Is baseline aerobic fitness associated with illness and attrition rate in military training?

BACKGROUND: Respiratory illnesses are a leading cause of morbidity and medical discharge in the military. This study aimed to investigate the effects of baseline aerobic fitness on haematological, salivary and mood variables, and simultaneously, in a novel approach, to identify factors precipitating illness and attrition rate in recruits during military training. METHODS: Thirty-five healthy male recruits from an Army Training Regiment undertaking 12 weeks of training were prospectively investigated. Their 2.4 km run time (RT) was used as a surrogate of baseline aerobic fitness. Saliva and venous blood samples were analysed for secretory IgA, full blood counts and cell cytokine production (interleukin (IL) 6 and IL-8), respectively. Each recruit completed questionnaires on mood profile, and gastrointestinal and upper respiratory tract symptoms (URTS). RESULTS: Significant salivary and haematological perturbations were observed and coincided with increased duration of URTS/week and mood disturbance over this military training period. From Start to End: leucocyte count decreased by 28% (p<0.001); neutrophil percentage (%) decreased by 13% (p<0.01); lymphocyte % increased by 17% (p<0.05); the neutrophil:lymphocyte ratio decreased by 22% (p<0.01); eosinophil% increased by 71% (p<0.01). From Start to Mid to End: monocyte% increased by 68% at Mid (p<0.01) but only by 30% at End (p<0.01); IL-6 increased by 39% at Mid (p<0.01) and a further 61% by End. The 2.4 km RT was significantly associated with URTS duration (p<0.01). In addition, a 1-min increase in 2.4 km RT increased a recruit's risk 9.8-fold of developing URTS lasting, on average, 3.36 days/week. In recruits ranked with high-URTS duration their RT was 48 s slower (p<0.01) than those with low-URTS, and their attrition rate reached 45%. CONCLUSIONS: The least fit recruits may have found training more physically demanding as reflected in the higher URTS duration, which may have led to a high attrition rate from the Army. It is worth considering that baseline aerobic fitness might be an important factor in illness development and attrition rate in recruits during this type of military training.

N-acetyltransferase 1 polymorphism increases cotinine levels in Caucasian children exposed to secondhand smoke: the CCAAPS birth cohort.

Cotinine is a proxy for secondhand smoke (SHS) exposure. Genetic variation along nicotine and cotinine metabolic pathways may alter the internal cotinine dose, leading to misinterpretations of exposure-health outcome associations. Caucasian children with available SHS exposure and hair cotinine data were genotyped for metabolism-related genes. SHS-exposed children had 2.4-fold higher hair cotinine (0.14±0.22 ng mg(-1)) than unexposed children (0.06±0.05 ng mg(-1), P<0.001). SHS-exposed children carrying the NAT1 minor allele had twofold higher hair cotinine (0.18 ng mg(-1) for heterozygotes and 0.17 ng mg(-1) for homozygotes) compared with major allele homozygotes (0.09 ng mg(-1), P=0.0009), even after adjustment for SHS dose. These findings support that NAT1 has a role in the metabolic pathway of nicotine/cotinine and/or their metabolites. The increased cotinine levels observed for those carrying the minor allele may lead to SHS exposure misclassification in studies utilizing cotinine as a biomarker. Additional studies are required to identify functional single-nucleotide polymorphism(s) (SNP(s)) in NAT1 and elucidate the biological consequences of the mutation(s).

Cost and disability trends of work-related musculoskeletal disorders in Ohio.

BACKGROUND: With expected changes in age demographics many industry sectors may see their workforce significantly increase in age. The impact of claims and costs associated with musculoskeletal disorders in these industries may also change accordingly. AIMS: To determine the age-related trends in musculoskeletal disorders, including claims and costs, in different industrial sectors in the state of Ohio, USA. METHODS: Worker's compensation claims for musculoskeletal disorders in the state of Ohio between 1999 and 2004 were analysed in respect of age, industry sector, body region, and impact on cost and medical care (percentage of claims associated with surgery and number of procedures costing in excess of US$600). RESULTS: More than 570000 claims were analysed. Patterns of cost and disability among the majority of body regions demonstrated an increasing trend until 55 years of age, decreasing in older age groups. However, many industries demonstrated a continued increasing trend in costs with age. Shoulder and lumbar spine disorders showed unique industry-specific trends for older age groups as compared to the bell-shaped relationships for other body regions. CONCLUSIONS: Ageing appeared to have a role in the frequency and costs of musculoskeletal disorder claims in this study. However, industry-specific trends in the data suggest that job-specific risk factors may also play a role. The impact of age alone on the cost of musculoskeletal disorders cannot be determined because age is confounded by numerous lifestyle and work-related factors not identifiable in this study.

Duration of day care attendance during infancy predicts asthma at the age of seven: the Cincinnati Childhood Allergy and Air Pollution Study.

BACKGROUND: Studies vary with respect to the reported effects of day care attendance on childhood asthma. OBJECTIVES: To evaluate the independent and combined effects of day care attendance and respiratory infections on the development of asthma at the age of seven in a prospective birth cohort. METHOD: At the age of seven, the study sample included 589 children with complete data of 762 enrolled at birth. Day care hours and number of respiratory infections were reported in follow-up questionnaires through age four. At 7 years of age, asthma was diagnosed in 95 children (16%), based on predefined symptoms criteria confirmed by either asthma FEV1 reversibility after bronchodilator or a positive methacholine test (PC20 ≤ 4 mg/mL). Logistic regression was used to investigate the relationships between asthma at the age of seven, cumulative hours of day care attendance and reported respiratory infections at ages 1-4. RESULTS: In the univariate analyses, day care attendance at 12 months was associated with an increased risk of asthma [odds ratio (OR) = 1.8, 95% confidence interval (CI) = 1.1-3.0]. Both upper and lower respiratory infections at 12 months also increased the likelihood of asthma [OR = 2.4 (1.4-4.1); OR = 2.3 (1.5-3.7), respectively]. In the final multivariate logistic model, cumulative hours of day care attendance and number of lower respiratory infections at 12 months were associated with asthma [OR = 1.2 (1.1-1.5); OR = 1.4 (1.2-1.7), respectively]. However, a threshold of greater than 37.5 hours per week of day care attendance was associated with a lower risk of asthma [OR = 0.6 (0.4-0.9)]. CONCLUSION: Depending on duration of attendance, day care during infancy can either increase or reduce risk of asthma at the age of seven.

Airway obstruction related to diacetyl exposure at microwave popcorn production facilities.

Obstructive lung diseases including bronchiolitis obliterans have been reported among microwave popcorn production employees. Butter flavourings including diacetyl have been associated with these findings. The present study was initiated at four microwave popcorn production plants to determine if exposure to diacetyl was associated with decrements in pulmonary function. Comprehensive diacetyl exposure assessment was undertaken for all job tasks. Spirometry was conducted for 765 full-time employees between 2005 and 2006. Outcomes included decrement in forced expiratory volume in one second (FEV(1)) % predicted, airway obstruction and persistent decline in FEV(1). Inclusion in the high-exposure group (mixers) prior to respirator use was associated with a significantly decreased FEV(1) % pred in non-Asian and Asian males at -6.1 and -11.8% pred, respectively, and an eight-fold increased risk for airway obstruction. Cumulative diacetyl exposure >or=0.8 ppm-yr caused similar results. No significant impact was seen in nonmixers or between current diacetyl exposure and persistent decline in FEV(1). Unprotected exposure as a mixer to butter flavouring including diacetyl resulted in decrements in FEV(1) (% pred) and increased airway obstruction. Control of employee exposure to butter flavouring additives is warranted in regard to both short-term peak and 8-h workday exposure.

Can a transitional work grant program in a workers' compensation system reduce cost and facilitate return to work?

Although previous research has shown returning the injured worker to work as soon as possible is important to the long-term prospects of the worker remaining in the work force, there is limited economic support for implementing such programs. Thus, the purpose of this case control study was to determine the cost savings of the implementation of a Transitional Work Grant (TWG) program, which consisted of several components including job analyses, education, communication and transitional work (TW). Companies that enrolled in the TWG program were matched to nonparticipating companies (NTW) based on employer size, type of industry, number of overall claims, and number of claims with > 7 days lost time (LT claims) submitted the year prior to enrollment. The study analyzed economic data: number of claims, number of LT claims, indemnity costs, medical costs, and days lost (days away from the workplace). An additional outcome was the ratio of LT claims (> 7 days lost work) to medical only (MO) claims (LT/MO ratio). Overall, participation in the TWG program was associated with decreased indemnity cost and decreased LT/MO ratio. However, effectiveness of the program varied by employer size and industry. In terms of the state of Ohio, these costs translate into substantial savings: more than $2.3 million per year. Although the cost savings and reduction in lost time claims is encouraging, the true benefit of TW has yet to be completely quantified. Future work must account for other potential co-factors and programs that could also contribute to the savings as well as document further the indirect benefits associated with a TWG program, such as improved employee morale and increased productivity and product quality that could be four times greater than the direct savings. In summary, programs such as this one adopted by several companies in Ohio can reduce the cost burden of injuries.

House dust (1-3)-beta-D-glucan and wheezing in infants.

BACKGROUND: (1-3)-Beta-D-glucan is a fungal cell wall component, suspected to cause respiratory symptoms in adults. However, very little is known on the possible health effects of (1-3)-beta-D-glucan during infancy. We examined the association between (1-3)-beta-D-glucan exposure and the prevalence of allergen sensitization and wheezing during the first year of life in a birth cohort of 574 infants born to atopic parents. Endotoxin exposure was included as a possible confounder. METHODS: (1-3)-Beta-D-glucan and endotoxin exposures were measured in settled dust collected from infants' primary activity rooms. The primary outcomes at approximately age one included parental reports of recurrent wheezing and allergen sensitization evaluated by skin prick testing to a panel of 15 aeroallergens as well as milk and egg white. RESULTS: Exposure to high (1-3)-beta-D-glucan concentration (within fourth quartile) was associated with reduced likelihood of both recurrent wheezing [adjusted OR (aOR) = 0.39, 95% CI = 0.16-0.93] and recurrent wheezing combined with allergen sensitization (aOR = 0.13, 95% CI = 0.03-0.61). Similar trends were found between (1-3)-beta-D-glucan concentrations and allergen sensitization (aOR = 0.57, 95% CI = 0.30-1.10). In contrast, recurrent wheezing with or without allergen sensitization was positively associated with low (1-3)-beta-D-glucan exposure within the first quartile (aOR = 3.04, 95% CI = 1.25-7.38; aOR = 4.89, 95% CI = 1.02-23.57). There were no significant associations between endotoxin exposure and the studied health outcomes. CONCLUSIONS: This is the first study to report that indoor exposure to high levels of (1-3)-beta-D-glucan (concentration >60 microg/g) is associated with decreased risk for recurrent wheezing among infants born to atopic parents. This effect was more pronounced in the subgroup of allergen-sensitized infants.

An epidemiological appraisal instrument - a tool for evaluation of epidemiological studies.

In recent years, ergonomics practices have increasingly relied upon the knowledge derived from epidemiological studies. In this regard, there is limited research devoted to the exclusive evaluation of the methodological qualities of ergonomics epidemiological studies. The aim of this study was to develop and test a general purpose 'epidemiological appraisal instrument' (EAI) for evaluating the methodological quality of existing or new ergonomic epidemiological studies using a critical appraisal system rooted in epidemiological principles. A pilot EAI version was developed and tested by a team of epidemiologists/physicians/biostatisticians, with the team leader being both epidemiologist and ergonomist. The pilot version was further tested with regard to other raters with/without a background in epidemiology, biostatistics and ergonomics. A revised version was evaluated for criterion validity and reliability. An assessor with a basic background in epidemiology and biostatistics would be able to correctly respond on four out of five questions, provided that subject matter expertise is obtained on specific items. This may improve with the article's quality. Training may have an effect upon assessors with virtually no background in epidemiology/biostatistics, but with a background in ergonomics. In this latter case, the inter-rater degree of agreement is largely above 90% and assessors can resolve their differences in a subsequent round. The EAI proved to be a valid and reliable appraisal instrument that may be used in various applications, such as systematic reviews and meta-analyses.

Microarray analysis of eosinophils reveals a number of candidate survival and apoptosis genes.

The increase in eosinophils at the site of antigen challenge has been used as evidence to suggest that this cell type plays a role in the pathophysiology of asthma. Aberrant production of several different cytokines, particularly interleukin (IL)-5, has been shown to result in eosinophilia. IL-5 influences the development and maturation of eosinophils in a number of different ways. Of note is the ability of IL-5 to act as a survival factor for eosinophils specifically inhibiting apoptosis. The precise mechanism by which IL-5 exerts its effect remains obscure. We used microarray technologies to investigate the changes in the messenger RNA expression profile of eosinophils after treatment with IL-5. Using the Affymetrix Hu6800 chip, a total of 80 genes were observed to be regulated by 2-fold or greater. Many of the genes previously identified as regulated by IL-5 were regulated in our microarray experiments. Of the 73 genes found to be upregulated, many were shown to play a role in adhesion, migration, activation, or survival of eosinophils or hematopoietic cells, whereas the function of others was unknown. To facilitate the identification of genes that govern the apoptosis and survivability of eosinophils, we used an alternative cellular model, TF1.8 cells, whose survival was also dependent on IL-5. Comparison of these models identified four genes, Pim-1, DSP-5 (hVH3, B23), CD24, and SLP-76, whose regulation was similarly coordinated in both systems. Identification of Pim-1 and SLP-76 as regulated by IL-5 led us to suggest a direct role for these proteins in the IL-5 signaling pathway in eosinophils. The tissue distribution of these genes demonstrated that Pim-1 and SLP-76 were relatively restricted to the eosinophil compared with their expression in brain, bone marrow, kidney, liver, and lung. By contrast, DSP-5 and CD24 were confirmed as ubiquitous in their expression by microarray.

Electron microscopy study of refractory ceramic fibers.

In epidemiological studies designed to identify potential health risks of exposures to synthetic vitreous fibers, the characterization of airborne fiber dimensions may be essential for assessing mechanisms of fiber toxicity. Toward this end, air sampling was conducted as part of an industry-wide study of workers potentially exposed to airborne fibrous dusts during the manufacture of refractory ceramic fibers (RCF) and RCF products. Analyses of a subset of samples obtained on the sample filter as well as on the conductive sampling cowl were performed using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize dimensions of airborne fibers. Comparison was made of bivariate fiber size distributions (length and diameter) from air samples analyzed by SEM and by TEM techniques. Results of the analyses indicate that RCF size distributions include fibers small enough in diameter (< 0.25 microm) to be unresolved by SEM. However, longer fibers (> 60 microm) may go undetected by TEM, as evidenced by the proportion of fibers in this category for TEM and SEM analyses (1% and 5%, respectively). Limitations of the microscopic techniques and differences in fiber-sizing rules for each method are believed to have contributed to the variation among fiber-sizing results. It was concluded from these data that further attempts to characterize RCF exposure in manufacturing and related operations should include analysis by TEM and SEM, since the smallest diameter fibers are not resolved with SEM and the fibers of longer length are not sized by TEM.

Reliability and validity of chest radiograph surveillance programs.

STUDY OBJECTIVES: Due to the lack of consensus in the literature in the use of posteroanterior (PA) vs PA with right and left oblique views as the optimum radiograph surveillance methodology to investigate pleural changes, a study was undertaken to evaluate the reliability, sensitivity, and specificity of these two approaches. DESIGN: Three experienced radiologist B readers used the 1980 International Labor Office classification system for pneumoconiosis to independently read chest radiographs of workers with individual identifiers masked. All radiographs were read first as a PA view only. Unknown to the B readers, each subject's PA was then matched to his or her corresponding right and left oblique views (film triad) and re-read several weeks later. SETTING AND PARTICIPANTS: The respiratory health of 652 workers exposed to refractory ceramic fiber was assessed as part of cross-sectional and longitudinal surveillance programs. MEASUREMENTS AND RESULTS: kappa Statistics for interreader and intrareader reliability between the PA view and film triad methods were calculated. Sensitivity, specificity, and positive predictive value were assessed by comparing the initial cross-sectional study to the longitudinal study. The film triad method had considerably higher interreader reliability (kappa = 0.59) compared to the PA-only method (kappa = 0.44). Results from the initial cross-sectional study were then compared to findings evaluated longitudinally. The film triad again was superior, demonstrating a positive predictive value of 73.7% compared to only 47.8% for the PA method. CONCLUSIONS: It is our recommendation that the film triad method be used in surveillance studies where both parenchymal and pleural changes are anticipated.

What is the potential measurement error in occupational exposure studies?

This paper demonstrates statistical methods that estimate measurement error from available industrial hygiene data. Errors in measuring a continuous exposure variable may arise when all individuals in a work area are assigned the same exposure. An example is when the mean of exposure measurements obtained on a sample of individuals is assigned to all workers with similar jobs. This may lead to inaccurate point and interval estimates in exposure-response modeling. A method of simulating the distribution of true (i.e., unobserved) individual exposures is described in order to estimate the mean and variance of measurement error. The minimum variance unbiased estimator approximates the mean of lognormally distributed exposure measurements. The distribution of true individual exposures is approximated by the distribution of simulated estimates of mean exposure. The methodology is illustrated by exposure data from work areas manufacturing refractory ceramic fiber (RCF) and RCF products. Results show that exposure is slightly underestimated in work areas with between 25 and 113 exposure measurements; measurement error variance averages about 1.3% of the total variance.

Weight change and lung function: implications for workplace surveillance studies.

This study evaluated the relationship between weight change and longitudinal measurement of lung function among 361 men providing at least five pulmonary function tests. The men in this study were participants in a workplace pulmonary surveillance program for subjects with exposure to refractory ceramic fibers (RCFs). Occupational and environmental studies are generally designed to evaluate factors suspected of causing excess decline in lung function. Failure to adequately account for all significant factors may lead to erroneous conclusions regarding change in lung function. This study utilized two different statistical models to evaluate longitudinal changes in a cohort of RCF workers. What was unique to this study was the modeling of longitudinally measured initial weight, weight change, and longitudinal exposure before and during the period of observation. Results showed a strong relationship between weight gain and longitudinal loss in lung function that approximated forced vital capacity declines of 16 mL for every kilogram of weight gain per year in both models. This value is comparable or greater in magnitude and significance to other factors known to be inversely related to lung function, such as age and pack-years smoking to time of initial testing. In conclusion, weight gain was found to have a significant impact on longitudinal change in lung function. Therefore, weight gain becomes a very important variable that requires consideration whenever longitudinal studies of pulmonary function are conducted.

Potential significance of airborne fiber dimensions measured in the U.S. refractory ceramic fiber manufacturing industry.

BACKGROUND: To determine dimensions of airborne fibers in the U.S. refractory ceramic fiber (RCF) manufacturing industry, fibers collected through personal air sampling for employees at RCF manufacturing and processing operations have been measured. METHODS: Data were derived from transmission electron microscopy analyses of 118 air samples collected over a 20-year period. RESULTS: Characteristics of sized fibers include: diameter measurements of <60; 0.19 to 1.0 micron, m of which 75% are less than 0.6 micron and length ranging from < 0.6 to > 20 micron, with 68% of fibers between 2.4 and 20 micron. CONCLUSIONS: Exposures in RCF manufacturing include airborne fibers with dimensions (diameter < 0.1-0.4 micron, length < 10 micron) historically associated with biological effects in pleural tissues. Air sampling data and a review of studies relating fiber size to pleural effects in animals and humans support the belief that information on fiber dimensions is essential for studies with synthetic vitreous fibers.

Male reproductive effects of solvent and fuel exposure during aircraft maintenance.

Few studies have addressed the effects of mixed, low-level exposures to complex mixtures on a man's reproductive potential. In this prospective study, each subject was evaluated before first exposure and at 15 and 30 weeks after exposures had begun. A total of 50 men working on aircraft maintenance at an Air Force installation were included in the study. In addition, eight unexposed men were concurrently sampled. Industrial hygiene (IH) sampling and expired breath samples were collected for jet fuel as measured by total napthas, benzene--a component of jet fuel, 1,1,1-trichloroethane, methyl ethyl ketone, xylenes, toluene, and methylene chloride. Sperm production, structure, and function (sperm concentration, sperm motion, viability, morphology, morphometrics, and stability of sperm chromatin) were evaluated. Exposures were low. All mean IH measures were below 6 ppm, which is less than 10% of the Occupational Safety and Health Administration standard for all chemicals except benzene. Sheet metal workers had the highest mean breath levels for both total solvents (24 ppb) and fuels (28.3 ppb). For most sperm measures, mean values remained in the normal range throughout the 30 weeks of exposure. When jobs were analyzed by exposure groups, some adverse changes were observed. The paint shop group had a significant decline in motility of 19.5% at 30 weeks. Internal dose measures, however, did not show a significant association with spermatogenic changes.

Comparison of internal dose measures of solvents in breath, blood and urine and genotoxic changes in aircraft maintenance personnel.

Solvents and fuels are in widespread use both in civilian and military populations. 1,1,1-trichloroethane (TCA), xylene, toluene, methyl ethyl ketone (MEK) and methylene chloride are found in a variety of compounds including degreasing agents, paints, coatings, pesticides and paint strippers. Toluene and xylene are also found in fuels, which are complex mixtures of hundreds of agents. The purpose of this investigation was twofold. The first was to determine the optimum medium to measure internal dose of solvents comparing blood, urine and breath. The second was to determine if low level exposures were associated with genotoxic changes after a short-term exposure of fifteen or thirty weeks. To accomplish the first goal a pilot study was initiated involving eight volunteers who worked in aircraft maintenance including sheet metal, painting and assembly mechanic jobs. Industrial hygiene measurements were evaluated over 30 working days. Breath, blood and a 24-hour urine sample were collected twice to compare internal dose parameters. To achieve the second goal, 58 newly hired subjects were monitored prior to exposure and over 30 weeks to determine if there were genotoxic changes as a result of solvent and/or fuel exposure as measured by sister chromatid exchanges (SCEs) and micronuclei (MN). Exposure groups included workers involved in sheet metal (fuel cell) activities, painting, fueling operations and flight line. Results of the pilot study demonstrated that industrial hygiene air samples and internal breath measures taken on the same day were highly correlated for measuring TCA (r = 0.93) and toluene (r = 0.90) but was not as well correlated for the other compounds. Breath measures were more sensitive for measuring low level exposure than were either analytes in blood or 24-hour urine samples; these latter two measures were usually below the limit of detection. A small but statistically significant increase in the frequency of SCEs occurred after 30 weeks of exposure for sheet metal workers (p = 0.003) and for painters (p = 0.05). The MN frequency in the sheet metal workers initially showed a significant increase by 15 weeks, but by 30 weeks had decreased. Chance occurrence of exposures to other occupational or non-occupational agents can not be eliminated as a cause of the genotoxic results since between 58 and 93 total analytes could be found in the breath of some aircraft maintenance personnel.

An industry-wide pulmonary study of men and women manufacturing refractory ceramic fibers.

An industry-wide pulmonary morbidity study was undertaken to evaluate the respiratory health of employees manufacturing refractory ceramic fibers at five US sites between 1987 and 1989. Refractory ceramic fibers are man-made vitreous fibers used for high temperature insulation. Of the 753 eligible current employees, 742 provided occupational histories and also completed the American Thoracic Society respiratory symptom questionnaire; 736 also performed pulmonary function tests. Exposure to refractory ceramic fibers was characterized by classifying workers as production or nonproduction employees and calculating the duration of time spent in production employment. The risk of working in the production of refractory ceramic fibers and having one or more respiratory symptoms was estimated by adjusted odds ratios and found to be 2.9 (95 percent confidence interval 1.4-6.2) for men and 2.4 (95 percent confidence interval 1.1-5.3) for women. The effect of exposure to refractory ceramic fibers on forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), the ratio of the two (FEV1/FVC), and forced expiratory flow (liters/second) between 25 percent and 75 percent of the FVC curve (FEF(25-75)) was evaluated by multiple regression analysis using transformed values adjusted for height, by dividing by the square of each individual's height. For men, there was a significant decline in FVC for current and past smokers of 165.4 ml (p < 0.01) and 155.5 ml (p = 0.04), respectively, per 10 years of work in the production of refractory ceramic fibers. For FEV1, the decline was significant (p < 0.01) only for current smokers at 134.9 ml. For women, the decline was greater and significant for FVC among nonsmokers, who showed a decrease of 350.3 ml (p = 0.05) per 10 years of employment in the production of refractory ceramic fibers. These findings indicate that there may be important sex differences in response to occupational and/or environmental exposure.

Hypersensitivity pneumonitis in a machinist.

Hypersensitivity pneumonitis (HP), or extrinsic allergic alveolitis, is a patchy, interstitial lung disease that involves an immunologic reaction of the lung to repeated inhalation of foreign antigens. In this report, we describe a machinist with exposure to metalworking fluids (MWFs) and biopsy-confirmed HP. Return to work, which could be equated with a retrospective workplace-specific bronchoprovocation test, proved that working within an environment in which MWFs were used was associated with clinical deterioration in the patient's pulmonary status and with clinical improvement after removal from exposure.