Evidence for Organic Film on an Impervious Urban Surface:  Characterization and Potential Teratogenic Effects

Chemical constituents of an organic film collected from an impervious urban surface, namely the exterior surface of windows, have been characterized. The organic portion of this film, that ranged in thickness from 11 to 100 nm, constitutes a previously unrecognized site for exchange of semivolatile organic contaminants in urban environments. The concentrations of total n-alkanes, total polycyclic aromatic compounds (PAH), and total polychlorinated biphenyls (PCB) ranged from 1010 to 22 500, 900 to 62 100, and 8 to 5820 ng/m2 of window surface, respectively. Whereas concentrations varied, the patterns of chemical and congener abundance were similar among samples. Alkanes were derived from mainly biogenic sources, while the PAH showed a weathered pattern and PCB congener patterns generally indicated an enrichment in higher chlorinated congeners. Film-to-air partition ratios, K FA, were calculated for selected PAH and PCB congeners and were comparable to reported values of octanol−air partition coefficients, K OA, suggesting that gas-phase compounds partition into this organic film. Potential biological effects of an organic film extract were evaluated using zebrafish embryo assays. Incubation at a concentration of 270 ppb ΣPAH plus 420 ppb ΣPCB showed 100% lethality, while concentrations 3−10 times lower produced a dose-dependent syndrome of abnormalities including cardiovascular, hematopoietic, neural crest-related, and behavioral defects.