Assessment of PAH toxicity and mutagenicity in emissions from coal and biofuel combustion.

Emissions from combustion of coal, wood and cowdung cakes in domestic cookstoves were sampled through a Stack Monitor on Glass Fibre thimbles. 16 PAH compounds were quantified in the samples extracted in dichloromethane by Gas Chromatography using FID detector. The toxic potencies of the quantified PAHs were determined by Toxicity Equivalence (TEF) Approach and their mutagenecities were tested by using Ames Plate Incorporation Method. All the 16 PAHs were determined in the emission of wood, including genotoxic compounds: carcinogens (BaA, Chy, BbF, BkF, BaP, DbA and IP) and co-carcinogens (Fla, Pyr, BghiP). In coal smoke, only 12 compounds were detected, while in cowdung cake 15 PAHs were detected except Phenanthrene. Emission factors on a fuel weight basis are highest for cowdung cake (120.23 mg/kg), followed by wood (48.97 mg/kg) and coal (28.85 mg/kg). Most of the contribution to the total PAH concentrations was from the high molecular weight compounds. Considering the genotoxic PAHs, the emission factor ranking order was from cow dung cake (115.85 mg/kg) to wood (43.03 mg/kg) and lowest for coal fuel (25.97 mg/kg). The emission factor for BaP was highest for cowdung cake (78.83 mg/kg) followed by coal (5.53 mg/kg) and wood fuel (4.47 mg/kg). Calculation of toxic potencies reveals that the carcinogenic contribution from low molecular weight PAHs is relatively much lower than high molecular weight PAHs for each tested fuel. Cow dung cake extracts did not show mutagenic activity in the Ames Salmonella test probably due to lower concentration of the direct-mutagens like Pyr, Chy. In contrast, the extracts of coal and wood had higher concentrations of direct-mutagens like Pyr, Chy, so positive results were obtained.

Measurements of polycyclic aromatic hydrocarbons at an industrial site in India.

Polycyclic Aromatic Hydrocarbon (PAH) concentrations were measured in Total Suspended Particulate Matter (TSPM) from December 2005 to August 2006 at Nunhai, an industrial site in Agra (India). Particulate matter samples were collected on glass fibre filters using High Volume Sampler (HVS-430) and were extracted using dichloromethane with ultrasonication and analyzed by GC. Total PAH concentration varies between 0.04 to 2.5 microg m(-3) accounting only 1.6 x 10(-3)% of TSPM. The mass distribution in air was dominated by high molecular weight DbA, BghiP, BaP, BkF and IP. Combustion PAH (CPAH) except BeP represents 58% of the total PAH mass and IARC classified total carcinogenic PAH accounting 63% of TPAH concentration. Correlation studies between PAH revealed the contribution of low molecular weight PAH was mainly due to primary emission from diesel exhaust while high molecular weight PAH were formed during combustion. The presence of specific tracers and calculation of characteristic molecular diagnostic ratios Fla/(Fla + Pyr), BaP/(BaP + Chy), BaA/(BaA + Chy), IP/(IP + BghiP), BaP/BghiP and IP/BghiP) were used to identify the sources of the emissions of PAHs in the atmospheric samples. Seasonal variation in atmospheric PAH showed four fold increase in winter concentration than summer. The BaP and relative BaP amount calculated from the measurements suggested that photo-oxidation may also be responsible for the variation in PAH concentrations during winter and summer. Seasonal trends in atmospheric PAH concentration in the study area were influenced by fossil fuel usage for domestic heating, boundary height and temperature.

Polycyclic aromatic hydrocarbons in ambient air at Agra: distribution and toxicity assessment.

Polycyclic Aromatic Hydrocarbons (PAHs) are a class of organic pollutants that are commonly found in the environment, largely due to combustion or processing of hydrocarbon fuels. PAHs are considered highly toxic for human beings and several of these compounds are carcinogenic, mutagenic and teratogenic. Human exposure to PAHs occurs principally by direct inhalation, ingestion or dermal contact as a result of the widespread presence and persistence of PAHs in the urban environment. With increasing awareness that PAHs are known and suspected carcinogens, this study was undertaken to monitor PAH compounds in Total Suspended Particulate Matter (TSPM) at the industrial site--Nunhai, Agra. For this purpose, TSPM samples were collected on glass fibre filter papers (EPM 2000) using High Volume Sampler (HVS 430) at Nunhai, Agra. 16 EPA priority PAH compounds were analyzed by a Gas Chromatograph equipped with FID detector. PAHs having high molecular weight, i.e., BghiP, BbF, DbA, BaA, BaP and IP, were the most abundant with concentrations ranging between 0.026 to 0.56 ng m(-3). The calculated mean TPAH value was 0.32 ng m(-3). The probably carcinogenic and possibly carcinogenic PAH as classified by International Agency for Research on Cancer (IARC) accounted for 42% and 38% respectively of the total PAH. The health risk associated with inhalatory exposure to PAHs was assessed on the basis of Benzo(a)pyrene concentration in air and Toxic Equivalency Factor (TEF) for individual PAH. In the present study, BaP concentrations ranged from 0.005 to 0.23 ng m(-3) with a mean value of 0.04 ng m(-3). Carcinogenic potencies for DbA and BaP in PAH mixtures based on TEF concept were 45% and 39% respectively. This underlines the importance of DbA and BaPas a surrogate compound of a PAH mixture in our environment in assessing human health risk.