1.   After nine months as people were getting accustomed to feeling well, they were less compliant with their follow up data.

2.   Analyses comparing rates of non-smoking among study groups at each follow up were repeated for non-smokers at baseline rather than never smokers.

3.   Follow up geophysical work has been done at selected sites to assess what water resources are actually present.

4.   Information for the follow up study was collected by means of personal interviews, death certificates, and records from hospitals and nursing homes.

5.   Many hoped to achieve a reduction in numbers of follow up appointments.