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PubMedDate not supplied

Passive sampling and head space analysis for quantitative determination of nitrous oxide exposure.

A new technique has been developed for determining the time-weighted average personal exposure to nitrous oxide gas. Nitrous oxide gas is passively collected on a molecular sieve contained in a glass tube and partially desorbed in a vial until solid-gas equilibrium at 100 degrees C. Next, nitrous oxide concentration in the head space air in the vial is measured with a gas chromatograph equipped with an electron capture detector. This study shows that nitrous oxide concentration in the head space is proportional to both the nitrous oxide concentration in the test atmosphere and the sampling time up to 1600 ppm/hr. The coefficient of variance is less than 10%. The performance of the sampler is not affected by water vapor or carbon dioxide in the atmosphere nor by air currents. The sampler can be stored for 2 weeks at either 4 or 25 degrees C. Because the passive sampler is small and light, it can be used to determine exposure to nitrous oxide during surgical operations.

Air Pollution, Indoor↗
PubMed2000

Size distribution and sources of aerosol in Launceston, Australia, during winter 1997.

As part of a pilot study into the chemical and physical properties of Australian fine particles, a suite of aerosol samples was collected at Ti Tree Bend in Launceston, Tasmania, during June and July 1997. This period represents midwinter in the Southern Hemisphere, a period when aerosol sources in Launceston are dominated by smoke from domestic wood burning. This paper describes the results from this measurement campaign, with the aim of assessing the effect of wood smoke on the chemical and physical characteristics of ambient aerosol. A micro orifice uniform deposit impactor (MOUDI) was used to measure the size distributions of the aerosol from 0.05 to 20 microns aerodynamic diameter. Continuous measurements of fine particle mass were made using a PM2.5 tapered element oscillating microbalance (TEOM) and light scattering coefficients at 530 nm were measured with nephelometers. Mass size distributions tended to be bimodal, with the diameter of the dominant mode tending to smaller sizes with increases in total mass. Non-sea salt potassium and polycyclic aromatic hydrocarbons (PAHs) were used as chemical tracers for wood smoke. Wood smoke was found to increase absolute particle mass (enough to regularly exceed air quality standards), and to concentrate mass in a single mode below 1 micron aerodynamic diameter. The acid-base equilibrium of the aerosol was altered by the wood smoke source, with free acidity hydrogen ion, non-sea salt sulfate, and ammonium concentrations being higher and the concentration of all species, including nitrate (to differing extents), focused in the fine particle size ranges. The wood smoke source also heavily influenced the aerosol scattering efficiency, adding to a strong diurnal cycle in both mass concentration and light scattering.

Aerosols↗
PubMed2004

[Preparation method of Pd/Ce0.5Zr0.5O2 three-way catalysts].

1% Pd/Ce0.5Zr0.5O2(CZ) catalysts were prepared by deposition-precipitation (DP), mixing (MIX) and conventional impregnation (IMP) methods, and the effects of the preparation methods on the three-way catalytic behaviors were investigated. Hydrogen temperature-programmed reduction (H2-TPR) and in situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) were performed to understand the Pd-support interaction and the three-way catalytic reaction mechanisms. The experiments results reveal that the catalyst prepared by deposition-precipitation (DP) method shows the strongest Pd-support interaction and the best light-off performance. In situ DRIFTS results suggest that there exists alternative route of NOx reduction over Pd-DP catalyst. And it is supposed that Pd-support interaction leads to the difference of reaction mechanism and then the diversity of light-off performances.

Adsorption↗
PubMed2005

The conditions and perception of work during painting behind screening.

OBJECTIVE: This study attempted to reveal whether airborne solvent concentrations during painting behind screening are comparable to solvent concentrations during painting indoors, what factors potentially influence work conditions during painting behind screens, both positively and negatively, and what can be done to eliminate the disadvantages of screening. METHODS: Measurements of volatile organic compounds (VOC), climate, light, and noise were made at three sites during 1 day each. VOC were measured at another 10 sites, again during 1 day each. Questionnaires were sent to painters working in 305 firms. RESULTS: The results of the first series of measurements (exposure to VOC) ranged from 3.4 to 22.9 mg/m3 with a geometric mean of 11.7 and a geometric standard deviation of 2.1. This range was less than the level expected in well-ventilated rooms. In the second series of measurements, with a few exceptions, the concentrations of the individual compounds were below 1 mg/m3. In both series, the exposure index was generally < or = 0.05. The advantages of working behind screening were more certainty of work during the winter months, better temperature conditions, better quality of work, less draft, and less temperature fluctuation. CONCLUSIONS: Painting behind screening, as studied in this project, results in low exposure to VOC when compared with indoor situations. The main factors that need to be improved are temperature, lighting, view from the workplace, and ventilation.

Adult↗
PubMed2000

Insoluble components of concentrated air particles mediate alveolar macrophage responses in vitro.

We sought to characterize the bioactive constituents of concentrated ambient air particles (CAPs) through correlation of alveolar macrophage (AM) biological responses (production of TNF, macrophage inflammatory protein (MIP-2), nitrite; cell viability) to components of particle samples. CAPs samples collected on different days showed a range of bioactivity and a strong correlation was found between AM cytokine release and increased AM light scatter, a flow cytometric measure of relative particle load. Evaluation of soluble and insoluble fractions of CAPs suspensions indicate that 1) most biological effects on AMs are mediated by insoluble components and certain particle adsorbed factors such as endotoxin; 2) the variable bioactivity of CAPs collected on different days arises primarily from differences in the relative proportion of insoluble and soluble mass present in particle suspensions; and 3) the activation state of the AM influences which insoluble components are most bioactive. Use of endotoxin neutralizing agents (e.g., polymyxin-B) showed particle-adsorbed endotoxin in CAPs suspensions causes activation of normal (control) AMs while other (nonendotoxin) components are predominantly responsible for the enhanced cytokine release observed by primed AMs incubated with CAPs. The AM biological response did not correlate with any of a panel of elements quantified within insoluble CAPs samples (Al, Cd, Cr, Cu, Fe, Mg, Mn, Ni, S, Ti, V). These data demonstrate an important role for cell activation and phagocytosis of insoluble particulate matter in the response of AMs to CAPs suspensions.

Air Pollutants↗
PubMed1999

Lung cancer, tobacco, and environmental factors in the African population of the Northern Province, South Africa.

DESIGN: Case-control study among incident African patients with cancer. Questionnaire assessment of exposure to tobacco, occupation, and place of birth. SETTING: Northern Province, South Africa. SUBJECTS: Between 1993 and 1995, 288 men and 60 women with lung cancer and 183 male and 197 female controls (consisting of patients newly diagnosed with cancers other than those known to be associated with smoking) were interviewed. Unmatched, unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) of developing lung cancer in relation to a number of variables. MAIN OUTCOME MEASURE: Risk of developing lung cancer related to exposure to tobacco, indoor pollution, dusty work environment, and residential exposure to asbestos. RESULTS: There was a significant increase in the risk of developing lung cancer through smoking. In men, the ORs were 2.2 (95% CI = 1.0 to 4. 6) in ex-smokers, 9.8 (95% CI = 5.9 to 16.4) in light smokers (0-14 g/day), and 12.0 (95% CI = 6.5 to 22.3) in heavy smokers. In women, the ORs were 5.8 (95% CI = 1.3 to 25.8) in ex-smokers and 5.5 (95% CI = 2.6 to 11.3) in current smokers. Work in a dusty industry showed an elevated risk (OR = 3.2, 95% CI = 1.8 to 5.8) for lung cancer only in men. Male residents of areas where asbestos was shipped for distribution (termed moderately polluted asbestos areas) had a 2.5-fold increase (95% CI = 1.0 to 4.4) in the risk (OR) of developing lung cancer, and residents of areas where asbestos was mined (termed heavily polluted asbestos areas) had a 2.8-fold increase in risk (95% CI = 0.7 to 10.4). Female residents of heavily polluted asbestos areas showed elevated risks of 5.4 (95% CI = 1.3 to 22.5) of developing lung cancer. CONCLUSION: The data suggest that tobacco smoking is the most important risk factor for the development of lung cancer in this setting. Risks for lung cancer are reminiscent of those observed in Western countries in the 1960s and 1970s. However, environmental exposure to asbestos, a dusty occupation (in men), and perhaps indoor air pollution may also contribute to the development of lung cancer in this province.

Adult↗
PubMed1994

Acute effects of summer air pollution on respiratory symptom reporting in children.

A daily diary of respiratory symptoms was collected from the parents of 1,844 school children in six U.S. cities to study the association between ambient air pollution exposures and respiratory illness. A cohort of approximately 300 elementary school children in each of six communities were asked to keep a daily log of the study child's respiratory symptoms for one year. Daily measurements of ambient sulfur dioxide, nitrogen dioxide, ozone, inhalable particles (PM10), respirable particles (PM2.5), light scattering, and sulfate particles were made, along with integrated 24-h measures of aerosol strong acidity. The analyses were limited to the five warm season months between April and August. Significant associations were found between incidence of coughing symptoms and incidence of lower respiratory symptoms and PM10, and a marginally significant association between upper respiratory symptoms and PM10. There was no evidence that other measures of particulate pollution including aerosol acidity were preferable to PM10 in predicting incidence of respiratory symptoms. Significant associations in single pollutant models were also found between sulfur dioxide or ozone and incidence of cough, and between sulfur dioxide and incidence of lower respiratory symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed2005

Flow cytometric analysis and optimisation for measuring phagocytosis in three Australian freshwater fish.

The phagocytic activity of fish immunocytes has been measured by a wide range of methods, and has been used as a bio-indicator to assess the immunotoxicity of environmental pollutants and the efficiency of immunostimulants used in aquaculture. This study demonstrates the utilisation of a flow cytometric technique for measuring phagocytosis as an alternative to manual evaluations by light microscopy. Optimal conditions for the phagocytosis of latex beads were ascertained, including incubation period, cell:bead ratio and media components, for head kidney cells isolated from three native Australian fish that inhabit the Murray-Darling basin, i.e. silver perch (Bidyanus bidyanus), golden perch (Macquaria ambigua) and crimson-spotted rainbowfish (Melanotaenia fluviatilis). Thus, standardised protocols have now been established for future use in the immunotoxicity testing of xenobiotics in native Australian freshwater fish.

Animals↗
PubMed2001

Ozone treatment affects pigment precursor metabolism in pine seedlings.

Five-week-old seedlings of Pinus halepensis Mill. and Pinus brutia Ten. were exposed to air polluted with ozone (O3) (250 nl l-1, 12 h day-1 for 4 days) or to ambient air containing ca 10-20 nl l-1 O3, in the light (180 &mgr;mol m-2 s-1 photosynthetic photon flux density [PPFD], 12 h day-1) and then fed for 24 h in the light (100 &mgr;mol m-2 s-1 PPFD) with various radioactive precursors of chlorophyll (Chl) and carotene biosynthesis: 5-[4-14C]-aminolevulinic acid (14C-ALA), L-[14C(U)]-glutamic acid (14C-Glu), or D,L-[2-14C]-mevalonic acid (14C-MVA). Pigments were then extracted from cotyledons and fully expanded needles. Chl a and carotene were separated by thin-layer chromatography and high-performance liquid chromatography and their specific activities were determined. 14C-ALA and 14C-Glu labels were incorporated into Chl a and carotene. Exposure to O3 did not inhibit incorporation of 14C-ALA into Chl a molecules, but hydrolysis of Chl a showed that O3 inhibited phytol labelling of Chl a. Labelling of carotene was also inhibited by O3, but not when 14C-MVA was used as the label. These data suggest that O3 treatment inhibits (directly or indirectly) the biosynthesis of isoprenoids from products of ALA and Glu metabolism in the plastid, but not from MVA in the cytosol. This inhibition was more prominent when 14C-ALA was used as the label than when 14C-Glu was the labelling precursor. A significant increase in pheophorbide a, a tetrapyrrole component of Chl a labelling, and a concomitant decrease in phytol labelling was observed following incubation of O3-treated pine seedlings with 14C-ALA and 14C-Glu. Stronger inhibition of carotene biosynthesis and activation of Chl a tetrapyrrole labelling by 14C-ALA (in comparison with 14C-Glu) indicated that exposure to O3 inhibits the conversion of ALA to Glu as the first step in ALA catabolism. These results also suggested a more intensive Glu metabolism (in comparison with ALA) for carotene biosynthesis in the cytosol, as well as cooperation between two pathways of isopentenyl diphosphate biosynthesis.

Journal Article↗
PubMed2000

Distance-weighted traffic density in proximity to a home is a risk factor for leukemia and other childhood cancers.

Occupational exposure to elevated concentrations of benzene is a known cause of leukemia in adults. Concentrations of benzene from motor vehicle exhaust could be elevated along highly trafficked streets. Several studies have reported significant associations between proximity to highly trafficked streets and the occurrence of childhood cancers and childhood leukemia. These associations may be due to chronic exposure to benzene or other carcinogenic components of vehicle exhaust from these nearby streets or to some other factor (e.g., noise, increased light exposure, or some unaccounted--for socioeconomic variable). We used data for homes studied in an earlier childhood cancer study conducted in Denver, CO, in the 1980s. No air pollution measurements were made in the original study. We identified the highest trafficked street near each study home and obtained the traffic density in 1979 and 1990. Traffic density was weighted for the distance from the street to the home using 3 different widths of Gaussian curves to approximate the decay of the emissions into the surrounding neighborhoods. The associations between the 750-ft-wide distance-weighted traffic density metrics and all childhood cancers and childhood leukemia are strongest in the highest traffic density category (> or = 20,000 vehicles per day [VPD]). The odds ratio is 5.90 (95% confidence interval [CI] 1.69-20.56) for all cancers and 8.28 (95% CI 2.09-32.80) for leukemia. The results are suggestive of an association between proximal high traffic streets with traffic counts > or = 20,000 VPD and childhood cancer, including leukemia.

Adult↗
PubMed2000

Metallothioneins in terrestrial invertebrates: structural aspects, biological significance and implications for their use as biomarkers.

During the last few years the subject of metallothioneins (MTs) in terrestrial invertebrates has gained increasing attention. One reason for this may be that terrestrial invertebrates provide new insights into the biological diversity of MTs, with the potential of discovering alternative models of structural and functional relationships. Four groups of terrestrial invertebrates have been studied in detail, namely nematodes, insects, snails and earthworms, with the present article focusing on MTs from the latter two groups. Snails are interesting because they possess distinct MT isoforms involved in different metal-specific tasks. In the Roman snail (Helix pomatia), for example, one isoform is predominantly expressed in the midgut gland, accounting for the accumulation, binding and detoxification of cadmium. The second isoform, which is present in the snail's mantle, is substantially different regarding its primary structure. Furthermore, it binds nearly exclusively copper, and thus is probably involved in the homeostatic regulation of essential trace elements. Earthworm MTs merit our attention because of another peculiarity: they seem to be much more unstable than snail MTs, particularly under conventional conditions of preparation. The cDNA of the brandling worm (Eisenia foetida), for instance, codes for a putative MT, which is about twice the size of the actual protein. The isolated MT peptide binds four Cd2+ ions and represents a one-domain MT entity that is stable and functional in vitro. This strongly suggests that earthworm MTs are either posttranslationally modified, or subjected to enzymatic cleavage during preparation. Both snail and earthworm MTs are inducible by metal exposure, especially by cadmium, thus supporting the idea of using them as potential biomarkers for environmental metal pollution. Whilst snail MTs have already been tested in this respect with some success, the use of earthworm MTs as biomarkers still remains to be evaluated, especially in the light of the unknown significance of their posttranslational instability.

Amino Acid Sequence↗
PubMed1989

[The importance of Bacillus cereus in food poisoning].

In the light of the available literature the present knowledge on the role of Bacillus cereus in alimentary intoxications is discussed, particularly the occurrence and role of B. cereus in food pollution, the most frequent alimentary intoxications in the world are reviewed, the biological tests on animals and studies on humans are described, and the metabolites of the organism are presented. Particular attention is given to the properties of enterotoxins responsible for diarrhoea and vomiting.

Animals↗
PubMed2002

Photocatalytic degradation of nitrotoluene in aqueous TiO2 suspension.

TiO2-mediated photocatalytic degradation process was employed to treat aqueous 2-, 3- and 4-NT (nitrotoluene) pollutants. The NT disappearance and TOC removal rates for three isomers showed no significant differences. Three hydroxylated aromatic intermediates resulting from the photocatalytic degradation of 4-NT were identified; this suggested two (initial) degradation pathways. Formation of acetic acid, formic acid, and formaldehyde was also noted. The mineralization products included NH4+, NO3- and CO2. N2 bubbling or the presence of a positive hole acceptor during 4-NT degradation resulted in a high 4-aminotoluene formation. This indicated an effective reduction of 4-NT's nitro group to amino moiety. Generally, Pt-loaded TiO2 (Pt-TiO2) had no influence on the disappearance rate of 4-NT. However, the use of Pt-TiO2 along with a higher light intensity source resulted in an accelerated TOC removal.

Catalysis↗
PubMed1999

Heterogeneous photocatalytic oxidation of organics for air purification by near UV irradiated titanium dioxide.

The photocatalytic degradation of high concentrations of various organic pollutants (acetone, 2-propanol and toluene) in dry and humid air streams was carried out using a specially designed photoreactor based on the UV-TiO2 principle. The influence of several parameters which control the destruction efficiency (flow rate, initial contaminant and water vapour concentration, temperature and light intensity) has been studied. The conversion was maximal at room temperature, low flow rates and low initial contaminant concentrations. The presence of water in the inlet stream strongly affected the performance of the catalyst. The primary oxidation product of 2-propanol was acetone.

2-Propanol↗