Researchers examined people who were children when they lived through 2001 World Trade Center attacks in New York.

Sixteen years after the 9/11 terror attacks left thousands dead in three states, researchers are still learning new ways the attacks have affected survivors.

In New York, first responders who worked for days and weeks on end in the rubble of the World Trade Center, were already known to be at risk for a host of health risks.

These include breathing problems, post-traumatic stress disorder (PTSD), rheumatoid arthritis (RA), and certain cancers.

Now in a recent study, researchers found that the estimated 2,900 children exposed to the dust, debris, and chemicals left behind after the World Trade Center attack could face health hazards years and decades later.

When the twin towers fell, the dust and debris that enveloped lower Manhattan was full of chemicals called perfluoroalkyl substances (PFAS), known to affect cardiac health among other systems.

In laboratory settings these chemicals have been found to disrupt “metabolic, cardiovascular, and renal function,” according to the study authors.

For this study, published recently in Environment International, the researchers wanted to study children’s exposure to PFAS since these chemicals are common in upholstery, carpet, and building and construction materials.

They looked at 308 children — 123 who had direct contact with the dust left behind in the collapse of the World Trade Center.

The team has been studying the effects of the World Trade Center attacks on the people who lived, worked, or went to school nearby.

Dr. Leonardo Trasande, lead author of the study and a physician at the Department of Pediatrics at NYU School of Medicine, said researchers focused on younger children because exposure to chemicals at an early age can affect health years down the line.

“This is a vulnerable subpopulation in which early life exposures are known to be key,” Trasande told Healthline. He explained these findings could be a “signal for later cardiovascular risk.”

The team found that the children who were exposed to the dust and debris following the 9/11 terror attacks in New York had higher levels of PFAS compared with those that were not exposed to the event.

Of these chemicals, perfluorooctanoic acid levels (PFOA) were tied to an average of 9 to 15 percent increases in blood fats in these children. These fats include LDL cholesterol or triglycerides, which can affect cardiac health.

Trasande said the children, who are now teens and young adults, will not definitely develop heart disease, but they can take extra steps, such as eating healthy and exercising, to diminish their risk.

Trasande said that these early findings show that more needs to be done to see how these chemicals affect the people who were exposed to them as children.

He pointed out that in the beginning the researchers did not realize how impactful these chemicals could be on young children.

“Unfortunately a lot of the attention has been on the psychological and respiratory consequence in kids in particular,” he said.

Now, he said, scientists know that these chemicals can have long-term consequences on hormones systems, as well as the cardiac system.

He hopes to study how these exposures may affect puberty or fertility in this group in the future.

“I hope research like this sets the stage for better anticipating and planning for and monitoring for health effects,” of disasters, Trasande said.

Dr. Michael Crane, from the World Trade Center Health Program Clinical Center, has been studying and treating the first responders to the 9/11 attacks.

He said it’s key to keep looking for potential health effects, especially since many people who were exposed to the debris from the 9/11 attacks have not come forward to have their health monitored by specialized experts.

“There’s a big need for more research to understand what happened in the community,” he said.

He pointed out that this kind of research is key in helping unravel the long-term effects of the 9/11 attacks, especially since these effects might appear decades down the line.

Additionally, many of those exposed might have moved away and may not be aware that they are at increased risk for a host of health effects related to the event.

“We’re really concerned that a lot of people living in the community aren’t getting the attention that they need now,” he said.

Crane did say that in the 16 years since the World Trade Center fell, he has seen a change in how medical experts and authorities respond to disasters.

He pointed out that in Houston, where Hurricane Harvey has affected thousands, authorities have recognized that the event can be traumatic and cause long term mental health problems.

Additionally, he was heartened that officials consistently warned people to stay out of the toxic flood waters to protect themselves from environmental dangers.

“I think the responders and the people who were trying to guide the response have things in mind that were really good lessons from the World Trade [attacks],” he said.