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©2000 Blackwell Science, Inc.

Introduction: Special Section on the Health Costs of

Ecological Degradation

At the recent International Congress on thetheme of “Managing for Ecosystem Health”

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inSacramento, California, August 15–20, 1999, theInternational Society for Ecosystem Health on be-half of Health Canada organized and coordinateda technical session entitled the Health Costs ofEcological Degradation (TS-23, August 17, 1999).The session featured four presentations, three ofwhich appear in this issue. These contributionshighlighted the considerable risks to humanhealth from ecological degradation, as well as theconsiderable opportunities for averting theserisks through collaborations between health sci-entists and ecosystem scientists.

Dr. Jonathan Patz, Johns Hopkins School ofHygiene and Public Health, demonstrated howquantitative methods are now being used to assessthe public health implications of global climatechange. He focused on six specific threats: (1)mortality related to heat waves in the UnitedStates; (2) hantavirus; (3) malaria; (4) dengue fe-ver; (5) water borne cryptosporidiosis; and (6)cholera. In each case, Dr. Patz elucidated the eco-logical determinates that governed the preva-lence of these diseases and associated health risks.These advanced methods, making use of remotelysensed data, GIS, and epidemiological assess-ments, have wide application to formulating strat-egies to minimizing human health risks from eco-logical change.

Professor Tony McMichael, London Schoolof Hygiene and Tropical Medicine, examined therisks to human health from global environmentalchange. His thesis was that a very long shadow isnow cast over the prospect for human health asthe result of the disruption of regional and globalecosystems. It is now possible to estimate the im-pact on population health as a result of global cli-mate change, ozone depletion, invasive species,etc. These estimates, to be sure, often compounduncertainties, and therefore the confidence inter-

vals on the final results are rather wide. Yet themodels do provide a basis for a more enlightenedhealth policy. For example, scenario-based mod-eling of the impact of stratospheric ozone destruc-tion indicates that European and North Americanpopulations will experience significant increasesin skin cancer (5–10% excess) over present ratesby the middle decades of this century. Other rela-tionships are more qualitative, but nonethelesssignificant. For example, the introduction of thewater hyacinth to East Africa’s Lake Victoria fromBrazil, has provided a fertile breeding groundsfor the water snail that transmits schistosomiasis,and for bacteria causing diarrheal diseases. Tak-ing into account considerable uncertainties as tohealth outcomes, Dr. McMichael argues that wemust act now on what is known, applying the pre-cautionary principle, and that conventional, single-risk factor analysis is no longer adequate but that asystem approach is required.

Dr. Richard Burnett, Health Canada, ad-dressed the topic of the impact of air pollution onhuman health in Canada and in other countries.He concluded that, although there are many con-founding factors, the overall consistency of epide-miological data strongly suggest that prematuremortality, cardiorespiratory hospitalization, andemergency department visits for respiratory dis-eases, asthma attacks, etc., are correlated with airpollution. The economic analysis suggests that bil-lions of dollars would be saved from more strin-gent air quality standards.

This technical session brings together state ofthe art methodology to the assessment of humanhealth implications of environmental degrada-tion. The articles cover critical dimensions of thisproblem, exploring the approaches to uncer-tainty, approaches to integrated data analysis andmodeling, approaches to cost-estimates of humanhealth damage associated with environmentalchange, and approaches to a comprehensive frame-work for decisions on public health related to en-vironmental degradation. Collectively, these pa-pers provide a thoughtful approach to integratinghuman health and the environment.

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http://www.vetmed.ucdavis.edu/centers/iseh/ecosystemhealth.html