Objective: To analyze vitamin D status based on serum 25-hydroxyvitamin D (25OHD) measurements, its determinants and health correlates in a representative sample of German adults. Subjects: A total of 1763 men and 2267 women, 18-to 79-year old, who participated in the representative German National Health Interview and Examination Survey 1998 and the integrated German Nutrition Survey. Results: The median vitamin D intake from both diet and supplements did not meet the recommended level of 5 mg/day, in either men (2.8 mg/day) or women (2.3 mg/day). Altogether 80.9% of men and 88.5% of women had vitamin D intakes below this level. Moderate (12.5-25 nmol/l serum 25OHD levels) and mild (25-50 nmol/l) vitamin D deficiency was prevalent in the adult population in Germany, even in younger age groups. Overall, 57% of men and 58% of women had vitamin D levels below 50 nmol/l. Among 65-to 79-year-old women, the proportion amounted to 75%, even during the sunnier half of the year. In sexspecific multiple linear regression models, independent determinants of serum 25OHD levels consistently included season, vitamin D intake from both diet and supplements, physical activity and living in a partnership. In addition, age and current menopausal hormone use contributed to the model among women, as opposed to time of day of blood sampling and body mass index (marginally) among men. Significantly lower serum 25OHD levels were observed in women with hypertension, cardiovascular diseases and noninsulin-treated diabetes mellitus as well as in men with insulin-treated diabetes mellitus compared with nonaffected participants. Conclusions: Vitamin D deficiency is a public health issue in Germany. We identified a number of determinants with potential for primary prevention of vitamin D deficiency. Risk and benefits of preventive actions need to be examined in further studies.

No abstract

Since the UN water conference at Mar del Plata in 1977, there have been international debates about how water governance could and should respond to the challenges of sustainable development. New global institutions were established to promote universal norms of governance based on the 1992 'Dublin Principles' and its version of 'Integrated Water Resource Management' (IWRM). Many of these prescriptions were contested, not least because of their advocacy of marketbased approaches to address what were posed as challenges of scarcity and environmental sustainability. The paper examines the drivers that have informed different conceptualisations of water governance. It shows how 'scarcity' has become central to narratives that sought to focus governance at the river basin scale, to restrict water use in favour of the protection and restoration of water resource ecosystems and to prioritize economic efficiency through market mechanisms. It then reviews the experience of a diverse set of countries, some of which have implemented systemic governance reforms and others whose trajectories have been more evolutionary, driven by domestic contexts. These practical experiences, supported by a growing understanding of polycentric approaches and how networks cross and link a range of geographic and administrative scales, have given rise to alternatives to the normative IWRM, river basin-focused approaches to water governance. Despite continuing concerns about 'planetary environmental boundaries' and transboundary security, these are proving to be weak motivations for adoption of formal global systems of water governance. Instead, new narratives emphasise locally-diverse approaches that see water governed within "problem-sheds" rather than "water-sheds". Water governance remains a scene of contestation between local and 'global' criteria and developmental and environmental goals. But, in the face of challenges of complexity and diversity and the emerging understanding of network governance, emerging practitioner-oriented guidance is focusing on general principles and explicitly avoiding normative approaches. 1. Introduction Water and its governance has attracted increased attention as a policy concern in recent years. The United Nations has determined that water is a human right (United Nations 2010). The global business community, through the World Economic Forum's Annual Global Risks Report has repeatedly identified water crises 1 as one of its top global risks (WEF, 2016) A broad goal for governments and business is to achieve "water security" usefully defined as "the reliable availability of an acceptable quantity and quality of water for health, livelihoods, ecosystems and production, coupled with an acceptable level of water-related risks to people, environments and economies" (Grey & Sadoff, 2007, p547-8). This definition includes the risks of flood and drought posed by water as well as the maintenance of important ecosystems and recognises that communities may have different "acceptable" levels of risk and protection. Co...

Water-related risks threaten society at the local, national and global scales in our inter-connected and rapidly changing world. Most of the world's poor are deeply water insecure and face intolerable water-related risks associated with complex hydrology. Most of the world's wealthy face lower water-related risks and less complex hydrology. This inverse relationship between hydrological complexity and wealth contributes to a divided world. This must be addressed if global water security is to be achieved. Using a risk-based framework provides the potential to link the current policy-oriented discourse on water security to a new and rigorous science-based approach to the description, measurement, analysis and management of water security. To provide the basis for this science-based approach, we propose an encompassing definition rooted in risk science: water security is a tolerable level of water-related risk to society. Water security policy questions need to be framed so that science can marshal interdisciplinary data and evidence to identify solutions. We join a growing group of scientists in asserting a bold vision for science leadership, calling for a new and comprehensive understanding of the planet's water system and society's water needs.

S ince May, winter rains have brought a reprieve to the citizens of Cape Town, South Africa. The city had endured severe drought for three years. Concerns that its water supply might run out in the summer have been set aside, hopefully, for another year. But the city remains vulnerable. The situation was very different in 2013. Then, Cape Town had one of its highest annual rainfalls in decades. Reservoirs brimmed, and officials declared there was no need to increase supplies before the 2020s. After another wet winter in 2014, the 6 main reservoirs that feed the city were 97% full. Then the drought began. Reservoir levels fell to 71% in 2015 and to 60% in 2016 (see 'Cape Town drought'). When they reached 38% in 2017, at the beginning of what The narrow body of water that remained at South Africa's Theewaterskloof Dam in May 2017.