Development of an Exposure Assessment Method for Epidemiological Studies of New York State Personnel who Responded to the World Trade Center Disaster

New York State Department of Health, Center for Environmental Health, 547 River Street, Troy, NY 12180, USA.
Annals of Occupational Hygiene (Impact Factor: 2.1). 04/2008; 52(2):83-93. DOI: 10.1093/annhyg/mem065
Source: PubMed


An exposure assessment method was developed for use in assigning an exposure score to New York State personnel who responded to the World Trade Center disaster site after the 11 September 2001 terrorist attacks.
The method consists of an algorithm with two instantiations. Each represents a major component of the overall exposures at the site: dust and smoke. The algorithm uses US Environmental Protection Agency air monitoring data collected between 23 September 2001 and 28 February 2002, as well as information on duration, location and time period of work assignment and type and frequency of personal protective respiratory equipment (PPE) use, collected by a self-administered mailed questionnaire. These data were used to calculate an overall exposure score for each participant. For each time period/location combination, individuals provided average number of hours and number of days worked. This was multiplied by a weighting factor derived from the median of the air monitoring data for the time period/location. Calcium was chosen as a surrogate for the dust exposure, so the weighting factors for the dust instantiation were calculated from calcium air monitoring data. Total hepta-chlorinated dibenzo-p-dioxin was chosen as a surrogate for the smoke exposure and was similarly used in the smoke instantiation.
More individuals in the highest exposure score category performed tasks such as search/rescue and hand digging than those in the lowest exposure category. Also, those in the highest exposure category had a higher mean number of hours at the site than other exposure groups.
The exposure assessment method presented accounts for PPE use, amount of time at the site, proximity to the site and ambient air monitoring results taken in the immediate vicinity. The algorithm can be used to rank individuals in the same study with very different patterns of exposure, such as high-level, short-term exposures and low-level, long-term exposures. The concepts could be modified for use in other epidemiological studies where long-term chronic exposure is a concern.

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    ABSTRACT: The collapse of the World Trade Center (WTC) on September 11, 2001 resulted in the release of several airborne pollutants in and around the site. Perfluorochemicals including perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), which are used in soil- and stain-resistant coatings on upholstery, carpets, leather, floor waxes, polishes, and in fire-fighting foams were potentially released during the collapse of the WTC. In this pilot study, we analyzed 458 plasma samples of New York State (NYS) employees and National Guard personnel assigned to work in the vicinity of the WTC between September 11 and December 23, 2001, to assess exposure to perfluorochemicals released in dust and smoke. The plasma samples collected from NYS WTC responders were grouped based on estimated levels of exposure to dust and smoke, as follows: more dust exposure (MDE), less dust exposure (LDE), more smoke exposure (MSE), and less smoke exposure (LSE). Furthermore, samples were grouped, based on self-reported symptoms at the time of sampling, as symptomatic and asymptomatic. Eight perfluorochemicals were measured in 458 plasma samples. PFOS, PFOA, perfluorohexanesulfonate (PFHxS), and perfluorononanoic acid (PFNA), were consistently detected in almost all samples. PFOA and PFHxS concentrations were approximately 2-fold higher in WTC responders than the concentrations reported for the U.S. general population. No significant difference was observed in the concentrations of perfluorochemicals between symptomatic and asymptomatic groups. Concentrations of PFHxS were significantly (p < or = 0.05) higher in the MDE group than in the LDE group. Concentrations of PFNA were significantly higher in the MSE group than in the LSE group. Significantly higher concentrations of PFOA and PFHxS were found in individuals exposed to smoke than in individuals exposed to dust. A significant negative correlation existed between plasma lipid content and concentrations of certain perfluorochemicals. Our initial findings suggest that WTC responders were exposed to perfluorochemicals, especially PFOA, PFNA, and PFHxS, through inhalation of dust and smoke released during and after the collapse of the WTC. The potential health implications of these results are unknown at this time. Expansion of testing to include all archived samples will be critical to help confirm these findings. In doing so, it may be possible to identify biological markers of WTC exposure and to improve our understanding of the health impacts of these compounds.
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