The 9/11 terrorists attacks happened 16 years ago, but it is still impacting people. Those who were children who lived by or went to school near the World Trade Center in Manhattan are showing early signs of risk for future heart disease, according to a new study by NYU Langone Health researchers.

The collapse of the two World Trade Center towers caused a huge cloud of toxic debris to take over the streets of Lower Manhattan, leading the children in the area to breath in the ash and fumes.

The children who were more likely to be exposed to the toxic dust are mostly young adults now. Researchers conducted blood tests on 308 individuals who were children at the time, including 123 who may have had direct contact with the debris cloud on that day. Experts found that the individuals with higher blood levels of the chemicals that are known to have been in the debris cloud had elevated levels of artery-hardening fats in their blood.

Toxic Debris Children Breathed In

Toxic debris from the buildings had “large amounts of contaminants,” including particulate matter, heavy metals and persistent organic pollutants (POP), elevated concentrations of perfluoroalkyl substances (PFASs), a group of chemicals widely used in various building and construction material, upholstery, carpet, and non-stick cookware, the study said.

The study’s lead investigator and health epidemiologist Dr. Leonardo Trasande said the long-term danger may have derived from exposure to specific PFASs, which are chemicals that rose up into the air when electronics and furniture were burned. Those chemicals include perfluorooctanoic acid (PFOA), which is used to add extra flexibility to plastic. U.S. manufacturers discontinued the use of PFOA in 2014 when realizing it was linked to health issues, including lower-than-normal birthweights and brain damage.

A separate study by Trasande earlier this year showed the same 123 children had significantly higher PFOA blood levels than 185 children who did not live or go to school in the city on 9/11. The recent study shows every threefold increase in blood PFOA levels was linked to about nine percent to 15 percent spike in blood fats, including low density lipoprotein (LDL) cholesterol and triglycerides. Raised fat levels in a person’s blood, especially LDL, can lead to heart disease, and leaving it unchecked can cause blood vessel blockages and heart attacks.

However, Trasande said the individuals have very early signs of cardiovascular risk, which means it can be treated by eating right, controlling weight and exercising.

“What's reassuring here is that we didn't see specific effects on heart stiffness and artery stiffness,” Trasande told International Business Times. “We know that healthy dieting and physical activity can help.”

He added that the findings are still “warning signals -- there’s no doubt about it.”

Trasande, an associate professor at NYU School of Medicine, said the study is the first to suggest long-term cardiovascular health risks in children from exposure to toxic debris on 9/11. He told IBT cardiovascular risks “in the context of disaster have been under recognized and understudied,” since the focus shifts heavily towards mental repercussions.

"Since 9/11, we have focused a lot of attention on the psychological and mental fallout from witnessing the tragedy, but only now are the potential physical consequences of being within the disaster zone itself becoming clear," Trasande said in a released statement.

The findings were published in the journal Environment International on Thursday.

The individuals who participated in the study were enrolled in the World Trade Center Health Registry (WTCHR). Through annual checkups, the registry helps track the physical and mental health of nearly 2,900 children who lived in or went to school in Lower Manhattan during the terrorist attacks. WTCHR is the biggest U.S. registry ever to track the health effects of a disaster.