Human carcinogenesis by arsenic

Arsenic is one of the few human carcinogens for which there is not yet a reliable animal cancer model. As such, the classification of arsenic as a carcinogen is based upon data derived from human epidemiologic studies. Although the mechanisms of action of arsenic as a toxic agent have been known for many years, the inability to produce cancer with arsenic in laboratory animals has confounded the operational characterisation of arsenic as initiator, promoter, complete carcinogen, or cocarcinogen for humans. Arsenic is clearly a genotoxic agent that induces chromosomal aberrations, micronuclei and sister chromatid exchange in mammalian cells as well as neoplastically transforms Syrian hamster embryo cells; however, it is not a classical point mutagen. This paper reviews some of the scientifically based issues relating to arsenic and risk assessment.     

MicroRNAs and their role in environmental chemical carcinogenesis

Environmental Geochemistry and Health - MicroRNAs (miRNAs) are a class of small, noncoding RNA species that play crucial roles across many biological processes and in the pathogenesis of major...     

Chemopreventive role of Indigofera aspalathoides against 20-methylcholanthrene-induced carcinogenesis in mouse

This investigation was undertaken to evaluate the chemopreventive effect of hydroalcoholic extract of Indigofera aspalathoides (HAIA) against 20-methylcholanthrene (20-MC)-induced carcinogenesis in mice. Tumor was induced by single subcutaneous administration of 20-MC (200 µg per mouse) in Swiss albino mice. After 24 h of 20-MC administration, HAIA was administered at the doses of 250 and 500 mg kg^?1 body weight orally for 90 consecutive days. Mice of all groups were observed for 15 weeks to record tumor incidence (fibrosarcoma) and survival time. After 15 weeks the mice were sacrificed for the estimation of hematological profiles like hemoglobin (Hb), white blood cell (WBC), red blood cell (RBC), and liver biochemical parameters, namely lipid peroxidation, reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT). HAIA treatment markedly reduced tumor incidence and prolonged the life span of sarcoma-bearing mice as compared to 20-MC control mice. Hematological profiles were significantly (p < 0.001) restored to normal levels in HAIA-treated mice as compared to 20-MC control mice. HAIA treatment significantly (p < 0.001) modulated the aforesaid liver biochemical parameters as compared to 20-MC control. The results concluded that I. aspalathoides demonstrated a remarkable chemopreventive effect in chemical-induced carcinogenesis in mouse. The potential chemopreventive action may be due to its antioxidant and detoxifying properties.     

Effect of electronic waste on E. coli genomic integrity: a possible role for metal induced carcinogenesis

Electronic waste (e-waste) poses a major public health threat for developing countries’ populations. The hazards of e-waste are exacerbated by crude recycling methods. In this study, the presence of metals in e-waste samples obtained from Lagos, Nigeria, was assessed using atomic absorption spectrometry. The effect of e-waste on Escherichia coli (E. coli) PQ-37 genomic integrity was evaluated using the SOS chromotest. The means of metal concentrations in the evaluated samples were 16 (cadmium), 7.3 (nickel), 11 (chromium), 20 (lead), 3100 (iron), 90 (zinc), and 2000 (copper) μg_L^?1. Damage to E. coli deoxyribonucleic acid (DNA) increased proportionally to the metal concentrations. Significant amounts of DNA damaging agents from inadequately processed e-waste are present in the studied environment, which will have implications for adverse effects on public and ecological health. Existing policies against dumping of toxic materials in susceptible communities should be enforced.     

Effect of gastric fluid on adsorption and desorption of endocrine disrupting chemicals on microplastics

• Effect of gastric fluid on EDCs adsorption-desorption to microplastics was evaluated. • The gastric fluid enhanced desorption of EDCs on the surface of microplastics. • Adsorption and desorption isotherms fitted the Freundlich model well. • Desorption ratios of EE2 (55%–59%) on PVC were larger than that of E2 (49%–55%). • Decrease in pH and increase in ionic strength in gastric fluid strengthen desorption. Microplastics and endocrine disrupting chemicals are emerging pollutants in the marine environment because of their potential hazards. The effect of gastric fluid on the adsorption and desorption of 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) to microplastics was investigated. The adsorption and desorption isotherms of E2/EE2 on microplastics could be well fitted by the Freundlich model while the Gibbs free energy of these processes were negative, proving that the reaction occurred spontaneously on the heterogeneous surface of the microplastics. Desorption ratios of EE2 (55%–59%) on PVC were larger than that of E2 (49%–55%) to indicate that EE2 was less stable in gastric fluid, which could be explained by the fact that the hydrophobicity of EE2 was greater than E2. E2/EE2 were more easily desorbed from PVC in the gastric fluid and the desorption amount (5.25–12.91/7.19–17.86 μg/g) increased by 2.51 times in comparison with that in saline solution (2.22–7.81/2.87–10.80 μg/g). The decrease of pH and the increase of ionic strength in gastric fluid could further strengthen desorption of E2/EE2 from PVC. The promotion of gastric juice on desorption of PVC was achieved by reducing the hydrophobicity of the PVC surface. The desorption rate of E2/EE2 at 18°C and 38°C was respectively 44%–47%/46%–50% and 49%–55%/56%–59%, indicating that PVC loaded with E2/EE2 had a relatively greater risk of releasing pollutants in the gastric fluid of constant temperature marine organisms while higher temperatures exposed higher hazards for variable temperature animals. The interaction between microplastics and pollutants might be mainly hydrophobic interaction.     

Characterisation of secondary metal-bearing phases in used dental amalgam and assessment of gastric solubility

Detailed SEM/EDS investigation of used dental amalgams was carried out in order to characterise morphology and chemical composition of secondary metal-bearing phases resulting from long-term exposure of dental amalgam to oral environment, and assess their solubility in gastric environment. The investigation revealed numerous secondary phases, represented by compositionally and morphologically complex Hg-, Cu-, Sn-, Ag-, Zn-bearing sulphides and oxides/hydroxides, while sulphates and phosphates are scarce. Secondary metal-bearing phases mostly occur at the amalgam/tooth interface; however, some phases were found only on the occlusal surfaces of amalgam. Secondary phases mostly form porous aggregates of minute crystallites and micro- or nanocrystalline crusts. In oral environment, these phases are mostly stable and represent trapping media for dissolved potentially toxic metals released during amalgam corrosion. Simplified PHREEQC calculations of solubility of secondary metal-bearing phases in aqueous environment under conditions similar to those in gastric environment showed that secondary phases are more soluble in gastric environment than in oral solutions, which is mostly due to their forms of occurrence. Secondary phases in gastric environment thus act as secondary sources of potentially toxic metals, particularly Sn, Zn and also Cu, which are released both under reducing and oxidising conditions especially in acidic environment. Only very small amounts of Hg are potentially released and should not represent serious threat. Secondary phases that contribute the most to bioaccessibility of these metals are Sn hydroxychlorides, Sn oxides/hydroxides, Sn sulphates/hydroxysulphates, Sn oxides, Zn sulphides and Cu sulphides (Cu₂S).

     

Enhanced desorption of fluoxetine from polyethylene terephthalate microplastics in gastric fluid and sea water

There are concerns that microplastics act as a vector of pharmaceuticals in the aquatic environment. Most studies have focussed on pharmaceutical adsorption and have not investigated desorption in the various matrices that microplastics enter. Therefore we studied the desorption of the antidepressant drug fluoxetine from polyethylene terephthalate (PET) microplastics in river water, sea water, and simulated gastric and intestinal fluids. We found that most desorption occurred rapidly, within a few hours of exposure. Fluoxetine desorption fitted well to the Freundlich isotherm with r² values ranging from 0.97 to 0.99. Desorption decreased in the following order: gastric fluid at 20 °C and 37 °C; sea water at 20 °C; intestinal fluid at 20 °C and 37 °C; then river water at 20 °C. The little difference in desorption in gastrointestinal fluids at 20 °C and 37 °C suggests a similar exposure risk to cold- and warm-blooded organisms following PET microplastic ingestion. Total desorption following sequential incubation 2 h in gastric fluid then 4 h in intestinal fluid to mimic gastrointestinal digestion was 37% at 20 °C and 41% at 37 °C. Interestingly, higher desorption of 18–23% occurred in sea water compared to river water, of 4–11%. Under a worst-case scenario, more than 44 mg kg⁻¹ body weight d⁻¹ or more than 52 mg kg⁻¹ body weight d⁻¹ of PET microplastics from river water or sea water, respectively, need to be consumed to exceed the mammalian acceptable daily intake for fluoxetine. Further studies are needed on microplastic ingestion and the bioavailability of adsorbed pharmaceuticals to a range of exposed aquatic organisms.

     

Morphology of the gastric mill in ten species of euphausiids

SEM observation revealed the detailed morphology of the gastric mill in ten species of euphausiids, Bentheuphausia amblyops, Thysanopoda acutifrons, Meganyctiphanes norvegica, Pseudeuphausia latifrons, Euphausia superba, Tessarabrachion oculatum, Thysanoessa longipes, Nematoscelis microps, Nematobrachion boopis, and Stylocheiron maximum. The well-developed gastric mill of euphausiids consists of a pair of cluster spines and a pair of lateral teeth displaying great diversity in morphology. It is suggested that there are three categories of gastric mill and filterpress (gland filter) within euphausiids. One is the well-developed gastric mill with filter-press of B. amblyops; a second is the well-developed gastric mill of M. norvegica, T. oculatum, E. superba, P. latifrons and T. longipes; and the third is the gastric mill without lateral teeth of T. acutifrons, N. microps, N. boopis and S. maximum.     

Metal passivity as mechanism of metal carcinogenesis: Chromium,nickel, iron,copper, cobalt,platinum, molybdenum

For the transition metals chromium, nickel, iron, copper, cobalt, platinum, and molybdenum, mechanisms of stable bonding in biochemistry (emphasis on carcinogenic mechanisms), chemistry, industrial chemistry, as well as epidemiological, occupational, orthopedic (implant devices) effects related to carcinogenesis, were reviewed. Hypothetically, the propensity to stable bonding (inertness), which ensures the metals’ performance capacity for consumers and industrial application, relates to their carcinogenicity. For chromium, a relationship between industrial/chemical and biological reactivity was noted for the tendency of Cr(III) ions to cause hydrolysis previous to stable bonding, as occurs during anodic passivation, leather tanning, and as indicated in biochemical studies pertaining to a mechanism of DNA condensation, which was suggested as a carcinogenic mechanism. The involvement of metal hydrolysis in both anodic passivation and biochemistry was noted also for nickel, iron, and platinum; the DNA interaction of platinum (cis-platin) is known to depend on hydrolysis. For nickel, issues of potential (V) were found important in both passivation and carcinogenicity. Comparably, the passivity behavior of cobalt and copper was found atypical, and their carcinogenicity yet unclear. Molybdenum, contained in passivated metallic implants, may relate to implant-associated carcinogenesis. Occupational carcinogenic effects were indicated for chromium, nickel, iron, and cobalt as caused by both reactive and passivated metal species. Exposure to acids and chronic respiratory irritation/infection/inflammation in workers were important cofactors in metal carcinogenesis. For wood and leather workers exposed to dust, the assumed presence in dust of metal particles abraded from alloys (sawing or cutting blades) may be a carcinogenic exposure hazard.     

香芋高产、优质栽培技术与产品分级及加工

香芋是多年生宿根草本植物,属天南星科(Araceae)一年生栽培,是我省重要的特种蔬菜之一,随着农业结构调整步伐的加快,香芋的种植面积也在不断扩大,为了提高香芋的产量和品质,达到绿色蔬菜的标准,该文提出了香芋高产、优质栽培技术与产品分级及加工.表3,参5.     

基因污染与生态环境安全

论述了基因污染可能对生态环境安全造成的影响。转基因作物有可能污染天然物种的基因库；有可能破坏传统农作物品种的遗传多样性，加速作物种植品种的单一化及基因资源的流失；使抗除草剂作物的基因向野生或半野生植物漂移的可能性加大，有可能创造出“超级杂草”；带有病毒型转基因作物的基因重组，有可能创造出新的植物病毒，导致新的病害；BT转基因抗虫作物分泌的毒素，在食物链中传递，很难加以控制，对非目标生物造成危害，并最终破坏自然生态系统的平衡。文章还从不同角度分析了基因污染的严重性。     

Nanosensors and nanobiosensors in food and agriculture

The food and agriculture sector controls the economic growth of a developing country. The food industries have practices of growing crops, raising livestock and sea foods, food processing and packaging, regulating production and distribution with quality and safety. The process control and monitoring quality are crucial steps. Here we review nanosensors and nanobiosensors as alternative of classical quantification methods. Nanoscale dimensions of metal nanoparticles, metal nanoclusters, metal oxide nanoparticles, metal and carbon quantum dots, graphene, carbon nanotubes, and nanocomposites expand the sensitivity by signal amplification and integrate several novel transduction principles such as enhanced electrochemical, optical, Raman, enhanced catalytic activity, and superparamagnetic properties into the nanosensors. The electrochemical nanosensors, optical nanosensors, electronic nose and electronic tongue, nanobarcode technology, and wireless nanosensors have revolutionized the sensing in food and agriculture sectors with multiplex and real-time sensing capabilities. Despite previous success stories of the remunerative health sector, the approaches are transferred subsequently to food and agriculture sector; with potential application in detection of food contaminants such as preservatives, antibiotics, heavy metal ions, toxins, microbial load, and pathogens along with the rapid monitoring of temperature, traceability, humidity, gas, and aroma of the food stuff.     

市场经济与土肥科技

土肥的基础地位是不随社会性质或社会经济类型的变化而变化的，它既具重要性，又具长久性．市场经济是仍然需要土肥科技的．土肥科技的教学、科研和推广的力度必须加大，局面必须改观，且宜快不宜迟．土肥科技工作者一定要将培肥地力作为中心工作．根据广东的实际，增施有机肥是培肥地力的主要措施，因而抓秸秆还田和发展冬绿肥是我们工作的重点．     

Indoor and outdoor air pollution and lung cancer in New Hampshire and Vermont

Indoor and outdoor air pollution is known to contribute to increased lung cancer incidence. This study is the first to address the contribution of home heating fuel and geographical course particulate matter (PM₁₀) concentrations to lung cancer rates in New Hampshire, USA. First, Pearson correlation analysis and geographically weighted regression were used to investigate spatial relationships between outdoor PM₁₀ and lung cancer rates. While the aforementioned analyses did not indicate a significant contribution of PM₁₀ to lung cancer in the state, there was a trend towards a significant association in the northern and southwestern regions of the state. Second, case-control data were used to estimate the contributions of indoor pollution and secondhand smoke to the risk of lung cancer with adjustment for confounders. Increased risk was found among those who used wood or coal to heat their homes for more than 10 winters before the age of 18, with a significant increase in risk per winter. Resulting data suggest that further investigation of the relationship between heating-related air pollution levels and lung cancer risk is needed.     

1株贫营养好氧反硝化菌的分离鉴定及其脱氮特性

从水库底泥样品中,以硝酸盐为唯一氮源进行驯化、分离筛选出1株能在贫营养及好氧条件下进行高效反硝化的菌株PY8,经过电镜形态学观察、生理生化和16S rDNA序列分析,并基于16SrDNA序列结果,构建了该菌株的系统发育树,最终确定菌株PY8为根瘤菌Rhizobiumsp.。考察了初始pH值、温度、C/N、初始硝酸钠质量浓度、投菌量对菌株PY8硝酸盐还原活性的影响,以及该菌株的异养硝化性能。结果表明,在pH6.0～10.0,温度25～30℃,C/N1.0～9.0,初始硝酸钠质量浓度0.01～0.50g·L-1,投菌量1%～15%时,菌株PY8培养72h后的硝氮去除率可达到95%以上。另外,该菌株具有同时硝化-反硝化作用,在培养过程中氨氮去除率可达到58%左右。实验结果表明,菌株PY8在微污染水体生物脱氮领域中具有很大的应用潜力。