Comparison of two floor mat lead dust collection methods and their application in pre-1950 and new urban houses.

This study investigated commercial floor mats as an alternative method to assess lead in residential dust in inner-city houses. Mats were placed for 3 weeks in interior entry-ways of 34 row houses built before 1950 and 17 new row houses in Baltimore City. A high volume sampler (an HVS3 floor model cyclone-based vacuum) and a hand-held portable cyclone sampler were used in the laboratory to collect side-by-side samples of mat dust. Both devices yielded comparable estimates of lead dust deposition, dust lead concentration, and dust deposition on field mat samples and had similar sampling efficiencies on mats spiked with various types of standard reference materials. The older houses had significantly higher daily lead dust deposition (mean = 130 micrograms/ft2/day by HVS3) than the newer houses (mean = 9 micrograms/ft2/day by HVS3), due to higher dust lead concentrations (mean = 1149 ppm vs mean = 107 ppm by HVS3) and not to differences in daily dust deposition (mean = 118 mg/ft2/day vs mean = 87 mg/ft2/day by HVS3) [corrected]. Mats were found to be a feasible method for the collection of dust that has accumulated for a known amount of time. Current wipe and vacuum methods do not allow for the estimation of dust deposition rates. Further research is needed to understand the role of floor mats as a risk assessment tool.

US Army Chemical Corps Vietnam veterans health study: preliminary results.

The long-term health consequences of exposure to phenoxyherbicides used in Vietnam has been a great concern to the veterans. In addition to the Air Force Ranch Hand personnel, Army Chemical Corps personnel who served in Vietnam are thought to have had some of the highest herbicide exposures. The Department of Veterans Affairs commenced a study of veterans who served in Vietnam as members of the Army Chemical Corps and a comparison cohort of Army Chemical Corps personnel who served elsewhere. A total of 2872 Vietnam veterans and 2737 non-Vietnam veterans who served in the Army Chemical Corps were identified for inclusion in a telephone health interview survey with a random 20% sample of veterans receiving serum dioxin and other congeners assessments. In a feasibility study which included 284 Vietnam veterans and 281 non-Vietnam veterans, 100 serum assessments were conducted of which 95 were included in the analysis. Vietnam veterans with a history of spraying herbicides were found to have a statistically significant elevation in their current serum 2,3,7,8-TCDD concentrations compared to non-Vietnam veterans without a spray history (P = 0.05). Other 2,3,7,8-substituted dioxins levels were comparable to the levels found in the non-Vietnam veterans. This feasibility study demonstrated that serum dioxin concentrations from a sample of the study participants can be used to identify exposure variables in the health survey that can serve as a surrogate measure of phenoxyherbicide exposure.

End-user exposures to synthetic vitreous fibers: II. Fabrication and installation fabrication of commercial products.

This article summarizes the results of exposure monitoring conducted during the installation and fabrication of commercial synthetic vitreous fiber (SVF) products. Included in this investigation were fiberglass duct insulation and construction applications (duct board, duct liner, and duct wrap), pipe and vessel insulation, batt insulation for prefabricated homes, and general fiberglass products. Commercial mineral wool products sampled as a part of this investigation included ceiling tiles, building safing, and loose insulation for prefabricated homes. A total of 520 valid air samples were collected as a part of this investigation and were analyzed using gravimetric, phase contrast microscopy (PCM), or scanning electron microscopy (SEM). Airborne fiber-size distributions were also determined for a subset of samples collected for SEM analysis. As a result of the task-based sampling strategy used in this study, sample times reflect exposures over the time the person was actually engaged in SVF-related work activities, and exposure results are therefore presented as task-length averages (TLAs). Thirty-five total dust samples were collected as a part of this investigation, resulting in 14 TLAs ranging from 0.3 to 7.6 mg/m3. A total of 125 PCM-based TLAs were collected, with the mean TLA time for all product and occupation categories ranging from 277 to 443 minutes. The mean PCM-based TLAs for all product/occupations were below 1.0 f/cm3, ranging from 0.04 to 0.68 f/cm3. A total of 116 SEM TLAs were determined. Average SEM-based TLA concentrations were slightly lower than the PCM-based estimates and ranged from <0.01 to 0.16 f/cm3. The geometric mean fiber diameters for commercial products and occupations sampled as a part of the investigation ranged from 0.8 microm to 1.9 microm. Geometric mean fiber length varied by a factor of approximately three, ranging from 9.5 microm to 29.5 microm.

Time trends in exposure measurements from OSHA compliance inspections of the pulp and paper industry.

Time trends in employee exposures to the air contaminants measured by the Occupational Safety and Health Administration (OSHA) during compliance inspections of pulp and paper manufacturing facilities conducted between 1979 and 1997 were evaluated based on the measurement results stored in the OSHA Integrated Management Information System (IMIS) database. The IMIS database is among the largest sources of occupational exposure measurements available for occupational health research in the United States. The IMIS database contains the results of 3,568 personal time-weighted average (TWA) measurements for 171 air contaminants made at 524 establishments in Standard Industrial Classification (SIC) 26. An analysis of these measurements revealed an overall decrease in the total number of measurements made per year since 1991, and a decrease in the percentage of measurements by year that exceeded the OSHA permissible exposure limits (PELs). Linear regression analyses detected decreasing trends in the geometric mean concentrations by year for 33 of the 36 agents analyzed.

Case-control study of intracranial tumors among employees at a petrochemical research facility.

This case-control study evaluated the relation between potential exposure to chemical and physical agents and the occurrence of intracranial tumors among employees at a petrochemical research facility. Cases were employees with glioma (n = 6) or benign intracranial tumors (n = 6). Controls (n = 119) were individually matched to cases on gender and birth year, and they were alive and did not have an intracranial tumor at the case's diagnosis date. Exposure information came from interviews with subjects or surrogates and from corporate records on agents used in research projects. Analyses computed matched odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for self-reported exposure to 15 agents and project-based estimates of exposure to 29 agents. For gliomas, the OR was elevated for self-reported exposure to ionizing radiation (OR, 15.7; CI, 1.4 to 179.4), n-hexane (OR, infinity; CI, 1.4 to infinity), organometallics (OR, 9.4; CI, 1.5 to 59.7), and amines other than nitrosamines (OR, 6.0; CI, 1.0 to 35.7). The OR also was elevated for project-based potential use of ionizing radiation (OR, 9.6; CI, 1.7 to 55.2) and for potential use of n-hexane lasting at least 4 years (OR, 16.2; CI, 1.1 to 227.6). For benign intracranial tumors, the OR was elevated only for self-reported exposure to ionizing radiation (OR, 5.4; CI, 1.7 to 43.1) and other amines (OR, 5.2; CI, 0.9 to 29.5). Occupational exposure may have contributed to the glioma excess, but the specific causal agents remain unknown. The study indicated that benign intracranial tumors were unlikely to be work-related.

Lung cancer among workers in chromium chemical production.

BACKGROUND: An elevated risk of lung cancer among workers in chromate production facilities has previously been reported. This excess risk is believed to be the result of exposure to hexavalent chromium. There have been mixed reports about whether trivalent chromium exposure is also associated with an excess lung cancer risk. Previous studies of measured hexavalent chromium exposure and lung cancer risk have not examined cigarette smoking as a risk factor. METHODS: A cohort of 2,357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Vital status of the workers was followed until December 31, 1992. Work histories of cohort members were compiled from the beginning of employment through 1985, the year the plant closed. Annual average exposure estimates, based on historical exposure measurements, were made for each job title in the plant for the years 1950-1985. These exposure estimates were used to calculate the cumulative hexavalent chromium exposure of each member of the study population. Following closure of the plant, settled dust samples were collected and analyzed for hexavalent and trivalent chromium. The trivalent/hexavalent concentration ratios in each plant area were combined with historic air-sampling data to estimate cumulative trivalent chromium exposure for each individual in the study cohort. Smoking status (yes/no) as of the beginning of employment and clinical signs of potential chromium irritation were identified from company records. RESULTS: Cumulative hexavalent chromium exposure showed a strong dose-response relationship for lung cancer. Clinical signs of irritation, cumulative trivalent chromium exposure, and duration of work were not found to be associated with a risk of lung cancer when included in a proportional hazards model with cumulative hexavalent chromium exposure and smoking. Age-specific data on cumulative hexavalent chromium exposure, observed and expected numbers of lung cancer cases, and person-years of observation are provided. CONCLUSIONS: Cumulative hexavalent chromium exposure was associated with an increased lung cancer risk; cumulative trivalent chromium exposure was not. The excess risk of lung cancer associated with cumulative hexavalent chromium exposure was not confounded by smoking status. The current study offers the best quantitative evidence to date of the relationship between hexavalent chromium exposure and lung cancer. Am. J. Ind. Med. 38:115-126, 2000. Published 2000 Wiley-Liss, Inc.

Clinical findings of irritation among chromium chemical production workers.

BACKGROUND: Several reports of workers in chromate production and chromeplating have indicated that exposure to hexavalent chromium is associated with skin and nasal irritation. METHODS: A cohort of 2, 357 workers first employed between 1950 and 1974 at a chromate production plant was identified. Clinical findings of irritation were identified by a physician as a result of routine examinations or visits to the medical clinic by members of the cohort. Percentages of the cohort with various clinical findings, the time from hire to occurrence of the first finding, and the mean and median annual hexavalent chromium (measured as CrO(3)) concentration for the job title where the clinical finding first occurred were determined. A proportional hazards model was used to evaluate the relationship between hexavalent chromium exposure and first occurrence of each of the clinical findings. RESULTS: Nasal irritation and nasal ulceration were the most common clinical findings reported, occurring in more than 60% of the cohort. The average time to first occurrence of these findings was less than 3 months, whereas the time to first occurrence of the other findings ranged from 10 to 22 months. Median exposure to hexavalent chromium at the time of occurrence for most of the findings was about 20 microg/m(3). The proportional hazards model indicated that ulcerated nasal septum, irritated skin, and perforated eardrum were significantly associated with ambient hexavalent chromium exposure; all clinical findings with the exception of conjunctivitis and irritated skin were associated with the calendar year of hire, with the risk being lower as the calendar year of hire became more recent. Annual average ambient hexavalent chromium concentrations generally dropped in the plant over the period of the study. CONCLUSIONS: Workers in the chromate production plant in this study experienced a variety of nasal and skin irritations. Irritated and ulcerated nasal septa, in particular, were quite common clinical findings, occurring in over 60% of the cohort, and they occurred in relatively short periods of time-less than 3 months from date of hire. Annual average concentrations of chromium may not be a good predictor of clinical findings of irritation. Am. J. Ind. Med. 38:127-131, 2000. Published 2000 Wiley-Liss, Inc.

Case-series investigation of intracranial neoplasms at a petrochemical research facility.

BACKGROUND: From 1970 through 1997, 17 intracranial neoplasms were identified among 6,800 employees of a petrochemical research facility. This investigation describes the case-series. METHODS: The intracranial neoplasms were identified by self reports and record linkages, and were confirmed by medical records and a pathology review. Standardized incidence ratios (SIRs) compare observed and expected numbers of cases according to certain work characteristics. RESULTS: Overall, there were 17 observed and 10.5 expected intracranial neoplasms, including 11/4.7 benign intracranial tumors and 6/5.9 brain cancers. All brain cancers occurred among male research scientists or technicians. Four had worked at some time on the same floor of one building (SIR=12.6, 95% CI=3.4-32.1), and several had worked on a research project with at least one other brain cancer case. The benign intracranial neoplasm cases did not have common building assignments or work activities. CONCLUSIONS: The occurrence pattern of brain cancers, but not that of benign tumors, suggests a possible occupational etiology.

Factors affecting the retention of dust mite allergen on carpet.

Carpeting is one of the most common and perhaps the most important reservoir of aeroallergens and other components of dust found in residential or commercial settings. This research evaluated factors that affect the retention of dust mite allergens on different types of tufted carpet commonly found in homes and offices. Twenty-six types of carpet were custom manufactured as part of a two-stage factorial experiment using 182 carpet samples. Carpets differed with respect to fiber denier, cross-sectional shape, presence of fluorocarbon treatment, carpet style, pile height, and pile density. The major hypothesis tested was that the amount of allergen-containing dust recovered from vacuum samples of tufted carpet sources was dependent on micro (fiber) or macro (construction) retention characteristics of the carpets. Carpet samples were doped in a uniform and reproducible manner using an allergen-containing reference dust. A standardized vacuum surface sampler was used to recover dust from samples. Allergen was assayed using a standard, monoclonal antibody ELISA. Carpet-surface area and presence of fluorocarbon were found to have the largest effects on retention and recovery of dust and allergen. Specifically, fluorocarbon treatment of fibers, square-hollow fiber shape, high-denier fiber, low-pile height in cut-pile carpets, and low-pile density in loop carpets were significantly associated with increased release and recovery of allergen. Results from this study suggest that carpet type be considered for both allergen avoidance and allergy and asthma risk assessment.

Industry-wide study of mortality of pulp and paper mill workers.

A study of pulp and paper mill workers indicated low risks of death from all causes (standardized mortality ratio (SMR) = 0.74) and all cancers (SMR = 0.81) compared with U.S. rates. The leukemia death rate in workers was not higher than the U.S. rate but was higher than the rate in county populations surrounding mills. Workers whose last jobs were in the finishing areas of the mills had an elevated SMR for liver cancer. An internal comparison of occupational characteristics indicated that workers employed in mills using other chemical pulping operations had significantly elevated mortality from all causes, all cancers, heart disease, lymphomas, and brain cancers. Lung cancer mortality was elevated in mills using kraft pulping. The internal comparisons confirmed the association between work in finishing and the risk of liver cancer. This study was designed to investigate whether pulp and paper mill workers have any risks that would indicate the need for studies detailing exposures.

Evaluation of integrity of gloves used in a flow cytometry laboratory.

This study was conducted to evaluate the effect of normal use on latex glove integrity in a flow cytometry laboratory. The gloves were tested using the 1,000 microL water-tight test and met industrial standards (less than 4% leakage) before, but not after use. More durable gloves, or more frequent changes of gloves, may be needed to ensure adequate barrier protection for laboratory workers during routine procedures.

Quantification of historical exposures in occupational cohort studies.

Relatively few investigators have estimated quantitative exposure levels in epidemiologic studies, and, for those that have, few have discussed the strengths and weakness of their estimation method with respect to other methods. This paper reviews the steps for developing quantitative exposure estimates that have been used in published studies. First, the qualitative considerations to be evaluated in the selection of the agent to be estimated (i.e., the disease mechanism, the effects of exposure mixtures and interactions, the physical state of the agent, and the routes of exposures) are discussed. Considerations for developing exposure groups are then presented, including work history and exposure information characteristics, the homogeneity of exposures within exposure groups, the exposure estimation method, and the disease risk analyses to be performed. The various exposure estimation approaches are reviewed for their strengths and weaknesses, including the calculation of the mean exposures from existing exposure measurements, statistical models, measurement data from surrogate exposures, and professional judgment. Recommendations for future studies are provided.

Combustion products and other firefighter exposures.

The author examines a wide variety of substances, from smoke, to synthetic products, and even the products that are used to fight fires. Measurements of exposure are discussed for carbon dioxide, carbon monoxide, hydrogen chloride, hydrogen cyanide, formaldehyde, acetaldehyde, benzene, and other chemicals.

Investigation of a spontaneous abortion cluster: development of a risk communication plan.

A risk communication plan was developed for a group of payroll office workers who were investigated for a possible cluster of spontaneous abortions (SABs). Survey and focus group methods were used to assess the workers' attitudes, beliefs, and information preferences. We found that four features of the workforce needed to be considered in developing an effective plan: 1) subgroups of workers varied on their levels of concern, awareness, involvement, and definitions of the problem; 2) workers did not have the necessary knowledge concerning SABs or the scientific method to participate in a two-way communication; 3) workers were highly stressed; and 4) workers were distrustful that they would be told the truth about the SABs. A multicomponent risk communication strategy was developed to overcome these barriers. Specifically, we recommended that background information on SABs and the scientific method be presented before the report of the study results and that follow-up sessions should be conducted on job stress and the emotional aspects of miscarriages.

Comparison of a wipe and a vacuum collection method for the determination of lead in residential dusts.

Lead-containing house dust is an important source of childhood lead exposure. Standard methods for collection of settled dust for evaluation of lead content have not been established. Little is known about the relationships between the various wipe and vacuum-based methods employed in past studies, preventing meaningful comparisons of results. This study characterized the relationship between a frequently used wipe dust collection method and a vacuum-based in-line filter method used to collect dust in a national survey of lead in paint and dust in U.S. housing. The correlation coefficient was 0.82 for estimates of lead loadings (PbD, mg/m2) from 71 pairs of side-by-side wipe and vacuum dust samples collected from uncarpeted floors, window sills, and exterior window wells in six dwellings. Geometric mean (GM) wipe PbD estimates exceeded those for vacuum samples by a factor of 3.9 and 5.7 for floors and window sills, respectively, findings consistent with the multiple sources of sample loss associated with the vacuum sampler. For window wells, the GM vacuum PbD estimate exceeded the GM wipe PbD estimate by a factor of 3.4, possibly due to the use of an alternative vacuum nozzle. The resulting increase in the estimated prevalence of U.S. homes with elevated dust lead loadings had wipe-sampling instead of vacuum-sampling methods been used in the national survey is discussed.

Investigation of a spontaneous abortion cluster: lessons learned.

An investigation of a reported spontaneous abortion excess in an office environment was undertaken employing a multidisciplinary approach, including (1) an epidemiologic/validation step; (2) an industrial hygiene survey, including electromagnetic field measurements and indoor air quality determinations; and (3) a risk perception/risk communication component. This approach was needed because there are numerous chemical and physical agents and psychosocial stressors that may potentially impact the reproductive status of female office workers. Although video display terminals (VDTs) are typically the focus of spontaneous abortion (SAB) investigations, one cannot ignore other stressors in the environment. Magnetic field exposures within a payroll area were determined using a hand-held survey meter and data logging dosimeter. On average, the full shift time-weighted average exposures of workers to extremely low frequency (ELF) magnetic fields in the payroll office area ranged from 1.0 to 5.6 mG. Influencing the investigation's protocol design were the Centers for Disease Control's (CDC's) recent Guidelines for Investigating Clusters of Health Events. Although these guidelines grew primarily out of cancer cluster investigations, we applied them in this instance and found them to be generalizable to reproductive hazards investigations. A spontaneous abortion excess was validated over a 2-year period among 26 women with 32 reproductive events, with rates 1.5-2.5 times the expected, depending on comparison figures used. Lessons learned in the investigation, including the applicability of the CDC's Cluster Investigation Protocol and the enormous importance of risk perception and risk communication, are described.

ELF magnetic field exposures in an office environment.

Potential exposures to extremely low frequency (ELF) magnetic fields were investigated in response to worker concerns about an apparent increased spontaneous abortion risk in a payroll office environment. Concern in this office centered on the use of video display terminals (VDTs), which have been investigated as a potential cause of adverse reproductive outcomes among women. In this investigation, magnetic field sources were evaluated using a hand-held survey meter. Emdex datalogging dosimeters were also used to determine full shift personal exposures for 15 women working in the payroll area. On average, the exposures of workers to ELF magnetic fields in the payroll office area ranged from 1.0 to 6.5 mG with a mean of 3.2 +/- 1.5 mG. The results of this study indicate that many sources of ELF magnetic fields, including printers, photocopiers, and the electrical distribution system, can contribute to a worker's exposure in an office environment.

Exposure of hospital pharmacists and nurses to antineoplastic agents.

Adverse effects of antineoplastic drug exposure have been well documented in therapeutically treated patients and proposed as a potential hazard for occupationally exposed populations. Concern stems from accrued evidence of mutagenicity, carcinogenicity, and teratogenicity of many of these drugs. While the clinical significance of occupational exposure is controversial, OSHA issued handling guidelines for these agents in 1986, principally suggesting usage of a vertical laminar airflow biological safety cabinet and good work practices. Industrial hygiene measures of workplace antineoplastic exposure have been few and are limited to air sampling, addressing only the inhalation exposure route. We report here air and surface cyclophosphamide sampling results in a hospital oncology pharmacy and outpatient clinic where OSHA guidelines are in place. Results reveal rare air samples with detectable cyclophosphamide, but multiple surface wipe samples with measurable cyclophosphamide concentrations. Occupational health personnel, therefore, must consider work practices as determinants of surface contamination and recognize the potential importance of dermal and ingestion routes of exposure.

Chromium and disease: review of epidemiologic studies with particular reference to etiologic information provided by measures of exposure.

Dozens of epidemiologic studies have been conducted since the late 1940s in an attempt to elucidate the relationship between exposure to chromium compounds and increased rates of certain cancers observed in several industries. The relationship between employment in industries producing chromium compounds from chromite ore and lung cancer has been well established in numerous studies. The relationship between exposure to certain chromium-based pigments and chromic acid and lung cancer, although not as strong, is fairly well accepted. The data concerning emissions from stainless-steel manufacturing and disease are contradictory. Although individual studies have indicated excesses of gastrointestinal and occasionally other cancers in these industries, results are not consistent and not universally accepted. There is general agreement that chromite ore does not have an associated risk of cancer. Although the chromium compound (or compounds) responsible for disease have yet to be identified, there is general agreement that hexavalent species are responsible for these diseases and that the trivalent species are not. Hypotheses about the carcinogenicity of specific chromium compounds generally relate to their solubility in body fluids. These hypotheses, however, have generally been produced as a result of toxicologic, not epidemiologic, investigation. Well-designed epidemiologic studies incorporating detailed assessments of worker exposures have the potential to help elucidate causality, identify specific carcinogenic compounds, and quantify risk in humans, eliminating the need to extrapolate from animal data. Although the need for exposure data crucial to this effort was identified in the earliest epidemiologic studies of chromium, such studies have not been conducted. As a result, little more is known today about the relationship between this chemical and disease in humans than was known 40 years ago.