Catalytic diesel particulate filters reduce the in vitro estrogenic activity of diesel exhaust

Abstract

An in vitro reporter gene assay based on human breast cancer T47D cells (ER-CALUX ® ) was applied to examine the ability of diesel exhaust to induce or inhibit estrogen receptor (ER)-mediated gene expression. Exhaust from a heavy-duty diesel engine was either treated by ironor copper/iron-catalyzed diesel particulate filters (DPFs) or studied as unfiltered exhaust. Collected samples included particle-bound and semivolatile constituents of diesel exhaust. Our findings show that all of the samples contained compounds that were able to induce ER-mediated gene expression as well as compounds that suppressed the activity of the endogenous hormone 17β-estradiol (E2). Estrogenic activity prevailed over antiestrogenic activity. We found an overall ER-mediated activity of 1.63±0.31 ng E2 CALUX equivalents (E2-CEQs) per m 3 of unfiltered exhaust. In filtered exhaust, we measured 0.74±0.07 (iron-catalyzed DPF) and 0.55±0.09 ng E2-CEQ m −3 (copper/iron-catalyzed DPF), corresponding to reductions in estrogenic activity of 55 and 66%, respectively. Our study demonstrates that both catalytic DPFs lowered the ER-mediated endocrine-disrupting potential of diesel exhaust.

In vitro estrogenicity of ambient particulate matter: contribution of hydroxylated polycyclic aromatic hydrocarbons

“…It has been hypothesized that chemicals bound to atmospheric particles play an important role . Some compounds found in vehicle exhaust, waste combustion emissions, and ambient air have been shown to act as endocrine disruptors (Clemons et al, 1998;Watanabe and Kurita, 2001;Wang et al, 2003Wang et al, , 2004Sidhu et al, 2005;Klein et al, 2006;Wenger et al, 2008a;2008b). Endocrine disruptors interfere with the normal functioning of the endocrine system by mimicking or antagonizing naturally occurring hormones and/ or by modulating hormonal responses (Damstra et al, 2002).…”

“…PM1 was collected at an urban and a rural site in Switzerland. Based on our findings that diesel exhaust contains considerable amounts of estrogenic compounds and potential precursors (Heeb et al, 2008;Wenger et al, 2008a), we hypothesized that ambient air in traffic-exposed areas must also have some estrogenic activity. On the other hand, airborne xenoestrogens formed via transformation of precursors might result in increased estrogenic activity of aged air masses even in rural areas far from direct emission sources.…”

Effects of an iron-based fuel-borne catalyst and a diesel particle filter on exhaust toxicity in lung cells in vitro

“…Analytical studies report how exhaust composition, particularly the concentration of known toxic exhaust components, is affected by changing the engine equipment [15,16,36], and toxicological studies report how exhaust toxicity is changed by such changes [20,21,37].…”

“…Wenger and coworkers [19][20] showed in in vitro cell assays that iron-based FBCs in combination with DPFs lowered emissions of agonists of the human aryl hydrocarbon receptor and the estrogen receptor.…”

“…It is commercially available, and its effects on exhaust composition including genotoxic compounds have been described before [15][16][17]. Only few studies discuss how iron-based FBCs affect exhaust toxicity in vitro or in vivo, however [18][19][20].…”