Health Implications of Polycyclic Aromatic Hydrocarbons in Indoor Environments

JUANA MARI DELGADO-SABORIT (1), Christopher Stark(1), Roy M. Harrison (1)

(1) Division of Environmental Health and Risk Management; School of Geography, Earth and Environmental Sciences; University of Birmingham; Birmingham; B15 2TT; United Kingdom

     Abstract Number: 57
     Last modified: October 9, 2009

Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment largely because of their formation in combustion of carbon-containing fuels. One of the main pathways of human exposure is through inhalation from the atmosphere and studies of occupationally exposed populations have shown significant excess of lung cancer incidence associated with PAH exposure. The excess of disease is sufficient to conclude that PAH represent a significant risk to public health at environmental concentrations. Unlike most carcinogenic pollutants, PAHs are not a single compound but a complex mixture of compounds of widely varying carcinogenicity. In recommending a UK air quality standard for PAHs in outdoor air, the U.K. Expert Panel on Air Quality Standards (EPAQS) adopted the approach of treating benzo(a)pyrene as a marker for the entire mixture of compounds and set a standard of 0.25 ng.m3 of benzo(a)pyrene as annual mean. In doing so, it satisfied itself that the percentage of the overall carcinogenic potential of the mixture represented by benzo(a)pyrene was very similar in UK urban air to that in the aluminium smelter from which epidemiological data were used to derive the air quality standard.
The main purposes of the present study are to determine the concentrations and relative abundance of individual PAHs in indoor environments and their contribution to the overall carcinogenicity of the PAH mixture, and to compare with data measured in outdoor air and the aluminium smelter referred to above in order to assess the suitability of the UK air quality standard derived for outdoor air for use as a guideline for indoor environments.
Concentrations of 16 particle-phase PAHs were measured in both indoor and outdoor environments. Indoor samples were collected in homes, workplaces and other public spaces and outdoor samples were collected on trafficked roadsides, background streets, pedestrian streets and parks.
PAH concentrations were generally lower indoors than outdoors, although those microenvironments subject to Environmental Tobacco Smoke showed the highest PAH levels. The relative abundance of benzo(a)pyrene relative to other high molecular weight PAH was found to be broadly similar in the indoor samples to those collected out-of-doors and to those examined by EPAQS. Using published relative carcinogenic potency factors for individual PAH, the proportion of carcinogenic potential represented by benzo(a)pyrene was evaluated in both indoor and outdoor samples and found to be broadly similar in both, and comparable to that in the atmosphere of the aluminium smelter used in setting the EPAQS recommendation. These results suggest the suitability of benzo(a)pyrene as a marker for the carcinogenic potential of the PAH mixture in both outdoor and indoor air.