Scientists don't know what causes it, but besides a genetic predisposition, they are now focusing on environmental exposure, or a combination of the two.

VOA: standard.2010.08.09

They live much longer lives and they live to die of something else and the leading causes of death currently haven't changed very much since 1997 when this data was published: they die of heart disease and cancer primarily.

人们活的更久了,不过会死于另一些疾病,如今导致死亡的主要原因,并没有太大的变化,自一九九七年有相关数据公开开始,其显示人们主要死于心脏病和癌症

耶鲁公开课 - 生物医学工程探索课程节选

"I don't see a need to overhaul the regulations. The regulations cover the major causes of pipeline failures,and we do not see any gaps."

VOA: special.2011.07.08

"While it provides a sometimes useful tool after an event, it doesn't address the root causes of crime and doesn't protect the public, " said the group's director, Nick Pickles.

WSJ: Bombing probe highlights expansion of surveillance

Scientists don't know what causes pancreatic cancer, according to the American Cancer Society.

CNN: What's the danger of an all-fruit diet?

And while scientists still don't know what causes the disease, they believe common irritants found in homes across the country can trigger an attack.

NPR: Calif. Program Helps Rid Triggers of Asthma