Medical research

A firefighter walks near the entrance to NuStar Energy fuel storage facility Wednesday, Oct. 16, 2019 after a Tuesday fire in Crockett, Calif. Officials were trying to determine Wednesday if a 4.5 magnitude earthquake triggered an explosion at a fuel storage facility in the San Francisco Bay Area that started a fire and trapped thousands in their homes for hours because of potentially unhealthy air. (AP Photo/Jeff Chiu)

Democratic presidential candidate Sen. Bernie Sanders, I-Vt., left, and former Vice President Joe Biden hug during a Democratic presidential primary debate hosted by CNN/New York Times at Otterbein University, Tuesday, Oct. 15, 2019, in Westerville, Ohio. (AP Photo/John Minchillo)

Leslie Begay, left, speaks with U.S. Rep. Deb Haaland, D-New Mexico, in a hallway outside a congressional field hearing in Albuquerque, N.M., highlighting the atomic age's impact on Native American communities on Monday, Oct. 7, 2019. Begay, a former uranium miner on the Navajo Nation with lung problems, says there are lingering injustices and health problems on his reservation decades after mines closed. An Indian Health Service official cited federal research at the hearing that she says showed some Navajo women, males and babies who were part of the study had high levels of uranium in their systems. (AP Photo/Mary Hudetz)

This undated photo provided by Johns Hopkins University shows Gregg L. Semenza at the university in Baltimore. Semenza, a Johns Hopkins University researcher, was awarded the Nobel Prize for Physiology or Medicine on Monday, Oct. 7, 2019. He will share the prize with Drs. William G. Kaelin Jr. and Peter J. Ratcliffe for their discoveries of how cells sense and adapt to oxygen availability, the Nobel Committee announced Monday. (Johns Hopkins University via AP)

FILE - In this Aug. 7, 2018 file photo, a doctor performs an ultrasound scan on a pregnant woman at a hospital in Chicago. A new study released Tuesday, Sept. 17, 2019, suggests when a pregnant woman breathes in air pollution, it can travel beyond her lungs to the placenta that guards her fetus. During pregnancy, particle pollution is linked to premature births and low birth weight, but scientists don’t understand why. (AP Photo/Teresa Crawford, File)

FILE - In this March 12, 2010 file photo Mercedes Grand Prix driver Michael Schumacher of Germany is pictured in the pits during the first practice session at the Formula One Bahrain International Circuit in Sakhir, Bahrain. A Paris newspaper says seven-time Formula One world champion Michael Schumacher is being treated with a cutting-edge stem-cell therapy in one of the French capital's hospitals. (AP Photo/Ben Curtis, File)

FILE - In this Wednesday, July 15, 2015 file photo, a lesbian couple holds hands in Salt Lake City. Released on Thursday, Aug. 29, 2019, the largest study of its kind found new evidence that genes contribute to same-sex sexual behavior, echoing research that says there is no single “gay gene.” (AP Photo/Rick Bowmer)