SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
An analysis of an atmospheric urban aerosol with regard to the nature and particle size distribution for different locations has been undertaken. Results indicate that 67% of total suspended matter, 87% of lead, and 70--80 % of polycyclic aromatic hydrocarbons (PAH) penetrate the respiratory tracts.
Experiments to evaluate the genotoxic potentialities of urban air particles sampled in Paris (France) after organic solvent extraction have been carried out using four in vitro genotoxicity tests. The two bacterial tests (the Ames test and the SOS Chromotest) demonstrate the genotoxicity of the organic extracts of atmospheric particles; two additional tests (induction of 6-thioguanine mutants and sister chromatid exchanges), carried out on V79 Chinese hamster cells, also confirm these potentialities. These results show clearly that particulate organic extracts induce point mutations in both bacteria and mammalian cells, or the cellular response (SOS repair) to these mutations in bacteria; likewise, they are responsible for clastogenic effects in mammalian cells. Genotoxicity is due either to direct genotoxic chemicals or to active metabolic products of the action of microsomal enzymes. The optimalization of testing procedures is discussed in order to appreciate the contribution of genotoxicity tests to the study of atmospheric pollution.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We analyzed the exogenous mineral particle concentration, size, type, and distribution for particles larger than 0.1 micron in the left lungs of 10 long-term male cigarette smokers. The mean number of particles found was 465 +/- 295 X 10(6)/g dry lung, of which 80% were kaolinite, micas, feldspars, free silica, and talc. Lead particles were extremely rare, despite their ubiquity in urban air. Overall there were no differences in particle concentration in upper vs lower lobes or central vs peripheral sampling sites. However, a significant correlation was found for upper lobe (r = 0.68), but not lower lobe (r = 0.08), particle concentration and amount of cigarette smoking. Overall, the geometric mean particle size was 0.6 +/- 2.1 microns; 56% of the particles in the upper lobes were larger than 0.75 micron in diameter, compared to 17% in the lower lobes, and the mean upper lobe particle size was greater than the mean lower lobe particle size for all individual mineral types. There was a remarkable homogeneity of mean particle size from patient to patient (mean intercase arithmetic particle size +/- SD of 0.8 +/- 0.1 micron). Particle size was not affected by the amount of smoking. We conclude that contrary to some published acute deposition data, there are no long-term differences in upper vs lower lobe particle concentration; total upper lobe particle retention is influenced by the amount of smoking as measured by pack-years, whereas total lower lobe particle retention appears to be independent by the amount of smoking; particles retained in the upper lobe are somewhat larger than those retained in the lower lobe, but the amount of smoking does not appear to influence retained particle size; the size of long-term retained particles most likely reflects largely atmospheric particle burden; and in the absence of overwhelming dust loads, the lung is able to regulate retained particle concentration and size in a fairly narrow range.
Assessing human exposure to chemicals from Superfund sites requires knowledge of basic physical, chemical, and biological processes occurring in the environment and specific information about the local environment and population in the vicinity of sites of interest. Although progress is being made in both areas, there is still a tremendous amount to be done. Participants at this meeting have identified several of the areas in need of greater understanding, and they are listed below. Movement of dissolved and volatile organics, especially NAPLs, in the subsurface environment. This includes study of the partitioning of compounds between NAPLs, air, water, and soil. Partitioning of volatilized chemicals between gaseous and aerosol components of the atmosphere. This includes understanding how these components influence both wet and dry deposition. Long-term movement from sediments into biota and how these affect chronic toxicity to sediment biota. Broad validation of PBPK models describing partitioning of compounds from sediment and water into fish. Reactions of chemicals sorbed to atmospheric particles. This includes application of laboratory models to real and varied atmospheric conditions. Interactions between biotic and abiotic transformations in soil and sediment. Applicability of physiological pharmacokinetic models developed in laboratory studies of experimental animals and clinical investigations of humans to environmental chemicals, concentrations, and routes of exposure in humans. Use of human and wildlife behavioral and biomonitoring information to estimate exposure. This includes better understanding of human variability and the applicability of information gathered from particular wildlife species. To successfully address these gaps in our knowledge, much more analytical data must be collected.(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVE: To evaluate the extent to which human airway carinas accumulate ambient atmospheric particles, a newly developed technique was used to micro-dissect and analyse particle concentration in tubular segments and carinas of the large airways of 10 necropsy lungs from non-smokers from the general population of Vancouver. METHODS: Ratios of the particle concentrations on the carinas to the tubular segment immediately preceding it were measured with analytical electron microscopy for the mainstem bronchus, upper and lower lobe bronchi, and four different segmental or subsegmental bronchi--that is, Weibel generations 1 to about 5. A total of 119 carinal-tubular pairs was evaluated. RESULTS: Over all cases, both carinal and tubular particle concentrations increased with increasing airway generation; the median ratio of carinal to tubular particle concentration was 9:1 and did not show any trend with airway generation. The ratio was > 5 in 71% of carinal-tubular pairs, > 10 in 42% of pairs, > 20 in 31% of pairs, and > 100 in 9% of pairs. Some subjects showed a notable tendency to high ratios, with many ratios > 100, and other subjects had a tendency toward low ratios. The predominant mineral species in both carinas and tubular airway segments was crystalline silica and the relative proportion was similar in both sites; however, mean particle diameter was consistently less in the carinal tissues. CONCLUSIONS: These findings suggest that the ratio of carinal to tubular retained particles in the large airways in non-smokers is higher than might be supposed from data generated in airway casts, and that there is considerable variation in this ratio between subjects. This finding is of potential interest in models of carcinogen, toxin, and dose of fibrogenic agent to the large airways as it suggests high and sometimes extreme concentrations of toxic particles at carinas, and thus reinforces the notion that carinas may be sites of initiation of disease.
Samples of total suspended particulate matter and inhalable particles were collected from the atmosphere in Beijing, Shanghai, Wuhan, Taiyuan, and Zibo. The size distribution of particles, the variations in their concentrations during different seasons, and the concentrations of 10 kinds of inorganic elements and polycyclic aromatic hydrocarbons were also obtained. This information provided a scientific basis for studying the effects of particle pollution on human health, for formulating health standards, and for taking preventive measures.