Chapter 1: Environment, Health and Risk
• Global warming, population growth, habitat destruction and resource depletion
have produced a widely acknowledged environmental crisis.
• These long term environmental pre thioblems are not amenable to quick technical
fixes and will require profound social changes for their solutions.
• The environmental crisis:
• Human beings are altering the basic operations of the earth’s atmosphere,
geosphere and biosphere.
• Four prominent biologists have noted with concern that “human alteration of earth
is substantial and growing.
• Between one third and on half of the land surface has been transformed by human
• There is a decline in frog populations around the world.
• The health and reproductive success of amphibians is being damaged by
interactions between an increase in the intensity of ultraviolet light, traces of
globally distributed toxic chemicals, competition from introduced predator
species and infections caused by virulent fungi and bacteria.
• Declining health of frogs, birds and thousands of other organisms may be the
clearest indication of environmental threats to human health.
• Today’s environmental degradation is rapidly creating an unprecedented global
crisis. The driving forces are population growth and industrialization.
• Human activity increased the atmospheric concentration of carbon dioxide by
nearly 30%, doubled the concentration of methane and introduced long lived
ozone destroying chlorofluorocarbons into the stratosphere.
• Human and Ecosystem Health:
• From a medical standpoint health is viewed as an attribute of the individual.
• An ecosystem based health perspective takes into account the health related
services that the natural environment provides and acknowledges the fundamental
connection between an intact environment and human health.
• An ecosystem health stance is a nonanthropocentric, holistic worldview
increasingly shared by biological scientist.
• In the anthropocentric view of the world, humans are the most important of all the
species and should have dominion over nature.
• Has been concluded that the earthy is warming and that green house gases are part
of the cause.
• Health and the environment:
• The health effects of global changes are often indirect and difficult to asses, and
the quality of evidence for the health related outcomes of global environment
change varies widely.
• The health science necessary to understand global environmental change is
increasingly interdisciplinary and requires collaboration over long periods among
meteorologist, chemists, biologists, agronomists and health scientists. • The sciences of global change frequently relies on computer models to suggest the
direction and magnitude of change, but politicians and policy makers are loath to
commit resources to predicted but unproven future outcomes.
• Environmental degradation exaggerates the imbalance between population and
resources, increases the costs of development and worsens the extent and severity
• Interaction between poverty, population growth and environmental degradation
impede sustainable economic development and worsen population health.
• Changes in natural system may be sudden and nonlinear.
• Two recent developments have drawn renewed attention to the health risks of
industrial chemicals known as persistent organic pollutants (POPs): the
indemnification of medical waste as a significant
• Medical waste incineration is a major source of dioxin and mercury released into
• The second development is the emerging toxicological field of endocrine
• Risk and Caution: Some Definition
• a risk is a potential threat to health and life
• How we assess, perceive, communicate and manage risk is termed risk analysis. o
• Risk analysis is a substantive, changing and controversial field.
• Risk assessments provide probability figures that apply to populations, not to
• Exposure refers to the intensity and duration of contact with a substance or with a
physical agent such as ultraviolet, x-ray or microwave radiation.
• Inhalation, skin absorption, and ingestation are the possible routes of