Here’s an article from Mayo Clinic:
Lead Poisoning
By Mayo Clinic staff
Lead poisoning occurs when lead builds up in the body, often over a period of months or years. Even small amounts of lead can cause serious health problems. Children under the age of 6 are especially vulnerable to lead poisoning, which can severely affect mental and physical development. At very high levels, lead poisoning can be fatal.
Lead-based paint and lead-contaminated dust in older buildings are the most common sources of lead poisoning in children. Other sources of lead poisoning include contaminated air, water, soil, and some toys and cosmetics.
Much More:
http://www.mayoclinic.com/health/lead-poisoning/fl00068