skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Global long-range transport and lung cancer risk from polycyclic aromatic hydrocarbons shielded by coatings of organic aerosol

Abstract

Polycyclic aromatic hydrocarbons (PAHs) have toxic impacts on ecosystems and human health. Laboratory measurements show that one of the most carcinogenic PAHs, benzo(a)pyrene, which is adsorbed on surfaces of soot particles, reacts very quickly with atmospheric oxidants like ozone within ~2 hours. Yet, field observations indicate that it actually persists for much longer periods in the atmosphere, and this large discrepancy is not well understood. Driven by novel experimental understanding, we develop a new modelling approach, whereby particle-bound BaP is shielded from oxidation by a coating of viscous organic aerosol (OA). We show that application of this new approach in a global climate model leads to higher atmospheric BaP concentrations that agree much better with measurements, compared to the default model, as well as stronger long-range transport and greater deposition fluxes. This new approach also predicts elevated lung-cancer risk from PAHs. Predicted oxidation of BaP is highest over a tropical belt where OA is liquid-like.

Authors:
ORCiD logo; ; ; ; ; ; ; ; ; ORCiD logo;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1344043
Report Number(s):
PNNL-SA-121554
Journal ID: ISSN 0027-8424; 48913
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America; Journal Volume: 114; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Environmental Molecular Sciences Laboratory

Citation Formats

Shrivastava, Manish, Lou, Silja, Zelenyuk, Alla, Easter, Richard C., Corley, Richard A., Thrall, Brian D., Rasch, Philip J., Fast, Jerome D., Massey Simonich, Staci L., Shen, Huizhong, and Tao, Shu. Global long-range transport and lung cancer risk from polycyclic aromatic hydrocarbons shielded by coatings of organic aerosol. United States: N. p., 2017. Web. doi:10.1073/pnas.1618475114.
Shrivastava, Manish, Lou, Silja, Zelenyuk, Alla, Easter, Richard C., Corley, Richard A., Thrall, Brian D., Rasch, Philip J., Fast, Jerome D., Massey Simonich, Staci L., Shen, Huizhong, & Tao, Shu. Global long-range transport and lung cancer risk from polycyclic aromatic hydrocarbons shielded by coatings of organic aerosol. United States. doi:10.1073/pnas.1618475114.
Shrivastava, Manish, Lou, Silja, Zelenyuk, Alla, Easter, Richard C., Corley, Richard A., Thrall, Brian D., Rasch, Philip J., Fast, Jerome D., Massey Simonich, Staci L., Shen, Huizhong, and Tao, Shu. Mon . "Global long-range transport and lung cancer risk from polycyclic aromatic hydrocarbons shielded by coatings of organic aerosol". United States. doi:10.1073/pnas.1618475114.
@article{osti_1344043,
title = {Global long-range transport and lung cancer risk from polycyclic aromatic hydrocarbons shielded by coatings of organic aerosol},
author = {Shrivastava, Manish and Lou, Silja and Zelenyuk, Alla and Easter, Richard C. and Corley, Richard A. and Thrall, Brian D. and Rasch, Philip J. and Fast, Jerome D. and Massey Simonich, Staci L. and Shen, Huizhong and Tao, Shu},
abstractNote = {Polycyclic aromatic hydrocarbons (PAHs) have toxic impacts on ecosystems and human health. Laboratory measurements show that one of the most carcinogenic PAHs, benzo(a)pyrene, which is adsorbed on surfaces of soot particles, reacts very quickly with atmospheric oxidants like ozone within ~2 hours. Yet, field observations indicate that it actually persists for much longer periods in the atmosphere, and this large discrepancy is not well understood. Driven by novel experimental understanding, we develop a new modelling approach, whereby particle-bound BaP is shielded from oxidation by a coating of viscous organic aerosol (OA). We show that application of this new approach in a global climate model leads to higher atmospheric BaP concentrations that agree much better with measurements, compared to the default model, as well as stronger long-range transport and greater deposition fluxes. This new approach also predicts elevated lung-cancer risk from PAHs. Predicted oxidation of BaP is highest over a tropical belt where OA is liquid-like.},
doi = {10.1073/pnas.1618475114},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 6,
volume = 114,
place = {United States},
year = {Mon Jan 23 00:00:00 EST 2017},
month = {Mon Jan 23 00:00:00 EST 2017}
}
  • Polycyclic aromatic hydrocarbons (PAHs) known for their harmful health effects undergo long-range transport (LRT) when adsorbed on and/or absorbed in atmospheric particles. The association between atmospheric particles, PAHs, and their LRT has been the subject of many studies, yet remains poorly understood. Current models assume PAHs instantaneously attain reversible gas-particle equilibrium. In this paradigm, during LRT, as gas-phase PAHs concentrations are depleted due to oxidation and dilution, particle-bound PAHs rapidly evaporate to re-establish equilibrium, leading to severe underpredictions of LRT potential of particle-bound PAHs. Here we present a new, experimentally based picture, in which the PAHs become trapped inside highlymore » viscous quasi-solid secondary organic aerosol (SOA) particles during particle formation, and thus prevented from evaporation, and shielded from oxidation. In contrast, surface-adsorbed PAHs rapidly evaporate, leaving no trace behind. We find synergetic effects between PAHs and SOA, in that the presence of PAHs inside SOA particles drastically slows SOA evaporation to the point that it can be ignored, and the highly viscous SOA prevents PAHs evaporation assuring efficient LRT. The data show that the assumptions of instantaneous reversible gas-particle equilibrium for PAHs and for SOA are fundamentally flawed, providing explanation for the persistent discrepancy between observed and predicted particle-bound PAHs.« less
  • The temporal trend of the particulate polycyclic aromatic hydrocarbon (PAH) level was observed at Gosan, a background site in Korea, for 4 years between November 2001 and January 2004. The total average concentration of ambient particulate PAH compounds was 3.65 +/- 4.74 ng m{sup -3}, which was mainly affected by a rather small number of very high PAH level samples. The PAH level at Gosan was 1 or 2 orders higher than those at other remote sites and 1 or 2 orders lower than those in urban areas in northeast Asia. The particulate PAH concentrations were high during cold periodsmore » mainly because of the seasonal variation of fossil fuel usage amount in northeast Asia. When the PAH levels were high, the ratio of BeP-to-BaP was also high, which is an indicator of particle residence time in the air. On the basis of the backward trajectory and upper wind direction analyses, it was observed that when air parcels were from China, the PAH levels were high. Also, the compositions of PAH compound ratios were similar to those in Beijing in winter. These indicate influence of emissions from China, especially from coal combustion and long-range transport. The relationship between the concentrations of PAHs and non-sea-salt-(nss)-SO{sub 4}{sup 2-} was generally good when the PAH levels were high. However, the periods of peaks were different, implying different emission patterns.« less
  • For identification of the substances chiefly responsible for the carcinogenic action of the emission condensate from coal-fired residential furnaces, the implantation method was used as a carcinogen-specific bioassay for comparison of the carcinogenic effect of various fractions with that of a total sample of flue gas condensate tested in 2 or 3 different doses. After implantation into the lungs of Osborne-Mendel rats, the condensate from coal-fired residential furnaces, a fraction containing polycyclic aromatic hydrocarbons (PAHs) and thiaarenes (sulfur-containing polycyclic aromatic compounds (S-PACs)) with 4-7 rings, as well as fraction containing more polar polycyclic aromatic compounds (PACs) and PAHs with highermore » molecular weight, induced lung carcinomas and sarcomas. According to probit analysis, the fraction containing PAHs plus S-PACs with 4-7 rings accounted for about 68.2% of the total carcinogenicity of flue gas condensate, whereas the fraction containing more polar PACs and higher PAHs accounted for about 54.6%. All other fractions, such as nonaromatic compounds and PACs with 2 and 3 rings, constituting about 70% of the weight of the total condensate, seemed not to be carcinogenic. Only 1.4% of the total carcinogenicity of the flue gas condensate was found to be attributable to the amount of benzo(a)pyrene (CAS: 50-32-8) present in the condensate (1.14 mg/g condensate). The contribution of more than 100% of both active fractions to the total carcinogenicity (68.2 and 54.6%) may suggest an interrelation of the fractions.« less
  • A retrospective industrial hygiene investigation was undertaken to explain the cause of a statistically significant excess lung cancer mortality observed in a subset of a large cohort of nickel workers involved in mining, smelting, and refining of nickel and copper in Ontario. The focus of this paper is to demonstrate how an industrial hygiene follow-up assessment of an epidemiologic finding can help to identify a likely cause. Polycyclic aromatic hydrocarbons (PAHs) alone or in association with particulate and gaseous contaminants (e.g., SO2) were likely the causative agents of the excess lung cancer observed among the lead welders, cranemen, and arcmore » furnace workers of the copper refinery.« less
  • When secondary organic aerosol (SOA) particles are formed by ozonolysis in the presence of gas-phase polycyclic aromatic hydrocarbons (PAHs), their formation and properties are significantly different from SOA particles formed without PAHs. For all SOA precursors and all PAHs, discussed in this study, the presence of the gas-phase PAHs during SOA formation significantly affects particle mass loadings, composition, growth, evaporation kinetics, and viscosity. SOA particles formed in the presence of PAHs have, as part of their compositions, trapped unreacted PAHs and products of heterogeneous reactions between PAHs and ozone. Compared to ‘pure’ SOA particles, these particles exhibit slower evaporation kinetics,more » have higher fractions of non-volatile components, like oligomers, and higher viscosities, assuring their longer atmospheric lifetimes. In turn, the increased viscosity and decreased volatility provide a shield that protects PAHs from chemical degradation and evaporation, allowing for the long-range transport of these toxic pollutants. The magnitude of the effect of PAHs on SOA formation is surprisingly large. The presence of PAHs during SOA formation increases mass loadings by factors of two to five, and particle number concentrations, in some cases, by more than a factor of 100. Increases in SOA mass, particle number concentrations, and lifetime have important implications to many atmospheric processes related to climate, weather, visibility, and human health, all of which relate to the interactions between biogenic SOA and anthropogenic PAHs. The synergistic relationship between SOA and PAHs presented here are clearly complex and call for future research to elucidate further the underlying processes and their exact atmospheric implications.« less