Public health, the environment and the 21st century: a wider field of vision

As we enter the 21st century, there is rising awareness that the global population of 6.7 billion humans is overloading many of Earth's environmental systems. The collective demand of Homo sapiens for materials, food, freshwater and waste absorption has escalated enormously over the past century. We currently use natural resources (sources, sinks and system stabilisers) at an estimated 25% higher rate than the planet can sustain.¹

A future brief history of environmental health in today's high-income countries might note three main phases: (i) latter 19th century: sanitary engineering, urban waste disposal, food safety and domestic hygiene, primarily to combat infectious disease risks; (ii) latter 20th century: environmental (and occupational) laws and policies to reduce exposures to specified toxic chemical exposures: air pollutants, heavy metals, industrial and agricultural chemical effluents and (iii) 21st century: recognition and (hopefully) reduction of health-endangering damage to Earth's geophysical and ecological systems.

With modern epidemiological methods, we have become adept at identifying recently emerged hazardous environmental exposures and then, reactively, cleaning up after ourselves. Now, however, we also need forward vision for two key, related, reasons—first, to better foresee the likely trajectory and magnitude of population health risks from human-induced environmental changes, and, second, proactively to assist society take preventive actions to avert potentially irreversible systemic environmental damage. This would be primary prevention writ large.

That word ‘systemic’ is important. During our industrial adolescence, we have thrown many ‘spanners in the works’, contaminating local environments and causing temporary hitches. Today, we are disrupting the ‘works’ themselves. Species are being lost, ecosystems disrupted, aquifers emptied, soils depleted, oceans acidified and the global climate changed. This weakening of Earth's life-support systems necessarily poses serious health risks.²

Species everywhere press, via increases in population size, on local environmental limits—and must then pay the consequences. Humans, though, with modern technologies and cultural expectations, do not readily take ‘No’ for an answer. Via environmental manipulation, trading and raiding, we can defer the ecological reckoning. Hence, initially, fertility does not necessarily fall nor mortality rise. But the reckoning must come. Recent historical analyses have recounted the fall of many great (e.g. the Mesopotamians and Mayans) and small (e.g. the West Vikings and the Rapa Nui of Easter Island) civilizations as regional and local resources have been exhausted—even as those societies went into end-game consumption and construction over-drive.³

Against this backdrop, it is naïve to imagine that population health protection and promotion can largely be achieved by the health sector itself. Yet, influenced by recently ascendant neoliberal ideas of personal responsibility and choice, there has been undue emphasis by the health sector on individual-focused ‘health promotion’ strategies. This, despite the emphasis by the Ottawa and Bangkok Charters (1986, 2005) that enduring gains in health require coordinated whole-of-government policies.

The advent of global environmental changes looms as an unfamiliar and dark cloud on the horizon. Yet, for the public health sector there is a potential silver lining. Resolving these daunting environmental problems requires a multi-sectoral response.⁴ The public health system must engage with this epoch-defining ‘sustainability’ project, proffering gains in population health as a prime reason for transforming our ways of living and our environmental and population policies. Indeed, there is a special opportunity here—such engagement could revitalize health promotion by enhancing the rationale for changes in urban design, transport and physical activity, sources and types of food and recreational choices. The University of Wisconsin has, for example, initiated a Triple Win Project, promoting the multiple health benefits conferred by a switch from cars to bicycles—thus reducing greenhouse gas emissions, improving ambient air quality and increasing physical activity and its attendant health benefits.⁵

WHO has chosen Climate Change and Health as its theme for 2008–09. The public health community should help convert that theme into multi-sectoral actions that seek environmental and social conditions able to sustain population health. This is a moment of great need and opportunity.

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