Anemia and the lack of iron have been proposed as causes of geophagia. But treatments with minerals and placebos has not often resulted in patients refraining from ingesting soil. Some researchers have claimed that iron deficiency and anemia are in fact the result of soil ingestion. Other factions within geophagia research point to developmental disturbances and a compulsive persistence of infantile hand to mouth behavior as the explanation of geophagia. The habit of eating soil is often attributed to the poorest regions of the world. But it is not clear if starvation can fully account for geophagia. It looks as though in some countries, geophagia is part of a cultural pattern among certain groups. In Ghana, for example, clay is sold as medication, and in Guatemala, clay briquettes with cathedral designs on them are sold to pregnant mothers. What makes geophagia even more complicated is that clay can in fact have a benign effect on different kinds of stomach problems and poisonings. In the US, the majority of geophagia cases have been among the poor black population in the south, but there have also been cases in New York City. Two different researchers (W. H. Crosby and R. P. Wedeen) propose the surprising theory that soil eating can no longer be connected to specific socioeconomic factors but has spread to a larger, less definable segment of the northern urban population in the US.