Margaret L. Phillips

A preliminary evaluation of the effect of glove use by food handlers in fast food restaurants

A study was conducted to determine whether the levels of selected microorganisms differed on foods handled by gloved and bare hands at fast food restaurants. Three hundred seventy-one plain flour tortillas were purchased from fast food restaurants and analyzed for Staphylococcus aureus, Escherichia coli, Klebsiella sp., coliform bacteria, and heterotrophic plate count bacteria. Approximately 46% of the samples were handled by workers wearing gloves compared with 52% of samples with bare hand contact. Coliform bacteria were found in 9.6% of samples handled by gloved workers and 4.4% of samples handled by bare hands, although this difference was not statistically significant. The distribution of heterotrophic plate count bacteria, a general measure of hygiene, was also higher in samples handled by gloved workers in one restaurant chain. The presence of E. coli, Klebsiella sp., and S. aureus was detected in one, two, and eight samples, respectively, and there were no significant differences between samples handled by gloved or bare hands. Neither direct contact of the tortilla with the food preparation surface nor gender of the worker affected the level of any organism tested. The observed tendency of food workers to wear the same pair of gloves for extended periods and complacency might account for the apparent failure of gloves to reduce or prevent bacterial contamination. The results further suggest that glove use might be counterproductive because workers might wash their hands less frequently when gloved.

Assessment of Medical Personnel Exposure to Nitrogen Oxides During Inhaled Nitric Oxide Treatment of Neonatal and Pediatric Patients

Objective. This study was an assessment of potential exposures of medical personnel to nitrogen oxides during simulated and actual inhaled nitric oxide treatment of newborn and pediatric patients. Design. Breathing zone exposures to nitric oxide (NO) and nitrogen dioxide (NO2) were monitored using data-logging personal dosimeters during simulated and actual administration of NO gas to patients in an intensive care setting. Sample. A total of 28 bedside nurses and 18 respiratory therapists were monitored during 6 different patient treatments. Analysis. The highest measured concentrations of NO and NO2 in the personal breathing zones of the nurses and respiratory therapists were peak readings (<1 minute in duration) of 6.7 parts per million (ppm) NO and 3.1 ppm NO2. Exposures averaged throughout 15 minutes and throughout the work shift were below the limit of detection (0.8-ppm NO and 0.5-ppm NO2). Conclusion. Detectable exposures to NO and NO2were brief, infrequent, and well below Occupational Safety and Health Administration permissible exposure limits or any other exposure guideline, eg, American Conference of Governmental Hygienists Threshold Limit Values.

Determinants of Respirable Silica Exposure in Stone Countertop Fabrication: A Preliminary Study

A preliminary study of personal exposure to respirable quartz was conducted in four shops that used a variety of wet and dry methods to fabricate countertops from granite and quartz-containing synthetic stone-like materials. Full-shift time-weighted average (TWA) exposures exceeded the ACGIH threshold limit value of 0.025 mg/m3 for all workers who used dry fabrication methods, even for very limited time, during any part of the work shift (n = 15 person-days). The geometric mean of exposures for workers who used dry methods extensively was about 1 mg/m3 (n = 12 person-days). Workers who operated only automated or remotely controlled stone cutting or shaping equipment had calculated TWA exposures of approximately 0.02 mg/m3 (n = 3 person-days). Task-specific geometric mean exposures for various wet and dry manual operations were ranked based on estimated concentrations extracted from multi-task partial-shift sample results using a linear algebra procedure. Limited use of dry methods was observed in shops that had previously reported using only wet methods. These results suggest that even shops that report using only wet methods might, in fact, resort to brief use of dry methods for specific operations. Therefore, there may be reason for concern over potential overexposure to respirable quartz in all stone countertop shops.

What is “powder free”? Characterisation of powder aerosol produced during simulated use of powdered and powder free latex gloves

OBJECTIVES To characterise the distribution of particle size and mass of glove powder aerosol released from powdered and powder free non-sterile latex gloves under controlled conditions. METHODS Gravimetric sampling and aerodynamic particle size analysis were performed during simulated use of gloves on a prosthetic hand in a chamber designed to minimise background particle concentrations. RESULTS Aerosol was detectable for both powdered and powder free gloves under both aggressive and non-aggressive handling conditions. Most of the particles detected had aerodynamic diameter less than 10 μm. CONCLUSION Powder free gloves were not entirely free of powder aerosol. Particles from both powdered and powder free gloves are sufficiently fine to penetrate into the thoracic region of the respiratory tract.

Thermotropic ionic liquid crystals. IV. Structural effects in sodium methylpentanoates

Thermotropic ionic liquid crystals sodium 4‐methylpentanoate and sodium 3‐methylpentanoate have been studied by polarization microscopy and NMR. The quadrupole coupling constant e2qQ/h of 23Na is obtained for the mesophase and the 23Na spin‐lattice relaxation time T1 is reported as a function of temperature in both the mesophase and the isotropic melt. A model is presented for the arrangement of the polar groups in the mesophase of all short chain Na carboxylates—the smectic A bilayer consists of R–COO−Na+ ion pairs with interdigitated polar groups. The observed dependence of the defect size and e2qQ/h of 23Na upon the molecular structure is interpreted in terms of this model. A qualitative discussion of possible relaxation mechanisms contributing to the T1 of 23Na is presented.

The Role of Electron‐Hole Recombination at MoS2 and MoSe2 Photoelectrodes

Analysis of impedance and current‐voltage data has revealed that electron‐hole recombination plays a significant role in the aqueous photoelectrochemistry of and single crystals. It is proposed that this recombination shortens the lifetime of the photoproduced hole to such an extent that few solution reductants are able to react with holes at the surface of these electrodes. The role of this recombination in diminishing photocurrents and photopotentials is discussed within the context of the Gerischer model for semiconductor electrochemistry.

Prevalence of dry methods in granite countertop fabrication in Oklahoma

Granite countertop fabricators are at risk of exposure to respirable crystalline silica, which may cause silicosis and other lung conditions. The purpose of this study was to estimate the prevalence of exposure control methods, especially wet methods, in granite countertop fabrication in Oklahoma to assess how many workers might be at risk of overexposure to crystalline silica in this industry. Granite fabrication shops in the three largest metropolitan areas in Oklahoma were enumerated, and 47 of the 52 shops participated in a survey on fabrication methods. Countertop shops were small businesses with average work forces of fewer than 10 employees. Ten shops (21%) reported using exclusively wet methods during all fabrication steps. Thirty-five shops (74%) employing a total of about 200 workers reported using dry methods all or most of the time in at least one fabrication step. The tasks most often performed dry were edge profiling (17% of shops), cutting of grooves for reinforcing rods (62% of shops), and cutting of sink openings (45% of shops). All shops reported providing either half-face or full-face respirators for use during fabrication, but none reported doing respirator fit testing. Few shops reported using any kind of dust collection system. These findings suggest that current consumer demand for granite countertops is giving rise to a new wave of workers at risk of silicosis due to potential overexposure to granite dust.

Thermotropic ionic liquid crystals. V. Deuterium NMR study of sodium n‐alkanoates

Deuterium NMR spectra and spin‐lattice relaxation timesT 1 were obtained as functions of temperature for α‐deuterated sodiumn‐alkanoates (n c =4–7) in the smecticA and ‘‘isotropic’’ liquid phases. The temperature dependence of the orientational order parameter is found to disagree with the predictions of McMillan’s and Woo’s theories for the smecticA phase. Reorientational models are presented to explain the experimental order parameters in terms of the structure of the anhydrous solid or the lyotropic gel phase of these compounds. The same models are used in the analysis of reorientational contributions to the 2D T 1 in the mesophase; order director fluctuations are also estimated to contribute significantly to the relaxation times. The 2D T 1 temperature dependence in the mesophase resembles that of the 2 3NaT 1 measured previously, implying shared relaxation mechanisms for the two nuclei. Estimated correlation times for 2D relaxation in the isotropic phase provide evidence for the persistence of local structure characterized by motion on a time scale of tens of picoseconds.

Respirable Silica Dust Suppression During Artificial Stone Countertop Cutting

Purpose: To assess the relative efficacy of three types of controls in reducing respirable silica exposure during artificial stone countertop cutting with a handheld circular saw. Approach: A handheld worm drive circular saw equipped with a diamond segmented blade was fitted with water supply to wet the blade as is typical. The normal wetted-blade condition was compared to (i) wetted-blade plus ‘water curtain’ spray and (ii) wetted-blade plus local exhaust ventilation (LEV). Four replicate 30-min trials of 6-mm deep, 3-mm wide cuts in artificial quartz countertop stone were conducted at each condition in a 24-m3 unventilated tent. One dry cutting trial was also conducted for comparison. Respirable cyclone breathing zone samples were collected on the saw operator and analyzed gravimetrically for respirable mass and by X-ray diffraction for respirable quartz mass. Results: Mean quartz content of the respirable dust was 58.5%. The ranges of 30-min mass and quartz task concentrations in mg m−3 were as follows—wet blade alone: 3.54–7.51 and 1.87–4.85; wet blade + curtain: 1.81–5.97 and 0.92–3.41; and wet blade + LEV: 0.20–0.69 and <0.12–0.20. Dry cutting task concentrations were 69.6mg m−3 mass and 44.6mg m−3 quartz. There was a statistically significant difference (α = 0.05) between the wet blade + LEV and wet blade only conditions, but not between the wet blade + curtain and wet blade only conditions, for both respirable dust and respirable silica. Conclusions: Sawing with a wetted blade plus LEV reduced mean respirable dust and quartz task exposures by a factor of 10 compared to the wet blade only condition. We were unable to show a statistically significant benefit of a water curtain in the ejection path, but the data suggested some respirable dust suppression.

Industrial Hygiene Investigation of Static Magnetic Fields in Nuclear Magnetic Resonance Facilities

Abstract An industrial hygiene survey concentrating on static magnetic field hazards was conducted at several nuclear magnetic resonance (NMR) facilities, including research laboratories and a clinical magnetic resonance imaging (MRI) center. The strongest magnetic fields routinely accessible to NMR staff were found to be 1.0 tesla for the torso and 4.7 tesla for the arms, due to a wide-bore research magnet. Estimates of typical exposure levels of NMR workers were made on the basis of fringe field measurements and observations of work practices. Estimated 8-hour time-weighted average (TWA) exposures ranged from 1.5 to 64.0 millitesla; duration of high field exposure was the major factor determining the TWA. People working for extended periods in close proximity to wide-bore superconducting magnets were exposed to static magnetic fields near or exceeding the threshold limit value of 60 millitesla for the whole-body TWA. Peak exposure to the extremities exceeded ceiling limits. No evidence exists for advers...