机制的影响，进而探讨汞的形态演化过程及其可能的自身免疫调节机制，为蒙药“孟根乌苏”药效机制提出合理的解释，为蒙药新剂型的开发提供参考。     

Photochemistry of oxidized Hg(I) and Hg(II) species suggests missing mercury oxidation in the troposphere

Mercury (Hg), a global contaminant, is emitted mainly in its elemental form Hg⁰ to the atmosphere where it is oxidized to reactive Hg^II compounds, which efficiently deposit to surface ecosystems. Therefore, the chemical cycling between the elemental and oxidized Hg forms in the atmosphere determines the scale and geographical pattern of global Hg deposition. Recent advances in the photochemistry of gas-phase oxidized Hg^I and Hg^II species postulate their photodissociation back to Hg⁰ as a crucial step in the atmospheric Hg redox cycle. However, the significance of these photodissociation mechanisms on atmospheric Hg chemistry, lifetime, and surface deposition remains uncertain. Here we implement a comprehensive and quantitative mechanism of the photochemical and thermal atmospheric reactions between Hg⁰, Hg^I, and Hg^II species in a global model and evaluate the results against atmospheric Hg observations. We find that the photochemistry of Hg^I and Hg^II leads to insufficient Hg oxidation globally. The combined efficient photoreduction of Hg^I and Hg^II to Hg⁰ competes with thermal oxidation of Hg⁰, resulting in a large model overestimation of 99% of measured Hg⁰ and underestimation of 51% of oxidized Hg and ∼66% of Hg^II wet deposition. This in turn leads to a significant increase in the calculated global atmospheric Hg lifetime of 20 mo, which is unrealistically longer than the 3–6-mo range based on observed atmospheric Hg variability. These results show that the Hg^I and Hg^II photoreduction processes largely offset the efficiency of bromine-initiated Hg⁰ oxidation and reveal missing Hg oxidation processes in the troposphere.

Annually, about 8 Gg of mercury (Hg) are released to the atmosphere from present-day anthropogenic (∼39%) and natural (∼6%) sources, and reemissions of previously deposited Hg from natural and anthropogenic sources (∼55%) (1). The average concentration of Hg in the atmosphere is relatively low, in the range of 1–2 ng/m³ (equivalent to ∼100–200 parts per quadrillion mixing ratio). Earth’s atmosphere is therefore a minor Hg reservoir of ∼5 Gg, compared with terrestrial soil and marine Hg pools (1,450 and 280 Gg, respectively) (2). However, the atmosphere is a key component of the global Hg cycle because it facilitates the planetwide dispersion of the metal. This global dynamic is governed by a complex combination of emissions, atmospheric chemical processing, transport, and surface deposition (3, 4). In the atmosphere, Hg cycles between elemental Hg⁰ and oxidized monovalent Hg^I and divalent Hg^II forms (5, 6). Oxidation mechanisms of atmospheric Hg have been reviewed several times [e.g., Si and Ariya, 2018 (7) and references therein]. The current view is that the slow gas-phase oxidation of Hg⁰ by hydroxyl radical (OH) (8) and ozone (O₃) is frequently complemented or replaced by the much more efficient oxidation by atomic bromine (Br) (9, 10). Although the knowledge of the amount and distribution of tropospheric Br has improved during the last decade (11, 12), more measurements of tropospheric Br concentrations and their spatial distribution are sorely needed to reduce uncertainty in atmospheric kinetic and transport models of Hg oxidation based on Br chemistry.Mercury is released to the atmosphere mostly as gaseous elemental Hg⁰, which is currently assumed to be oxidized to Hg^II by a two-step mechanism (6, 9, 10, 13). The first step is initiated by photochemically produced Br atoms to form HgBr, a radical Hg^I intermediate that can then photolytically or thermally decompose back to Hg⁰, or be further oxidized to Hg^II compounds by atmospheric radicals such as NO₂, HO₂, Br, OH, I, Cl, BrO, ClO, and IO (6, 9, 13, 14). Based on this scheme, and despite Br being a minor atmospheric constituent, Holmes et al. (14) proposed that Hg⁰ oxidation by Br is potentially the dominant oxidation pathway at a global scale. Field and model studies have reported evidence of the Br-initiated oxidation over different environments where Br chemistry is active and relatively abundant such as the polar regions [e.g., ref. (15)], salt lakes [e.g., ref. (16)], tropical marine boundary layer (13) and free troposphere (17). Several models, however, still consider Hg⁰ oxidation by O₃ and OH as the main pathway (18, 19), particularly in the continental atmosphere.Once oxidized, gaseous Hg^II species are more water soluble and particle reactive, and eventually partition into aerosols and clouds, before efficient deposition to the Earth’s surface by wet and dry deposition processes. Recent theoretical work has shown that divalent (Hg^II: syn-HgBrONO, anti-HgBrONO, HgBrOOH, HgBrOH, HgBrNO₂, HgBr₂, HgCl₂, HgBrOCl, HgBrI, HgBrOBr, HgBrOI) (20) and monovalent (Hg^I: HgBr, HgCl, HgOH, HgI) (21) species strongly absorb ultraviolet-visible light. Therefore, daytime solar radiation leads to efficient gas-phase photolysis, which can dominate Hg^I and Hg^II reduction in the atmosphere and shorten the lifetime of oxidized Hg species compared to previous reaction schemes where Hg reduction was restricted to the aqueous cloud phase (6). Experimental evidence of photoreduction of oxidized Hg has been reported from observations on the remote Tibetan Plateau (22) and in urban air (23). The rapid photodissociation of syn-HgBrONO has been suggested to produce the HgBrO radical, which upon reaction with volatile organic compounds swiftly forms HgBrOH (24). Finally, a recent computational study has reported quantitative photodissociation channels and photoproducts of the likely major gaseous oxidized Hg^II compounds (syn-HgBrONO, HgBrOOH, HgBrO, and HgBrOH), and constructed a quantitative mechanism of the photochemical and thermal conversion between Hg⁰, Hg^I, and Hg^II species in the atmosphere (25).These recent theoretical works suggest that gas-phase photodissociation of oxidized Hg^I,II is a key process in the global atmospheric cycling of this metal. However, the influence of these combined new photochemical mechanisms on the redox chemistry, lifetime, and surface deposition of Hg in the global atmosphere is currently unknown. Here, a state-of-the-art global Hg chemical transport model is used to evaluate the impact of the recently proposed Hg photoreduction mechanisms against atmospheric Hg measurements. The evaluation includes the different photodissociation processes for Hg^I and Hg^II, and their impact on atmospheric Hg concentrations and surface deposition patterns, lifetime, and vertical profiles in the troposphere.     

仿生提取-高效液相色谱-电感耦合等离子体质谱技术测定冰硼散及朱砂药材中可溶性汞的含量

目的： 建立仿生提取-高效液相色谱-电感耦合等离子体质谱技术测定冰硼散及朱砂药材中可溶性汞含量的分析方法，可用于研究冰硼散及朱砂药材的用药安全性。方法： 通过模拟人体胃肠道环境，采用人工胃液提取冰硼散及朱砂中的可溶性汞，结合高效液相色谱（以十八烷基硅烷键合硅胶为填充剂；8%甲醇-0.06 mol·L^-1乙酸铵-0.05% 2-巯基乙醇的水溶液为流动相；流速0.4 mL·min^-1；进样体积20 μL）-电感耦合等离子体质谱技术进行分析测定。结果： 通过检测15批冰硼散样品及9批朱砂药材，结果甲基汞、乙基汞、无机汞分别在0.0007~0.28、0.007~1.4、0.17~34 ng·mL^-1范围内，浓度与峰面积呈良好的线性关系，r值分别为0.9997、0.9995、0.9998，平均回收率分别为96.8%、99.7%、98.0%，RSD分别为2.3%、2.8%、5.5%（n=6）。冰硼散中甲基汞含量为0.00046~0.018 mg·kg^-1，无机汞含量为0.64~4.73 mg·kg^-1，乙基汞含量为0.075~0.096 mg·kg^-1；朱砂中甲基汞含量为0~0.034 mg·kg^-1，无机汞含量为8.54~101.07 mg·kg^-1，乙基汞含量为0~0.82 mg·kg^-1。结论： 该方法简便、快速、灵敏，重现性好，可用于冰硼散及朱砂药材中可溶性汞的测定。