Human exposure to aluminum

Aluminum is the third most abundant element in nature, accounting for nearly 8% of the Earth's crust. Because of its chemical activity, aluminum is not found naturally in its free, or metallic, state. However, in its ionic or combined forms, aluminum is a truly ubiquitous element.Because of the widespread use of metallic aluminum in cooking and packaging applications, the Aluminum Association has funded critical reviews of the world's literature on the health effects of aluminum and aluminum compounds for the past 30 years.More recently, an extensive research and literature surveillance effort was developed to provide information on the neurological implications of aluminum, dietary intakes and body balance, and analytical capabilities. Based on these efforts the following conclusions can presently be drawn: (1) the cause (or causes) of Alzheimer's disease is not known; (2) the biological significance of aluminum found in the brain is not understood; (3) aluminum is poorly absorbed by the body; and (4) the normal ingestion of aluminum from food and water should have no adverse effects on human health.     

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.     

人体肠道耐药基因组的研究进展

人类肠道菌群是耐药基因(antibiotic resistance genes,ARGs)的"储存库",且与人体健康密切相关。目前,抗生素的滥用严重,进一步加剧了耐药基因的传播和扩散。细菌耐药问题严重影响人体健康、食品安全和生态安全,携带耐药基因的致病菌对临床治疗造成巨大威胁。本文结合国内外研究进展,在总结人体肠道耐药基因组研究方法的基础上,探讨了肠道耐药基因的组成、来源、传播和进化,并对未来研究进行了展望,旨在促进公众对肠道耐药基因的认知,并为抗生素的合理使用提供理论支持。     

地下水污染与人类健康

现代化的社会对地下水的污染问题是十分关切的。本文旨在介绍一些在地下水污染的控制和治理以及地下水污染所至的健康风险评价等方面的技术。     

Aquatic Chemistry and the Human Environment

The evident physical continuity in the cycles of water in air, soil, lake, river, estuary and sea is difficult to describe accurately; there is also a chemical continuity that is impossibly complex in detail but has unifying principles that need to be explored. Amid current somewhat myopic concern about the effects of certain toxic metals in the environment specifically in relation to man it is appropriate to reflect on the wider issues of aquatic chemistry that affect the human environment. These issues embrace the aquatic chemistry of the countryside and the health of the population and reciprocally the impingement of human activities on the aquatic realm. If one can demonstrate a coherent core of chemical principles there may also be an implied need for more enlightened co-ordination in the study of aquatic chemistry, its applications and developments. At present, fundamental chemistry, water and wastewater technologies, environmental chemistry and epidemiology are discrete provinces of aquatic science. Insularity is even more serious in professional affiliations and consequently job qualifications; also among the central, local and industrial bodies who establish legislation and set and administer standards for water.

Benefits of greater collaboration and co-ordination would reach not only scientists, learned institutions, managers and the general public here but would also lead to much more effective understanding and practical help in other lands where water supply and water-related problems are enormously more acute.     

Training Conservation Biologists in Human Interaction Skills

Questionnaires were sent to 298 graduate programs in conservation biology and other areas of the biological and agricultural sciences and to 702 public and private organizations that employ, or might employ, conservation biologists. The focus of the questionnaires was on the need for training conservation biologists in human interaction skills (e.g., interpersonal communication, leadership, group decision making). Respondents were asked to indicate the current availability of such training at their institutions or organizations. Questionnaires were returned by 28.5% of the graduate programs and 21.1% of the conservation organizations. A majority of both groups of respondents indicated a high need for training in the following seven areas: written and oral communication; explaining science and values of biodiversity to the lay public; group decision making; interpersonal skills; group planning; leadership; and advocacy. Despite the high level of perceived training need, relatively few academic institutions and even fewer conservation organizations offer or require courses in human interaction skills (with the exceptions of written and oral communication and foreign languages). Sixty-four percent of the graduate faculty respondents and 78% of the employer organization respondents indicated that human interaction skills are equally important or more important to the work of conservation biologists than science knowledge and skill. We suggest that follow-up research should be conducted to delineate further the need for human interaction skills training and to assess the relationship between specific human interactions skills and conservation outcomes. We also recommend that a curriculum on human interaction should be designed and developed for conservation biologists, perhaps through a cooperative effort of interested faculty and employers facilitated by the Society for Conservation Biology and conservation organizations.     

Human influence on California fire regimes.

Periodic wildfire maintains the integrity and species composition of many ecosystems, including the mediterranean-climate shrublands of California. However, human activities alter natural fire regimes, which can lead to cascading ecological effects. Increased human ignitions at the wildland-urban interface (WUI) have recently gained attention, but fire activity and risk are typically estimated using only biophysical variables. Our goal was to determine how humans influence fire in California and to examine whether this influence was linear, by relating contemporary (2000) and historic (1960-2000) fire data to both human and biophysical variables. Data for the human variables included fine-resolution maps of the WUI produced using housing density and land cover data. Interface WUI, where development abuts wildland vegetation, was differentiated from intermix WUI, where development intermingles with wildland vegetation. Additional explanatory variables included distance to WUI, population density, road density, vegetation type, and ecoregion. All data were summarized at the county level and analyzed using bivariate and multiple regression methods. We found highly significant relationships between humans and fire on the contemporary landscape, and our models explained fire frequency (R2 = 0.72) better than area burned (R2 = 0.50). Population density, intermix WUI, and distance to WUI explained the most variability in fire frequency, suggesting that the spatial pattern of development may be an important variable to consider when estimating fire risk. We found nonlinear effects such that fire frequency and area burned were highest at intermediate levels of human activity, but declined beyond certain thresholds. Human activities also explained change in fire frequency and area burned (1960-2000), but our models had greater explanatory power during the years 1960-1980, when there was more dramatic change in fire frequency. Understanding wildfire as a function of the spatial arrangement of ignitions and fuels on the landscape, in addition to nonlinear relationships, will be important to fire managers and conservation planners because fire risk may be related to specific levels of housing density that can be accounted for in land use planning. With more fires occurring in close proximity to human infrastructure, there may also be devastating ecological impacts if development continues to grow farther into wildland vegetation.