Collaborative studies on the geographic distribution of caries-resistant naval recruits illustrate the type of data available when scientists from many disciplines become interested in a health problem. In a study of the state of Ohio it was found that the residences of 62 percent of the caries-resistant men were on high-lime Wisconsin Till soils associated with rocks that contain extensive celestite deposits. The water supplies had significantly more boron, lithium, molybdenum, and strontium than the finished water supplies for the seven largest cities in Ohio. A rat-feeding experiment is described in which the water from the caries-resistant area produced a reduction in caries of rats. A vegetable-cooking experiment showed that certain trace elements in the water are taken up by the vegetable and other elements are released to the water from the vegetable. This may be an important factor in daily mineral intake. Selenium concentrations in human blood show an association with geographic differences in selenium distribution in plants. A plea is made for a pooling of resources between environmental geochemists and medical, dental, and animal investigators.