9.5.1 Need for EHIA

The WHO has identified a number of reasons for the need to undertake an EHIA. They include: prevention is better than cure, as with other forms of assessment; it is specified in many forms of EIA legislation; environmental degradation is linked to health impacts; the methodology can be incorporated in EIA; systematic inclusion of health impacts improves the legitimacy of the decisions made and the process by which they are taken; human health issues often prompt a public response and/or involvement; and there is no argument against it!

Although the need for EHIA is self-evident and is clearly spelt out by the WHO, there are some inherent difficulties in undertaking an EHIA: lack of baseline data on humans in local communities; the timescale for health effects to show up is very long; the interaction of different chemical, physical, and biological agents, their synergistic/antagonistic effects, etc., make it difficult to isolate the individual agent or group of agents responsible for the adverse impact - in other words, a clear cause/effect relationship is difficult to determine; the variety of human responses and exposures; limited knowledge of dose-response relationships; and planners and decision makers may feel that health is not their responsibility.