Photomutagenicity of 16 polycyclic aromatic hydrocarbons from the US EPA priority pollutant list

Abstract

The photomutagenicity of 16 polycyclic aromatic hydrocarbons (PAHs), all on the United States Environmental Protection Agency (US EPA) priority pollutant list, was studied. Concomitant exposing the Salmonella typhimurium bacteria strain TA102 to one of the PAHs and light (1.1 J/cm2 UVA+2.1 J/cm2 visible) without the activation enzyme S9, strong photomutagenic response is observed for anthracene, benz[a]anthracene, benzo[ghi]perylene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, and pyrene. Under the same conditions, acenaphthene, acenaphthylene, benzo[k]fluoranthene, chrysene, and fluorene are weakly photomutagenic. Benzo[b]fluoranthene, fluoranthene, naphthalene, phenanthrene, and dibenz[a,h]anthracene are not photomutagenic. These results indicate that PAHs can be activated by light and become mutagenic in Salmonella TA102 bacteria. At the same time, the mutagenicity for all the 16 PAHs was examined with the standard mutagenicity test with 10% S9 as the activation system. Benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, acenaphthylene, and fluorene are weakly mutagenic, while the rest of the PAHs are not. In general, the photomutagenicity of PAHs in TA102 does not correlate with their S9-activated mutagenicity in either TA102 or TA98/TA100 since they involve different activation mechanisms.

Fig. 1

Structures and nomenclatures of the 16 PAHs on the EPA priority pollutant list.

Fig. 2

Effect of light doses from the 300 W Xe/Hg lamp on S. typhimurium TA98.

Fig. 3

Effect of light doses from the 300 W Xe/Hg lamp on S. typhimurium TA102.

Fig. 4

Photomutagenic response of S. typhimurium TA102 upon exposure to 10 µg per plate of 8-MOP and various light doses from the 300 W Xe/Hg lamp.

Fig. 5

Photomutagenicity of pyrene and anthracene in Salmonella typhimurium TA102. The PAH assayed at different amount of chemicals was mixed with TA102 in the agar plate and irradiated with a Xe/Hg lamp for 5 min (light dose: 1.1 J/cm² UVA plus 2.1 J/cm² visible light). After the irradiation, it was incubated for 48 h before the revertant colonies were counted.

Fig. 6

Mutagenicity of benzo[k]fluoranthene in Salmonella typhimurium TA102. Values are means of three parallel incubations without S9 (○) and with S9 mix as an external metabolizing system (●).