Research published in the journal Occupational & Environmental Medicine has found that 9/11 rescue and recovery workers had a 24% higher risk of prostate cancer, with the highest risk being among the earliest responders. While there are some caveats which the researchers include, it’s not the first study to come to the same conclusion.

Exposure levels to “toxic dust” — cancer-causing agents, such as asbestos, sulfuric acid, benzo(a)pyrene, benzene, and arsenic — at Ground Zero twenty years ago created a dangerous environment to those who responded to the call to assist in rescue and recovery. Unlike prior studies, this latest report also wanted to tell if there were specific time periods after the attacks during which prostate cancer risk might be significantly higher.

“The increased hazard among those who responded to the disaster earliest or were caught in the dust cloud suggests that a high intensity of exposure may have played some role in premature oncogenesis,” explain the researchers in their report.

The researchers tracked the health of 69,102 first responders from three groups: the New York City Fire Department, the General Responder Cohort and participants from the World Trade Center Health Registry. Their findings indicate a shorter latency period from occupational exposure to cancer development than that reported from other studies of men not involved in 9/11 rescue work.

The study compared the front-line workers to a sample of men in New York State during the same period, using the same inclusion criteria, though weren’t involved in work at the WTC following the attacks. Relative to rates among these men, the risk of the disease among World Trade Center rescue/recovery workers was 24% higher, from 2007 through to the end of 2015, after accounting for potentially influential factors, such as smoking. Further analysis revealed a dose–response trend in both the early (2002–06) and later (2007–15) periods of monitoring, with the largest risk estimated in the early period.

Researchers concentrated on the time of arrival at the WTC site: on the day of the attacks when there was the greatest dust cloud resulting from the collapse of the twin towers, the following day and any other time from Sept. 13, 2001 to June 30, 2002. The study consisted of 54,394 men, 1,120 of whom were diagnosed with prostate cancer between Mar. 12, 2002 and Dec. 31, 2015. The average age at diagnosis was 60.

While unclear how much of an impact it had on the outcome, current or former smokers were the most likely to develop cancer. They were also more likely to have any other type of cancer diagnosed within the study period. The average latency period from exposure until they were diagnosed with prostate cancer was 9.4 years, with two-thirds of cases (734) diagnosed between 2009 and 2015.

Though the length of time of exposure to the toxins at the disaster site for each person cannot be quantified, the study did conclude that more than three out of four prostate cancer cases (867; 77%) were early stage and localized; just over 15% (171) had spread locally; and 2.5% (28) had spread to other parts of the body. Cancer detections were tracked via linkage with 13 state cancer registries across the nation up to the conclusion of the study period in 2015.

However, the researchers note that the study is purely observational, and as such, can’t establish specific causes. They give the caveat that while the cancer rates are higher, it is possible that statistics could be skewed if first responders had a higher-than-average screening rate

Nor were they able to determine the extent to which other behavioral, occupational, and environmental exposures other than cigarette smoking might have contributed to prostate cancer risk.

Nevertheless, their “evidence suggests a relationship between [World Trade Center] exposure and prostate cancer not fully explained by random or systematic error,” and that their findings support the need for continued research evaluating prostate cancer in WTC responders.

According to the CDC’s latest Morbidity and Mortality Weekly Report, of the 104,223 enrollees in the World Trade Center Health Program, a federal benefits plan for survivors and responders, 58% of all program members contracted at least one illness associated with the Sept. 11 attacks as of last year. Cancers related to 9/11 among members increased by more than 1,000% from 1,870 confirmed cases in 2013 to 20,612 cases in 2020.