Gas-phase ambient air contaminants exhibit significant dioxin-like and estrogen-like activity in vitro

Gail P. Klein, Erin M. Hodge, Miriam L. Diamond, Amelia Yip, Tom Dann, Gary Stern, Michael S. Denison, Patricia A. Harper

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Several adverse health effects, such as respiratory and cardiovascular morbidity, have been linked to exposure to particulate matter in ambient air; however, the biologic activity of gas-phase ambient organic air contaminants has not been examined as thoroughly. Using aryl hydrocarbon receptor (AHR)-based and estrogen receptor (ER)-based cell bioassay systems, we assessed the dioxin-like and estrogenic activities of gas-phase organic ambient air contaminants compared with those of particulate-phase contaminants using samples collected between seasons over 2 years from an urban and a rural location in the Greater Toronto Area, Canada. The concentration of the sum (∑) of polycyclic aromatic hydrocarbons, which was highest in the gas phase, was 10-100 times more abundant than that of ∑polychlorinated biphenyls, ∑nitro-polycyclic aromatic hydrocarbons, and ∑organochlorine pesticides, and 103 to 104 times more abundant than ∑polychlorinated dibenzo-p-dioxins/dibenzofurans. Gas-phase samples induced significant AHR- and ER-dependent gene expression. The activity of the gas-phase samples was greater than that of the particulate-phase samples in the estrogen assay and, in one case, in the AHR assay. We found no strong associations between either summer or winter seasons or urban or rural locations in the relative efficacy of the extracts in either the ER or AHR assay despite differences in chemical composition, concentrations, and abundance. Our results suggest that mechanistic studies of the health effects of ambient air must consider gas and particulate phases because chemicals present in both phases can affect AHR and ER signaling pathways.

Original languageEnglish (US)
Pages (from-to)697-703
Number of pages7
JournalEnvironmental Health Perspectives
Issue number5
StatePublished - May 2006


  • AHR
  • Air pollution
  • Complex mixtures
  • Endocrine disruption
  • ER
  • PAH

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Public Health, Environmental and Occupational Health


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