Priority risks and future trends

From longstanding to emerging hazards, environmental factors are a root cause of a significant burden of death, disease and disability – particularly in developing countries. The resulting impacts are estimated to cause about 25% of death and disease globally, reaching nearly 35% in regions such as sub-Saharan Africa. This includes environmental hazards in the work, home and broader community/living environment.

A significant proportion of that overall environmental disease burden can be attributed to relatively few key areas of risk. These include: poor water quality, availability, and sanitation; vector-borne diseases; poor ambient and indoor air quality; toxic substances; and global environmental change. In many cases, simple preventive measures exist to reduce the burden of disease from such risks, although systematic incorporation of such measures into policy has been more of a challenge.

Below are estimates of deaths globally from the most significant environmentally-related causes or conditions, and from certain diseases with a strong environmental component:

Unsafe water, and poor sanitation and hygiene kill an estimated 1.7 million people annually, particularly as a result of diarrhoeal disease.

Indoor smoke – primarily from the use of solid fuels in domestic cooking and heating – kills an estimated 1.6 million people annually due to respiratory diseases.

Malaria kills over 1.2 million people annually, mostly African children under the age of five. Poorly designed irrigation and water systems, inadequate housing, poor waste disposal and water storage, deforestation and loss of biodiversity, all may be

contributing factors to the most common vector-borne diseases, including malaria, dengue and leishmaniasis.

Urban air pollution generated by vehicles, industries, and energy production kills approximately 800 000 people annually.

Road traffic injuries are responsible for 1.2 million deaths annually; low- and middle-income countries bear 90% of the death and injury toll. Degradation of the built urban and rural environment, particularly for pedestrians and cyclists, has been cited as a key risk factor.

Lead exposure kills more than 230 000 people per year and causes cognitive effects in one third of all children globally; more than 97% of those affected live in the developing world.

Climate change impacts – including more extreme weather events, changed patterns of

disease and effects on agricultural production – are estimated to cause over 150 000 deaths

annually.

Unintentional poisonings kill 355 000 people globally each year. In developing countries – where two-thirds of these deaths occur – such poisonings are associated strongly with excessive exposure to, and inappropriate use of, toxic chemicals and pesticides present in occupational and/or domestic environments.

Future trends and emerging issues

Over the next 30 years, most of the world’s population growth will occur in the urban areas of poor countries. Rapid, unplanned and unsustainable styles of urban development are making developing cities the key focal points for emerging environmental and health hazards.

These hazards include the synergistic problems of urban poverty, traffic fatalities and air pollution. In addition, increased urbanization and motorization and diminishing space for walking/recreation in cities is associated with

more sedentary lifestyles and a surge in related noncommunicable diseases.

Globally, physical inactivity is estimated to be responsible for some 1.9 million deaths each year as a result of diseases such as heart ailments, cancer and diabetes. Increased industrial and agricultural production has intensified poorer countries’ production and use of both newer and older chemicals, including some formulations that are banned in other countries.

The Organisation for Economic Co-operation and Development (OECD) has estimated that the global output of chemicals in 2020 will be 85% higher than in 1995, and nearly one third of the world's chemical production will take place in non-OECD countries, as compared to about one fifth in 1995. The shift of chemical production from more affluent to poorer settings could increase the overall health and environmental risks arising from the production and use of such chemicals.

Already in many developing countries a range of toxic effluents is emitted directly into soil, air and water – from industrial processes, pulp and paper plants, tanning operations, mining, and unsustainable forms of agriculture – at rates well in excess of those tolerable to human health. Along with the problem of acute poisonings, the cumulative health impacts of human exposures to various chemical combinations and toxins can be a factor in a range of chronic health conditions and diseases.

At the global level, demand for and unsustainable use of energy resources, (particularly fossil fuels), has placed stress on global ecosystems, including the mechanisms controlling and regulating climate. These, in turn, generate health impacts, e.g. from changed patterns of vector-borne disease to more extreme weather events. Climate change-related health impacts, which currently are responsible for an estimated 150,000 deaths annually, can be expected to increase in the future.

Other global environmental changes, such as loss of biodiversity, can have health consequences by increasing instability in disease transmission in animal populations, which are the source of most of the pathogens affecting humans. Loss of biodiversity can have other health consequences as well, as a result of the depletion of the genetic resources available for future crop/food production and development of medicines.

The health impacts of environmental risks are heaviest among poor and vulnerable populations in developing countries. For instance, poor coastal populations in developing countries may be among the most vulnerable to sea-level rises and extreme weather events.

The poor in developing countries generally have the least access to clean water sources, and those same populations also may be the most directly exposed to environmental risks such as vector-borne diseases and indoor air pollution from solid fuel use.

At the same time, poor people also may be the most dependent on natural resources as sources of livelihoods and well-being, and thus be most impacted by unsustainable exploitation or depletion of those resources.

Health, environment and the Millennium Development Goals (MDGs)

Promoting environmental sustainability is therefore a means of addressing both poverty and ill health. That is reflected in the Millennium Development Goals (MDGs) – approved by the UN General Assembly in the year 2000 – which set global goals and specific targets for sustainable development, improvement of health, and poverty reduction.

MDG 7 calls upon nations to "ensure environmental sustainability". Targets identified as part of MDG-7 include:

Integrate the principles of sustainable development into country policies and programmes and reverse the loss of environmental resources.

Halve, by 2015, the proportion of people without sustainable access to safe drinking water and sanitation.

Achieve, by 2020, a significant improvement in the lives of at least 100 million slum dwellers.

Addressing the root environmental causes of disease is vital not only to the achievement of MDG-7, but also may play an important role in the achievement of other Millennium Development Goals. A few examples of such linkages are noted below.

MDG 1 – Eradicate Extreme Poverty and Hunger. Integrated environment and health policy can reduce the impact of vector-borne disease in irrigated agricultural areas, improving farmer performance overall.

Better agriculture practice in relation to pesticide use, management of livestock and their waste, as well as improved land and water conservation practices, can increase agricultural yields and improve food security, as well as health.

MDG 4 – Reduce Child Mortality. Shifting to cleaner household fuels and/or to improved cook stoves can reduce indoor air pollution, and thus have a direct impact on child mortality from acute respiratory disease, a key childhood killer. Improved water and sanitation provision as well as better household water management can potentially have an impact on childhood mortality and morbidity both from diarrhoeal and vector-borne diseases.

MDGs 3 and 5 – Promote Gender Equality and Empower Women/Improve Maternal Health. More sustainable agricultural policy and practices, can yield benefits for women – both in their capacity as cultivators/food providers and as mothers – in terms of improved food security and in terms of reduced exposures to agro-chemicals.

Shifting to cleaner household fuels and/or improved cook stoves can reduce the risks of chronic respiratory diseases in women, who in their capacity as mothers and caregivers are responsible

for most food preparation as well as for time-consuming fuel collection.

Notes and references

Notes

Mortality from urban air pollution is estimated with reference to small particulates as an indicator for exposure; mortality from exposure to lead (both from airborne particles and from other sources) is thus presented here as a separate estimate.

Mortality rates from malaria, diarrhoea and unintentional poisonings are derived from estimates of annual deaths by cause, age and WHO subregion in 2002, cited in the World health report 2003. Mortality from indoor air pollution is derived from attributable mortality by risk factor and age group, for the year 2000, cited in the World health report 2002.

Mortality from road traffic accidents is derived from the World report on road traffic injury prevention. Proportion of deaths among pedestrians in poor countries is from Nantulya VM, Reich MR.

"The neglected epidemic: road traffic injuries in developing countries". Reference to "developing countries" refers to region and mortality stratum as defined in the World health report 2003.