Leukemia and the Environment

Leukemia is cancer of the blood cells. When leukemia develops, the body makes many abnormal blood cells.

Leukemia comprises a group of diseases that includes four major types:

• Acute myeloid
• Chronic myeloid
• Chronic lymphocytic leukemia (primarily adult diseases)
• Acute lymphocytic leukemia (a childhood disease).

Sometimes considered a children's disease, leukemia usually occurs in adults older than 65 years. Additional research is needed to better understand the relationship between leukemias and the environment. Exposure to high levels of ionizing radiation has been linked to specific types of leukemia in both adults and children.

Exposure and Risk

As with most cancers, the cause of most leukemias is unknown. Generally, some risk factors include:

• High doses of ionizing radiation
• Genetic abnormalities, including Downs syndrome
• Rare viruses
• Long-term benzene exposure
• Smoking
• Chemotherapy drugs known as alkalating agents

The relationship of these factors may depend on the type of leukemia. Moreover, adult leukemia risk factors differ from those of children. For adult-onset leukemia, the most firmly established environmental risk factor is exposure to ionizing radiation; benzene, agricultural exposures, and smoking also have been linked to elevated risk. For acute lymphocytic leukemia in children, their exposure to ionizing radiation and a parent's exposure to pesticides and other chemicals may increase risk.

Prevention

Not smoking can reduce the risk for acute myeloid leukemia. Avoiding unnecessary radiation exposure can prevent many types of cancer.