Lewandowski et al alkene oxidation mutagenicity data 10-28-24

Below are the raw mutagenicity data for two categories of experiments:  (1) a VOC + UV and NOx (Figure 1) and (2) a VOC + ozone (Figure 3).  The data are the number of mutant colonies (called revertants or rev) per petri plate of strain TA100 of Salmonella using the Salmonella (Ames) mutagenicity assay as described below.
Generation of Simulated Atmospheres.  The details of how the atmospheres were generated have been described previously.  Briefly, the precursor hydrocarbon, along with NO and low concentration ammonium sulfate seed aerosol, were injected continuously into a 14.5-m3 smog chamber until concentrations of ~10 ppmC hydrocarbon and ~500 ppbv NO were achieved.  Relative humidity within the chamber was held at 30%. The mixture was then irradiated and allowed to come to steady state before exposing the Salmonella cells at the air-agar interface to the resulting atmosphere to assess mutagenic potential.  Input and sampling flows were such that the average chamber residence time was ~4.5 h.    
Mutagenicity Assays.  The Salmonella plate-incorporation assay using the base-substitution strain TA100 was used as described previously. When the smog-chamber reactions reached steady state, we delivered a continuous and constant concentration of the atmosphere into the MICs.  We exposed the cells for 5 or more time periods spanning 10 min to 16 h, depending on the mutagenic potency and cytotoxicity of the atmosphere.  After exposures, we incubated the plates at 37C for 3 days and then counted the resulting mutant colonies, revertants (rev), on an automatic colony counter (ProtoCOL 3, Microbiology International, Frederick, MD). We conducted two independent mutagenicity experiments with two plates per time point with each atmosphere, resulting in a total of four plates per time point.  We combined the mutagenicity data (rev plate-1) from two replicate experiments to construct exposure time-response curves from which we calculated linear regressions; the slopes were the mutagenic potencies of the atmospheres expressed as rev h-1.  These rev h-1 values were normalized to the estimated mass concentration of non-precursor gas-phase carbon during the exposure to give mutagenic potencies expressed as rev m3 mgC-1 h-1 ± SE.  A positive mutagenic response was considered to be a reproducible, time-related increase in rev plate-1 that approached or exceeded a twofold increase relative to the unexposed spontaneous control and whose slopes were significantly (p < 0.05) greater than zero based on a trend test.  Linear regressions (slopes), p-values, and r2-values were calculated using Prism (GraphPad, San Diego, CA).  Pair-wise comparisons of mutagenic potencies were made by two-tailed Student’s t-tests using Prism. 

This dataset is associated with the following publication:
Lewandowski, M., T. Riedel, J. Krug, T. Kleindienst, M. Meier, A. Long, S. Warren, and D. DeMarini. Molecular Compositions, Mutagenicity, and Mutation Spectra of Atmospheric Oxidation Products of Alkenes and Dienes Initiated by NOx + UV or Ozone: A Structure-Activity Analysis.   ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 58(12): 18846−18855, (2024).

Tags: cims, dienes, photooxidation-products, salmonella, smog-chamber, vocs
Organization: U.S. Environmental Protection Agency