Relations between nasopharyngeal carcinoma and magnesium and other alkaline earth elements in soils in China.

Comparison of maps shows a striking geographical relation between high mortality rates from nasopharyngeal cancer in China and low contents of magnesium, calcium and strontium in the soil. We suggest that deficiencies of these elements in the soil could be indirect markers of aetiological factors, e.g. inhalable carcinogens of local natural origin. A search for such factors could be fruitful in further studies of environmental factors in the aetiology of nasopharyngeal carcinoma.