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Final Progress Reports: University of Iowa: The AESOP Study: Airborne Exposures to Semi-volatile Organic Pollutants

Superfund Research Program

The AESOP Study: Airborne Exposures to Semi-volatile Organic Pollutants

Project Leader: Peter S. Thorne
Co-Investigators: Andres Martinez, Rachel F. Marek
Grant Number: P42ES013661
Funding Period: 2006-2025
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Final Progress Reports

Year:   2019  2014  2009 

The AESOP Study (Airborne Exposures to Semi-volatile Organic Pollutants) is a community-based participatory research study that assesses exposures and body burdens of atmospheric PCBs among an urban cohort of children and their mothers in an area contaminated with legacy PCBs and where dredging of 3.5 million m3 of PCB-laden sediments is now underway. Airborne PCB exposures plus serum and urine levels of PCBs and metabolites are assessed and compared to levels in the cohort before the dredging began as well as to a rural Iowa cohort in an area without legacy PCBs. The AESOP Study is identifying the determinants of PCB exposures among children and their mothers, including exposure levels indoors and out, dietary intake, and other exposure pathways. The Study is also determining how to best monitor exposures and metabolites. The AESOP Study collects exposure and health data among urban and rural residential cohorts in East Chicago and Columbus Junction from questionnaires; collects air samples inside and outside at homes and schools to measure congener-specific concentrations of atmospheric PCBs; collects blood annually from all subjects to measure PCB congeners and congener-specific metabolites and report these values to participants; and models exposures and body burdens for PCBs from the cohorts. The study is facilitated by strong community support garnered through Community Advisory Boards. The AESOP Study employs bilingual community-based field staff and has enrolled and followed 264 subjects in these racially and ethnically diverse communities (59% Hispanic, 23% Black, 18% other) and provided new insight into airborne exposures and resulting body burdens.

Researchers continued to maintain these two cohorts in 2014, collecting blood on all subjects and measuring exposures inside and outside at all homes and schools. In 2014, they analyzed year 2 blood serum from AESOP children and their mothers (n=200) for all 209 PCBs and 12 hydroxylated PCBs (OH-PCBs). The sum total of PCBs measured (∑PCB) ranged from 4 to 199 ng/g lipid weight (5th-95th percentile; median=45 ng/g lw) while the sum of OH-PCBs ranged from 0.04 to 0.27 ng/g fresh weight (5th-95th percentile; median=0.09 ng/g fw). A subset of these participants (n=155) also had blood PCB and OH-PCB concentration analyzed during the previous calendar year. Year-to-year variability in PCBs ranged from -87% to 567% and in OH-PCBs ranged from -51 to 358% (5th-95th percentile). This was the first study to report variability of all PCBs and major metabolites in mother-child pairs and showed that short-term exposures to PCBs may be a significant component of what is measured in human serum.

In 2014, researchers evaluated the inhalation and dietary intake of PCBs among participants and used these data and activity logs for integrated exposure modeling. They assessed congener-specific inhalation and dietary exposure for a subset of AESOP Study participants including 78 adolescent children and their mothers (n=68). Congener-specific PCB inhalation exposure was modeled using 293 measurements of indoor and outdoor airborne PCB concentrations at homes and schools, analyzed via tandem quadrupole GS-MS/MS, combined with questionnaire data from the AESOP Study. Dietary exposure was modeled using Canadian Total Diet Survey PCB concentrations and National Health and Nutrition Examination Survey (NHANES) food ingestion rates. For ∑PCB, dietary exposure dominates. For individual lower-chlorinated congeners, inhalation exposure was as high as ⅓ of the total (dietary + inhalation) exposure. ∑PCB inhalation was greater for urban mothers and their children than for rural mothers and children. Schools attended by AESOP Study children had higher indoor PCB concentrations than homes, and accounted for the majority of children's inhalation exposure.

The AESOP Study has changed prevailing views on how most Americans are exposed to PCBs. Researchers have demonstrated that subjects have substantial exposure to PCB congeners from inhalation in addition to ingestion and their blood shows enrichment with inhaled lower-chlorinated congeners. This has important implications for children's environmental health.

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