DESCRIPTIONS OF POTENTIAL PROJECTS

Project: Toxic Trace Air Pollutants

Research Mentor :  P. Eversole-Cire


Project Background:

Catalytic converters have been instrumental in reducing major pollutant exhaust emissions from light duty motor vehicles and have played a significant role in improving air quality. However, secondary reactions (i.e., post-combustion) on the catalyst may produce unregulated emissions (e.g., hydrogen cyanide, HCN, and ammonia, NH3) that could have an adverse impact on human health and the environment. Of particular concern is a highly toxic class of compounds termed (chemically-)reduced nitrogen compounds (RNCs) that include HCN; N-nitrosamines; amines; hydrazine; methylhydrazine; hydroxylamine; as well as their reaction products with co-emitted aldehydes, where relevant. While these compounds have received little attention in the past, their presence in vehicle exhaust, even at low concentrations, could lead to significant adverse health effects, particularly in high exposure scenarios such as freeway communities, vehicle cabins, and enclosed spaces (e.g., residential and parking garages). Over the past 5 years, two faculty members, two postdoctoral associates, and three undergraduate students at Oak Crest have investigated RNC emissions by motor vehicles. We developed a novel remote sensing instrument capable of measuring over 20 compounds emitted in vehicle exhaust and used this device in parking lot1 and freeway on-ramp studies.2,3 One important accomplishment was the first-ever measurement of NH3 in vehicle exhaust by remote sensing, which allowed us to determine mean fleet NH3 emission rates of 36 mg-km-1 from measurements on exhaust emitted by 2091 vehicles as they traveled up a Southern California freeway on-ramp. These findings could have significant implications on air quality in the Los Angeles area, since ammonium salts are primarily present in the atmosphere as fine particles, which have been associated with numerous deleterious health effects.

Project Description:

The mutagenic properties of individual RNCs identified in our research will be examined using bacterial and human cell mutagenicity assays. The Salmonella typhimurium TM677 forward mutation assay4,5 will be used as a broad screen to identify mutagenic compounds. RNCs also will be tested using a human cell forward mutation assay to assess the possible human health effects associated with exposure to these compounds. Forward mutation assays have been chosen in both cases as these are more sensitive to a broad range of compounds and eliminate the need to screen multiple strains, a requirement of reversion assays.6-8 The assays have been previously used to study the mutagenicity of organic aerosol samples.9-14 In addition, detected RNCs will be screened for  possible embryotoxic potential, using a molecular multiple endpoint embryonic  stem cell test that assesses tissue-specific developmental  toxicity of chemicals on cardiomyocyte, osteogenic, chondrogenic, and  neural differentiation in cultured mouse embryonic stem cells using both  morphological as well as molecular markers of differentiation as  endpoint analyses.15

1)      Baum, M. M.; Kiyomiya, E. S.; Kumar, S.; Lappas, A. M.; Lord, H. C., III "Multi-Component Remote Sensing of Vehicle Exhaust by Dispersive Absorption Spectroscopy. 1. Effect of Fuel Type and Catalyst Performance". Environ. Sci. Technol. 2000, 34, 2851-2858.

2)      Baum, M. M.; Kiyomiya, E. S.; Kumar, S.; Lappas, A. M.; Kapinus, V. A.; Lord, H. C., III "Multi-Component Remote Sensing of Vehicle Exhaust by Dispersive Absorption Spectroscopy. 2. Direct On-road Ammonia Measurements". Environ. Sci. Technol. 2001, 35, 3735-3741.

3)      Baum, M. M.; Kiyomiya, E. S.; Kumar, S.; Lappas, A. M.; Kapinus, V. A.; Lord, H. C. "Multicomponent Remote Sensing of Vehicle Exhaust by Dispersive Absorption Spectroscopy. 2. Direct On-road Ammonia Measurements (Vol 35, Pg 3735, 2001)". Environ. Sci. Technol. 2002, 36, 4705-4705.

4)      Skopek, T. R.; Liber, H. L.; Kaden, D. A.; Hites, R. A.; Thilly, W. G. "Mutation of Human Cells by Kerosine Soot". J. Natl. Cancer Inst. 1979, 63, 309-312.

5)      Busby, W. F.; Smith, H.; Bishop, W. W.; Thilly, W. G. "Mutagenicity of Mononitropyrenes and Dinitropyrenes in the Salmonella-typhimurium-TM677 Forward Mutation Assay". Mutat. Res.-Genet. Toxicol. 1994, 322, 221-232.

6)      Nielsen, P. A.; Lagersted, A.; Danielsen, S.; Jensen, A. A.; Hart, J.; Larsen, J. C. "Mutagenic Activity of 9 N,N-Disubstituted Hydrazines in the Salmonella Mammalian Microsome Assay". Mutation Res. 1992, 278, 215-226.

7)      Prival, M. J.; Zeiger, E. "Chemicals Mutagenic in Salmonella-typhimurium Strain TA1535 but not in TA100". Mutat. Res. Genet. Toxicol. Environ. Mutagen. 1998, 412, 251-260.

8)      Prival, M. J. "The Unusual Effect of pKM101 on the Mutagenicity of Acetaldehyde Oxime in Salmonella-typhimurium". Mutat. Res. Genet. Toxicol. Environ. Mutagen. 2003, 537, 201-208.

9)      Hannigan, M. P.; Cass, G. R.; Lafleur, A. L.; Longwell, J. P.; Thilly, W. G. "Bacterial Mutagenicity of Urban Organic Aerosol Sources in Comparison to Atmospheric Samples". Environ. Sci. Technol. 1994, 28, 2014-2024.

10)    Hannigan, M. P.; Cass, G. R.; Lafleur, A. L.; Busby, W. F.; Thilly, W. G. "Seasonal and Spatial Variation of the Bacterial Mutagenicity of Fine Organic Aerosol in Southern California". Environ. Health Perspect. 1996, 104, 428-436.

11)    Hannigan, M. P.; Cass, G. R.; Penman, B. W.; Crespi, C. L.; Lafleur, A. L.; Busby, W. F.; Thilly, W. G. "Human Cell Mutagens in Los Angeles Air". Environ. Sci. Technol. 1997, 31, 438-447.

12)    Hannigan, M. P.; Cass, G. R.; Penman, B. W.; Crespi, C. L.; Lafleur, A. L.; Busby, W. F.; Thilly, W. G.; Simoneit, B. R. T. "Bioassay Directed Chemical Analysis of Los Angeles Airborne Particulate Matter Using a Human Cell Mutagenicity Assay". Environ. Sci. Technol. 1998, 32, 3502-3514.

13)    Pedersen, D. U.; Durant, J. L.; Penman, B. W.; Crespi, C. L.; Hemond, H. F.; Lafleur, A. L.; Cass, G. R. "Seasonal and Spatial Variations in Human Cell Mutagenicity of Respirable Airborne Particles in the Northeastern United States". Environ. Sci. Technol. 1999, 33, 4407-4415.

14)    Pedersen, D. U.; Durant, J. L.; Penman, B. W.; Crespi, C. L.; Hemond, H. F.; Lafleur, A. L.; Cass, G. R. "Human-cell Mutagens in Respirable Airborne Particles in the Northeastern United States. 1. Mutagenicity of Fractionated Samples". Environ. Sci. Technol. 2004, 38, 682-689.

15)    zur Nieden, N. I.; Kempka, G.; Ahr, H. J. "Molecular Multiple Endpoint embryonic Stem Cell Test - a Possible Approach to Test for the Teratogenic Potential of Compounds". Toxicol. Appl. Pharmacol. 2004, 194, 257-269.