Ecosystem health: challenges for ecotoxicology and environmental health.

Restoring and safeguarding ecosystem health is a major challenge for the 21st century. Man-made substances, particularly persistent bioaccumulative substances have been among the forces that have contributed to weakening the health of ecosystems. However there are other stresses that interact synergistically with chemical stress. These forces, such physical restructuring (habitat change) tend to enhance the impacts of chemical stresses. A dose-response framework that encompasses an array of stresses with synergistic and occasional antagonistic effects is proposed for the assessment of ecosystem health. The flow of ecosystem services is curtailed in damaged systems. These services, such as provision of biodiversity, potable water, foodstuffs, sequestering of contaminants, will determine the suitability of ecosystems for humans. Linking ecotoxicology to ecosystem health provides an avenue for relating a variety of pressures on ecosystems to the conditions essential to sustain life that includes human communities.