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R J Rando

Publications and source records attributed to R J Rando.

34 records · Page 2Linked to original sources
PubMed1988

Cigarette smoke-sensitive asthma: challenge studies.

The effects of exposure to environmental tobacco smoke on pulmonary function were assessed in 21 subjects with asthma who claimed respiratory complaints (cough, shortness of breath, and chest tightness) on previous exposure to cigarette smoke. Exposure to mechanically produced tobacco smoke was performed in a static inhalation chamber for two-hour intervals at two distinct smoke levels (as measured by carbon monoxide, nicotine, and particulate levels). Seven of the 21 smoke-challenged subjects experienced a significant (greater than 20%) decline in FEV1 during passive exposure to tobacco smoke. One of these seven subjects was nonatopic, whereas a second subject had a negative response to methacholine challenge. The smoke-challenge responses were reproducible in all seven reactive subjects. Increasing concentrations of tobacco smoke failed to elicit pulmonary changes in previously challenged, unreactive or "smoke-tolerant" subjects. There was no association between a positive smoke challenge and the presence of serum IgE antibodies and/or a positive immediate wheal-and-flare skin test to a tobacco leaf extract. Collectively, these studies document a significant decline in pulmonary function in a substantial percentage (33%) of a population of "smoke-sensitive" subjects with asthma exposed to environmental tobacco smoke. The data also dissociate this effect from tobacco-leaf hypersensitivity.

Adult↗
PubMed1988

Recurrent asthma induced by toluene diisocyanate.

A worker developed toluene diisocyanate induced asthma in 1974. On reassessment, 11 years after leaving the chemical plant where toluene diisocyanate was produced, he had no respiratory symptoms and normal bronchial reactivity in response to methacholine, and showed no reaction when challenged with a subirritant concentration of toluene diisocyanate. He developed asthma within five months of returning to the workplace. Repeat challenge testing showed bronchial hyperreactivity to methacholine and to the specific sensitising agent, toluene diisocyanate. This clinical pattern could be due to underlying toluene diisocyanate sensitivity with resolution and reappearance of hyperresponsiveness to methacholine and toluene diisocyanate reactivity associated with workplace toluene diisocyanate exposure. Alternatively, this worker may have developed sensitisation to toluene diisocyanate anew.

Adult↗
PubMed1987

Long-term cotton dust exposure in the textile industry.

A three-year survey was conducted in six cotton-yarn manufacturing mills and one mill processing synthetic polyester fibers as part of a longitudinal epidemiologic investigation of the health experience of workers employed in the textile industry. A total of 1324 elutriated and total dust samples were collected during the three years of the study. The results indicate that the average elutriated dust concentrations in the surveyed mills were generally at or below the current OSHA standard and they ranged from 0.069 to 0.396 mg/m3, 0.089 to 0.391 mg/m3, and 0.106 to 0.210 mg/m3 for the first, second and third year surveys, respectively. Introduction of modern automated yarn processing equipment and elimination of some of the classic processes were associated with a decreasing trend in airborne dust concentrations in these mills.

Dust↗
PubMed1987

A sequential tape monitor for toluene diisocyanate.

An electronic microcircuit controller has been designed to convert a commercially available continuous tape monitor for toluene diisocyanate (TDI) into a sequential sampler in order to eliminate deficiencies in response and resolution of fluctuating TDI concentrations. The modified monitor will collect up to fourteen 12-min samples per work shift. The sensitivity of the monitor was doubled approximately by the inclusion of a blue filter in the optics of the reader unit. Recalibration of several modified monitors indicated a wide range in response to TDI necessitating individual calibrations. No significant difference in response to the 2,4 and 2,6 isomers of toluene diisocyanate was noted for modified personal monitors, in contrast to a 25% lower response to 2,6-TDI by an area monitor in which the same detection tape was used. The modified monitor has shown a reliability rate of about 90% during a three-year field survey of TDI exposures.

Air Pollutants, Occupational↗
PubMed1987

Toluene diisocyanate exposures in the flexible polyurethane foam industry.

A 3-year survey of toluene diisocyanate exposure in two flexible polyurethane foam manufacturing facilities has been conducted. The geometric mean time-weighted average exposures were 2.36 ppb, 1.10 ppb, and 1.50 ppb for the foam line workers, finishing workers, and maintenance personnel, respectively. The OSHA ceiling standard of 20 ppb was exceeded by 1.3% of the short-term (12 min) exposure measurements taken. Exposures were shown to be predominantly to the 2,6 isomer of TDI.

Air Pollutants, Occupational↗
PubMed1986

Absence of hyperresponsiveness to methacholine in a worker with methylene diphenyl diisocyanate (MDI)-induced asthma.

A 29-year-old man had a persuasive history of respiratory illness following exposures to methylene diphenyl diisocyanate (MDI). He was evaluated by measuring bronchial reactivity to methacholine, both before and after controlled laboratory exposures to MDI. Despite evidence of progressive declines in FEV1 with increasing (but subirritant) doses of MDI on three consecutive days, there was no bronchial hyperresponsiveness to methacholine, before or after MDI challenge. We conclude that the absence of nonspecific bronchial hyperresponsiveness does not exclude the possibility of isocyanate asthma. In the face of a compelling history, a negative result of methacholine challenge should not deter observation or laboratory testing for specific respiratory allergy to these chemicals.

Adult↗
PubMed1985

Modified Marcali method for the determination of total toluenediisocyanate in air.

The Marcali method for the analysis of airborne toluenediisocyanate was evaluated for its response to the two isomers of the compound. The absorbance of the chromophore obtained from 2,6 TDI is approximately 47% less than that from the 2,4 isomer of TDI when measured at 550 nm. In addition, the absorbance spectra of the 2,6 isomer exhibits a shifting of the wavelength of maximum absorbance from 550 nm to 565 nm. A simple modification of the method involving changes in diazotization time and temperature is proposed to eliminate this isomer effect.

Air Pollutants, Occupational↗
PubMed1984

Isomeric composition of airborne TDI in the polyurethane foam industry.

The isomeric composition of airborne toluene diisocyanate has been determined in two plants producing slab stock flexible polyurethane foam. The high performance liquid chromatographic technique used for analysis of the collected samples was optimized for the quantitative and qualitative determination of 2,4 and 2,6-TDI. The data indicates that there is a very large increase in the amount of airborne 2,6-TDI relative to the 2,4 isomer, as compared to the starting material used in the process. The magnitude of the increase was dependent on the stage of production. These results are consistent with the hypothesis of increased offgassing of 2,6-TDI, due to its lower reactivity.

Air Pollutants, Occupational↗
PubMed1982

Formaldehyde asthma: challenge exposure levels and fate after five years.

Because of current concern regarding possible adverse health effects of formaldehyde, we have reinvestigated two renal dialysis unit nurses shown to have formaldehyde asthma by inhalation provocation tests in 1973 and 1975, respectively. Their original tests were repeated and the formaldehyde levels generated (previously unknown) were measured. One nurse had not worked with formaldehyde since 1976 and had had no further symptoms. Her 1981 test (15-minute exposure to 6 parts per million [ppm] formaldehyde) provoked no asthmatic response. The other nurse had continued to work with formaldehyde, though under much improved conditions, and mild intermittent attacks of asthma had continued. Her test (five-minute exposure to 3 ppm formaldehyde) provoked a late asthmatic reaction similar to that observed in 1975. We conclude that in sensitized subjects specific late asthmatic reactions may be provoked by brief exposures to formaldehyde at about the current Occupational Safety and Health Administration standard (3 ppm); and that while asthmatic responsiveness may persist with continuing low levels of intermittent exposure, it may be lost following complete cessation of exposure.

Adult↗
PubMed1980

Dynamic calibration of a continuous organo-isocyanate monitor for hexamethylene diisocyanate.

In 1978, NIOSH recommended new exposure standards for all diisocyanates. They are 5 ppb TWA for a 10-hour work shift and 20 ppb ceiling for a 10-minute period (or the equivalent microgram/m3). Recently, a new continuous reading monitor, which responds immediately to both aliphatic and aromatic diisocyanates, has become commercially available. This instrument factory calibrated for measuring toluene diisocyanate, has different responses for different diisocyanates. The monitor was dynamically calibrated to measure hexamethylene diisocyanate (HDI) against the recommended high pressure liquid chromatographic methods. The standard atmospheres of HDI were generated using permeation and an evaporation method. The monitor reading is 50% of the true concentration up to 50 ppb. Beyond that, the monitor reading reaches a plateau and the measured concentrations could be unreliable.

Calibration↗
PubMed1980

Critical evaluation of continuous monitors for toluene diisocyanate.

This paper describes the experiments and the results of an exhaustive and critical laboratory study which evaluated the performance of continuous area and personal monitors popularly used in measuring the concentrations of TDI in industrial environments. The studies consisted of dynamic calibrations, the effect of humidity and temperature on the measurements, and the interferences due to commonly encountered contaminants in a TDI manufacturing plant. The response and resolution of the personal monitor for short-term fluctuations of TDI concentration in time and space are also reported.

Air Pollutants↗
PubMed1979

A new method for the generation of standard atmospheres of organo isocyanates.

A new and versatile method for the generation of standard atmospheres of several organo isocyanates based on permeation technique has been developed. Several membranes were screened for integrity, compatibility and permeability of these isocyanates. Silicone membrane was found to be the best membrane for the construction of permeation devices. Two types of permeation are described: liquid phase and gas phase. The liquid phase permeation tubes are recommended for generation of high concentrations (ppm) and gas phase permeation is preferred for generation of atmospheres with low concentrations (ppb). Several simple designs for construction of permeation devices are described. The permeation of isocynates were evaluated gravimetrically and were shown to be constant, provided the temperature and the flow rate of air over the permeation tube are maintained constant.

Cyanates↗
PubMedDate not supplied

Development and application of a dichotomous vapor/aerosol sampler for HDI-derived total reactive isocyanate group.

A dichotomous vapor/aerosol sampler was developed for measurement of HDI (1,6-hexamethylene diisocyanate)-derived total reactive isocyanate group (TRIG). The sampler consisted of an impactor or cyclone inlet, followed by an annular diffusional denuder, and a glass-fiber filter backup. The denuder walls and backup filter were each coated with 20 mg tributylphosphate and 1 mg MAMA reagent (9-N-methylamino-methylanthracene). After collection, MAMA-derivatized isocyanates were desorbed from the sampler and determined by high-performance liquid chromatography with dual-wavelength ultraviolet absorbance and fluorescence detection. Test atmospheres of HDI vapor and of HDI/HDI-biuret aerosols were generated in the laboratory and sampled with the optimized dichotomous sampler. Vapor phase HDI was completely collected by the diffusional denuder. When a mixture of HDI-biuret and HDI (approximately 30 ppb) was nebulized and collected with the dichotomous sampler, approximately 78% of the HDI was in the vapor phase, whereas about 22% was associated with the aerosol fraction. The dichotomous sampler was then used to measure vapor and condensed phase TRIG in a paint spray booth during application of a polyurethane paint. Measured levels of TRIG during the spraying operation averaged 391 +/- 154 micrograms/m3. Concentrations of HDI monomer averaged only 14 +/- 6.5 micrograms/m3. HDI-biuret was the largest component of TRIG found in these samples and was completely in the condensed aerosol phase. In contrast, the majority of the HDI was in the vapor phase, but significant (15-26%) amounts were measured in the aerosol fraction of the paint overspray. Thus, significant partitioning of HDI between vapor and condensed phases was demonstrated in both the laboratory and field, even when its concentration was well below the vapor saturation point.

Aerosols↗
PubMedDate not supplied

Determination of carbon monoxide with a modified zeolite sorbent and methanization-gas chromatography.

The purpose of this study was to develop an alternative sorbent sampling technique to concentrate CO from an air sample for subsequent instrumental analysis. Y52 zeolite doped with 9.4 wt % cuprous ions was found to have high capacity, stability to air, and thermal reversibility for CO. The Cu(I)-modified zeolite was packed in glass tubes, preceded by a drying tube containing silica gel. Air was sampled through the tubes at the flow rate of 100 mL/min. Collected CO was thermally desorbed at 300 degrees C and determined by gas chromatography with reduction of CO to methane and flame ionization detection (TD-GC-CH4-FID). Breakthrough capacity of the sorbent was found to be 2.74 mg CO per gram of sorbent. For 2-L air samples containing 12.5 to 100 ppm CO and 50% relative humidity at room temperature, recovery of CO was found to be 96.6% with pooled relative standard deviation of 5.8%. The estimated detection limit for a 2-L sample was 0.2 ppm. Collected CO was stable at room temperature for 1 day and up to 7 days at 4 degrees C if the sorbent tube was flushed with helium before storage. In field testing, the ratio of CO measured by the new technique and by a reference technique was found to be 0.93 with pooled relative standard deviation of 6.3%. This unique new sorbent coupled with TD-GC-CH4-FID shows promise as a sensitive and specific alternative for measurement of CO in air.

Air Pollutants↗
PubMedDate not supplied

Can We protect workers from developing the adverse respiratory effects of isocyanate exposure?

In this review, the authors have attempted to present the difficulty in defining a permissible exposure limit (PEL) to agents that act as sensitizers and may induce asthma-even at exposure levels less than the PEL. One approach to this relatively unaddressed problem may be to define the separate aspects of exposure to the specific sensitizing agent. The first effect is an accelerated rate of decline in lung function in nonsensitized individuals who are exposed to the agent (in this case the model used is isocyanates). The second effect is sensitization. Rules for developing a PEL might take this sensitizing effect into account, and this group of agents with such dual effects may be defined as "sensitizers." Exposure to agents with this designation would require special educational and surveillance initiatives to facilitate early detection. The elimination of sensitization may be a greater challenge. An important form of prevention is medical screening of exposed workers, yet it is unclear which screening approach best identifies workers with early isocyanate asthma.

Asthma↗