For several months in April and November 2004, U.S. troops were engaged in some of the heaviest fighting they had seen since the Vietnam War, dropping more than 300 bombs, 391 rockets and roughly 4,000 artillery rounds to support intense ground battles to reclaim the Iraqi city of Fallujah from insurgents.

In 2014, Islamic State members captured the city, occupying it for more than two years until it was retaken by Iraqi forces.

Today, as Fallujah slowly rebuilds, the cost of the fighting is evident in the public health of its residents, according to a new study. For the first time ever, researchers have detected uranium in the bones of living Fallujah residents, high levels of lead in residents of previously bombarded neighborhoods, and a significant number of birth defects in babies born to those in the city.

Read Next: NATO Chief Says 4 US Soldiers Who Went Missing in Lithuania Died

According to the authors of the study, “Lessons from Fallujah: War Returnees Face Long-Term Health Risks from Heavy Metal Exposure,” there are takeaways from the research for anyone living in a former combat zone but also those who experienced short-term exposure, such as U.S. troops who fought on contaminated soil, inhaled the dust, and lived near the burn pits used to dispose of battlefield waste.

“What we are finding in the environment, in the body, is the sheer permanence of war’s effects,” said Kali Rubaii, an assistant professor in the anthropology department at Purdue University. “In an interesting way, we measured that with numbers.”

According to the study, supported by Brown University’s Costs of War Project, Fallujah’s population has seen a 17-fold increase in birth defects and anomalies since 2003. Using a special bone scan known as X-ray fluorescence, or XRF, the researchers found uranium in the bones of 29% of study participants. And the scans also showed lead contamination in 100% of those tested, at rates 600% higher than average U.S. rates.

Lead poisoning in children can harm the brain and central nervous system; cause learning, behavior, hearing and speech issues; and slow development, according to the Centers for Disease Control and Prevention.

In adults, lead accumulates over time in the bones. While it largely remains locked there, with age, it can be released back into the bloodstream, especially during pregnancy or in the presence of osteoporosis or kidney disease.

Although adult lead poisoning is uncommon, it can cause depression, fatigue, irritability, memory loss, impotence, and heart conditions, according to the National Organization for Rare Disorders.

Regarding uranium exposure, the Agency for Toxic Substances and Disease Registry, the federal agency concerned with public health risks associated with exposure to hazardous substances, said uranium can cause damage to the kidneys and respiratory tracts, but “no health effects other than kidney damage have been consistently found in humans after inhaling or ingesting uranium compounds or in soldiers with uranium metal fragments in their bodies.”

In the late 2010s, XRF testing conducted on 38 U.S. troops — mainly Special Forces members — found they had higher-than-normal bone lead levels as a result of their jobs, with four having roughly twice the expected amount. The numbers tested were small, but the soldiers in the study had struggled for years with unexplained symptoms, according to reports in The New York Times and Military.com.

U.S. veterans of Fallujah did not experience the long-term exposure that current residents of the city do and aren’t likely to experience the health consequences that the Iraqis have had, Rubaii said. They also have access to quality nutrition and health care, factors that are key to addressing the health consequences of heavy metal exposure, she added.

But that doesn’t mean that there aren’t steps that former service members can take to protect their health, she added. Since heavy metals are absorbed into bones, where they largely remain stable, taking precautions to limit lifetime exposure from further contaminants in water, the soil and air is recommended, she said.

“It means making sure your city doesn’t allow industries to pollute, advocate for air quality regulations, smog checks — prevent the additional burden to their bodies,” Rubaii said.

The report also recommends that those returning to a former war zone don masks or scarves to avoid inhaling fine particles; bury trash instead of burning it; consume a diet high in calcium and vitamins C and D to protect bones; and for pregnant women, increase the amount of folate consumed to promote the healthy growth of their fetuses.

Rubaii said more research should be conducted on the long-term health effects of war exposure, especially in U.S. troops, and she suggested that a database kept by the nonprofit group Burn Pits 360, which maintains a registry of medical diagnoses and treatments of U.S. service members in Iraq and Afghanistan, is fertile ground for studies.

In an open letter to President Donald Trump earlier this year, the group urged the federal government to support such investigations.

“Strengthen research, prevention and early screening programs,” the group wrote. “Veterans deserve proactive rather than reactive care. Implementing advanced lung and cancer screenings, biomarker testing, and toxic exposure health monitoring programs will save lives by detecting diseases early.”

Rubaii added that her group is looking at how women who live in these environments can improve the health outcomes of future babies and generations.

“The next level is to do analysis of the factors that might play a role for reproductive health outcomes, so really trying to help women understand what environmental factors they can control to affect the next generation,” Rubaii said.

Related: Military Medical System Not Ready for War Due to Cuts and Delayed Reforms, Experts Warn