Lead is a highly toxic metal that can severely impact children's health. Lead poisoning can be responsible for everything from mood swings and disrupted sleep to kidney damage and retardation. Although it is known to cause behavioral changes, lead poisoning is nearly impossible to diagnose without a blood test, so it's important to make sure children are tested regularly. Most homes built before 1978 used paint that contained lead, so paint dust is a big concern in older homes, because it can easily get onto children's hands. Luckily, lead poisoning is completely preventable if you learn about it and take steps to eliminate exposure and risks.