Preparing for expected bioterrorism attacks

The threat of bioterrorism in the United States is increasing. Health professionals, especially "front-line" practitioners, must be able to recognize the potential for major impacts from a bioterrorism event. Although an effective attack could produce numbers of casualties equivalent to those resulting from a nuclear weapon, an unannounced attack would be unlikely to be recognized immediately. Health workers may be the first to recognize an attack. However, only limited assistance is available to aid local community medical organizations in planning for bioterrorism. Military medical personnel have had more experience in planning for terrorist activities than many of their civilian colleagues. Their experience may be invaluable to local civilian treatment facilities in developing practical plans to meet the unique aspects of bioterrorism. In addition to considering agent-specific medical problems and requirements, it is particularly important for plans to address command and control, communication, and coordination if the resultant response is to be effective.

External Practicum-Year Residency Training in Occupational and Environmental Medicine: the University of Pennsylvania Medical Center Program

We describe a competency-based training program that allows physicians employed full-time in occupational and environmental medicine to satisfy the supervised practicum year of training required by the American Board of Preventive Medicine (ABPM). The program is designed for trainees with greater clinical experience than the 1 clinical year required by the ABPM. To date, 25 physicians from clinic-based, academic, corporate, and government employment across most geographic regions of the United States have been admitted into the program. Most completed a master's in public health (MPH) in a distance-learning, on-job, on-campus, or executive program. The practicum-year training has been highly successful, as evidenced by improvements in resident self-assessment of competency, resident satisfaction with the training, faculty evaluation of resident performance, and success rate in the ABPM examination. The program has opened a new pathway for physicians making a mid-career shift to occupational and environmental medicine to obtain high-quality, in-depth education and board certification.

Characterization of publication rotogravure press emission rates and compositions

Emission compositions and rates were determined during production for a publication rotogravure press room at a large rotogravure printing company. The press room housed a single 4-color, 8-print-stand press, with an 84" paper web. Average press speed was 1800 feet per minute. Data were collected over a 2-day period and included measurements of ventilation, room area concentrations, duct exhaust compositions, amount and composition of inks used, and worker exposures. These data were used with mass balance models that were appropriate for the workspace. Toluene comprised more than 90 percent of the inks and solvents and accounted for more than 90 percent of the press emissions. Average toluene emissions during press operation and press off conditions were 222 kg/hr and 8-38 kg/hr, respectively. The uncontrolled toluene emission on the basis of printed paper throughput was 3 g/m2. Of the total toluene released, 90 percent was captured by the local exhaust ventilation. The measured control efficiency was much lower than the average efficiency of 97 percent for the month of the test reported by the plant. A mass balance model evaluation demonstrated that only the lower efficiency was consistent with measured room concentrations. Using the measured emission rates and actual monthly press on and press off conditions, the difference in efficiency for the plant (10 rotogravure presses) extrapolates to the additional release to the workspace and ambient environment of over 700 tons/yr of toluene.

Volatile organic compounds, polycyclic aromatic hydrocarbons and elements in the air of ten urban homes

Ten homes were monitored at regular intervals from June 1994 through April 1995 as part of a Public Health Assessment in Southeast Chicago for exposure to volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and elements. Simultaneous 24-h indoor and outdoor samples were collected. VOCs were and analyzed using USEPA Method TO-14 with Selected Ion Monitoring Mass Spectrometry (GC/MS). PAHs were analyzed using USEPA Method TO-13 with GC/MS. Elements were collected on quartz fiber filters and analyzed by Inductively Coupled Argon Plasma (ICP) spectroscopy or Graphite Furnace Atomic Absorption (GFAA). Continuous measurements of CO2 and temperature were recorded for each indoor sample. Twenty-four h total CO2 emissions were determined from occupancy and estimated gas stove usage and were moderately correlated (R2 = 0.19) with 24 h average indoor CO2 concentrations. Modeled 24-h air exchange rates ranged from 0.04 to 3.76 air changes h-1 (ACH), with mean of 0.52 ACH. Median particle penetration was 0.89. Emission rates were calculated for each pollutant sampled. Using a detailed housing survey and field sampling questionnaires, it was possible to evaluate associations between housing characteristics and source activities, and pollutant source rates. The data indicate that several predictor variables, including mothball storage, air freshner use, and cooking activities, are reasonable predictors for emission rates for specific pollutants in the homes studied.

Prevention of lead poisoning in construction workers: a new public health approach

BACKGROUND

In 1990, Yale University, the Connecticut Departments of Health Services and of Transportation, the Connecticut Construction Industries Association, and the state's construction trade unions created the Connecticut Road Industry Surveillance Project (CRISP).

METHODS

Data from 90 bridge projects from 1991 to 1995 and approximately 2,000 workers were evaluated. The distribution of peak lead concentrations in the blood for CRISP workers classified into five groups were compared to that from workers outside of Connecticut.

RESULTS

This demonstration project was instrumental in lowering bridge worker blood lead levels. After 1992, only the painting contract employees experienced peak blood lead levels with < or = 2% exceeding 50 microg/dl. Compared to similar workers in other states, Connecticut workers had significantly lower peak blood lead levels.

CONCLUSIONS

Two thousand workers and over 120 contractors benefited directly from CRISP. Two key features of the CRISP model differed from the 1993 OSHA standard: a contract-specified lead health protection program and a centralized system of medical monitoring. These differences may account for the improved protection observed between the CRISP and non-Connecticut cohorts.

Using fault tree analysis to identify causes of non-compliance: enhancing violation outcome data for the purposes of education and prevention

An enhanced coding system for the characterization of notices of violation (NOV's) issued to radiation permit holders in the State of Texas was developed based on a series of fault tree analyses serving to identify a set of common causes. The coding system enhancement was retroactively applied to a representative sample (n = 185) of NOV's issued to specific licensees of radioactive materials in Texas during calendar year 1999. The results obtained were then compared to the currently available summary NOV information for the same year. In addition to identifying the most common NOV's, the enhanced coding system revealed that approximately 70% of the sampled NOV's were issued for non-compliance with a specific regulation as opposed to a permit condition. Furthermore, an underlying cause of 94% of the NOV's was the failure on the part of the licensee to execute a specific task. The findings suggest that opportunities exist to improve permit holder compliance through various means, including the creation of summaries which detail specific tasks to be completed, and revising training programs with more focus on the identification and scheduling of permit-related requirements. Broad application of these results is cautioned due to the bias associated with the restricted scope of the project.

Reconciling animal and human data in a cancer risk assessment of acrylonitrile

OBJECTIVES

Bioassays of rats exposed to acrylonitrile have consistently detected an elevated incidence of central nervous system (CNS) cancer. In contrast, epidemiologic studies have not found a statistically stable increase in CNS cancer mortality. The purpose of this paper is to examine whether or not CNS cancers predicted from the most appropriate inhalation bioassay in rats are consistent with CNS cancers observed in 3 recent, large epidemiologic studies.

METHODS

A linearized multistage model was fit to dose-response data from a rat inhalation bioassay to estimate carcinogenic potency. This potency was applied to epidemiologic studies of acrylonitrile-exposed workers. After adjustment for less than complete lifetime follow-up in the epidemiologic studies, consistency was examined between CNS cancers predicted by the model fit to the animal data for the exposure levels and sample sizes of the epidemiologicy studies and the CNS cancers observed in the epidemiologic studies.

RESULTS

The model predicted totals of 17.7, 3.6, and 7.6 CNS cancer deaths for the studies. These predictions were not far from the observed CNS cancer deaths (12, 6, and 6) and were well within their 95% confidence intervals of 6.9-22.3, 2.2-13.1, and 2.2-13.1, respectively.

CONCLUSIONS

The CNS cancer potency estimated from the best available inhalation bioassay was consistent with the observed deaths in the epidemiologic studies as long as continuous lifetime exposure was chosen as the exposure metric. The lack of observed excess in CNS cancer among the studied workers may have been due to low exposures, insufficient follow-up times, or both.

Risk of sick leave associated with outdoor air supply rate, humidification, and occupant complaints

We analyzed 1994 sick leave for 3,720 hourly employees of a large Massachusetts manufacturer, in 40 buildings with 115 independently ventilated work areas. Corporate records identified building characteristics and IEQ complaints. We rated ventilation as moderate (approximately 25 cfm/person, 12 ls-1) or high (approximately 50 cfm/person, 24 ls-1) outdoor air supply based on knowledge of ventilation systems and CO2 measurements on a subset of work areas, and used Poisson regression to analyze sick leave controlled for age, gender, seniority, hours of non-illness absence, shift, ethnicity, crowding, and type of job (office, technical, or manufacturing worker). We found consistent associations of increased sick leave with lower levels of outdoor air supply and IEQ complaints. Among office workers, the relative risk for short-term sick leave was 1.53 (95% confidence 1.22-1.92) with lower ventilation, and 1.52 (1.18-1.97) in areas with IEQ complaints. The effect of ventilation was independent of IEQ complaints and among those exposed to lower outdoor air supply rates the attributable risk of short-term sick leave was 35%. The cost of sick leave attributable to ventilation at current recommended rates was estimated as $480 per employee per year at Polaroid. These findings suggest that net savings of $400 per employee per year may be obtained with increased ventilation. Thus, currently recommended levels of outdoor air supply may be associated with significant morbidity, and lost productivity on a national scale could be as much as $22.8 billion per year. Additional studies of IEQ impacts on productivity and sick leave, and the mechanisms underlying the apparent association are needed.

Clinical management and the duration of disability for work-related low back pain

Clinical practice guidelines recommend a conservative approach to management of acute low back pain (LBP). The present study sought to determine whether health care utilization and the physician's initial management of work-related LBP were associated with disability duration. Clinical management information was obtained for 98 randomly selected, workers' compensation claimants with acute, uncomplicated, disabling work-related LBP. Length of disability was based on indemnity (wage replacement) payments. Disability was significantly associated with increased utilization of specialty referrals (P = 0.013) and provider visits (P < 0.001), use of magnetic resonance imaging (P = 0.003), and use of opioids for more than 7 days (P = 0.013). Effects of early diagnostic imaging (first 30 days of care) on length of disability were observed (P = 0.001). Patients whose treatment course did not involve extended opioid use and early diagnostic testing were 3.78 times more likely (95% confidence interval, 1.6 to 8.9) to have gone off disability status by the end of the study. The nature of the association between these initial clinical management aspects and LBP disability duration merits further exploration.

Indoor air quality in a middle school, Part I: Use of CO2 as a tracer for effective ventilation

The overall objective of the study was to evaluate the indoor air quality at a middle school with an emphasis on characterizing baseline conditions. The focus of this article is on the relationship between occupancy and measured concentrations of carbon dioxide, and an evaluation of the use of carbon dioxide as a tracer for ventilation in the school. The school was characterized as having no health complaints, good maintenance schedules, no carpeting within the classrooms or hallways, and no significant remodeling, and its officials had agreed to allow the sampling to take place during school hours. Monitoring followed the guidelines recommended in the "Preliminary Draft: Conceptual Standardized EPA Protocol For Characterizing Indoor Air Quality in School Buildings." Four indoor locations including the cafeteria, a science classroom, an art classroom, and the lobby outside the main office, and one outdoor location were sampled for various environmental comfort and pollutant parameters for one week in February 1997. A consistent relationship between hourly occupancy and corresponding carbon dioxide concentrations was seen. Carbon dioxide concentrations in the cafeteria, art room, and lobby were within specified American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) guidelines for comfort (< 1000 ppm). The science room had the highest concentrations (frequently exceeding 1000 ppm) due to high occupancy and non-functioning unit ventilators. Measured ventilation rates were within specified ASHRAE guidelines for the art room, cafeteria, and lobby. The science room, which relied on natural ventilation only, was not able to meet the ASHRAE guideline on one of the three days studied. The use of a completely mixed space, one compartment mass balance model with estimated CO2 generation rates and measured CO2 concentrations is shown to be a useful method for evaluating ventilation. Modeled effective ventilation, air changes per hour, and mixing factors reflected measured carbon dioxide concentrations and measured ventilation in each room. Mechanical ventilation afforded better mixing than natural ventilation. This study demonstrates the usefulness of collecting indoor CO2 and occupancy data when carrying out indoor air quality evaluations in schools.

Particle settling after lead-based paint abatement work and clearance waiting period

This study investigated the evolution of airborne particle concentration and size distribution following abatement work in a controlled environment utilizing direct real-time particle monitoring and used it to project potential lead loadings as those particles settle. An 860 ft3 environmental test chamber with sophisticated ventilation and air purifying systems was built. Wooden doors with lead-based paint were dry sanded or scraped to generate the highest feasible airborne lead concentrations. Size-fractional airborne particle concentrations decreased exponentially with time in all tests, even with no air exchange, consistent with the stirred model of constantly mixed air, which predicts longer settling than for tranquil settling. Very low levels of air mixing generated by temperature gradients and initial room air turbulence affected particle settling. About 90% of airborne lead mass settled within 1 hour after active abatement, before final cleaning began. During the second waiting period of 1 hour, which followed cleaning of the floor, additional dust settled so that the additional potential lead loading from remaining airborne lead was less than 20 microg/ft2. For this worst case scenario, the underestimate of the lead loading done by the clearance sampling did not exceed about 30%. For more realistic conditions, the underestimates are projected to be much lower than the new 40 microg/ft2 Housing and Urban Development (HUD) clearance standards for floor dust lead. These results were obtained for the first waiting period (between the end of active abatement and the beginning of cleaning) of 1 hour, as recommended by HUD guidelines. Thus, this study demonstrates no need to increase either the first or second waiting period.

Indoor air quality in a middle school, Part II: Development of emission factors for particulate matter and bioaerosols

A middle school (grades 6 to 8) in a residential section of Springfield, Illinois, with no known air quality problems, was selected for a baseline indoor air quality survey. The study was designed to measure and evaluate air quality at the middle school with the objective of providing a benchmark for comparisons with measurements in schools with potential air quality problems. The focus of this article is on the development of emission factors for particulate matter and bioaerosols. The school was characterized as having no health complaints and good maintenance schedules. Four indoor locations including the cafeteria, a science classroom, an art classroom, the lobby outside the main office, and one outdoor location were sampled for various environmental comfort and pollutant parameters for one week in February 1997. Integrated samples (eight-hour sampling time) for respirable and total particulate matter, and short-term measurements (two-minute samples, three times per day) for bioaerosols were collected on three consecutive days at each of the sampling sites. Continuous measurements of carbon dioxide were logged at all locations for five days. Continuous measurements of respirable particulate matter were also collected in the lobby area. A linear relationship between occupancy and corresponding carbon dioxide and particle concentrations was seen. A completely mixed space, one compartment mass balance model with estimated CO2 generation rates and actual CO2 and particulate matter concentrations was used to model ventilation and pollutant emission rates. Emission factors for occupancy were represented by the slope of emission rate versus occupancy scatter plots. The following particle and bioaerosol emission factors were derived from the indoor measurements: total particles: 1.28 mg/hr/person-hr; respirable particles: 0.154 g/hr/person-hr; total fungi: 167 CFU/hr/person-min; thermophilic fungi: 35.8 CFU/hr/person-min; mesophilic fungi: 119 CFU/hr/person-min; total bacteria: 227 CFU/hr/person-min; gram-negative bacteria: 69.5 CFU/hr/person-min; gram-positive bacteria: 191 CFU/hr/person-min; Aspergillus: 17.0 CFU/hr/person-min; Penicillium: 161 CFU/hr/person-min; and yeasts: 16.4 CFU/hr/person-min.

Performance of Air-O-Cell, Burkard, and Button Samplers for total enumeration of airborne spores

Performance of three devices used for the total enumeration of airborne spores-the Air-O-Cell sampling cassette, the Burkard personal volumetric air sampler, and the Button Aerosol Sampler--was evaluated under controlled laboratory conditions. The first two are glass-slide impactors; the third collects spores on a filter. The samplers were challenged with 0.44-5.10 microm polystyrene latex particles and five microorganisms of 0.84-3.07 microm mean aerodynamic diameter: Streptomyces albus, Bacillus subtilis, Cladosporium cladosporioides, Penicillium brevicompactum, and Penicillium melinii. An optical particle counter measured the particle concentrations upstream and downstream of each sampler, and thus determined the physical collection efficiency of the three samplers. Collection efficiency of the Button Aerosol Sampler was close to 100% for the entire particle size range studied. The cut-off size of each impactor was 2.3-2.4 microm. Acridine orange (with epifluorescent microscopy) and lactophenol cotton blue (with bright light microscopy) staining techniques were used for the microscopic enumeration of spores. No significant difference in microscopic counts was found (at the 95% significance level) when using these two techniques with the Button Aerosol Sampler filters. When the lactophenol cotton blue staining was used to compare total microbial counts yielded by all three samplers, the Button Sampler showed significantly higher counts for the smaller size microorganisms (B. subtilis and C. cladosporioides). For the larger microorganisms (P. brevicompactum and P. melinii) all three samplers yielded similar results. Uniformity of particle deposition on the collection surface was highest for the Button Aerosol Sampler due to the design of its inlet. Thus, the filter collection method used with the Button Aerosol Sampler is suitable and can be advantageous for the enumeration of total airborne spores.

Ecological model of occupational stress. Application to urban firefighters

1. Multiple individual and organizational barriers make it difficult for occupational health nurses and other providers to understand and handle stress in the workplace. 2. Recent research suggests adverse health effects resulting from occupational stress are more related to the context or conditions of work than workers' characteristics. 3. The ecological approach described in this article provides a means to examine the context in which stress occurs through an analysis of four levels of influence. The levels of influence include the microsystem, the organizational system, the peri-organizational system, and the extra-organizational system. 4. Through a careful analysis using this approach, an identification of the entire spectrum of factors contributing to the occurrence of workplace stressors can be identified, and more effective interventions addressing existing and potential problems related to occupational stress can be developed.

Release of lead-containing particles from a wall enclosure

The 1995 Department of Housing and Urban Development (HUD) Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing discusses using interior and exterior wall enclosures for lead hazard control. Leaded dust may be aerosolized inside enclosures and released through gaps and cracks into a room. The effects of airflow and mechanical disturbances on dust release were studied using a laboratory wall enclosure model with dust collected from homes with lead-based paint hazards. Airflows relevant to residences were blown down the enclosure and out a 4-, 6-, or 8-mm horizontal gap at its bottom, simulating potential enclosure failure. Then, low-frequency mechanical vibrations also were applied to the enclosure. No significant dust release was found when blowing air down the enclosure even at 37 cm/sec (representing extremely high flow); release occurred only with this high flow and 3 Hz mechanical disturbances. Dust was released primarily from the floor area immediately adjacent to the enclosure gap; the release rate fluctuated over time. Most dust initially settled near the enclosure. Dust release for 1 hour at extreme conditions (high airflow with vibration) yields lead loading above the 1995 HUD clearance level of 100 microg/ft2 only within 3-4 cm of the wall; for the HUD standard (1 ft2) sampling area, the lead loading does not exceed 30 microg/ ft2. Redistributing dust over the room's 16 m2 floor space yields average extreme-condition loading rate of 2 microg/ft2/hour. At less-than-extreme conditions, dust would have to be released for years without cleaning to yield a hazard.

Occupationally related hydrogen sulfide deaths in the United States from 1984 to 1994

Alice Hamilton described fatal work injuries from acute hydrogen sulfide poisonings in 1925 in her book Industrial Poisons in the United States. There is no unique code for H2S poisoning in the International Classification of Diseases, 9th Revision; therefore, these deaths cannot be identified easily from vital records. We reviewed US Occupational Safety and Health Administration (OSHA) investigation records for the period 1984 to 1994 for mention of hazardous substance 1480 (hydrogen sulfide). There were 80 fatalities from hydrogen sulfide in 57 incidents, with 19 fatalities and 36 injuries among coworkers attempting to rescue fallen workers. Only 17% of the deaths were at workplaces covered by collective bargaining agreements. OSHA issued citations for violation of respiratory protection and confined space standards in 60% of the fatalities. The use of hydrogen sulfide detection equipment, air-supplied respirators, and confined space safety training would have prevented most of the fatalities.

Mutations in the X-linked pyruvate dehydrogenase (E1) alpha subunit gene (PDHA1) in patients with a pyruvate dehydrogenase complex deficiency

Defects in the pyruvate dehydrogenase (PDH) complex are an important cause of primary lactic acidosis, a frequent manifestation of metabolic disease in children. Clinical symptoms can vary considerably in patients with PDH complex deficiencies, and almost equal numbers of affected males and females have been identified, suggesting an autosomal recessive mode of inheritance of the disease. However, the great majority of PDH complex deficiencies result from mutations in the X-linked pyruvate dehydrogenase (E1) alpha subunit gene (PDHA1). The major factors that contribute to the clinical variation in E1alpha deficiency and its resemblance to a recessive disease are developmental lethality in some males with severe mutations and the pattern of X-inactivation in females. To date, 37 different missense/nonsense and 39 different insertion/deletion mutations have been identified in the E1alpha subunit gene of 130 patients (61 females and 69 males) from 123 unrelated families. Insertion/deletion mutations occur preferentially in exons 10 and 11, while missense/nonsense mutations are found in all exons. In males, the majority of missense/nonsense mutations are found in exons 3, 7, 8 and 11, and three recurrent mutations at codons R72, R263 and R378 account for half of these patients with missense/nonsense mutations (25 of 50). A significantly lower number of females is found with missense/nonsense mutations (25). However, 36 females out of 55 affected patients have insertion/deletion mutations. The total number of female and male patients is thus almost the same, although a difference in the distribution of the type of mutations is evident between both sexes. In many families, the parents of the affected patients were studied for the presence of the PDHA1 mutation. The mutation was never present in the somatic cells of the father; in 63 mothers studied, 16 were carriers (25%). In four families, the origin of the new mutation was determined to be twice paternal and twice maternal.

High-performance, low-cost solar collectors for disinfection of contaminated water

Although the germicidal action of sunlight has long been recognized, its potential for practical applications has to be researched more thoroughly. This paper summarizes the progress made toward a commercially practical collector for solar disinfection applications. Nontracking compound parabolic collectors (CPCs), developed originally for capturing solar photons for thermal energy applications, were examined as potential solar photoreactors. A field demonstration of solar disinfection treatment using commercially manufactured solar reactors was conducted. Field tests showed successful destruction of Escherichia coli and Enterococcus faecalis and have provided data for full-scale design of water treatment systems. From above observations, a throughput value of 50 L/m2 h for the low-cost CPC reactor tested was estimated. For a 190 m3/d (0.05 MGD) facility, the estimated total costs for disinfection using UV-A is U.S. $0.19/m3 ($0.70/1000 gal). The use of near-UV sunlight to disinfect water supplies seems promising in rural communities of developing countries where treated water is unavailable.

Performance characteristics of the button personal inhalable aerosol sampler

The button inhalable aerosol sampler with a curved porous inlet recently was developed and evaluated as a stationary sampler in the laboratory and in the field. The present study focused on investigating its suitability for personal inhalable aerosol sampling. The button sampler was tested at two wind velocities (0.5 and 2.0 m/sec), three particle sizes (7, 29, and 70 microm) and three orientations to the wind (0, 90, and 180 degrees). The performance characteristics of the button sampler were compared with those of three other personal samplers--the IOM (Institute of Occupational Medicine), GSP, and 37-mm closed-face filter cassette. The experiments were conducted in a wind tunnel with the samplers mounted on a full-size manikin. The direction-specific sampling efficiency of the button sampler was found to be essentially independent of the wind direction and dependent on the wind velocity to a much smaller degree than that of the three other samplers. When direction-averaged, the fit of its sampling efficiency curve to the inhalability curve was found to be better than that of the 37-mm closed-face cassette, comparable with that of the GSP sampler, and less than that of the IOM sampler. The precision of the button sampler was found to be generally equal to or better than the precision of the comparison samplers. It was concluded that the button sampler can be successfully used as a personal inhalable aerosol sampler.

Metabolism of styrene by human liver and lung

In mice, styrene is pneumotoxic, and there is some evidence of tumorigenicity. This toxicity is thought to be related to its bioactivation to styrene oxide in lung. To determine if human tissues have this capacity, the metabolism of styrene to styrene oxide was measured in human liver and lung microsomal preparations. Hepatic microsomes metabolized styrene to styrene oxide, but lung microsomes had essentially no activity. However, microsomes from both tissues metabolized benzene to phenol. The data suggest that human lung has low styrene metabolizing activity and may be much less of a target organ than in mouse.

Skin cleaning with kerosene facilitates passage of carcinogens to the lungs of animals treated with used gasoline engine oil

Solvents such as kerosene or gasoline may be used by workers to clean their skin following contact with oily materials. This practice is not recommended, as it is well known that the solvent will defat the skin. Many also suspect that solvent washing may increase exposure by carrying materials through the skin; however, there is little documentation of this. Auto mechanics may be exposed to used gasoline engine oil (UGEO), an animal carcinogen which forms carcinogen-DNA adducts in skin and lung following topical application. This study was designed to determine if cleaning with kerosene following exposure to UGEO altered absorption of carcinogens from this material. UGEO or new oil (NO) was applied to the shaved skins of groups of HSD-ICR mice for five days. At 1 or 8 hours after application, the treated skins were cleaned with either kerosene or a commercial cleaner, or were not cleaned. Animals were sacrificed 24 hours after the last application, skins and lungs harvested, and DNA analyzed for carcinogen-DNA adducts by 32P-postlabeling. Five applications of UGEO significantly increased carcinogen-DNA adduct levels in both lungs and skin compared to animals treated with NO. DNA adduct levels in the skin were reduced significantly in groups washed with kerosene or commercial cleaner. Washing at one as opposed to eight hours after UGEO application resulted in lower adduct levels regardless of cleaner. DNA adduct levels in the lung were reduced when the commercial cleaner was used, again in a time-related fashion. However, cleaning with kerosene resulted in mean carcinogen-DNA adduct levels in the lung which were significantly higher than even the positive controls, regardless of cleaning time. This is the first demonstration that kerosene cleaning facilitates passage of carcinogens through the skin, resulting in higher levels of genetic damage in a critical internal organ.

Too hot to handle: an unusual exposure of HDI in specialty painters

BACKGROUND

Hexamethylene Diisocyanate (HDI) is a color stable aliphatic isocyanate that is used in specialty paints as a hardener. Due to the lower vapor pressure of its commercial biuret form, it is considered a relatively "safe" isocyanate from an exposure standpoint. This case series reports on an unusual toxic exposure to HDI. Between November 1993 and May 1994, seven specialty painters and one boiler maker who were working at three different power plants were examined at the Institute of Occupational and Environmental Health at West Virginia University. At their respective work sites, HDI was applied to the hot surfaces of boilers that were not shut down, and allowed sufficient time to cool. Consequently, these workers were exposed to volatile HDI and its thermal decomposition products.

METHODS

All of these workers underwent a complete physical examination, spirometry, and methacholine challenge testing.

RESULTS

All 8 workers complained of dyspnea, while 4 of the 8 also complained of rash. On examination 3 workers were methacholine challenge positive and 2 had persistent rash. At follow-up 4 years later, 5 workers still had to use inhalation medication and one had progressive asthma and dermatitis. All 8 workers, by the time of the follow-up, had gone through economic and occupational changes.

CONCLUSIONS

This case series reports on an unusual exposure to HDI. It is unusual in that: 1) There were two simultaneous sentinel cases with two different Material Safety Data Sheets (MSDS) for the same product, 2) Exposure was to volatile HDI and its decomposition products and 3) Hazardous conditions of exposure occurred at three different sites.

Occipital lobe meningioma in a patient with multiple chemical sensitivities

BACKGROUND

The concurrent diagnosis of meningioma with increased intracranial pressure has not been reported previously in a patient who meets diagnostic criteria for multiple chemical sensitivities (MCS).

METHODS

A patient who had been evaluated in an occupational medicine practice, and by several other physicians for sensitivity to chemical odors was found to have papilledema and a visual field deficit. The patient met the clinical criteria set forth by Cullen in 1987 for MCS. A magnetic resonance imaging (MRI) scan was performed.

RESULTS

The MRI revealed a large occipital lobe meningioma, which was surgically resected. Removal of the meningioma had little effect on the patient's symptoms. She has been unable to return to her job as a custodian.

DISCUSSION

The etiology of MCS has been disputed and is currently unresolved. Those who evaluate patients with MCS are reminded that meningiomas and other intracranial mass lesions can affect olfaction, and that patients with MCS can have treatable intracranial abnormalities.

Cytochromes P450 involved with benzene metabolism in hepatic and pulmonary microsomes

Benzene is an occupational hazard and environmental toxicant found in cigarette smoke, gasoline, and the chemical industry. The major health concern associated with benzene exposure is leukemia. The toxic effects of benzene are dependent on its metabolism by the cytochrome P450 enzyme system. Previous research has identified CYP2E1 as the primary P450 isozyme responsible for benzene metabolism at low concentrations, whereas CYP2B1 is involved at higher concentrations. Our studies using microsomal preparations from human, mouse, and rat indicate that CYP2E1 is the P450 isozyme primarily responsible for benzene metabolism in lung and in liver. CYP2B isozymes have little involvement in benzene metabolism by either lung or liver. Our results also indicate that isozymes of the CYP2F subfamily may play a role in benzene metabolism by lung.

Induction of DNA double-strand breaks in mammalian cells and yeast

Induction of DNA double-strand breaks (dsb) and their distribution are dependent on the energy deposition pattern within the cell nucleus (physical structure) and the ultrastructure of the chromosomes and its variation by the cell cycle and gene activities (biological structure). For electron radiation very similar RBE-values are observed for mammalian and yeast cells (AlK, 1.5 keV, 15 keV/micrometer: 2.6 in mammalian cells and 2.2 in yeast; CK 0.278 keV, 23 keV/micrometer: approx. 2.5 in mammalian cells and 3.8 in yeast). In contrast, the RBE-values for the induction of dsb of 4He2+ and light ions in the LET range from about 100 keV/micrometer up to 1000 keV/micrometer are significantly higher for yeast cells compared to mammalian cells. For example, the RBE-value of alpha-particles (120 keV/micrometer) is about 1.2 for mammalian cells whereas for yeast the RBE-value is about 2.5. The yeast chromatin has less condensed fibres compared with mammalian cells. Since a single CK photoelectron can induce only one dsb, the different condensation of the mammalian and yeast chromatin has no influence. However, particles may induce more than one dsb when traversing a chromatin fibre. The probability for the induction of closely neighboured dsb is higher the more condensed the chromatin fibres are. Since small DNA fragments (50 bp up to several kbp) are lost by standard methods of lysis, the underestimation of dsb yields increases with fibre condensation, which is in accordance with the observes dsb yields in mammalian cells and yeast. In order to obtain relevant yields of dsb (and corresponding RBE-values) the measurement of all DNA fragments down to about 50 bp are needed.