Biomedical subjects

Patrick N Breysse

Publications and source records attributed to Patrick N Breysse.

5 recordsLinked to original sources

PubMed2003

Summary of historical beryllium uses and airborne concentration levels at Los Alamos National Laboratory.

Beryllium operations and accompanying medical surveillance of workers at Los Alamos National Laboratory began in the 1940s. In 1999 a Former Workers Medical Surveillance Program that includes screening for chronic beryllium disease was initiated. As part of this program, historical beryllium exposure conditions were reconstructed from archived paper and electronic industrial hygiene data sources to improve understanding of past beryllium uses and airborne concentration levels. Archived industrial hygiene sampling reports indicated beryllium was principally used in technical areas-01 and -03, primarily being machined. Beryllium was also used at 15 other technical areas in activities that ranged from explosives detonation to the manufacture of X-ray windows. A total of 4528 personal breathing zone and area air samples for beryllium, combined for purposes of calculating summary statistics, were identified during the records review phase. The geometric mean airborne beryllium concentration for the period 1949-1989 for all technical areas was 0.04 microg Be/m(3) with 97 percent of all sample below the 2.0 microg Be/m(3) occupational exposure limit (OEL). Average beryllium concentrations per decade were less than 1 microg Be/m(3) and annual geometric mean concentrations in technical area-03, the largest user of beryllium, were generally below 0.1 microg Be/m(3), indicating exposure was generally well-controlled, that is, below the OEL. Typical of many retrospective exposure assessments, not all archived data could be extracted and summarized. Despite this, we report a reasonable summary of potential beryllium uses and airborne concentration levels a worker may have encountered from 1949-1989. These data can be used to more effectively identify former worker populations at potential risk for chronic beryllium disease and to offer these workers screening as part of the Former Worker Medical Surveillance Program, and in the event that a case is diagnosed, help to understand historical exposure conditions.

Air Pollutants, Occupational↗

PubMed2002

Development of a medical examination program for former workers at a Department of Energy national laboratory.

BACKGROUND: As a part of the U.S. Department of Energy (DOE) Former Workers' Medical Surveillance Program, a Needs Assessment was conducted at Los Alamos National Laboratory (LANL). The objective was to identify former LANL employees who may be at significant risk for occupational disease and determine whether a medical examination program could reduce morbidity or mortality. We describe the needs assessment approach used at LANL. METHODS: An algorithm was developed to make needs determinations. Information on factors including exposure, health impacts, size of exposed populations, and LANL worker concerns and recommendations were obtained. Each of these factors was scored from 1 to 3. The resulting factor sum was then multiplied by a binary (1 or 0) intervention suitability factor which was 1 if both of the following were available: (1) a screening test with acceptable sensitivity and specificity for the health outcome of concern; and (2) an intervention that decreases morbidity or mortality. This resulted in an Intervention Needs Score that was used to set priorities for the medical examination program for the estimated 35,000 former LANL workers. RESULTS: Analysis of the algorithm output suggested that six exposure categories be recommended for consideration in a medical examination program. Beryllium, asbestos, and noise clearly warranted inclusion. Lead and ionizing radiation required careful consideration regarding availability of screening tests. Solvents were problematic due to the lack of screening tests and suitable intervention in formerly exposed workers. CONCLUSIONS: The algorithm approach to the needs assessment at LANL documented that six chemical and physical agents should be considered as candidates for inclusion in a medical examination program for former workers.

Aged↗

PubMed2002

Complement factor 3 mediates particulate matter-induced airway hyperresponsiveness.

Epidemiologic studies have suggested that exposure to airborne particulate matter (PM) can exacerbate allergic airway responses; however, the mechanism(s) are not well understood. We and others have recently shown that development of airway hyperresponsiveness (AHR) may be a complement-mediated process. In the present study, we examined the role of complement factor 3 (C3) in the development of PM-induced AHR and airway inflammation by comparing responses between C3-deficient (C3(-/-)) and wild-type mice. Mice were exposed to 0.5 mg of ambient particulate collected in urban Baltimore. Forty-eight hours later, airway responsiveness to intravenous acetylcholine was assessed and bronchoalveolar lavage was conducted. PM exposure of wild-type mice resulted in significant increases in AHR, whereas it did not significantly increase airway reactivity in C3(-/-) mice. Interestingly, PM induced similar inflammatory responses in both wild-type and C3(-/-) mice. Immunohistochemical staining demonstrated marked C3 deposition in the airway epithelium and connective tissue of wild-type mice after PM exposure. These results suggest that exposure to PM may induce AHR through activation of complement factor 3 in the airways.

Air Pollution↗

PubMedDate not supplied

Comparison of extremely low frequency (ELF) magnetic field personal exposure monitors.

The MultiWave System III (MW III), a recently developed personal monitor for extremely low frequency (ELF) magnetic fields, was compared with the standard EMDEX Lite (Electric and Magnetic Field Digital Exposure System), the type of monitor widely used in epidemiology and other exposure assessments. The MW III captures three-axis magnetic field waveforms for the calculation of many exposure metrics, while the EMDEX monitors measure only the root-mean-squared (RMS) vector magnitude (or resultant). Thirty-eight partial period personal samples were monitored in six different job classifications. The sampling time for each personal sample ranged from 90 to 133 min, with a mean sample time of 110 min. The EMDEX Lite and MW III were evaluated by comparing the maximum and partial period time-weighted average (TWA) of the ELF magnitude. TWA exposures measured for the 38 partial period samples by the EMDEX Lite ranged from 1.2 to 65.3 mG, with a mean of 18.1 mG, while corresponding values for the MW III ranged from 1.1 to 65.8 mG, with a mean of 17.7 mG. The maximum magnetic field exposures measured for the 38 partial period personal samples by the EMDEX Lite ranged from 27.0 to 420.2 mG, with a mean of 216.3 mG, while corresponding values for the MW III ranged from 40.2 to 1311.8 mG, with a mean of 368.4 mG. The maximum and TWA ELF magnetic field exposures measured by the EMDEX Lite and MW III were compared using a two-tailed, paired t-test. Analyses indicate that there was no significant difference in the TWA magnetic field magnitude measured by the EMDEX Lite and MW III. On the other hand, the EMDEX Lite reported significantly lower (P=0.002) maximum magnetic field measurements compared to the MW III. From a detailed analysis of the time traces, the EMDEX Lite appears to measure the ELF magnitude inaccurately when the field changes rapidly over a 4-s sampling interval. The results of this comparison suggest that the standard EMDEX Lite and MW III provide similar measure of the TWA magnetic field in a variety of occupational settings and ELF magnetic field magnitudes. However, the EMDEX Lite underestimates maximum exposures when compared to the MW III.

Electromagnetic Fields↗

PubMedDate not supplied

Surface area of respirable beryllium metal, oxide, and copper alloy aerosols and implications for assessment of exposure risk of chronic beryllium disease.

The continued occurrence of chronic beryllium disease (CBD) suggests the current occupational exposure limit of 2 microg beryllium per cubic meter of air does not adequately protect workers. This study examined the morphology and measured the particle surface area of aerodynamically size-separated powders and process-sampled particles of beryllium metal, beryllium oxide, and copper-beryllium alloy. The beryllium metal powder consisted of compact particles, whereas the beryllium oxide powder and particles were clusters of smaller primary particles. Specific surface area (SSA) results for all samples (N=30) varied by a factor of 37, from 0.56 +/- 0.07 m(2)/g (for the 0.4-0.7 microm size fraction of the process-sampled reduction furnace particles) to 20.8 +/- 0.4 m(2)/g (for the </=0.4 microm size fraction of the metal powder). Large relative differences in SSA were observed as a function of particle size for the powder of beryllium metal, from 4.0 +/- 0.01 m(2)/g (for the particle size fraction >6 microm) to 20.8 +/- 0.44 m(2)/g (for the particle size fraction </=0.4 microm). In contrast, little relative difference in SSA (<25%) was observed as a function of particle size for the beryllium oxide powder and particles collected from the screening operation. The SSA of beryllium metal powder decreases with increasing particle size, as expected for compact particles, and the SSA of the beryllium oxide powders and particles remains constant as a function of particle size, which might be expected for clustered particles. These associations illustrate how process-related factors can influence the morphology and SSA of beryllium materials. To avoid errors in predicting bioavailability of beryllium and the associated risks for CBD, the mechanisms of particle formation should be understood and the SSA of beryllium particles should be measured directly.

Aerosols↗