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At least 613 records · Page 34Linked to original sources
PubMed1995

Risk assessment of environmentally influenced airway diseases based on time-series analysis.

Threshold values are of prime importance in providing a sound basis for public health decisions. A key issue is determining threshold or maximum exposure values for pollutants and assessing their potential health risks. Environmental epidemiology could be instrumental in assessing these levels, especially since the assessment of ambient exposures involves relatively low concentrations of pollutants. This paper presents a statistical method that allows the determination of threshold values as well as the assessment of the associated risk using a retrospective, longitudinal study design with a prospective follow-up. Morbidity data were analyzed using the Fourier method, a time-series analysis that is based on the assumption of a high temporal resolution of the data. This method eliminates time-dependent responses like temporal inhomogeneity and pseudocorrelation. The frequency of calls for respiratory distress conditions to the regional Mobile Medical Emergency Service (MMES) in the city of Leipzig were investigated. The entire population of Leipzig served as a pool for data collection. In addition to the collection of morbidity data, air pollution measurements were taken every 30 min for the entire study period using sulfur dioxide as the regional indicator variable. This approach allowed the calculation of a dose-response curve for respiratory diseases and air pollution indices in children and adults. Significantly higher morbidities were observed above a 24-hr mean value of 0.6 mg SO2/m3 air for children and 0.8 mg SO2/m3 for adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Determination of phthalates in water using fiber introduction mass spectrometry.

Fiber introduction mass spectrometry (FIMS)-a direct coupling of SPME and MS-using selective ion monitoring (SIM) was used to detect and quantify dimethylphthalate (DMP), diethylphthalate (DEP) and dipropylphthalate (DPP) in mineral water. In FIMS, a chromatographic silicone septum is the only barrier between ambient and the high-vacuum mass spectrometer, permitting direct introduction of the SPME fiber into the ionization region of the equipment. After their thermal desorption and ionization and dissociation, the extracted phthalates are detected and quantitated by MS. Three types of SPME fibers were screened for best analyte sorption/desorption behaviors: 100 microm polydimethylsiloxane (PDMS), 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) and 65 microm Carbowax/divinylbenzene (CW/DVB). The PDMS/DVB and CW/DVB fibers were then evaluated for precision, and quantitative figures of merit were assessed for extractions using the PDMS/DVB fiber, which displayed the best overall performance. FIMS with the PDMS/DVB fiber allows simple extraction and MS detection and quantitation of DMP in water with good linearity and precision, and at concentrations as low as 3.6 microg L(-1). The LD and LQ of FIMS are below the maximum phthalate concentration allowed by the USEPA for drinking water (6 microg L(-1)).

Glass↗
PubMed1987

Chemical cartridge respirator performance: 1,3-butadiene.

The chemical 1,3-Butadiene recently has been classified as a potential occupational carcinogen; subsequently, a reduction in the 8 hr TWA from 1000 ppm to 10 ppm has been proposed. Substantial quantities of 1,3-Butadiene are produced annually for use in the manufacture of a variety of rubber compounds, foams, resins and chemicals. Existing process environments may present a potential health hazard under the proposed standards, and the need for proper respiratory protection is evident. As a result, the performance of Scott organic vapor (642-OV), organic vapor/acid gas (642-OA) and acid gas (642-AG) twin cartridges has been determined for 1,3 butadiene. A cartridge test system was developed to generate challenge concentrations of 100 ppm and 1000 ppm; an infrared analyzer was used to measure breakthrough at 10 ppm. The residence time modeling concept developed previously was used to produce the performance characteristics for three types of activated carbon for residence times of 0.1 less than or equal to tau less than or equal to 1.0 sec. Kinetic adsorption capacities and adsorption rate constants were computed from this data, and cartridge performance also was predicted. The twin cartridges tested demonstrated reasonable adsorption capacity for 1,3 butadiene. Cartridge service life was found to be inversely proportional to airflow rate; it was reduced at elevated temperature and humidity conditions. Breakthrough times were approximately three times longer at 100 ppm than at 1000 ppm. When clean air was drawn through cartridges saturated with 1000 ppm 1,3 butadiene, desorption occurred readily. The rate of desorption and the peak concentration were found to be dependent upon the temperature, humidity and degree of saturation.

Adsorption↗
PubMed1985

An evaluation of the external radiation exposure dosimetry and calculation of maximum permissible concentration values for airborne materials containing 18F, 15O, 13N, 11C and 133Xe.

To better understand the dose equivalent (D.E.) rates produced by airborne releases of gaseous positron-emitting radionuclides under various conditions of cloud size, a study of the external radiation exposure dosimetry of these radionuclides, as well as negatron, gamma and x-ray emitting 133Xe, was undertaken. This included a calculation of the contributions to D.E. as a function of cloud radii, at tissue depths of 0.07 mm (skin), 3 mm (lens of eye) and 10 mm (whole body) from both the particulate and photon radiations emitted by these radionuclides. Estimates of maximum permissible concentration (MPC) values were also calculated based on the calculated D.E. rates and current regulations for personnel radiation protection (CFR84). Three continuous air monitors, designed for use with 133Xe, were evaluated for applications in monitoring air concentrations of the selected positron emitters. The results indicate that for a given radionuclide and for a cloud greater than a certain radius, personnel radiation dosimeters must respond acceptably to only the photon radiations emitted by the radionuclide to provide acceptable personnel dosimetry. For clouds under that radius, personnel radiation dosimeters must also respond acceptably to the positron or negatron radiations to provide acceptable personnel dosimetry. It was found that two out of the three air concentration monitors may be useful for monitoring air concentrations of the selected positron emitters.

Air Pollutants↗
PubMed1976

Precision and accuracy of foundry dust exposure estimates from air sampling data.

Errors in the sampling methods and in the determination of respirable size quartz in foundry dust have been evaluated and discussed. In general, the total precision of dust sampling and analysis was better than 20%. The term "exposure dose" is introduced and defined. The temporal variation associated with measuring exposure dose is assessed with reference to the use of a log-normal distribution of air sampling results. The logarithmic standard deviations of dust concentrations at fixed sites and jobs are calculated.

Air Pollutants↗
PubMed1989

[Exposure to vinyl chloride in the Polish industry].

Information concerning exposure to vinyl chloride collected in Occupational Hygiene Departments of Sanitary-Epidemiological Stations were verified. On the basis of the studies performed it was found that about 3700-4000 persons in Poland are occupationally exposed to vinyl chloride; 400 of these workers are employed at the synthesis and polymeryzation of vinyl chloride, and the others at plasticination and processing of polyvinyl chloride. About 200 workers employed in 3 plants of vinyl chloride polymerization and synthesis and about 30 employees of one of the plants processing this compound are exposed to vinyl chloride whose concentration exceeds the hygienic standard accepted in Poland (30 mg/m3).

Air Pollutants, Occupational↗
PubMed1984

Glyceryltrinitrate as a problem in industry.

Workers engaged in manufacture and use of dynamite experience acute toxic reactions with headache during work, weakness at the end of the working day, tachycardia and hypotension. Sudden death has been reported in dynamite workers after 2-4 days freedom of exposure, possibly due to rebound vasoconstriction resulting in acute hypertension or myocardial ischemia. In the present study 12 volunteers were examined before and during GTN exposure. Most of them experienced headache during work, and a slight but significant rise in heart rate and a fall in systolic blood pressure was found. In serial blood samples from cubital vein very high concentrations of GTN were detected. These high values can be explained by local absorption through the skin of the hand and the lower arm, and do not reflect the mixed venous plasma concentrations. Great interindividual variations were found in GTN plasma concentrations during work, probably indicating different working habits.

Air Pollutants, Occupational↗