No adverse health effects from the radioactivity or other trace elements have been demonstrated and calculations show that level of radioactivity would probably be much too low to be detected in the population. These unusual soils are very rich in phosphate, but it is not accessible to plants, being in the very insoluble form of iron phosphate, or crandallite. It is thought that rather similar radioactive soils may exist on Lifou and Mare near New Caledonia, and Rennell in the Solomon Islands, but no other locations are known.The time difference between Niue and mainland New Zealand is 23 hours during the Southern Hemisphere winter and 24 hours when the mainland uses Daylight Saving Time.