choice water according to researchers at virginia tech. the city wasn t treating it krorth federal law. lead pipes began to core rode, leeching into the water. if you were to put something into a population for generations to come, it would be lead. reporter: this doctor is a pediatrician at flint children s hospital. it is a well known potent mineral toxic. there is tons of evidence. and it is one of the most damming things you can do to a population. it drops your iq. it affects your behavior. it is linked to criminalality. it has multigenerational impact. there is no safe level. reporter: after hearing about water that looked and tasted funny. she decided to investigate, using publicly available data on lead levels on children in flint she found the percentage of lead in kids doubled, even tripled in some places after the water