Levels Of Benzo[a]pyrene Research Articles

Analytical study of cigarette smoke enriched in benzo[a]pyrene for use in model animal studies

Cigarette smoke has been significantly enriched in benzo[ a]pyrene (BAP) by injecting 200 μl of a cyclohexane solution, containing a total of 40 μg of BAP, into a cigarette. After injection, the cigarette is conditioned and smoked according to standard protocol. When the cigarette smoke condensate is analyzed by fluorescence spectroscopy, liquid scintillation counting, gas chromatography with flame ionization detection, and gas chromatography-mass spectrometry, it is found that the level of BAP has increased by 1000 times with respect to levels reported for unenriched cigarette smoke. No chemical transformation of the BAP has been detected, and the BAP-enriched fraction does not appear to be perturbed to a detectable degree. Approximately 28% of the BAP is measured in the mainstream smoke, 46–48% in the sidestream smoke from the burning end of the cigarette, and 7% in the butt and ash. Correcting for analytical losses, about 10% appears to escape in the gaseous state. This material may prove suitable for model animal studies.

Ambient Total Suspended Particulate Matter and Benzo (a) Pyrene Concentrations from Residential Wood Combustion in a Mountain Resort Community

This research investigated community air pollution in Telluride, Colorado, resulting from particulate matter emissions generated by residential wood combustion. Total suspended particulate matter and benzo (a) pyrene (BaP) concentrations were highest in the center of town, averaging 61 µg/m3 and 7.4 ng/m3, respectively. The mean BaP level of 7.4 ng/m3 appears to be several times greater than that which would be expected in a major metropolitan area. Residential wood combustion is suspected as the primary source of BaP in this community.

Carcinogenic agents in cigarette smoke and the influence of nitrate on their formation.

The nitrate level of a nonfilter reference cigarette was elevated from 0.52% to 1.2, 1.8, 2.4 and 3.05%, respectively, by addition of sodium nitrate. Data from the mainstream smoke analyses of these cigarettes were compared. Yields of carbon monoxide and carbon dioxide were not significantly altered as a result of nitrate elevation. Tar, nicotine, benzo[a]pyrene (BaP) and catechol in mainstream smoke were reduced while yields of nitrogen oxides (NOx), volatile N-nitrosamines (VNA) and tobacco-specific N-nitrosamines (TSNA) were significantly increased. On the basis of previous bioassays with smoke condensates from high-nitrate cigarettes, it was expected that the cutaneous tumorigenicity of these tars would be reduced due to lower levels of BaP (and other carcinogenic PAH) and catechol. However, the total carcinogenic potential of whole smoke from high nitrate cigarettes is considered by us to be significantly increased due to the elevated yields of Nox, VNA and TSNA. The nitrosamines are regarded as a major group of carcinogens in tobacco smoke; the nitrogen oxides are the most important precursors for the endogenous formation of N-nitrosamines upon smoke inhalation. The findings of this model study support the recommendation that the nitrate content of tobacco products should be reduced.

Factors affecting plasma benzo[ a]pyrene levels in environmental studies

Benzo[ a]pyrene (BaP) is a useful indicator of exposure to polycyclic aromatic hydrocarbons (PAHs), airborne carcinogenic compounds. Radioimmunoassay was used to test for plasma BaP differences in 61 subjects divided into three groups based on geographic-demographic locale: urban-industrial, urban-residential, and outer suburban. The results showed that the urban-industrial area participants had a significantly higher mean plasma BaP level than did the outer suburban subjects. The urban-residential subjects did not have a significantly different mean plasma benzo[ a]pyrene level from either of the other two groups. Obesity, as measured by Quetelet's index, was found to have a significant correlation with BaP levels. These results indicate that radioimmunoassay of plasma for BaP may be used successfully to judge environmental exposure to PAHs, provided physiological considerations such as obesity are taken into account.

Carcinogenicity of Airborne Fine Particulate Benzo(a)pyrene: An Appraisal of the Evidence and the Need for Control

Benzo(a)pyrene(BaP) originating from fossil fuel and other organic combustion processes is largely adsorbed on fine particulate and hence is a widespread atmospheric pollutant. Available emissions and air quality data are based on the total weight of particulate matter without reference to size and give little information on trends and concentrations of fine particulate BaP. Greater reliance on coal, synfuels and diesel fuel for energy production and transportation will significantly increase ambient levels of BaP. Because of the particulate size, BaP is substantially deposited in the lower lung and readily eluted into surrounding tissue. After elution in the lung, BaP is metabolically activated to its electrophilic, carcinogenic from by a complex enzyme system whose activity is increased by prior exposure to air pollutants, cigarette smoke and certain drugs. The resultant diol epoxide metabolite has been shown to bind covalently with the DNA of the lung. In experimental animals, BaP is a potent initiating carcinogen whose action is enhanced by sulfur dioxide, promoting agents and carrier fine particles. The effect of small, divided doses of BaP has been shown to be greater than that of a single high dose; no threshold has been established. Epidemiological studies show that mixtures containing BaP (such as urban air, industrial emissions and cigarette smoke) are carcinogenic and may interact synergistically. Occupational studies indicate that the action of BaP-containing mixtures is enhanced in the presence of SO2. However, quantitative risk assessment for BaP is precluded by problems in extrapolating to the general population from small-scale animal studies; uncertainties in findings of epidemiology; and imprecise exposure data. Existing stationary and mobile controls preferentially remove coarse particulate matter and are inefficient collectors of the particulate BaP. In the current absence of health and environmental standards for BaP, there is little incentive to control BaP emissions. BaP meets the criteria for regulation under the Clean Air Act; however, no such BaP standards have yet been proposed.

Carcinogenicity of airborne fine particulate benzo(a)pyrene: an appraisal of the evidence and the need for control.

Benzo(a)pyrene(BaP) originating from fossil fuel and other organic combustion processes is largely adsorbed on fine particulate and hence is a widespread atmospheric pollutant. Available emissions and air quality data are based on the total weight of particulate matter without reference to size and give little information on trends and concentrations of fine particulate BaP. Greater reliance on coal, synfuels and diesel fuel for energy production and transportation will significantly increase ambient levels of BaP. Because of the particulate size, BaP is substantially deposited in the lower lung and readily eluted into surrounding tissue. After elution in the lung, BaP is metabolically activated to its electrophilic, carcinogenic from by a complex enzyme system whose activity is increased by prior exposure to air pollutants, cigarette smoke and certain drugs. The resultant diol epoxide metabolite has been shown to bind covalently with the DNA of the lung. In experimental animals, BaP is a potent initiating carcinogen whose action is enhanced by sulfur dioxide, promoting agents and carrier fine particles. The effect of small, divided doses of BaP has been shown to be greater than that of a single high dose; no threshold has been established. Epidemiological studies show that mixtures containing BaP (such as urban air, industrial emissions and cigarette smoke) are carcinogenic and may interact synergistically. Occupational studies indicate that the action of BaP-containing mixtures is enhanced in the presence of SO2. However, quantitative risk assessment for BaP is precluded by problems in extrapolating to the general population from small-scale animal studies; uncertainties in findings of epidemiology; and imprecise exposure data. Existing stationary and mobile controls preferentially remove coarse particulate matter and are inefficient collectors of the particulate BaP. In the current absence of health and environmental standards for BaP, there is little incentive to control BaP emissions. BaP meets the criteria for regulation under the Clean Air Act; however, no such BaP standards have yet been proposed.

Enhancement of plasma alpha-fetoprotein, as measured by sandwich-type radioimmunoassay, and induction of gamma-glutamyl transpeptidase-positive hepatic cell foci in rats fed benzo[a]pyrene.

Male Fischer rats were fed semipurified diets containing 0, 1, 100, and 1000 ppm benzo[a]pyrene (BaP) for 6 or 13 wk. Plasma samples were assayed for alpha-fetoprotein (AFP) by a new sandwich-type radioimmunoassay (RIA) utilizing a special controlled porous-glass solid phase. This procedure is described in detail. Significant AFP elevation (p less than or equal to 0.01) was observed in the highest BaP treatment group after 5 wk of treatment. The 1 and 100 ppm Bap groups exhibited no AFP elevation throughout the study. Liver sections from the 1000 ppm groups had discrete gamma-glutamyl transpeptidase (GGT)-positive foci 10-20 cells in diameter by the 6th wk. GGT-positive foci were not evident in liver sections from the other treatment groups. Thus a high level of dietary BaP appears to rapidly alter rat liver cells, indicating hepatic neoplasia.

Forest Fires: An Important Source of Benzo(a)Pyrene in the Caracas Valley

The levels of benzo(a)pyrene (BaP) were determined in downtown Caracas in order to have a first approach to the problem related to polycyclic aromatic hydrocarbons in this city. Caracas, the capital city of Venezuela is located 10.30° N and 66.77°E in a valley at an altitude of 996 m above sea level with an average temperature ranging from 18° to 23°C, and two distinctive climatic regimes, a dry and a wet season. The population is approximately 2.5 million with a car density of approximately 1000 vehicles/km2 and no industry. The valley is surrounded by mountains, the Avila National Park at the northern edge of the city with peaks of around 2200 m being the most important contribution to the green belt that has been preserved. As far as we know no other studies to determine the levels of BaP have been made in a populated urban area located near the equator.