Gold mining practices in the northern Nigerian state of Zamfara have resulted in the deaths of 400 children from lead poisoning over the past two years, according to an international human rights group.

Human Rights Watch claims that thousands of children require urgent medical treatment, such as chelation therapy, and that many villages in the region are contaminated from lead dust, created when processing ore to retrieve gold.

The children become exposed to the dust while working down the mines, when coming into contact with relations who are miners or when the lead-filled ore is processed at home.

The group is concerned that the region