The Environment and Human Health: An agenda for research. Background paper for the Environment and Health Research Theme



The environment and health are intricately linked. The environment is the life support system
that provides fundamental needs for water, land, air, shelter and climate for humans and for all
other forms of life. Changes in these conditions, however, can significantly alter humans’ well
being and their health. These changes are in the physical and biogeochemical environment,
either caused naturally or influenced by human activities such as deforestation, fossil fuel
consumption, urbanisation, land reclamation, agricultural intensification, freshwater extraction,
fisheries overexploitation and waste production, which are driven by complex socioeconomic
and natural processes, giving rise to ‘global environmental change’ (Leemans et al., 2009:1).
These are ‘global’ in the sense of either being globally integrated (i.e., entailing a systemic
change to a global system, such as the climate system) or occurring by worldwide aggregation of
widespread local changes (e.g., land degradation, species extinctions) (Confaloneri and
McMichael, 2007:8). Approximately 60 per cent of the benefits the environment provides in
order to support life on earth are being degraded or used unsustainably. The World Health
Organisation (2005) warns of the harmful consequences of these degradation processes on
human health, which could grow significantly in the next fifty years. While the environment
plays a fundamental role, socioeconomic, demographic, technological advancement and human
body metabolism factors equally influence human health, which WHO defines as “a state of
complete physical, mental, and social wellbeing and not merely the absence of disease or
infirmity”. These health conditions are the ‘bottomline’ for human welfare and a crosscutting
issue within ecological services. Understanding the interaction between these two systems is
therefore vital for adapting and preventing disease, as well as for alleviating poverty.
Scientific evidence to support the associations between environmental contaminants and
human diseases remains circumstantial. The Global Burden of Diseases reveals water, sanitation
and hygiene as the major risk factors for global ecological deaths (Table 1), followed by indoor
air pollution. Overall, environmental pollutants account for 8 per cent of the total global disease
burden. The magnitude of health implications from exposure to environmental factors was only
assessed a decade ago with the standardisation measure of health outcomes (Disability
Adjusted Life Years or DALYs refer to Box 1) across various causes of illness and death (Murray
and Lopez, 1996). The estimates (Table 2) reveal that the disease burden from environmental
factors is higher in developing countries than in others (27 per cent in Africa and 18 per cent in
Asia), as these countries house most of the world’s poor people.

Table 1: Global Burden of Disease Attributable to Selected Sources of Pollution
In thousands Per cent In Thousand Per cent
Total (all risk factors) 55,861 1,456,473
Water, Sanitation and Hygiene 1,730 3.1 54,158 3.7
Urban Outdoor Air Pollution 799 1.4 6,404 0.4
Indoor Smoke from Solid Fuels 1,619 2.9 38,539 2.5
Lead 234 0.4 12,926 0.9
Total Ecological Pollution
4,382 7.8 112,027 7.6
Note: This information does not include people affected by chemical and geogenic pollution as a result of
global environmental change.
Source: Ezzati et al. (2002), cited in Eyles & Consitt (2004:26).
The burden of disease from major environmental risks is at its highest in SubSaharan Africa,
Asian & Pacific islands and Middle Eastern and North African countries (Table 2). Of the
mentioned factors, inadequate water supply and sanitation pose the largest threats, while air
pollution causes the most damage in China and in European transition economies. Indoor air
pollution is the greatest threat in Asia and SubSaharan Africa, and malaria has taken a heavy
toll, but only in SubSaharan Africa. These international estimates do not include people
DALYs as a measure of the burden of disease
Disabilityadjusted life years are a standard measure of the burden of disease. The
concept of DALYs combines life years lost due to premature death and fractions of years
of healthy life lost as a result of illness or disability. A weighting function that
incorporates discounting is used for years of life lost at each age to reflect the different
social weights that are usually given to illness and premature mortality at different ages.
The combination of discounting and age weights produces the pattern of DALY lost by a
death at each age. For example, the death of a baby girl represents a loss of 32.5 DALYs,
while a female death at age 60 represents 12 lost DALYs (values are slightly lower for
males). The use of DALYs as a measure of the burden of disease has provided a consistent
basis for systematic comparisons of the costeffectiveness of alternative interventions
designed to improve health. When combined with the results of largescale
epidemiological studies, it enables public health specialists to identify priorities and focus
attention on development programs that have the potential to generate significant
improvements in the health status of poor people in the developing world.
Source: Murray and Lopez (1996), cited in Lvovsky (2001:3).

affected by industrial and domestic water pollution or health impacts from the degradation of
Table 2: Burden of Disease from Major Environmental Risks
(% of all DALY’s in each country group)
Health Groups
SSA India Asia &
Water Supply &
10.0 9.0 8.0 3.5 8.0 5.5 1.5 1.0 7.0
Vector Disease
9.0 0.5 1.5 0.0 0.3 0.0 0.0 0.0 3.0
Indoor Air
5.5 6.0 5.0 3.5 1.7 0.5 0.0 0.0 4.0
Urban Air
1.0 2.0 2.0 4.5 3.0 3.0 3.0 1.0 2.0
1.0 1.0 1.0 1.5 1.0 2.0 2.0 2.5 1.0
All Causes 26.5 18.5 17.5 13.0 14.0 11.0 6.5 4.5 18.0
Notes: SSA: SubSaharan Africa; Asia & Pacific includes countries from East and South Asia, except India,
China, Pakistan and Afghanistan; MENA: Middle East and North Africa; LAC: Latin America and Caribbean;
FSE: Former Socialist Economies of Europe and does not include Central Asia; IC: industrialised nations;
and DC: developing countries.
Source: Lvovsky, 2001
The linkage between the environment and health is evident: the (mis)management of natural
resources, natural disasters and global environmental change has increased the risk to human
health (Table 3). Diseases such as diarrhoea and malaria are largely related to inadequate
drainage of surface water, which encourages the breeding of bacterial pathogens and malarial
vectors. Other diseases are the result of excessive use of existing water sources and the
discharge of polluted water, which has not only resulted in impacts on human health, but also
on land, water and other ecological systems. Land degradation plays a crucial role in influencing
human health due to changes in landuse patterns, offering a favourable breeding ground for
disease vectors such as malaria and diarrhoea and resulting in airborne pollution. Air pollution1
resulting from land degradation, excessive use of forest products and forest fires has impacts on
respiratory disorders and cancerous diseases. These natural resourcerelated impacts caused by
natural disasters such as flooding, tsunamis, landslides and earthquakes and from global
environmental change have become a major threat. The literature on the environment and
health is vast, so given the limitation of scope the current paper focuses on waterrelated and
landrelated diseases.
1 This also results from burning of petrochemical products.

Table 3: Environmental Health Disorders
Infectious waterrelated Diarrhoea and vectorrelated diseases (such as malaria,
schistosomasis, dengue)
Noninfectious Water Related Fluorosis, arsenicrelated disorders
Industrial and domestic pollution Diverse health impacts ranging from rashes to cancer
desertification, loss of wetland, flood
Increased exposure to infectious agents
Deficiencies in vitamin A, zinc and iodine.
AIRRELATED (indoor and outdoor air
pollution) Respiratory disorders, cancer, tuberculosis
DISASTERS (earthquake, tsunami
flooding, landslide)
Increased risk of infection leading to diarrhoea,
malaria, dengue and West Nile fever.
Tuberculosis, bloodborne viruses, gastrointestinal
infections, damage to health infrastructures
Transboundary SARS, AIDS and Avian influenza
Climate change Increase in malaria, diarrhoea
The paper examines the underlying question about how environmental factors align with man
made changes to influence human health2, by drawing on a wide range of published peer
reviewed research papers and reports from national and international agencies. Specifically, the
review examines the literature to define the incidence of environmentallyrelated diseases, the
role of factors in influencing these diseases, their distribution across social and geographical
plains and the adaptive capacity of societies to manage these diseases, illnesses or disorders.
The paper tends to focus on highly populated developing and fastgrowing economies in
mainland of Asia, Latin America and Africa. It is in these countries where half the worlds’
population live, and at the same time has a large proportion of population undernourished and
are living in poverty