Comparison of spirometric reference values for Caucasian and African American blue-collar workers.

Interpretation of lung-function test results, specifically the forced vital capacity and forced expiratory volume in one second, generally involves the comparison of these parameters with reference values based on an individual's age, height, sex, and race. Such comparisons are often used to make important decisions concerning an individual, such as job placement or disability rating. Several studies have shown that predicted values for African Americans are approximately 15% less than those for Caucasians, most likely because of the use of standing height to estimate the size of the thorax. When an adjustment for race is applied to reference values based on a Caucasian population, a single value (15%) is usually applied to all individuals. When using a group of blue-collar workers (766 Caucasian and 633 African-American subjects) without any race adjustment, 10.2% of the Caucasians and 37.4% of the African-American subjects were below the lower limit of normal. When a single adjustment factor was used, 11.5% of the African-American subjects were below the lower limit of normal. Between-subject variability within an ethnic group was far greater than variability between groups. Our results suggest that although a difference between Caucasian and African-American test results for forced vital capacity and forced expiratory volume in one second exists, an application of a single adjustment factor universally applied to all individuals, regardless of their age, sex, and height, is not optimal, and alternative approaches are needed.

Comparing MiniWright and spirometer measurements of peak expiratory flow.

The accuracy and instrument variability of the MiniWright (Clement Clarke) peak expiratory flow (PEF) meter was determined with 6 of the 24 American Thoracic Society's (ATS) standard waveforms using a mechanical pump. Both room air and air heated to 37 degrees C and saturated with water vapor were used. In addition, MiniWright-determined PEF measurements were compared with those obtained using a dry rolling-seal spirometer (Ohio No. 822; Ohio Medical Products; Madison, Wis) from 75 subjects on 2 different days. The MiniWright average coefficient of variation within a waveform was found to be 2.8%. Results using heated and humidified air (body temperature, ambient pressure, and saturated with water: body conditions) were 2.5% lower than those obtained using room air. Comparisons with mechanically simulated PEF and with spirometry-determined peak flow in 75 human subjects showed that MiniWright meters over-estimated flows at lower flow rates and slightly under-estimated flows at higher flow rates. These results suggest that the new "mechanical PEF" MiniWright scale should be used instead of the "traditional" MiniWright scale.

Silicosis surveillance in New Jersey: targeting workplaces using occupational disease and exposure surveillance data.

To identify workplaces in New Jersey with potential for silica exposure, the New Jersey Department of Health compared four-digit Standard Industrial Classifications (SICs) identified by three different data sources: the National Occupational Exposure Survey (NOES), a new Jersey silicosis case registry, and regulatory agency compliance inspections in New Jersey. In total, the three data sources identified 204 SICs in New Jersey with potential for silica exposure. Forty-five percent of these SICs were identified by NOES only, 16% by registry cases only, 6% by compliance inspections only, and 33% by two or more sources. Since different surveillance sources implicate different SICs, this type of analysis is a useful first step in planning programs for prevention of silicosis.

Changes in forced expiratory volume in one second and peak expiratory flow rate across a work shift among unexposed blue collar workers.

Pre- and postshift spirometry was obtained on 1,113 blue collar workers employed at 35 work sites judged to have no hazardous occupational respiratory exposures on the basis of inspection visits and environmental sampling. In addition to spirometry, a standardized questionnaire was administered by trained personnel. A study population of 944 remained after exclusion of workers for incomplete demographic data and/or spirometry with poor within-session reproducibility, i.e., greater than or equal to 10% variability in the two largest values of either FVC and/or FEV1. Overall mean values of changes across the work shift in FEV1 and peak expiratory flow rate (PEFR) were -0.8% (-0.04 L) and +2.1% (+0.13 L/s), respectively. Standard deviations for these across-shift changes were 5.8% (0.19 L) and 13.2% (1.19 L/s) for FEV1 and PEFR, respectively. In univariate analyses, mean values of across-shift changes were not statistically related to age, race, sex, smoking status, work shift, or FEV1/FVC ratio. However, variability (i.e., standard deviation) of across-shift changes were significantly related to some of these factors. These observations provide a basis for interpreting results of occupational respiratory morbidity surveys involving measurement of changes in FEV1 and/or PEFR across a work shift.

A comparison of pneumoconiosis interpretation between Chinese and American readers and classifications.

As a preliminary step in joint Sino-American pneumoconiosis research efforts, a formal chest X-ray pneumoconiosis reading trial was conducted among Chinese and American radiologists. Twelve Chinese readers from different institutions located in south central China used the 1986 Chinese Roentgenodiagnostic Criteria of Pneumoconioses. Three American radiologists, centified as NIOSH "B" readers, used the International Labour Office Classification of Pneumoconioses. The chest X-ray study set consisted of 150 posterior-anterior films. One-half were Chinese X-rays of silica-exposed workers, and the other half were American films of variously exposed workers but primarily coal miners. All readings were done independently. The results showed that the inter-reader variability among the Chinese was similar to that of the American readers, both being in an acceptable range. In addition, there was general agreement between the Chinese and American interpretations. For small opacity profusion, the Chinese readers tended to read slightly more diseases than their American counterparts, although there was exact agreement as to the major category in two-thirds of the films. Agreement for film quality, and pleural disease was less, but was not different from reported variation among American "B" readers. Overall, the results suggest that despite the use of two different classification systems, a valid correspondence exists between the Chinese and American Interpretations, which is suitable for use in epidemiologic research.

Inhaled endotoxin and decreased spirometric values. An exposure-response relation for cotton dust.

The early stages of byssinosis, the chronic lung disorder caused by the inhalation of cotton dust, are characterized by repeated episodes of mild and reversible obstruction of airways on exposure to cotton dust. To define the relation between exposure to endotoxin and the airway response to inhaled cotton dust, we pooled and analyzed data from several previous studies of experimental exposure. The pooled data set involved a total of 108 separate sessions of exposure to dust and 32 different cottons. Each dust-exposure session had involved exposing a group of 24 to 35 prescreened healthy subjects to dust from one of the cottons for six hours. The following data were obtained for each session: average concentrations of airborne dust (range, 0.12 to 0.55 mg per cubic meter) and endotoxin (range, 6 to 779 ng per cubic meter) as determined in air samples collected by vertical elutriators, and group mean percentage change in forced expiratory volume in one second (range, +0.5 to -9.1 percent), as determined by preexposure and postexposure spirometry. When data from the 108 exposure sessions were pooled, the dust concentration was not correlated with the group mean percentage change in forced expiratory volume in one second (r = -0.08; P = 0.43). In contrast, a clear exposure-response relation was observed between endotoxin concentration and group mean percentage change in forced expiratory volume in one second (r = -0.74; P less than 0.0001). Logarithmic transformation of endotoxin values clarified this relation at low-exposure concentrations and improved the correlation (r = -0.85; P less than 0.0001). Our observations strongly support the hypothesis that endotoxin has a causative role in the acute pulmonary response to inhaled cotton dust.

Respiratory health status of gilsonite workers.

Gilsonite, a solidified hydrocarbon used in the manufacture of automotive body seam sealers, is mined only in the Uinta Basin of Eastern Utah and Western Colorado. Health effects of gilsonite dust exposure have not previously been published and exposure to gilsonite dust is not regulated. To examine potential respiratory health effects associated with gilsonite dust exposures, this cross-sectional study surveyed the 100 current male employees who had been exposed to gilsonite dust at 3 existing gilsonite companies. Total dust exposures up to 28 times the nuisance dust standard were found, and 5 of 99 (5%) workers had chest radiographs consistent with pneumoconiosis of low profusion. Increased prevalences of cough and phlegm were found in workers with high-exposure jobs, but no evidence for dust-related pulmonary function impairment was noted. To prevent pulmonary health effects, we recommend reducing dust exposures for those workers in jobs currently characterized by relatively high dust exposures.

Effect of spirometer temperature on measurement of FEV1 shift changes.

Spirometric parameters are generally obtained at ambient (spirometer) temperature pressure saturated (ATPS) and then converted to body temperature pressure saturated (BTPS) by multiplying each observed value by a BTPS correction factor. At ambient temperatures of 23 degrees C or higher, the accepted practice of using a constant BTPS factor introduces a relatively small error in forced expiratory volume in one second (FEV1), but as the temperature decreases below 23 degrees C the error in FEV1 increases. A dynamic BTPS correction factor model has recently been developed to reduce this error. Analysis of across-shift spirometry data from a recent survey indicates that, with an increase in temperature over a work shift of greater than 3 degrees C, 27.1% of 302 subjects were classified as having a greater than or equal to 5% FEV1 drop over the shift using the dynamic BTPS factor model, compared with 41.4% when the standard BTPS correction factor was used (P less than .005). These results indicate the importance of correcting for ambient temperature differences when analyzing for shift changes in spirometric parameters.