Assessment of Alkylated and Unsubstituted Polycyclic Aromatic Hydrocarbons in Air in Urban and Semi-Urban Areas in Toronto, Canada

Abstract

22 alkylated polycyclic aromatic hydrocarbons (alk-PAHs) were characterized in ambient air individually for the first time in urban and semi-urban locations in Toronto, Canada. Five unsubstituted PAHs were included for comparison. Results from the measurements were used to estimate benzo­[a]­pyrene equivalent toxicity (BaPeq) of individual compounds in order to investigate the significance of a single compound in contributing to the overall toxic equivalency (TEQ) of air mixtures. To determine which compounds merit further investigation, BaPeq values of individual compounds were compared to the measured BaP toxicity. Our results showed that both unsubstituted and alkylated PAHs were more abundant in the urban area (38 and 30%, respectively). Benzo­[a]­pyrene levels at the urban location exceeded Ontario’s 24 h guideline (40% of the events), and on average, it was 5 times higher than that at the semi-urban area. Gas-phase two- and three-ring compounds contributed up to 39% (urban) and 76% (semi-urban) of the TEQ of all compounds analyzed. Some alk-PAHs such as 7,12-dimethylbenzo­[a]­anthracene had a huge impact on the toxicity of urban air, and its BaPeq was on average 8 times higher than that of BaP. We emphasize that the toxic impact of alkylated and gaseous PAHs, which is not routinely included in many air monitoring programs, is significant and should not be neglected.

Polycyclic aromatic hydrocarbons in silicone wristbands of Uruguayan children: measurement and exposure source exploration

“…36 Four of these compounds are alkylated derivatives and are not classied by the EPA as hazardous. Alkylated PAHs have higher abundance than their non-alkylated forms in many environmental media, including crude oil, 35 ambient air, 37,38 cigarette smoke 36 and plant and animal tissue samples. 39 A recent study in sh found that 3 ring alkylated PAHs were more persistent, bioaccumulated, and toxic than their parent compounds.…”

Heterogeneous ozonolysis of alkyl substituted-polycyclic aromatic hydrocarbons (AlkPAHs) in the atmosphere

“…1-ethylpyrene is only one of the alkylated analogs of pyrene; other AlkPAHs like 4,5-dimethylpyrene and 1-propylpyrene have been reported in the atmosphere. 15,17,18 It is worth noting that the levels of AlkPAHs in the atmosphere surpass those of the original PAHs, and each PAH can have multiple alkylated analogs. 15,17,18 Based on the ndings of this study, it is evident that AlkPAHs exhibit a higher reactivity with ozone compared to PAHs and produce a greater variety of OPAHs.…”

“…13,14 Notably, recent research has reported higher AlkPAH levels than PAH levels at several Canadian locations. [15][16][17][18] Given the growing evidence of AlkPAHs' prevalence in the atmosphere and their potential health risks, investigating their transformations in the atmosphere is imperative. PACs undergo photolysis upon ultraviolet exposure and oxidation through reactions with gas-phase oxidants.…”

Chemically speciated air pollutant emissions from open burning of household solid waste from South Africa

“…The cancer risks of PAHs and nitro-PAHs are often estimated using the equivalents of benzo(a)pyrene (BaP eq ), one of the most potent PAHs with known carcinogenic characteristics. The toxic equivalent factor (TEF) for BaP is set to 1, and other PAHs and nitro-PAHs are assigned a TEF value by comparing their relative toxicity to that of BaP (ATSDR, 2022;Samburova et al, 2017;Moradi et al, 2022). For PAHs, dibenzo[a,h]anthracene has the highest TEF of 2.4, followed by BaP, benzo[e]pyrene and dibenzo[a,e]pyrene, with a TEF of 1.0 (ATSDR, 2022;Samburova et al, 2017).…”