environmental health policy role in health

environmental health policy role in health. Choose an environmental health policy to research and evaluate its effectiveness in achieving health protection. Be sure to include the issue the policy was developed to address, the relevancy of the policy, and (if possible) the cost effectiveness of the policy using evidence (research). Some examples of environmental health policy can be found in the areas of water treatment, food safety, air quality, waste treatment, and others. 
What are some challenges that are encountered during the evaluation process? What impact could this have on resource allocation for public health programs?