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EPIDEMIOLOGY
Before the September 11, 2001, World Trade Center (WTC) attack, the use of DNA profiling for victim identification in mass casualties (e.g., plane crashes) was typically limited to situations with fewer than 500 persons (1-5). Often, the condition of the remains allows rapid recovery of intact bodies. However, the number and condition of the remains in the WTC attack were unprecedented.
After many deaths, especially in the aftermath of a mass fatality, there is an element of disbelief. Accepting the loss is a component of a complex grief process (6). Our motivation was to provide a tangible artifact of remains to survivors to facilitate coping and grief processes. Enabling family participation in some of the identification decisions was a critical component of the effort.
At the time of the attack, no infrastructure existed for rapid, effective victim identification in large-scale disasters (>1000 victims). Processes had to be scaled up to collect and analyze massive amounts of data in order to return identified remains to the families of almost 3000 victims. We summarize some challenges of the DNA-based component of the victim identification process, how these were met, and considerations for the future.
Some mass fatality identification projects begin with a list of victims (e.g., airline flight manifests listing passengers and crew). In contrast, the WTC mass fatality was initially "open" because the number of victims was unknown. Concerns about unreported or fraudulently reported victims made estimates difficult. The condition of the remains ranged from a few nearly complete bodies to multitudes of tiny fragments of charred bone, often difficult to distinguish from inorganic material. The fires affected the remains with temperatures exceeding 1000°C (7) that burned for more than 3 months. The towers' collapse fragmented and commingled victim remains and admixed building material. Many tissue fragments were retrieved months after the crashes, and bacterial and other processes further compromised the DNA. These factors made it difficult to isolate and genotype the DNA from the specimens.
Identification of human remains by DNA typing requires reference samples for comparison. These and other sources of information formed a deluge of material and data to be cataloged, archived, and analyzed. Preexisting sample collection and identification methods were insufficient for these needs.
Identification of WTC victim remains was...