Setting occupational exposure limits for antimicrobial agents: A case study based on a quaternary ammonium compound-based disinfectant.

Antimicrobial agents have become an essential tool in controlling the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and guidelines on their use have been issued by various public health agencies. Through its Emerging Viral Pathogen Guidance for Antimicrobial Pesticides, the US Environmental Protection Agency has approved numerous surface disinfectant products for use against SARS-CoV-2. Despite their widespread use and range of associated health hazards, the majority of active ingredients in antimicrobial products, such as surface disinfectants, lack established occupational exposure limits (OELs) to assist occupational health professionals in characterizing risks from exposures to these chemicals. Based on established approaches from various organizations, a framework for deriving OELs specific to antimicrobial agents was developed that relies on a weight-of-evidence evaluation of the available data. This framework involves (1) a screening-level toxicological assessment based on a review of the existing literature and recommendations, (2) identification of the critical adverse effect(s) and dose-response relationship(s), (3) identification of alternative health-based exposure limits (HBELs), (4) derivation of potential OELs based on identified points of departure and uncertainty factors and/or modification of existing alternative HBELs, and (5) selection of an appropriate OEL. To demonstrate the use of this framework, a case study is described for selection of an OEL for a disinfectant product containing quaternary ammonium compounds (quats). Three potential OELs were derived for this product based on irritation toxicity data, developmental and reproductive toxicity (DART) data, and modification of an existing HBEL. The final selected OEL for the quats-containing product was 0.1 mg/m3, derived from modification of an existing HBEL. This value represented the lowest resulting value of the three approaches, and thus, was considered protective of irritation and potential DART.

An updated evaluation of potential health hazards associated with exposures to asbestos-containing drywall accessory products.

Following a previously published (2012) evaluation of the potential health hazards related to the use of asbestos-containing drywall accessory products, additional information regarding asbestos exposures during the use of accessory products, as well as studies of chrysotile asbestos risk as a function of exposure, have been published in the peer-reviewed literature. The purpose of this analysis is to update the original evaluation with this new information. It was previously estimated that a professional drywaller performing joint compound-associated tasks could have a lifetime cumulative chrysotile exposure of 12-26 f/cc-year. Using conservative assumptions regarding airborne asbestos levels during different drywalling tasks, task duration, and job tenure, we found that a range of 4.3-36.3 f/cc-year is a plausible estimate of a career drywaller's cumulative asbestos exposure from historical joint compound use. The estimated range for bystander exposures would be below (sometimes significantly below) this range depending on the frequency and duration of work near drywallers. Further, the estimated drywaller and bystander total fiber exposures were well below a recently published "no-observed adverse effect level, best estimate" for predominately chrysotile exposures of 89-168 f/cc-year for lung cancer and 208-415 f/cc-year for mesothelioma. We also determined that, even if the chrysotile or possibly talc ingredients in the drywall products had contained asbestiform tremolite, the cumulative tremolite exposures would have been well below a recently published tremolite no-effect level of 0.5-2.6 f/cc-year. Based on our calculations, typical drywall work using asbestos-containing drywall accessory products is not expected to increase the risk of asbestos-related lung cancer or mesothelioma. These conclusions are consistent with the lack of epidemiological evidence that drywall work resulted in an increased incidence of asbestos-related disease in the drywall trades.

Derivation of an occupational exposure limit for diacetyl using dose-response data from a chronic animal inhalation exposure study.

Occupational exposure limits (OELs) have been previously proposed for diacetyl; however, most of these values are based on worker cohort studies that are known to have several limitations and confounders. In this analysis, an 8 hour time-weighted average (TWA) OEL for diacetyl was derived based on data from a chronic, 2 year animal inhalation study recently released by the US National Toxicology Program. In that study, complete histopathology was conducted on male and female mice and rats exposed to 0, 12.5, 25 or 50 ppm diacetyl. Several responses in the lower respiratory tract of rats (the more sensitive species) were chosen as the critical endpoints of interest. Benchmark concentration (BMC) modeling of these endpoints was used to estimate BMC values associated with a 10% extra risk (BMC10 ) and the associated 95% lower confidence bound (BMCL10 ), which were subsequently converted to human equivalent concentrations (HECs) using a computational fluid dynamics-physiologically based pharmacokinetic (CFD-PBPK) model to account for interspecies dosimetry differences. A composite uncertainty factor of 8.0 was applied to the human equivalent concentration values to yield 8 hour TWA OEL values with a range of 0.16-0.70 ppm. The recommended 8 hour TWA OEL for diacetyl vapor of 0.2 ppm, based on minimal severity of bronchiolar epithelial hyperplasia in the rat, is practical and health-protective.

Ambient Asbestos Fiber Concentrations and Long-Term Trends in Pleural Mesothelioma Incidence between Urban and Rural Areas in the United States (1973-2012).

Over the past 40 years, measured ambient asbestos concentrations in the United States have been higher in urban versus rural areas. The purpose of this study was to determine whether variations in ambient asbestos concentrations have influenced pleural mesothelioma risk in females (who generally lacked historic occupational asbestos exposure relative to males). Male pleural mesothelioma incidence trends were analyzed to provide perspective for female trends. Annual age-adjusted incidence rates from 1973 to 2012 were obtained from the SEER 9, 13, and 18 databases for urban and rural locations, and standardized rate ratios were calculated. Female rural rates exceeded urban rates in almost half of the years analyzed, although the increases were not statistically significant, which is in line with expectations if there was no observable increased risk for urban locations. In contrast, male urban rates were elevated over rural rates for nearly all years examined and were statistically significantly elevated for 22 of the 40 years. Trend analyses demonstrated that trends for females remained relatively constant over time, whereas male urban and rural incidence increased into the 1980s and 1990s, followed by a decrease/leveling off. Annual female urban and rural incidence rates remained approximately five- to six-fold lower than male urban and rural incidence rates on average, consistent with the comparatively increased historical occupational asbestos exposure for males. The results suggest that differences in ambient asbestos concentrations, which have been reported to be 10-fold or greater across regions in the United States, have not influenced the risk of pleural mesothelioma.

Evaluation of the presence of asbestos in cosmetic talcum products.

Talc has been used for over a century in a variety of cosmetic products. While pure cosmetic talc (free of asbestos) is not considered a risk factor for mesothelioma, it has been recently suggested that inhalation of cosmetic talc containing trace levels of asbestos is a risk factor for mesothelioma. Bulk analyses of cosmetic talcum products were performed in the 1960s and 1970s, however, the analytical methods used at that time were incapable of determining whether asbestos minerals were present in the asbestiform versus non-asbestiform habit. The distinction between these two mineral habits is critical, as non-asbestiform amphibole minerals do not present an asbestos-related cancer risk via inhalation. As such, we evaluated six historical talcum powders using modern-era analytical methods to determine if asbestos is present, and if so, to identify the mineral habit (asbestiform versus non-asbestiform) of the asbestos. Based on their labels, the products were produced by four manufacturers and sold between 1940 and 1977. The products were analyzed in duplicate by two laboratories using standard protocols. Laboratory A analyzed samples using X-ray diffraction (XRD) and polarized light microscopy (PLM), and Laboratory B analyzed samples using PLM and transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX) and selected area electron diffraction (SAED). No asbestiform minerals were found in any of the products. Nonetheless, even if some historical cosmetic talcum products contained trace amounts (≤0.1%) of asbestiform minerals, any resulting asbestos exposure would be expected to be exceedingly low, and comparable to exposures from breathing ambient air.

Combined analysis of job and task benzene air exposures among workers at four US refinery operations.

Workplace air samples analyzed for benzene at four US refineries from 1976 to 2007 were pooled into a single dataset to characterize similarities and differences between job titles, tasks and refineries, and to provide a robust dataset for exposure reconstruction. Approximately 12,000 non-task (>180 min) personal samples associated with 50 job titles and 4000 task (<180 min) samples characterizing 24 tasks were evaluated. Personal air sample data from four individual refineries were pooled based on a number of factors including (1) the consistent sampling approach used by refinery industrial hygienists over time, (2) the use of similar exposure controls, (3) the comparability of benzene content of process streams and end products, (4) the ability to assign uniform job titles and task codes across all four refineries, and (5) our analysis of variance (ANOVA) of the distribution of benzene air concentrations for select jobs/tasks across all four refineries. The jobs and tasks most frequently sampled included those with highest potential contact with refinery product streams containing benzene, which reflected the targeted sampling approach utilized by the facility industrial hygienists. Task and non-task data were analyzed to identify and account for significant differences within job-area, task-job, and task-area categories. This analysis demonstrated that in general, areas with benzene containing process streams were associated with greater benzene air concentrations compared to areas with process streams containing little to no benzene. For several job titles and tasks analyzed, there was a statistically significant decrease in benzene air concentration after 1990. This study provides a job and task-focused analysis of occupational exposure to benzene during refinery operations, and it should be useful for reconstructing refinery workers' exposures to benzene over the past 30 years.

Anthophyllite asbestos: state of the science review.

Anthophyllite is an amphibole form of asbestos historically used in only a limited number of products. No published resource currently exists that offers a complete overview of anthophyllite toxicity or of its effects on exposed human populations. We performed a review focusing on how anthophyllite toxicity was understood over time by conducting a comprehensive search of publicly available documents that discussed the use, mining, properties, toxicity, exposure and potential health effects of anthophyllite. Over 200 documents were identified; 114 contained relevant and useful information which we present chronologically in this assessment. Our analysis confirms that anthophyllite toxicity has not been well studied compared to other asbestos types. We found that toxicology studies in animals from the 1970s onward have indicated that, at sufficient doses, anthophyllite can cause asbestosis, lung cancer and mesothelioma. Studies of Finnish anthophyllite miners, conducted in the 1970s, found an increased incidence of asbestosis and lung cancer, but not mesothelioma. Not until the mid-1990s was an epidemiological link with mesothelioma in humans observed. Its presence in talc has been of recent significance in relation to potential asbestos exposure through the use of talc-containing products. Characterizing the health risks of anthophyllite is difficult, and distinguishing between its asbestiform and non-asbestiform mineral form is essential from both a toxicological and regulatory perspective. Anthophyllite toxicity has generally been assumed to be similar to other amphiboles from a regulatory standpoint, but some notable exceptions exist. In order to reach a more clear understanding of anthophyllite toxicity, significant additional study is needed. Copyright © 2016 John Wiley & Sons, Ltd.

An independent evaluation of plutonium body burdens in populations near Los Alamos Laboratory using human autopsy data.

In the mid-1940s, the United States began producing atomic weapon components at the Los Alamos National Laboratory (LANL). In an attempt to better understand historical exposure to nearby residents, this study evaluates plutonium activity in human tissue relative to residential location and length of time at residence. Data on plutonium activity in the lung, vertebrae, and liver of nearby residents were obtained during autopsies as a part of the Los Alamos Tissue Program. Participant residential histories and the distance from each residence to the primary plutonium processing buildings at LANL were evaluated in the analysis. Summary statistics, including Student t-tests and simple regressions, were calculated. Because the biological half-life of plutonium can vary significantly by organ, data were analyzed separately by tissue type (lung, liver, vertebrae). The ratios of plutonium activity (vertebrae:liver; liver:lung) were also analyzed in order to evaluate the importance of timing of exposure. Tissue data were available for 236 participants who lived in a total of 809 locations, of which 677 were verified postal addresses. Residents of Los Alamos were found to have higher plutonium activities in the lung than non-residents. Further, those who moved to Los Alamos before 1955 had higher lung activities than those who moved there later. These trends were not observed with the liver, vertebrae, or vertebrae:liver and liver:lung ratio data, however, and should be interpreted with caution. Although there are many limitations to this study, including the amount of available data and the analytical methods used to analyze the tissue, the overall results indicate that residence (defined as the year that the individual moved to Los Alamos) may have had a strong correlation to plutonium activity in human tissue. This study is the first to present the results of Los Alamos Autopsy Program in relation to residential status and location in Los Alamos.

Derivation of a chronic oral reference dose for cobalt.

Cobalt (Co) is an essential element in humans as a component of vitamin B12. However, at high levels Co exposure has been shown to have detrimental effects. This study was designed to identify a chronic oral reference dose (RfD) for Co. Currently available data indicate that non-cancer health effects associated with Co exposure may include hematological, neurological, immunological, reproductive, cardiovascular, and endocrine responses. This analysis employs the standard US EPA risk assessment methodology for establishing a chronic RfD. In this analysis, the Jaimet and Thode (1955) 10-week, multiple dose human study of thyroid effects (decreased iodine uptake) in children was determined to be the most robust and sensitive study for identifying a potential point of departure dose (POD). A dose of 0.9 mgCo/kg-day was chosen as the POD. Consistent with the US EPA's previous derivation of the perchlorate RfD, which is also based on decreased iodine uptake in humans, we considered several uncertainly factors (UFs), and determined that a factor of 10 for human variability was appropriate, as well as a factor of three for database adequacy. Applying an aggregate uncertainty factor of 30 to the POD yields a chronic oral RfD of 0.03 mg/kg-day. We believe this value would be protective of non-cancer health effects in the general population for a lifetime of daily exposure to Co.

An independent review and prioritization of past radionuclide and chemical releases from the Los Alamos National Laboratory--implications for future dose reconstruction studies.

From 1999 through 2010, a team of scientists and engineers systematically reviewed approximately eight million classified and unclassified documents at Los Alamos National Laboratory (LANL) that describe historical off-site releases of radionuclides and chemicals in order to determine the extent to which a full-scale dose reconstruction for releases is warranted and/or feasible. As a part of this effort, a relative ranking of historical airborne and waterborne radionuclide releases from LANL was established using priority index (PI) values that were calculated from estimated annual quantities released and the maximum allowable effluent concentrations according to The U.S. Nuclear Regulatory Commission (USNRC). Chemical releases were ranked based on annual usage estimates and U.S. Environmental Protection Agency (USEPA) toxicity values. PI results for airborne radionuclides indicate that early plutonium operations were of most concern between 1948 and 1961, in 1967, and again from 1970 through 1973. Airborne releases of uranium were found to be of most interest for 1968, from 1974 through 1978, and again in 1996. Mixed fission products yielded the highest PI value for 1969. Mixed activation product releases yielded the highest PI values from 1979 to 1995. For waterborne releases, results indicate that plutonium is of most concern for all years evaluated with the exception of 1956 when (90)Sr yielded the highest PI value. The prioritization of chemical releases indicate that four of the top five ranked chemicals were organic solvents that were commonly used in chemical processing and for cleaning. Trichloroethylene ranked highest, indicating highest relative potential for health effects, for both cancer and non-cancer effects. Documents also indicate that beryllium was used in significant quantities, which could have lead to residential exposures exceeding established environmental and occupational exposure limits, and warrants further consideration. In part because of the close proximity of residents to LANL, further study of historical LANL releases and the potential impact to public health is recommended for those materials with the largest priority index values; namely, plutonium, uranium, and selected chemicals.

Airborne concentrations of benzene for dock workers at the ExxonMobil refinery and chemical plant, Baton Rouge, Louisiana, USA (1977-2005).

OBJECTIVES: Benzene is a natural constituent of crude oil and natural gas (0.1-3.0% by volume). Materials that are refined from crude oil and natural gas contain some residual benzene. Few datasets have appeared in the peer-reviewed literature characterizing exposures to benzene at specific refineries or during specific tasks. In this study, historical samples of airborne benzene collected from 1977-2005 at the ExxonMobil Baton Rouge, Louisiana, USA, docks were evaluated. METHODS: Workers were categorized into 11 job titles, and both non-task (≤180 min sample duration) and task-related (<180 min) benzene concentrations were assessed. Approximately 800 personal air samples (406 non-task and 397 task-related) were analyzed. RESULTS: Non-task samples showed that concentrations varied significantly across job titles and generally resulted from exposures during short-duration tasks such as tank sampling. The contractor - tankerman job title had the highest average concentration [N=38, mean 1.4 parts per million (ppm), standard deviation (SD) 2.6]. Task-related samples indicated that the highest exposures were associated with the disconnection of cargo loading hoses (N=134, mean 11 ppm, SD 32). Non-task samples for specific job categories showed that concentrations have decreased over the past 30 years. Recognizing the potential for benzene exposure, this facility has required workers to use respiratory protective equipment during selected tasks and activities; thus, the concentrations measured were likely greater than those that the employee actually experienced. CONCLUSIONS: This study provides a job title- and task-focused analysis of occupational exposure to benzene during dock facility operations that is insightful for understanding the Baton Rouge facility and others similar to it over the past 30 years.

Occupational exposure to benzene at the ExxonMobil refinery in Baytown, TX (1978-2006).

Although occupational benzene exposure of refinery workers has been studied for decades, no extensive analysis of historical industrial hygiene data has been performed focusing on airborne concentrations at specific refineries and tasks. This study characterizes benzene exposures at the ExxonMobil Baytown, TX, refinery from 1978 to 2006 to understand the variability in workers' exposures over time and during different job tasks. Exposures were grouped by operational status, job title, and tasks. More than 9000 industrial hygiene air samples were evaluated; approximately 4000 non-task (> 3 h) and 1000 task-related (< 3 h) personal samples were considered. Each sample was assigned to one of 27 job titles, 29 work areas, and 16 task bins (when applicable). Process technicians were sampled most frequently, resulting in the following mean benzene concentrations by area: hydrofiner (n=245, mean=1.3 p.p.m.), oil movements (n=286, mean=0.23 p.p.m.), reformer (n=575, mean=0.10 p.p.m.), tank farm (n=9, mean=0.65 p.p.m.), waste treatment (n=446, mean=0.13 p.p.m.), and other areas (n=460, mean=0.062 p.p.m.). The most frequently sampled task was sample collection (n=218, mean=0.40 p.p.m.). Job title and area did not significantly impact task-related exposures. Airborne concentrations were significantly lower after 1990 than before 1990. Results of this task-focused study may be useful when analyzing benzene exposures at other refineries.

Benzene exposure in refinery workers: ExxonMobil Joliet, Illinois, USA (1977-2006).

While petroleum industry studies have indicated low benzene exposure potential for refinery workers, most provide limited data for assessing job or task-related benzene exposures. This study characterizes job and task-specific airborne benzene concentrations and variability over time for the ExxonMobil refinery in Joliet, Illinois from 1977 to 2006. A database of 2289 industrial hygiene air samples, including 1145 non-task (≥180 min) personal samples and 480 task-related (<180 min) personal samples, were analyzed. Samples were grouped by operational status, job, and task. Benzene concentrations were determined for each job category and task bin, with additional analyses conducted to determine whether benzene concentrations changed over time. The results indicate that the benzene concentrations for non-task and task samples were relatively low. For all non-task samples, the arithmetic mean benzene concentration was 0.12 part per million (ppm). The most frequently sampled workers (process technicians during routine operations) had an arithmetic mean benzene concentration of 0.038 ppm. The most frequently sampled task bin (blinding and breaking) had an arithmetic mean benzene concentration of 1.0 ppm. This study provides benzene air concentration data that can be used in combination with job histories to reconstruct historical benzene exposures for workers at the Joliet Refinery over the past 30 years.

Occupational exposure to benzene at the ExxonMobil refinery in Beaumont, TX (1976-2007).

Because crude oil and refined petroleum products can contain benzene and benzene is considered a known carcinogen by numerous independent and governmental agencies, including the International Agency for Cancer Research, the petroleum industry has implemented exposure control programs for decades. As part of the benzene control programs, significant exposure assessments have been performed; both qualitatively and through quantitative measurements. In this study, we evaluated the airborne concentrations of benzene and their variability over time at the ExxonMobil refinery in Beaumont, TX between 1976 and 2007. The results of 5854 personal air samples are included in this analysis; 3761 were considered non-task (> or =180 min) personal samples, and 2093 were considered task-related (<180 min) personal samples. Dock and loading rack samples were analyzed separately from the refinery samples because in addition to refinery products, employees at the dock and loading rack also handled chemical plant products. In general, the non-task personal refinery air samples indicated that exposures of the past 30 years were generally below the occupational exposure limit of 1 ppm (mean=0.30 ppm, SD=3.1), were higher during routine (mean=0.32 ppm, SD=3.3) than turnaround operations (mean=0.16 ppm, SD=0.87), and decreased slightly over time. The job sampled most frequently during routine operations was that of process technician, and, as broken down by area, resulted in the following mean benzene air concentrations: coker (n=146, mean=0.014 ppm, SD=0.036), lube extraction unit (n=31, mean<0.070 ppm), pipestills (n=136, mean=0.12, SD=0.47), waste treatment (n=107, mean=0.20, SD=0.28), and all other areas (n=1115, mean=0.059 ppm, SD=0.36). Task-based samples indicated that the highest exposures resulted from the tank cleaning tasks, although the overall task mean benzene air concentration was 1.4 ppm during routine operations. The most frequently sampled task during routine operations was blinding and breaking, and the mean benzene air concentrations associated with this task were statistically higher in the reformer area of the refinery (n=311, mean=3.2 ppm, SD=7.9) than in all other areas (n=200, mean=0.92 ppm, SD=3.1). However, task-related exposures were found to be statistically similar across job categories for a given task. This study thus provides a task-focused analysis for occupational exposure to benzene during refinery operations, and will be useful for understanding exposures at this refinery.

Lead testing wipes contain measurable background levels of lead.

Lead is registered under the California Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65) as both a carcinogen and a reproductive hazard. As part of the process to determine if consumer products satisfy Proposition 65 with respect to lead, various wipe sampling strategies have been utilized. Four commonly used wipe materials (cotton gauze, cotton balls, ashless filter paper, and Ghost Wipes) were tested for background lead levels. Ghost Wipe material was found to have 0.43 +/- 0.11 microg lead/sample (0.14 microg/wipe). Wipe testing for lead using Ghost Wipes may therefore result in measurable concentrations of lead, regardless of whether or not the consumer product actually contains leachable lead.

Occupational exposure to benzene at the ExxonMobil refinery at Baton Rouge, Louisiana (1977-2005).

Because crude oil contains up to 3% benzene and there is an association between high chronic exposure to appreciable concentrations of benzene and acute myelogenous leukemia, exposure of refinery workers has been studied for many years. To date, no extensive industrial hygiene exposure analyses for historical benzene exposure have been performed, and none have focused on the airborne concentrations in the workplace at specific refineries or for specific tasks. In this study, the authors evaluated the airborne concentrations of benzene and their variability over time at the ExxonMobil refinery in Baton Rouge between 1977 and 2005. Refinery workers were categorized into 117 worker groups using company job descriptions. These 117 groups were further collapsed into 25 job categories based on similarity of measured exposure results. Results of 5289 personal air samples are included in this analysis; 3403 were considered nontask (>or= 180 min) personal samples, and 830 were considered task-related (< 180 min) personal samples; the remainder did not fit in either category. In general, nontask personal air samples indicated that exposures of the past 30 years were generally below the occupational exposure limit of 1 ppm, but there was only a small, decreasing temporal trend in the concentrations. The job sampled most frequently during routine operations was process technician and, as broken down by area, resulted in the following mean benzene concentrations: analyzers (mean = 0.12 ppm), coker (mean = 0.013 ppm), hydrofiner (mean = 0.0054 ppm), lube blending and storage (mean = 0.010 ppm), waste treatment (mean = 0.092 ppm), and all other areas (mean = 0.055 ppm). Task-based samples indicated that the highest exposures resulted from the sampling tasks, specifically from those performed on process materials; in general, though, even these tasks had concentrations well below the STEL of 5 ppm. The most frequently sampled task was gauging (mean = 0.12 ppm). Task-related exposures were also similar across job categories for a given task, with a few exceptions. This study thus provides a task-focused analysis for occupational exposure to benzene during refinery operations, which can be insightful for understanding exposures at this refinery and perhaps others operated since about 1975.

A proposed approach for setting occupational exposure limits for sensory irritants based on chemosensory models.

OBJECTIVES: Setting occupational exposure limits (OELs) for odorous or irritating chemicals is a global occupational health challenge. However, often there is inadequate knowledge about the toxicology of these chemicals to set an OEL and their irritation potencies are usually not recognized until they are manufactured or used in large quantities. METHODS: In this paper, the importance of accounting for risk perception and communication; conditioned responses; and interindividual variability in tolerance, detection and susceptibility with respect to setting an OEL are discussed in relation to three chemosensory models. These parameters and models were then used to construct a flowchart-style methodology that can be used to set an OEL for a specific chemical. RESULTS: The OEL identified for a chemical odorant or irritant will depend on the type of chemosensory effect that the chemical is likely to exhibit. For example, experience has shown that chemicals with a low odor threshold often require low OELs even though many are not toxic or do not cause irritation at those air concentrations. CONCLUSION: In order to establish the appropriate OEL, organizations need to agree upon the percentage of the workforce that they are attempting to protect and the types of toxicological end points that are sufficiently important to protect against (e.g. transient eye irritation, enzyme induction or other reversible effects). This is particularly true for sensory irritants. The method described in this paper could also be extended to setting limits for ambient air contaminants where risk perception plays a dominant role in whether the public views the exposure as being reasonable or safe.

The role of odor and irritation, as well as risk perception, in the setting of occupational exposure limits.

OBJECTIVE: This paper reviews current research regarding the relationship between odor perception or irritation and setting an occupational exposure limit (OEL). Special focus was directed at those settings where a small fraction of persons report unacceptable responses to concentrations well below the OEL. METHODS: We evaluated the published literature on the topic of irritation and olfactory response to exposure to industrial chemicals. More than a dozen researchers have been active in this area over the past 10 years. RESULTS: It was found that for some chemicals, even when one maintains airborne concentrations below a particular OEL, this level of exposure may not be adequate to prevent all persons from reporting an appreciable adverse response. In some cases, worker's pre-existing belief systems about the source of an odor may be sufficient to require that they have not be exposed to any detectable concentration. In addition, detection of odors by workers may tap into the person's aversion to odors, in general. In both situations, it is often necessary to address these specific issues through risk communication and dealing directly with risk perception. CONCLUSIONS: For practical reasons, the current objective of organizations charged with setting OELs for chemicals is to identify concentrations that do not cause irritation or widespread reports of unpleasant sensory stimulation in the vast majority of workers (e.g., about 80-95%).