Cleaning Tasks and Products and Asthma Among Health Care Professionals

OBJECTIVE

Health care workers are at risk for work-related asthma, which may be affected by changes in cleaning practices. We examined associations of cleaning tasks and products with work-related asthma in health care workers in 2016, comparing them with prior results from 2003.

METHODS

We estimated asthma prevalence by professional group and explored associations of self-reported asthma with job-exposure matrix-based cleaning tasks/products in a representative Texas sample of 9914 physicians, nurses, respiratory/occupational therapists, and nurse aides.

RESULTS

Response rate was 34.8% (n = 2421). The weighted prevalence rates of physician-diagnosed (15.3%), work-exacerbated (4.1%), and new-onset asthma (6.7%) and bronchial hyperresponsiveness symptoms (31.1%) were similar to 2003. New-onset asthma was associated with building surface cleaning (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.10-3.33), use of ortho-phthalaldehyde (OR, 1.77; 95% CI, 1.15-2.72), bleach/quaternary compounds (OR, 1.91; 95% CI, 1.10-3.33), and sprays (OR, 1.97; 95% CI, 1.12-3.47).

CONCLUSION

Prevalence of asthma/bronchial hyperresponsiveness seems unchanged, whereas associations of new-onset asthma with exposures to surface cleaning remained, and decreased for instrument cleaning.

Development of Job Exposure Matrices to Estimate Occupational Exposure to Solar and Artificial Ultraviolet Radiation

Objectives

Job exposure matrices (JEMs) are important tools for estimating occupational exposures in study populations where only information on industry and occupation (I&O) are available. JEMs The objective of this work was to create JEMs for solar and artificial ultraviolet radiation (UVR) using a US standardized coding scheme.

Methods

Using U.S. Census Bureau industry and occupation codes, separate lists of I&O pairs were developed for solar and artificial UVR by a panel of Certified Industrial Hygienists who assigned exposure ratings to I&O pairs with potential exposure. Parameters for exposure included prevalence (P) and frequency (F) for solar UVR and P, F, and intensity (I) for artificial UVR. Prevalence, or percent of all workers employed in an I&O pair who were exposed, was categorically rated: 0 to <1, 1 to <20; 20 to <80, and ≥80. Frequency of exposure, defined by the number of hours per week workers were exposed, was categorically rated: 0 to <5, 5 to <20, 20 to <35, and ≥35 h per week. For artificial UVR only, intensity of exposure was assigned three ratings: low, low with rare excursions, and >low under normal conditions. Discrepant ratings were resolved via consensus.

Results

After excluding I&O pairs assigned P and F ratings of 0 (solar UVR) and P, F, and I ratings of 0 (artificial UVR) from the JEM, 9206 I&O pairs were rated for solar UVR and 2010 I&O pairs for artificial UVR. For solar UVR, 723 (7.9% of all rated pairs) had ratings in the highest category for P and F; this group included 45 occupations in varied industries. Construction and extraction occupations represented most of the occupations (n = 20; 44%), followed by farming, fishing, and forestry occupations (n = 6; 13%). For artificial UVR, 87 I&O pairs (4.3% of all rated pairs) had maximum ratings for P, F, and I; these comprised a single occupation (welding, soldering, and brazing workers) in diverse industries.

Conclusions

JEMs for solar and artificial UVR were developed for a broad range of I&O pairs in the US population and are available for use by researchers conducting occupational epidemiological studies.

Association of organic solvents and occupational noise on hearing loss and tinnitus among adults in the U.S., 1999-2004

PURPOSE

Exposure to organic solvents and noise may be causal agents in the development of hearing loss and tinnitus. The objectives of the present study were to examine the association of organic solvents with hearing loss and tinnitus and to assess the interaction of organic solvent and occupational noise exposure on hearing loss and tinnitus.

METHODS

A secondary data analysis of data from the National Health and Nutrition Examination Survey and Occupational Information Network (O*NET) among a study population ranging from 1085 to 2471 study participants from 1999 to 2004. Multiple multivariate logistic regression models were used to assess the associations of individual organic solvent exposures as measured by blood biomarkers (1,4-dichlorobenzene, benzene, ethylbenzene, styrene, toluene, o-xylene, and m-/p-xylene) with self-reported hearing loss, audiometrically assessed hearing loss, and self-reported tinnitus. Models were adjusted for age, gender, race/ethnicity, diabetes, non-occupational noise exposure, smoking, and income. Organic solvents found to be statistically significantly associated with the outcome after adjusting for covariates were tested for interaction with occupational noise exposure.

RESULTS

Solvent exposure was not statistically significantly associated with self-reported tinnitus. Benzene (OR 1.43, 95% CI 1.15-1.78), ethylbenzene (OR 1.24, 95% CI 1.02-1.50), and toluene (OR 1.27, 95% CI 1.06-1.52) concentrations were statistically significantly associated with increased adjusted odds of high-frequency hearing loss. No statistically significant interaction was observed between these solvents and occupational noise on high-frequency hearing loss.

CONCLUSIONS

We found no evidence of an association between organic solvents and tinnitus; however, there was evidence of an association between organic solvent exposure and prevalence of high-frequency hearing loss.

A Pilot Examination of the Methods Used to Counteract Insider Threat Security Risks Associated with the Use of Radioactive Materials in the Research and Clinical Setting

While many organizations maintain multiple layers of security control methodologies to prevent outsiders from gaining unauthorized access, persons such as employees or contractors who have been granted legitimate access can represent an "insider threat" risk. Interestingly, some of the most notable radiological events involving the purposeful contamination or exposure of individuals appear to have been perpetrated by insiders. In the academic and medical settings, radiation safety professionals focus their security efforts on (1) ensuring controls are in place to prevent unauthorized access or removal of sources, and (2) increasing security controls for the unescorted accessing of large sources of radioactivity (known as "quantities of concern"). But these controls may not completely address the threat insiders represent when radioactive materials below these quantities are present. The goal of this research project was to characterize the methodologies currently employed to counteract the insider security threat for the misuse or purposeful divergence of radioactive materials used in the academic and medical settings. A web-based survey was used to assess how practicing radiation safety professionals in academic and medical settings anticipate, evaluate, and control insider threat security risks within their institutions. While all respondents indicated that radioactive sources are being used in amounts below quantities of concern, only 6 % consider insider threat security issues as part of the protocol review for the use of general radioactive materials. The results of this survey identify several opportunities for improvement for institutions to address security gaps.

Maternal occupational physical activity and risk for orofacial clefts

OBJECTIVES

To perform a case-control study of maternal occupational physical activity and risk for orofacial clefts in Texas during 1999-2009.

METHODS

We used logistic regression to assess 14 measures of physical activity estimated from a job exposure matrix, using the maternal occupation reported on the birth certificate, among 887 children with cleft lip with or without cleft palate (CLP), 436 children with cleft palate only (CP), and 1932 controls.

RESULTS

After adjusting for several potential confounders, seven measures of physical activity (as a categorical and/or continuous variable) were significantly associated with CLP, CP, or both. Positive associations were seen for keeping balance, kneeling, standing, and walking/running (odds ratio 95% confidence interval range 1.0-1.9 for fourth versus first quartile). A significant positive trend was also seen for bending/twisting. Negative associations were seen for repetitive motion and sitting.

CONCLUSIONS

Maternal occupational physical activity may be related to the etiology of orofacial clefts.

Depression Prevalence and Exposure to Organophosphate Esters in Aircraft Maintenance Workers

INTRODUCTION

Previous studies found that aircraft maintenance workers may be exposed to organophosphates in hydraulic fluid and engine oil. Studies have also illustrated a link between long-term low-level organophosphate pesticide exposure and depression.

METHODS

A questionnaire containing the Patient Health Questionnaire 8 depression screener was e-mailed to 52,080 aircraft maintenance workers (with N = 4801 complete responses) in a cross-sectional study to determine prevalence and severity of depression and descriptions of their occupational exposures.

RESULTS

There was no significant difference between reported depression prevalence and severity in similar exposure groups in which aircraft maintenance workers were exposed or may have been exposed to organophosphate esters compared to similar exposure groups in which they were not exposed. However, a dichotomous measure of the prevalence of depression was significantly associated with self-reported exposure levels from low (OR: 1.21) to moderate (OR: 1.68) to high exposure (OR: 2.70) and with each exposure route including contact (OR: 1.68), inhalation (OR: 2.52), and ingestion (OR: 2.55). A self-reported four-level measure of depression severity was also associated with a self-reported four-level measure of exposure.

DISCUSSION

Based on self-reported exposures and outcomes, an association is observed between organophosphate exposure and depression; however, we cannot assume that the associations we observed are causal because some workers may have been more likely to report exposure to organophosphate esters and also more likely to report depression. Future studies should consider using a larger sample size, better methods for characterizing crew chief exposures, and bioassays to measure dose rather than exposure. Hardos JE, Whitehead LW, Han I, Ott DK, Waller DK. Depression prevalence and exposure to organophosphate esters in aircraft maintenance workers. Aerosp Med Hum Perform. 2016; 87(8):712-717.

Maternal exposure to radiographic exams and major structural birth defects

BACKGROUND

An increasing number of radiologic exams are performed in the United States, but very few studies have examined the effects of maternal exposure to radiologic exams during the periconceptional period and birth defects.

OBJECTIVES

To assess the association between maternal exposure to radiologic exams during the periconceptional period and 19 categories of birth defects using a large population-based study of birth defects.

METHODS

We studied 27,809 case mothers and 10,200 control mothers who participated in the National Birth Defects Prevention Study and delivered between 1997 and 2009. Maternal exposure to radiologic exams that delivered ionizing radiation to the urinary tract, lumbar spine, abdomen, or pelvis were identified based on the mother's report of type of radiologic exams, organ or body part scanned and the month during which the exam occurred

RESULTS

Overall, 0.9% of mothers reported exposure to one of these types of radiographic exams during the periconceptional period. We observed significant associations between maternal exposure during the first trimester and isolated Dandy-Walker malformation (odds ratio = 7.7; 95% confidence interval, 1.8-33) and isolated d-transposition of the great arteries (odds ratio = 3.8; 95% confidence interval, 1.4-10.3). However, the result for isolated Dandy-Walker malformation was based on only two exposed cases.

CONCLUSION

These results should be interpreted cautiously because multiple statistical tests were conducted and measurements of exposure were based on maternal report. However, our results may be useful for generating hypotheses for future studies. Birth Defects Research (Part A) 106:563-572, 2016. © 2016 Wiley Periodicals, Inc.

Maternal occupational exposure to ionizing radiation and major structural birth defects

BACKGROUND

Ionizing radiation (IR) is known to be carcinogenic and mutagenic, but little is known about the association between maternal occupational exposure to IR and birth defects.

METHODS

We studied 38,009 mothers who participated in the National Birth Defects Prevention Study and delivered between 1997 and 2009. We assessed odds ratios [ORs] for the association between maternal occupations with potential exposure to IR and 39 birth defects.

RESULTS

We observed significant odds ratios (ORs) for isolated hydrocephaly (adjusted OR [AOR], 2.1; 95% confidence interval [CI], 1.1-4.2), isolated anotia/microtia (AOR, 2.0; 95% CI, 1.0-4.0), isolated colonic atresia (crude OR, 7.5; 95% CI, 2.5-22.3), isolated omphalocele (AOR, 2.3; 95% CI, 1.1-4.6) and isolated anencephaly (crude OR, 0.23; 95% CI, 0.06-0.94). We also observed a nonsignificant OR for birth defects in aggregate (AOR, 2.0; 95% CI, 0.9-4.6) among mothers with potential occupational exposure to fluoroscopy.

CONCLUSION

We assessed 39 birth defects, observing that maternal occupations with potential exposure to IR were associated with a significantly increased risk for 4 birth defects and a significantly protected risk for 1 birth defect. These results should be interpreted cautiously because our measurement of exposure is qualitative, some of these associations may be due to occupational exposures that are correlated with IR and some may be due to chance. However, these findings serve as the first evaluation of these relationships in a large study and may be useful for generating hypotheses for future studies.

Assessing the Biological Safety Profession's Evaluation and Control of Risks Associated with the Field Collection of Potentially Infectious Specimens

Because the origins of the biological safety profession are rooted in the control and prevention of laboratory-associated infections, the vocation focuses primarily on the safe handling of specimens within the laboratory. But in many cases, the specimens and samples handled in the lab are originally collected in the field where a broader set of possible exposure considerations may be present, each with varying degrees of controllability. The failure to adequately control the risks associated with collecting biological specimens in the field may result in illness or injury, and could have a direct impact on laboratory safety, if infectious specimens were packaged or transported inappropriately, for example. This study developed a web-based survey distributed to practicing biological safety professionals to determine the prevalence of and extent to which biological safety programs consider and evaluate field collection activities. In cases where such issues were considered, the data collected characterize the types of controls and methods of oversight at the institutional level that are employed. Sixty-one percent (61%) of the survey respondents indicated that research involving the field collection of biological specimens is conducted at their institutions. A majority (79%) of these field collection activities occur at academic institutions. Twenty-seven percent (27%) of respondents indicated that their safety committees do not consider issues related to biological specimens collected in the field, and only 25% with an oversight committee charged to review field collection protocols have generated a field research-specific risk assessment form to facilitate the assembly of pertinent information for a project risk assessment review. The results also indicated that most biosafety professionals (73% overall; 71% from institutions conducting field collection activities) have not been formally trained on the topic, but many (64% overall; 87% from institutions conducting field collection activities) indicated that training on field research safety issues would be helpful, and even more (71% overall; 93% from institutions conducting field collection activities) would consider participation in such a training course. Results obtained from this study can be used to develop a field research safety toolkit and associated training curricula specifically targeted to biological safety professionals.

A Global Survey of Occupational Health Competencies and Curriculum

The World Health Organization has identified a worldwide shortage of occupational health professionals, but evidence suggests that the work and education of these professionals vary across countries. This survey examined the professional development of occupational physicians, occupational nurses, industrial hygienists, and ergonomists in terms of practice competencies and academic curriculum. Of 89 countries that received the survey, 48 (54%) responded. Important differences in competencies and curricula were identified for all groups. More competencies were identified more frequently in developed countries. Academic programs existed more often in developed countries, but curriculum contents varied. The study provides a concrete reference point for discussion and development of competencies and curriculum.

Physical activity guideline in Mexican-Americans: does the built environment play a role?

Given disproportionate burden of physical inactivity among US Hispanics and emerging interests in the potential role of the built environment on physical activity, we tested the hypothesis that residing in a more walkable block group is associated with increased physical activity in a cohort of Mexican-American adults. 10,183 Mexican-American adults from Houston, TX, USA were studied. Physical activity was assessed through self-report. Geographical information systems were used to create a "walkability index" (WI). We examined the relationship between WI and physical activity using regression models. Findings for the entire study population suggested a direct association between neighborhood walkability and physical activity that approached statistical significance (High WI vs. Low WI: OR = 1.16; 95% CI 0.95-1.40). Furthermore, participants who lived in a higher WI neighborhood were more likely to meet physical activity guidelines in 2 groups: (1) men whose recreational physical activity included walking (High WI vs. Low WI: OR = 5.43; 95% CI 1.30-22.73) and (2) men whose only recreational physical activity was (High WI vs. Low WI: OR = 9.54; 95% CI 1.84-49.60). Our findings suggest gender differences in the association between the built environment and physical activity in Mexican-American adults. Attempts to encourage walking among Mexican-American adults may be easier in high-walkability neighborhoods than in low-walkability neighborhoods.

Diffractive imaging using partially coherent x rays

The measured spatial coherence characteristics of the illumination used in a diffractive imaging experiment are incorporated in an algorithm that reconstructs the complex transmission function of an object from experimental x-ray diffraction data using 1.4 keV x rays. Conventional coherent diffractive imaging, which assumes full spatial coherence, is a limiting case of our approach. Even in cases in which the deviation from full spatial coherence is small, we demonstrate a significant improvement in the quality of wave field reconstructions. Our formulation is applicable to x-ray and electron diffraction imaging techniques provided that the spatial coherence properties of the illumination are known or can be measured.

Occupational risk factors and asthma among health care professionals

RATIONALE

Recent U.S. data suggest an increased risk of work-related asthma among health care workers, yet only a few specific determinants have been elucidated.

OBJECTIVES

To evaluate associations of asthma prevalence with occupational exposures in a cross-sectional survey of health care professionals.

METHODS

A detailed questionnaire was mailed to a random sample (n=5,600) of all Texas physicians, nurses, respiratory therapists, and occupational therapists with active licenses in 2003. Information on asthma symptoms and nonoccupational asthma risk factors obtained from the questionnaire was linked to occupational exposures derived through an industry-specific job-exposure matrix.

MEASUREMENTS

There were two a priori defined outcomes: (1) physician-diagnosed asthma with onset after entry into health care ("reported asthma") and (2) "bronchial hyperresponsiveness-related symptoms," defined through an 8-item symptom-based predictor.

MAIN RESULTS

Overall response rate was 66%. The final study population consisted of 862 physicians, 941 nurses, 968 occupational therapists, and 879 respiratory therapists (n=3,650). Reported asthma was associated with medical instrument cleaning (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.34-3.67), general cleaning (OR, 2.02; 95% CI, 1.20-3.40), use of powdered latex gloves between 1992 and 2000 (OR, 2.17; 95% CI, 1.27-3.73), and administration of aerosolized medications (OR, 1.72; 95% CI, 1.05-2.83). The risk associated with latex glove use was not apparent after 2000. Bronchial hyperresponsiveness-related symptoms were associated with general cleaning (OR, 1.63; 95% CI, 1.21-2.19), aerosolized medication administration (OR, 1.40; 95% CI, 1.06-1.84), use of adhesives on patients (OR, 1.65; 95% CI, 1.22-2.24), and exposure to a chemical spill (OR, 2.02; 95% CI, 1.28-3.21).

CONCLUSIONS

The contribution of occupational exposures to asthma in health care professionals is not trivial, meriting both implementation of appropriate controls and further study.

Validation of an asthma questionnaire for use in healthcare workers

BACKGROUND

Previous studies have described increased occurrence of asthma among healthcare workers, but to our knowledge there are no validated survey questionnaires with which to study this occupational group.

AIMS

To develop, validate, and refine a new survey instrument on asthma for use in epidemiological studies of healthcare workers.

METHODS

An initial draft questionnaire, designed by a multidisciplinary team, used previously validated questions where possible; the occupational exposure section was developed by updating health services specific chemical lists through hospital walk-through surveys and review of material safety data sheets. A cross-sectional validation study was conducted in 118 non-smoking subjects, who also underwent bronchial challenge testing, an interview with an industrial hygienist, and measurement of specific IgE antibodies to common aeroallergens.

RESULTS

The final version consisted of 43 main questions in four sections. Time to completion of the questionnaire ranged from 13 to 25 minutes. Test-retest reliability of asthma and allergy items ranged from 75% to 94%, and internal consistency for these items was excellent (Cronbach's alpha > or = 0.86). Against methacholine challenge, an eight item combination of asthma related symptoms had a sensitivity of 71% and specificity of 70%; against a physician diagnosis of asthma, this same combination showed a sensitivity of 79% and specificity of 98%. Agreement between self-reported exposures and industrial hygienist review was similar to previous studies and only moderate, indicating the need to incorporate more reliable methods of exposure assessment. Against the aerollergen panel, the best combinations of sensitivity and specificity were obtained for a history of allergies to dust, dust mite, and animals.

CONCLUSIONS

Initial evaluation of this new questionnaire indicates good validity and reliability, and further field testing and cross-validation in a larger healthcare worker population is in progress. The need for development of more reliable occupational exposure assessment methods that go beyond self-report is underscored.

Characterization and geographic location of sources of radioactivity lost downhole in the course of oil and gas exploration and production activities in Texas, 1956 to 2001

Case reports describing sources of radioactivity lost downhole in Texas from 1956 to 2001 were obtained from the Texas Department of Health Bureau of Radiation Control and entered into a computerized database. The events of the 45-y period of analysis were characterized, examining aspects such as source type, amount of activity, location of loss, depth, and date of occurrence. Results of the study found that 316 downhole source incidents were reported to the agency during this period of time, representing a total of 426 distinct sources of radioactivity lost downhole within the boundaries of the State of Texas. The sources lost were predominantly AmBe, accounting for 74 TBq of radioactivity at the time of loss, and Cs, accounting for 16.3 TBq of radioactivity. A longitudinal analysis of the data showed the average loss per active oil and gas rig in Texas (known as "rig count") at approximately 24 losses per 1,000 rigs. Specific geographic information was largely missing from many of the records, which prevented the geolocation of wells described to contain lost radioactive sources. As a result, most wells could only be located to the county level, and no comprehensive geographical information system (GIS) map could be accurately created from the data. However, when available, source location information was standardized to permit the characterization of the sources reported as lost. This effort produced the first dedicated compendium of lost downhole sources for the State of Texas and provides an important source of information for regulatory agencies. The ability to provide prompt information about the fate and location of sources of radioactivity is important to regulatory officials, given the recent concerns about radiation source inventory control in the post 9/11 world as it relates to the possible creation of radiological dispersal devices.

Wood dust exposure and the association with lung cancer risk

BACKGROUND

Wood dust was designated as a human carcinogen based on increased sinus and nasal cancer rates among exposed workers. However, data on an association with lung cancer have been inconclusive.

METHODS

Self-reported wood dust exposure was compared between 1,368 lung cancer patients and 1,192 cancer-free adults, in a lung cancer case-control study. Epidemiological information was collected through a detailed personal interview.

RESULTS

Using several definitions of wood dust exposure we consistently observed statistically significant elevated adjusted risk estimates; for example, the adjusted odds ratio (OR) for combined wood dust related occupations and industries was 3.15 (95% confidence intervals (CI) 1.45-6.86) and for an overall summary exposure measure it was 1.60 (95% CI 1.19-2.14). The association was maintained when stratified by histopathological type. Among those exposed to cigarette smoke and wood dust, 21% of the cases were attributable to biologic interaction.

CONCLUSIONS

Wood dust exposure is a potential risk factor for lung cancer.

Occupational exposures associated with work-related asthma and work-related wheezing among U.S. workers

BACKGROUND

National estimates of occupational asthma (OA) in the United States are sparse.

METHODS

Using data from the Third National Health and Nutrition Examination Survey (NHANES III) 1988-1994, we analyzed associations between occupation and work-related asthma and work-related wheezing among U.S. workers.

RESULTS

This study identified several occupations that were at risk of developing work-related asthma and/or wheezing, with cleaners and equipment cleaners showing the highest risks. Other major occupations identified were farm and agriculture; entertainment; protective services; construction; mechanics and repairers; textile; fabricators and assemblers; other transportation and material moving occupations; freight, stock, and material movers; and motor vehicle operators. The population attributable risks for work-related asthma and work-related wheezing were 26% and 27%, respectively.

CONCLUSIONS

This study adds evidence to the literature that identifies work-related asthma as an important public health problem. Several occupations are targeted for additional evaluation and study. Of particular interest are cleaners, which are being increasingly reported as a risk group for asthma. Future intervention strategies need to be developed for effective control and prevention of asthma in the workplace.

Prevalence and risk factors of asthma and wheezing among US adults: an analysis of the NHANES III data

The prevalence of asthma has been on the increase in the USA and worldwide. To understand the worsening epidemiological trends of asthma, this study analysed the data from the third National Health and Nutrition Examination Survey (NHANES III) to determine the prevalence and risk factors for asthma and wheezing among US adults. This analysis used data from 18,825 US adults aged > or = 20 yrs who had participated in the NHANES III project. After excluding subjects with physician-diagnosed emphysema, a total of 18,393 subjects were included in the final analysis. The prevalence of current asthma (asthma) was 4.5% and the prevalence of wheezing in the previous 12 months (wheezing) was 16.4%. Mexican-Americans exhibited the lowest prevalence of asthma when compared with other race/ethnic groups. Multiple logistic regression analysis showed that Mexican-Americans were less likely to report asthma when compared to non-Hispanic whites. Low education level, female sex, current and past smoking status, pet ownership, lifetime diagnosis of physician-diagnosed hay fever and obesity were all significantly associated with asthma and/or wheezing. No significant effect of indoor air pollutants, as derived from the use of household heating/cooking appliances, on asthma and wheezing was observed in this study. In conclusion, this study observed racial/ethnic differences in the prevalence of asthma and wheezing and identified several important risk factors that may contribute to development and/or exacerbation of asthma and wheezing. Contrary to earlier reports, the proxy measures of indoor air pollution used in this study were not found to be associated with increased risk of asthma and wheezing.

Prevalence and risk factors of work related asthma by industry among United States workers: data from the third national health and nutrition examination survey (1988-94)

OBJECTIVES

To estimate the prevalence of work related asthma and work related wheezing in United States workers. To identify high risk industries that could be targeted for future intervention. To determine the population attributable risk of work related asthma and work related wheezing.

METHODS

The third national health and nutrition examination survey, 1988-1994 (NHANES III) was analyzed to determine the prevalence of work related asthma and wheezing and to identify initially defined industries at risk among United States workers aged 20 and older. Separate logistic models were developed with work related asthma and work related wheezing as outcomes. Work related asthma was defined as affirmative response to questions on self reported physician diagnosed asthma and work related symptoms of rhinitis, conjunctivitis, and asthma. Work related wheezing was defined as affirmative response to questions on self reported wheezing or whistling in the chest in the previous 12 months and work related symptoms of rhinitis, conjunctivitis, and asthma. All analyses were adjusted for age, sex, smoking, and atopy.

RESULTS

The prevalence of work related asthma was 3.70% (95% confidence interval (95% CI) 2.88 to 4.52) and the prevalence of work related wheezing was 11.46% (95% CI 9.87 to 13.05). The main industries identified at risk of work related asthma and wheeze included the entertainment industry; agriculture, forestry, and fishing; construction; electrical machinery; repair services; and lodging places. The population attributable risk for work related asthma was 36.5% and work related wheezing was 28.5%.

CONCLUSIONS

The findings provide impetus for further research and actions by public health professionals which prioritise occupational asthma on the public health agenda. Future intervention strategies need to be developed for effective control and prevention of asthma in the workplace.

A myeloperoxidase polymorphism associated with reduced risk of lung cancer

Myeloperoxidase (MPO) is a metabolic/oxidative enzyme found in neutrophils and monocytes that contributes to pulmonary carcinogenesis through activation of specific procarcinogens including benzo[a]pyrene intermediates, 4-aminobiphenyl and the arylamines. There is a G-->A polymorphism located in the 5' untranslated region of the MPO gene that may be responsible for reduced transcriptional activity due to the decreased binding affinity for the SP1 transcription factor. Individuals with one or two copies of the A-allele may be afforded protection due to decreased transcriptional activity of MPO and subsequent decreased metabolic activation of procarcinogens. Previous studies have reported a range of protective effects in different ethnic populations. We employed a restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) assay to identify the MPO genotypes in 375 lung cancer cases and 378 healthy controls, all of whom were Caucasian. Our results demonstrate a reduced risk of lung cancer when the A-allele genotypes (G/A+A/A) were combined (odds ratio (OR)=0.66; 95% confidence interval (CI) 0.49-0.90). We also noted a protective effect (OR=0.63; 95% CI 0.45-0.87) in ever smokers with the A-allele genotypes which was not evident in never smokers (OR=1.14; 95% CI 0.42-3.11). We observed an incremental decrease in the protective effects as cigarette pack-years increased. Thus, lightest smokers were provided the greatest protection. When the data were stratified by gender, there was a statistically significant reduced risk of lung cancer among men (OR=0.55; 95% CI 0.36-0.84), but not among women (OR=0.81; 95% CI 0.55-1.26) for the A-allele genotypes. Lastly, an age effect was evident only in men but not women. The protective effects of the A-allele genotypes decreased with increasing age. This report provides further support for the hypothesis that a single nucleotide polymorphism in the MPO gene is a protective factor in lung cancer carcinogenesis.

Association between asbestos exposure, cigarette smoking, myeloperoxidase (MPO) genotypes, and lung cancer risk

BACKGROUND

As observed in tobacco-associated carcinogenesis, genetic factors such as the polymorphic metabolic/oxidative enzyme myeloperoxidase (MPO) could modulate individual susceptibility to asbestos-associated carcinogenesis.

METHODS

RFLP-PCR analysis identified the MPO genotypes in 375 Caucasian lung cancer cases and 378 matched controls. An epidemiological interview elicited detailed information regarding smoking history and occupational history and exposures.

RESULTS

Asbestos exposure was associated with a significantly elevated risk estimate (OR = 1.45; 95% CI 1.04-2.02). On stratified analysis, we found the MPO genotypes modified the effect of asbestos exposure on lung cancer risk. Specifically, G/G carriers who were exposed to asbestos had an odds ratio (OR) of 1.72 (95% CI; 1.09-2.66), while A-allele carriers (G/A + A/A) exposed to asbestos exhibited a reduced OR of 0.89 (95% CI; 0.56-1.44). The OR was further reduced to 0.73 (0.49-1.06) for A-allele carriers not exposed to asbestos. A similar trend was observed for the joint effects between the MPO genotypes and pack-years smoking. Next, all three risk factors (MPO genotypes, asbestos exposure, and smoking) were analyzed simultaneously for joint effects. Heavy smokers with the G/G genotype and a history of asbestos exposure demonstrated a statistically significant elevated risk estimate (OR = 2.19; 95% CI 1.16-4.11), while the A-allele carriers with the same exposure profile were at a lower risk for lung cancer (OR = 1.18; 95% CI 0.58-2.38). The A-allele genotypes demonstrated similar protective effects for the other three exposure profiles.

CONCLUSIONS

For a similar level of exposure to established carcinogens, individuals with the MPO A-allele genotypes appear to have a reduced risk of lung cancer.

Environmental allergens and irritants in schools: a focus on asthma

As part of the Partners in School Asthma Management Program, environmental data were collected from 385 rooms in 60 elementary schools in southeast Texas, using an Environmental Observation Checklist and a Q-TRAK Indoor Air Quality Monitor. Dust samples for allergen analysis were collected from floors, carpets, and area rugs in 80 classrooms in a subset of 20 schools. CO2 levels > 1,000 ppm were found in 86% of rooms; 69% had indoor humidity above recommended levels. Der p I dust mite allergen levels > 2,000 ng/g were present in 20% of rooms, but only 2.5% of rooms had Der f I mite allergen levels exceeding recommended tolerances. Detectable levels of cockroach allergen (Bla g II) were found in all schools (median 5.5 ng/g), with 10% of rooms over the recommended threshold. Almost two-thirds of classrooms had mold spore counts > 10,000 col/g (median, 14,400 col/g; range, 2,000-52,000 col/g).

Survey of the Asp f 1 allergen in office environments

Sick Building Syndrome remains a prevalent problem with patient complaints similar to typical allergy symptoms. Unlike household allergens typically found in domestic reservoirs, the allergen from a common fungus like Aspergillus fumigatus (i.e., Asp f 1) is conceivably widespread in the work environment. This project surveyed airborne levels of the Asp f 1 allergen in office and non-industrial occupational environments, as well as the dust reservoirs of A. fumigatus believed to be responsible for those levels. Airborne and bulk dust samples were collected, extracted, and assayed for Asp f 1. Concurrently, bulk dusts collected from the same locations were selectively cultured for A. fumigatus, and mesophilic fungi and bacteria. Samples were collected during both wet and dry climatological conditions from paired wet and dry building locations to examine the possibility of Asp f 1 increases due to fungal growth blooms. Very low levels of Asp f 1 were detected but only in the airborne samples (2/120 positive samples, with 3.6 ng/m3 and 1.8 ng/m3; LOD < 1.2 ng/m3). No dust samples showed even detectable traces of the allergen (LOD = 5 ng/g dust). Although A. fumigatus counts from dusts fluctuated significantly with exterior moisture events, analysis of wet versus dry period samples showed no differences in Asp f 1 levels. These results indicate that even in the presence of measurable fungal concentrations, background levels of Asp f 1 are low. Nonindustrial office buildings devoid of indoor air quality issues were not observed to have significant levels of the Asp f 1 allergen in the geographical region studied.

A system linking occupation history questionnaire data and magnetic field monitoring data

A method is presented which links on-site electromagnetic field monitoring data with pre-existing work history data. The linkage is used to estimate cumulative and average annualized magnetic field exposure for a case-control study. On-site electromagnetic field monitoring data for 1,966 volunteer utility employees, at 59 sites in the United States and three other countries, were obtained from a large project (the EMDEX project) designed to collect, analyze, and document 60-Hz electric and magnetic field exposures for a diverse population. These data represent 9 primary work environments, and 16 job classification categories, amounting to 144 unique job categories which were consolidated using the job-exposure matrix presented into 282 three-digit Dictionary of Occupational Title (DOT) codes. The DOT code categories were then linked to lifetime occupational histories from a case-control study of leukemia. The method may be extended to link additional job titles with monitoring information. Job titles linked with electromagnetic field monitoring information provide more specific estimates of exposure intensity than previous ordinal estimates of exposure. Therefore, estimates of cumulative electromagnetic field exposure are achievable, as well as high and low level exposure estimates.

The influence of task and location on solvent exposures in a printing plant

A work measurement technique was used to monitor the activities of seven printing press operators. Repeated observations were made to learn workers' tasks and workers' locations in the plant, and a photoionization detector was used to measure the instantaneous solvent concentration in each worker's breathing zone. Location data, analyzed using a computer aided design system, did not show any indication that there were high or low exposure areas. Regression, however, showed that a significant amount of variability in a worker's exposures was accounted for by the number of times the worker performed a certain "hazardous task" (r2 = 0.57). The results indicate that it may be possible to simplify industrial hygiene sampling strategies by using work measurement data, such as time study or work sampling, to identify maximum risk employees.

Respiratory symptoms associated with the use of azodicarbonamide foaming agent in a plastics injection molding facility

Respiratory health variables were studied cross-sectionally in 227 employees of a plastics molding facility where numerous complaints had been apparently associated with the use of azodicarbonamide foaming agent in injection molding. Pre- and postshift respiratory status measures and azodicarbonamide concentrations were also obtained for 17 employees. Cross-sectional pulmonary function differences by injection molding status were not observed. Modest decrements in pulmonary function measures were observed between start and end of shift but with no dose-effect relationship. A strong association was observed for injection molding workers for eye/nose/throat irritation, cough, and wheezing. Additionally, wheezing, chest tightness, and symptoms of chronic bronchitis were strongly associated with work in injection molding during periods in which azodicarbonamide was in use. These results suggest respiratory symptom causation by some combination of azodicarbonamide itself, reaction products of azodicarbonamide formed during injection molding, or other unidentified agents uniquely associated with the process of injection molding with azodicarbonamide foaming agent.

Potential exposure to metal fumes, particulates, and organic vapors during radiotherapy shielding block fabrication

The shielding-block fabrication areas of three hospitals were surveyed to assess inhalation exposure to lead (Pb), cadmium (Cd), bismuth (Bi), and tin (Sn) fumes, as well as styrene and methyl chloride vapors. Area and personal breathing zone samples were collected for various steps in the block fabrication process. Only 3 of 16 air samples for metals resulted in detectable levels of Pb and/or Cd. The levels were well below the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limits, excluding a sample which contained a visible metal fragment. Bi and Sn were not detected in any samples. Methyl chloride and styrene vapors were not detected in any air samples during foam cutting procedures. Total particulates (TP) were measurable in 11 of 17 air samples (ranging from 0.01 to 2.1 mg/m3). TP values were below the OSHA federal standard for nuisance particulates, which is 15 mg/m3. The data suggest that the materials and procedures sampled do not present an inhalation hazard to employees who construct shielding blocks. Precautions should, however, be exercised to prevent exposure under extreme procedural conditions such as soldering or overheating of alloy, and by other means such as ingestion. Care should also be taken during cleanup or housekeeping to prevent re-entrainment into the work atmosphere of mechanically generated metal particles or materials condensed within melting pots (which may be high in metal content).

Behavioural evaluation of workers exposed to mixtures of organic solvents

Reports from Scandinavia have suggested behavioural impairment among long term workers exposed to solvents below regulatory standards. A cross sectional study of behavioural performance was conducted among printers and spray painters exposed to mixtures of organic solvents to replicate the Scandinavian studies and to examine dose-response relationships. Eligible subjects consisted of 640 hourly workers from four midwestern United States companies. Of these, 269 responded to requests to participate and 240 were selected for study based on restrictions for age, sex, education, and other potentially confounding variables. The subjects tested had been employed on average for six years. Each subject completed an occupational history, underwent a medical examination, and completed a battery of behavioural tests. These included the Fitts law psychomotor task, the Stroop colour-word test, the Sternberg short term memory scanning test, the short term memory span test, and the continuous recognition memory test. Solvent exposure for each subject was defined as an exposed or non-exposed category based on a plant industrial hygiene walk-through and the concentration of solvents based on an analysis of full shift personal air samples by gas chromatography. The first definition was used to maintain consistency with Scandinavian studies, but the second was considered to be more accurate. The average full shift solvent concentration was 302 ppm for the printing plant workers and 6-13 ppm for the workers at other plants. Isopropanol and hexane were the major components, compared with toluene in Scandinavian studies. Performance on behavioural tests was analysed using multiple linear regression with solvent concentration as an independent variable. Other relevant demographic variables were also considered for inclusion. No significant (p greater than 0.05) relation between solvent concentration and impairment on any of the 10 behavioural variables was observed after controlling for confounding variables. Exposed/non-exposed comparisons showed a significantly poorer digit span among those exposed, but this has not been generally reported in the Scandinavian studies. The medical examination showed no abnormalities of clinical significance. The inability to replicate the findings of the Scandinavian studies could have been due to the shortness of the duration of workers' exposure, the type of solvents in the mixtures, use of different behavioural tests, or to selection factors.

Computerized spirometry using a portable microcomputer

The reliable conduct of pulmonary function studies, while in the field, is increasingly important as various standards mandate this activity. Versatile, portable and accurate equipment is required. A lightweight and computerized portable spirometer system is discussed, PSPIRO, which uses a standard volumetric spirometer and a briefcase-sized microcomputer. The system, compact enough to be easily moveable by one person, performs tests for FVC, FEV(1), FEV(3), the percentage of predicted pulmonary function for each, and the ratio of FEV(1)/FVC. Back extrapolation is used to establish the start of each forced expiratory maneuver, reproducibility checks are performed, and accuracy is within acceptable epidemiologic standards. A small, portable analog to digital interface (PLAD) was developed for performing A/D conversions through the RS-232C port of the portable microcomputer.

Solvent vapor exposures in booth spray painting and spray glueing, and associated operations

Time-weighted average exposures for all solvents present at detectable levels were obtained for eighty-nine solvent-using workers and thirty-six control-group (unexposed) workers in seven plants of three companies applying paints and glues, primarily by spraying. Over twenty solvents were quantified if detected. Concentrations of specific solvents and cumulative fractions of TLVs were measured for various job types. All spray painting and most spray glueing was conducted in operating spray booths. Only low to moderate exposures were observed, with one TWA exceeding the cumulative TLV and three additional TWAs exceeding 50 percent of the cumulative TLV. It may be concluded that solvent TWA exposures in spraying of paints and glues are often well-controlled by common spray booths, and further, that other solvent-use operations including light-duty solvent wiping and manual paint mixing do not frequently produce high exposures (relative to TLV levels) in the presence of ordinary general room ventilation.

Health effects of wood dust--relevance for an occupational standard

Wood dust is coming under increasing scrutiny as an industrial exposure posing greater risk than that of a nuisance dust. In light of this increased interest, this paper will review key reports of wood dust-related health effects, and will summarize the available information which relates exposure levels to effects. Numerous case reports exist of skin reactions and obstructive-pattern respiratory changes of either a hypersensitivity or irritant nature for various woods. Reports have also been published of apparently non-allergic obstructive respiratory effects including lung function test reductions and reduction of mucociliary clearance. Wood dust exposure also appears to be linked to the occurrence of adenocarcinoma of the nasal sinuses. Occasional reports link wood dust to other types of cancer, but these relationships are much less consistent than the association with nasal cancer. Various standards have been proposed for wood dust. Most are lower than the nuisance dust standard currently applicable in the U.S. This review of several key papers on wood dust permits some association of exposure data and effects, particularly with suppressed mucociliary clearance, from which it may be suggested from the available evidence that a standard of 2 mg/m3 total suspended wood dust, not differentiated by type of wood, would protect against observed effects except for extreme allergic hypersensitivity.

Pulmonary function status of workers exposed to hardwood or pine dust

Wood dusts may have substantial health impacts beyond those of nuisance dust. This project reports results linking pulmonary function changes with exposure to maple and pine dust. A cross-sectional survey of 1157 woodworkers was conducted in 1978 in accordance with NHLBI standards for respiratory epidemiologic surveys. Area dust levels were determined, permitting definition of groups exposed to estimated high, medium or low cumulative levels of dry hardwood or softwood dust. Prevalence of reduced (lower fifth percentile of normal) pulmonary function was ascertained, using prediction equations, for Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1), FEV1/FVC and Maximal Mid-expiratory Flow Rate (MMEFR). Relationships between pulmonary impairment and dust exposure were examined, adjusting for smoking status by means of the log odds ratio method. The results support an association between dry hardwood or softwood dust exposure and reduced pulmonary flow rates. The odds ratios for reduced pulmonary function, comparing low and high hardwood (maple) dust exposure, were 3.12 for FEV1/FVC and 2.14 for MMEFR. Comparing low and medium hardwood exposure, the odds ratios were 2.61 for FEV1/FVC and MMEFR. Comparison of low and high softwood (pine) dust exposure yielded odds ratios of 4.03 for FEV1/FVC and 2.45 for MMEFR. The ratios noted are significant at p less than .05.