Terrible price of 9/11: Rescuers still suffer health problems
A decade after terrorists attacked the World Trade Centre in New York, rescue and recovery workers are still bearing the physical and mental scars, research has shown.
Data gathered on more than 27,000 police officers, firefighters, and construction and municipal workers revealed that many suffer continuing ill-health.
A separate study showed that firefighters exposed to toxic dust and chemicals in the aftermath of the outrage had a 19% increased risk of cancer.
Almost 3,000 people died when Islamic extremists flew two passenger jets into the World Trade Centre twin towers on September 11 2001. Among them were 343 firefighters.
The collapsing buildings released choking clouds of dust and debris containing toxic substances, including known cancer chemicals.
More than 50,000 rescue and recovery workers are estimated to have provided assistance after the attacks.
One of a series of studies published in The Lancet medical journal looked at how many of them continued to suffer from a range of health problems.
It showed that the risk of asthma, sinusitis and gastro-oesophageal reflux disease (GERD) - a condition marked by chronic heartburn - was greatest in workers with the highest levels of exposure.
Overall, almost a tenth of rescue and recovery workers had been diagnosed with all three conditions while 18% suffered from two of the disorders.
Large numbers of affected workers were also afflicted by post-traumatic stress disorder (PTSD). Among those with asthma, for instance, almost half (48%) had the mental condition.
The authors, led by Dr Juan Wisnivesky, from Mount Sinai School of Medicine in New York, wrote: "Our findings show a substantial burden of persistent physical and mental disorders in rescue and recovery workers who rushed to the site of the WTC and laboured there for weeks and months 10 years ago. Many of these individuals now suffer from multiple health problems.
"The findings of this study emphasise the need for continued monitoring and treatment of the rescue and recovery worker population and underscore the importance of providing adequate health monitoring and treatment for these individuals."
Another Lancet paper reported on the cancer risk faced by firefighters involved after the attacks.
The study of 9,853 firefighters found that those who took part in the rescue and clean-up operation were 19% more likely to be diagnosed with cancer than their non-exposed colleagues.
Among the exposed group, there were 263 recorded cases of cancer affecting various parts of the body including the stomach, bowel, skin, prostate, bladder and pancreas.
"An association between WTC exposure and cancer is biologically plausible because some contaminants in the WTC dust, such as polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and dioxins, are known carcinogens," wrote the researchers, led by Dr David Prezant, chief medical officer at the New York City Fire Department.
"Although some contaminants could cause cancer directly, WTC exposure could also trigger chronic inflammation, through microbial infections, auto-immune diseases, or other inflammatory disorders, all of which have been reported as factors in oncogenesis (cancer generation), both experimentally and epidemiologically."
Despite the findings, a third study found that so far World Trade Centre-exposed rescue workers and civilians had lower death rates than New York's general population.
However this was not thought to be surprising because of the long time it took for deaths to result from illnesses caused by exposure to toxic substances.
People in full time employment also tended to be healthier than the general population, the authors pointed out. This was known as the "worker cohort effect" and could influence the results of population death rate studies.