Polynuclear Aromatic Fractions Research Articles

Mutagenecity and contents of polycyclic aromatic hydrocarbons in new high-viscosity naphthenic oils and used and recycled mineral oils

Mutagenic activity on the Ames test was evaluated in 15 samples of naphthenic high-viscosity minerals oils and 12 samples of used lubricants (recovered and pooled) and their recycled products. Bacterial mutagenesis was assayed using both the standard technique and Blackburn's modification. The contents of polycyclic aromatic hydrocarbons (PAH) was also evaluated, as polynuclear aromatic fraction (PAF) and total PAH, determined respectively with the semi-quantitative dimethylsulphoxide-refractive index method and the Grimmer method. Only four samples (three acid-treated naphthenic oils and one recycled fraction of a used oil) showed mutagenic activity higher than 6 revertants/mg of oil, considered by Blackburn and coworkers as indicating a potential carcinogenic risk for these compounds. Limited mutagenecity was found in all used and recycled oils, but also in samples of acid- or solvent-treated oils. No hydrogen-treated naphthenic oils turned out to have any mutagenic activity. PAF contents of oils were closely correlated with those of total PAH ( n = 15, r = 0.83; n = 12, r = 0.91; p<0.01 for both naphthenic and used/recycled oils respectively). No recycled oil had high PAF contents. Eleven samples had PAF contents higher than 3%, the arbitrary danger threshold suggested by the CONCAWE (1988). Of these 11 samples, the majority were acid-treated products, although there was one hydrogen-treated oil and one used and recycled oil. No mutagenic activity could be demonstrated in almost half the oils with PAF > 3%. In this study, the presence of mutagens was not correlated either with PAF or with total or mutagenic PAH. The difficulty of predicting the mutagenecity of mineral oil is stressed. Most naphthenic and some recycled oils clearly have components which inhibit the metabolizing system in the bacterial mutagenesis test, with consequent possible false negative results.

Pulmonary carcinogenesis in rats given implants of shale oil in beeswax pellets

Pellets of crude shale oil, neutral, basic, or polynuclear aromatic fractions of shale oil, or crude petroleum were implanted in the lungs of rats through a thoracotomy. The pellets had a beeswax-tricaprylin vehicle that allowed the slow release of material into the surrounding parenchyma. A dose-related incidence of lung cancer was observed with each of the materials studies. A greater risk for lung cancer was not demonstrated for crude shale oil compared to crude petroleum.

H.p.l.c. separation and g.c. characterization of polynuclear aromatic fractions of bitumen, heavy oils and their synthetic crude products

Characterization of bitumen, heavy oils, crude oil distillation residues and their processed products involves separation of the mixtures into several compound classes according to their molecular structure. However, these fractions are still very complex and often need further separation in order to get a better insight into their composition as well as the processing reactions involved in their upgrading. In this paper, the polynuclear aromatic fraction is divided into three subfractions by high performance liquid chromatography. Gas chromatography is then used to quantify these fractions and to determine their average molecular weight by a new method derived from simulated distillation. Crude oil distillation residues and their hydrocracked products are used to demonstrate this method.

Clean-up of polynuclear aromatic hydrocarbons from air particulate matter on XAD-2

A clean-up procedure is developed for polynuclear aromatic compounds. It is based on adsorption chromatography on XAD-2 and stepwise elution with ethanol, n-pentane and toluene. The polynuclear aromatic fraction of air particulate matter is isolated by this method and analyzed by glass capillary gas chromatography. Recoveries of nine polynuclear aromatic compounds are reported. The efficiency of group isolation is demonstrated with mixtures of polyaromatic compounds, phthalates and hydrocarbons.

Relative Potency Estimation for Synthetic Petroleum Skin Carcinogens

A procedure for quantitative analysis of skin carcinogenesis data, for the purpose of establishing carcinogenic potency, has been applied to observations obtained from C3H mice exposed continuously to synthetic and natural petroleums. The importance of total polynuclear aromatic (PNA) content to the skin carcinogenic activity of the crude materials was also examined. Of three synthetic petroleums evaluated, all were shown capable of inducing skin neoplasms within a two-year exposure period. Under comparable exposure conditions a composite sample of five natural petroleums was noncarcinogenic. Comparison of the distributions of times to initial skin neoplasm versus dose rate, for groups exposed to synthetic fossil liquids and the reference skin carcinogen, benzo(a)pyrene, provided estimates of relative carcinotenic potency for the synthetic petroleums ranging from 1/500 to 1/1400 the potency of benzo(a)pyrene. The carcinogenic activity of a chemically isolated PNA fraction versus the crude from which it was derived suggested that this fraction was responsible for the carcinogenic activity of these synthetic petroleums in mouse skin.

Mutagenicity of airborne particles from a nonindustrial town

AbstractThe mutagenic activity of ambient air particles from Morgantown, West Virginia, has been monitored for 6 months using the Ames Salmonella assay system. Airborne particles, collected on glass fiber filters using a Hi‐Vol sampler, were extracted with dichloromethane (DCM) and/or ethyl acetate plus methanol (E + M) in sequence. A dose‐dependent mutagenic response was observed in Salmonella typhimurium TA 98 for DCM extracts from all samples. E + M extracts were mutagenic only when samples were extracted with E + M before DCM extraction. The mutagenic activity of samples collected in June and July was independent of S‐9 in vitro activation, whereas the mutagenicity of those collected from October to December increased in the presence of S‐9 activation. The class fractionation of extracts showed that only acidic and polynuclear aromatic fractions were mutagenic. The mutagenicity of particles from Morgantown air was also detected with the Salmonella arabinose‐resistant assay system.

Profiles of the polynuclear aromatic fraction from engine oils obtained by capillary-column gas-liquid chromatography and nitrogen-selective detection

Profiles of the polynuclear aromatic fraction from engine oils obtained by capillary-column gas-liquid chromatography and nitrogen-selective detection

Studies of fretting wear. 1. The effect of physical variables

Mutagenic activity on the Ames test was evaluated in 15 samples of naphthenic high-viscosity minerals oils and 12 samples of used lubricants (recovered and pooled) and their recycled products. Bacterial mutagenesis was assayed using both the standard technique and Blackburn's modification. The contents of polycyclic aromatic hydrocarbons (PAH) was also evaluated, as polynuclear aromatic fraction (PAF) and total PAH, determined respectively with the semi-quantitative dimethylsulphoxide-refractive index method and the Grimmer method.Only four samples (three acid-treated naphthenic oils and one recycled fraction of a used oil) showed mutagenic activity higher than 6 revertants/mg of oil, considered by Blackburn and coworkers as indicating a potential carcinogenic risk for these compounds. Limited mutagenecity was found in all used and recycled oils, but also in samples of acid- or solvent-treated oils. No hydrogen-treated naphthenic oils turned out to have any mutagenic activity. PAF contents of oils were closely correlated with those of total PAH (n = 15, r = 0.83; n = 12, r = 0.91; p<0.01 for both naphthenic and used/recycled oils respectively). No recycled oil had high PAF contents. Eleven samples had PAF contents higher than 3%, the arbitrary danger threshold suggested by the CONCAWE (1988). Of these 11 samples, the majority were acid-treated products, although there was one hydrogen-treated oil and one used and recycled oil. No mutagenic activity could be demonstrated in almost half the oils with PAF > 3%. In this study, the presence of mutagens was not correlated either with PAF or with total or mutagenic PAH.The difficulty of predicting the mutagenecity of mineral oil is stressed. Most naphthenic and some recycled oils clearly have components which inhibit the metabolizing system in the bacterial mutagenesis test, with consequent possible false negative results.