Human carrying capacity and human health

The silence around overpopulation prevents the global health community from making the necessary link between the planner's limited ability to support its people and health and development crises. The author describes how popular thinking on population control has been shaped over the last 200 years and how out failure to address the population explosion may be one cause of recent epidemics and social unrest.

Human carrying capacity and human health

The issue of human overpopulation has fallen out of favor among most contemporary demographers, economists, and epidemiologists. Discussing population control has become a taboo topic. Yet, this taboo has major implications for public health.

The silence around overpopulation prevents the global health community from making the necessary link between the planet's limited ability to support its people (its carrying capacity—see sidebar on following page) and health and development crises. In this article, I describe how popular thinking on population control has been shaped over the last 200 years, and how our failure to address the population explosion may be one cause of recent epidemics and social unrest.

Climate change and human health: what can GPs do?

In recent months articles in the most respected peer reviewed medical journals in Australia, the USA and Britain have called for urgent action to reduce climate change.1–4 The chief scientist of the United Kingdom has described climate change as ‘the most severe problem that we are facing today – more serious even than the threat of terrorism’.5 Yet, many of you will wonder if this is really such an urgent issue, and – even if it is – what on earth has it got to do with general practice?

Aquaculture effluent : impacts and remedies for protecting the environment and human health

Knowledge in the field of environmental health is growing rapidly. Within the context of external factors that define its boundaries, environmental health has evolved over time into a complex, multidisciplinary and ill-defined field with uncertain solutions. Many of the key determinants and solutions to environmental health lie outside the direct realm of health and are strongly dependent on environmental changes, water and sanitation, industrial development, education, employment, trade, tourism, agriculture, urbanization, energy, housing and national security. Environmental risks, vulnerability and variability manifest themselves in different ways and at different time scales. While there are shared global and transnational problems, each community, country or region faces its own unique environmental health problems, the solution of which depends on circumstances surrounding the resources, customs, institutions, values and environmental vulnerability. This work will contain critical reviews and assessments of environmental health practices and research that have worked in places and thus can guide programs and economic development in other countries or regions.

Anthropogenic change and human health

The chapter provides and introduction to the impacts human activity have had and continue to have on human health, especially in the context of urbanization and increasing population density.

People, places and public health : evaluating the benefits of civic environmentalism in an urban local government context

Recent political, economic and social trends pose threats to the sustainability both of ecosystems and of human health. Australia’s environmental management record is poor, and while by international standards Australians enjoy good health, this is variable (AIHW, 2000). Within developed nations, heart disease, depression, alcohol dependence and stroke are major health issues (Mathers et al. 2002). In Australia, mental disorder is the number one contributor to the disease burden (Vos & Mathers 2000). Recent research has highlighted the role of social capital as a key determinant of health (Kawachi et al., 1997). Despite this, Putnam (1995) observes that social connectedness and civic engagement are in decline. People have less time for leisure and for volunteering, as many juggle paid work and caring for children. Anecdotal evidence suggests that engagement in civic environmentalism has human health benefits, relating to a combination of exposure to natural environments and increased social capital (Maller, Brown, Townsend & St. Leger, 2002). This link is supported by Furnass (1996) who defines well-being as including: satisfactory human relationships, meaningful occupation, opportunities for contact with nature, creative expression, and making a positive contribution to human society. Research conducted by Deakin University confirms the efficacy of linking people and places through civic environmentalism for addressing both ecosystem sustainability and human health and wellbeing. The research has included a pilot study to explore the human health benefits of membership of a local parkland ‘Friends’ group, and a more detailed follow-up study. The aims of the pilot study included:- To identify the range of motivations for joining the Friends group;- To document members’ perceptions of the benefits gained from membership of the group;- To assess the potential for Friends groups to be used as an ‘upstream’ health promotion measure.Face-to-face interviews were conducted with eleven members of a ‘Friends’ group in the eastern suburbs of Melbourne. Data was analysed thematically and key findings included:- Motivations: environmental; social; and pragmatic.- General benefits: community belonging; personal satisfaction; learning opportunities; physical activity; and better environment.- Health benefits: physical health; mental health; and social support. There was unanimous support for the use of ‘Friends’ groups as a tool for health promotion.The follow-up study, in the western suburbs of Melbourne, expanded on the pilot study by measuring the group’s social capital and by collecting self-report data on levels of health service usage. Data was collected through face-to-face interviews and a questionnaire. The findings were similar to the pilot study in relation to the motivations, benefits and the health promotion potential of such groups. However, health service usage data highlighted an apparent anomaly: while respondents perceived significant health benefits, some were nevertheless utilising health services at a relatively high level. This poses some questions requiring further exploration: Is this due to the poorer baseline health of the high health service usage members compared with their fellow members? Does involvement in the group offer health benefits that enable people who would otherwise be too unhealthy to participate in community groups to continue such involvement?If this is the case, then we may do well to look to locally-based mechanisms for promoting ecological sustainability as a tool also for promoting human health. Instead of prescribing a pill, connecting people and places through engagement with a local friends group may address our health problems at the same time as addressing local environmental problems.

Linking human and ecosystem health: the benefits of community involvement in conservation groups

This study explored the health, well-being, and social capital benefits gained by community members who are involved in the management of land for conservation in six rural communities across Victoria. A total of 102 people participated in the study (64 males; 38 females) comprising 51 members of a community-based land management group and 51 controls matched by age and gender. Mixed methods were employed, including the use of an adapted version of Buckner’s (1988) Community Cohesion Scale. The results indicate that involvement in the management of land for conservation may contribute to both the health and well-being of members, and to the social capital of the local community. The members of the land management groups rated their general health higher, reported visiting the doctor less often, felt safer in the local community, and utilized the skills that they have acquired in their lifetime more frequently than the control participants. Male members reported the highest level of general health, and the greatest satisfaction with daily activities. Members also reported a greater sense of belonging to the local community and a greater willingness to work toward improving their community than their control counterparts. Of equal importance is evidence that involvement in voluntary conservation work constitutes a means of building social capital in rural communities which may help reduce some of the negative aspects of rural life.

Human health, well-being and global ecological scenarios

This article categorizes four kinds of adverse effects to human health caused by ecosystem change: direct, mediated, modulated, and systems failure. The effects are categorized on their scale, complexity, and lag-time. Some but not all of these can be classified as resulting from reduced ecosystem services. The articles also explores the impacts that different socioeconomic–ecologic scenarios are likely to have on human health and how changes to human health may, in turn, influence the unfolding of four different plausible future scenarios. We provide examples to show that our categorization is a useful taxonomy for understanding the complex relationships between ecosystems and human well-being and for predicting how future ecosystem changes may affect human health.

Macronutrient innovations: the role of fats and sterols in human health

Dietary intake of fats and sterols has long been known to play a critical role in human health. High proportions of saturated fat, which increase blood cholesterol levels, are mainly found in animal fat and some plant oil (e.g. cocoa butter, palm oil etc.). The predominant polyunsaturated fatty acid (PUFA) in the Western diet is linoleic acid (LA; 18:2n-6), an essential fatty acid, which is commonly found in vegetable seed oils. This is the parent fatty acid of n-6 series PUFA, which can be converted in vivo to C20 and C22 n-6 long chain (LC) PUFA. α‐linolenic acid (ALA; 18:3n-3) is less abundant than LA and is another essential fatty acid; ALA is also present in some vegetable oils such as perilla, flaxseed, canola, soybean and walnut oils, and is the precursor of C20 and C22 n-3 LC PUFA. Sterols are widely distributed in animal tissue and plants, with cholesterol being the major sterol in animal tissue and β-sitosterol, campesterol and stigmasterol being the main sterols in plants. It has long been recognized that an increased dietary intake of saturated fat and (to a lesser extent) cholesterol, raises plasma/serum total and low-density lipoprotein (LDL)-cholesterol, and PUFA decreases these levels. Results from recent studies have shown that plasma/serum levels of lipids and lipoprotein lipids can also be decreased by plant sterols (phytosterols) and diacylglycerol (DAG). Conjugated linoleic acid (CLA, cis-9,trans-11−18:2) has been reported to have anticancer and antidiabetic activities. Fat as the DAG form has also been reported to have anti-obesity effects. Omega-3 PUFA have a beneficial effect on increased heart rate variability, decreased risk of stroke, reduction of both systolic and diastolic blood pressure and may be effective in managing depression in adults. Gamma-linolenic acid (GLA) and phytosterols have an anti-inflammatory activity. The GLA, when combined with docosahexaenoic acid (DHA), have been reported to have a beneficial effect in hyperactive children. These data show that various lipids are powerful bioactive compounds.