In order to quantify the firefighter risk level, the scientists compared the new cases of cancer among 10,786 New York firefighters who had worked at the World Trade Centre during the 9/11 attack with 8,813 fire fighters who did not work at that site.
The World Trade Center firefighters were divided based on the exposure level of harmful toxins; the morning of 9/11, 1741 (16%), representing the highest risk; the afternoon of 9/11, 5683 (53%); following day, 1873 (17.5%); period between 13 and 24 September, 1315 (12%); and any time after 24 September 2001, 174 (1.5%), representing the lowest risk. Their health was monitored until death and the cancer incidence among them was compared with the other US men belonging to the general population.
The results showed that
●About 915 cancers were diagnosed in 814 of firefighters who worked at the World Trade Center during the attack
●1002 cases were diagnosed among 909 other firefighters
Taking into consideration various factors like smoking and previous involvement in military combat the World Trade Center firefighters were 13% more likely to develop cancer than colleagues who didn’t work at the site.
The risk of prostate cancer was 39% higher while thyroid cancer was more than twice as high. The cancer incidence was compared with US men in the general population; both groups of firefighters had higher rates of both prostate and skin cancer.
According to researchers “Some proportion of the excess prostate cancer risk may be due to [World Trade Center] exposure on top of usual firefighting risks, as some chemicals, like PCBs, commonly found at building sites, including the [World Trade Center], are known endocrine disruptors, interfering with androgen metabolism,”
“Alternatively, high rates of some cancers, including thyroid and prostate cancers, could have resulted from non-biological factors like enrolment in screening programmes, especially [World Trade Center]-related health programmes,” says the study.
This is an observational study and more studies are required to understand the actual cause of cancer among the firefighters.