Lead poisoning refers to the condition where there are high levels of lead present in the blood. Lead is a toxic metal that can enter the body through various sources such as contaminated water, paint, or soil. When lead accumulates in the blood, it can cause serious health problems, especially in children. Symptoms of lead poisoning include abdominal pain, headaches, developmental delays, and cognitive impairment. Therefore, the correct answer is high levels of lead in the blood.