Human Cell Mutagenicity

Similarly, the structure of a nitro-PAH lactone found in ambient aerosols and also formed in laboratory irradiations of phenathrene-NO -air mixtures, 2-nitro-6//-dibenzo[h,rf]pyran-6-one, which is a powerful, direct-acting bacterial mutagen and potent human cell mutagen, is commonly shown as (XI) (Helmig et al., 1992a Arey et al., 1992 Sasaki et al., 1995, 1997b Arey, personal communication). 

TABLE 10.13 Carcinogenicities of Selected PAHs in Ambient Air As Evaluated by IARC, U.S. EPA, and U.S. DHHS, Cancer Potency Equivalence Factors Relative to BaP = 1.00 from Nielsen et al. (1996), CARB (1994), and Collins et al. (1998), and Human Cell Mutagenicities Relative to BaP = 1.00... 

IARC Class" U.S. EPA U.S. DHHS Potency equivalence factors Relative human cell mutagenicity... 

We discuss the bacterial and human cell mutagenicities and related atmospheric chemistry of these biologically active N-PACs in subsequent sections. Box 10.8 contains examples of literature on this subject. 

Cyclopenta[cd]pyrene (CPP, XXVIII) is a powerful human cell mutagen in strain hlAlv2, 7 times more potent than BaP (Durant et al., 1996 Hannigan et al., 1998), and a strong promutagen in both the Ames Salmonella typhimurium reversion assay (Eisenstadt and Gold, 1978) and the Salmonella typhimurium strain TM677 forward mutation assay (Kaden et al.., 1979) ... 

The human cell mutagenicities of several mono- and dinitropyrenes were determined by Busby and coworkers (1994b) in a forward mutation assay using a metabolically competent line of MCL-5 cells. Minimum detectable mutagen concentrations (MMC, in nmol ml-1 the smaller the detectable concentration, the greater the potency) were as follows 1,6-dinitropyrene, 0.8 1,8-dinitropyrene, 1.5 4-nitropyrene, 3.1 1-nitro-pyrene, 9.1. Other PACs tested, 2-nitropyrene, 1,3-dinitropyrene, and pyrene, were nonmutagens in this... 

The toxicology-based conclusion that the minimum concentration for 2-nitrofluoranthene to be an important human cell mutagen is 1 p.g/g, coupled with air quality sampling data showing its concentrations in respirable particles sampled from ambient air can in fact reach 10 pg/g, provides a useful example of a productive symbiotic interaction between atmospheric chemists and toxicologists. Such interactions are essential for reliable risk assessments of air pollution and human health effects of complex combustion-generated mixtures of gases and particles. 

D. BACTERIAL AND HUMAN CELL MUTAGENICITIES OF POLLUTED AMBIENT AIR... 

With the carcinogenic and mutagenic properties of certain key airborne PAHs and PACs as background, let us now examine the contributions of these genotoxic compounds to the bacterial and human cell mutagenicities of ambient air. 

TABLE 10.24 Average Concentrations (ng m 3) and Their Ranges" of Selected PAH which Are Animal Carcinogens and/or Human Cell Mutagens in Ambient Aerosols" Collected at Six Sites in California Four Southern California Cities, Hamilton, Ontario, Canada ... 

For cancer potency equivalence factors and human cell mutagenicities, see Table 10.13. See text for more information on sampling times and dates... 

In the studies of Hannigan et al. (1997) described in the previous subsection, the contributions of specific PAHs and PACs to the total human cell mutagenicity of fine ambient aerosols in southern California air were not identified and quantified. However, previous investigators had determined ambient levels of a number of carcinogenic PAHs (IARC classes 2A and 2B see... 

D. BACTERIAL AND HUMAN CELL MUTAGENICITIES OF POLLUTED AMBIENT AIR TABLE 10.27 Motor Vehicle Use and Emissions Inventory for California s South Coast Air Basinb the Years 1982 and 1993 f 501 for... 

Busby, W. F., Jr., B. W. Penman, and C. L. Crespi, Human Cell Mutagenicity of Mono- and Dinitropyrenes in Metabolically Competent MCL-5 Cells, Mutat. Res., 322, 233-242 (1994b). 

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