Have a science question on a public policy issue? Ask us.
Q: Do people with serious mental health disorders pose a greater risk of becoming mass shooters?
A: People with mental illnesses are somewhat more likely to be violent than those without a diagnosis. But a majority are never violent, and very little is known specifically about mass murder.
Q: Does the Amazon produce 20% of the world’s oxygen?
A: No. Scientists estimate the percentage is closer to 6 to 9%, and the Amazon ultimately consumes nearly all of that oxygen itself.
Q: When is the human heart fully developed, and when are heartbeats audible during pregnancy?
A: A developing heart has all of its primary structures after about nine weeks of pregnancy. Some forms of ultrasound can detect cardiac activity in an embryo in the sixth week, but a heartbeat wouldn’t be audible until about 10 weeks on a Doppler fetal monitor.
Q. Did the Environmental Protection Agency change its rules to allow companies to use asbestos in manufacturing?
A. No. Asbestos is already allowed in numerous products. A proposed EPA rule would prohibit the use of asbestos in certain products unless granted EPA approval.
Q: Did people develop cancer because of the polio vaccine?
A: There are no known cases, and it’s very unlikely. In the 1950s and 1960s, people did receive polio vaccines contaminated with a virus that causes cancer in rodents. But research suggests this virus doesn’t cause cancer in humans.
Q: Does the National Institutes of Health fund research on human-animal chimeras, or organisms that are part-human, part-other animal?
A: With some exceptions, the NIH doesn’t fund research on human-animal chimeras. But the agency has proposed a rule to widen the scope of research it funds in this area.
Q: Did climate change cause the wildfires out West?
A: Scientists say a hot and dry summer — conditions more likely in a warmer world — caused widespread wildfires in Western states. But land use changes also have played a role.
Q: Does the herbicide glyphosate cause cancer?
A: There is evidence to suggest it may cause cancer at very high doses, but not at the low doses typically found in foods.
Q: Is bacon better for you than tilapia? Does tilapia cause cancer and/or Alzheimer’s disease?
A: No. These false claims, spread by multiple websites, are not supported by solid scientific evidence.
Q: Have scientists confirmed that e-cigarettes cause an incurable respiratory disease called “popcorn lung”?
A: No. The vapor of some e-cigarettes contains a chemical associated with popcorn lung, and a case report suggests a possible link. But there’s not enough evidence to conclude the vapors cause the disease.