(AP) -- U.N. officials are warning that a lead poisoning outbreak that has killed more than 400 children in northern Nigeria has become "a neglected, underfunded emergency."
The report released Friday warns that the outbreak in Zamfara state remains an "alarming, continuing health risk" for an unknown number of villages in the rural area. The report says tests conducted by U.N. officials in September and October found lead levels in the air as high as 500 times the standard limit, while water and soil also were heavily contaminated.
The outbreak began in March, when small-scale gold mining operations in villages came across a vein of gold containing high levels of lead.
Lead poisoning can cause brain damage, blindness, deafness and death in young children.
Explore further: Transgender people pass on health care to avoid social stigma