DDT pesticide exposure linked to Alzheimer's disease, study shows

Scientists have known for more than 40 years that the synthetic pesticide DDT is harmful to bird habitats and a threat to the environment. Now researchers say exposure to DDT -- banned in the United States since 1972 but still used as a pesticide in other countries -- may also increase the risk and severity of Alzheimer's disease in some people, particularly those over the age of 60.