Evaluation of airborne asbestos concentrations associated with the maintenance of brakes on an industrial overhead crane.

OBJECTIVES: To evaluate potential airborne asbestos exposures during brake maintenance and repair activities on a P&H overhead crane, and during subsequent handling of the mechanic's clothing. METHODS: Personal (n = 27) and area (n = 61) airborne fiber concentrations were measured during brake tests, removal, hand sanding, compressed air use, removal and reattachment of chrysotile-containing brake linings, and reinstallation of the brake linings. The mechanic's clothing was used to measure potential exposure during clothes handling. RESULTS: All brake linings contained between 19.9% to 52.4% chrysotile asbestos. No amphibole fibers were detected in any bulk or airborne samples. The average full-shift airborne chrysotile concentration was 0.035 f/cc (PCM-equivalent asbestos-specific fibers, or PCME). Average task-based personal air samples collected during brake maintenance, sanding, compressed air use, and brake lining removal tasks ranged from 0 to 0.48 f/cc (PCME). The calculated 30-minute time-weighted average (TWA) airborne chrysotile concentration associated with 5-15 minutes of clothes handling was 0-0.035 f/cc PCME. CONCLUSION: The results indicated that personal and area TWA fiber concentrations measured during all crane brake maintenance and clothes handling tasks were below the current OSHA 8-h TWA Permissible Exposure Limit for asbestos of 0.1 f/cc. Further, no airborne asbestos fibers were measured during routine brake maintenance tasks following the manufacturer's maintenance manual procedures. All short-term airborne chrysotile concentrations measured during non-routine tasks were below the current 30-minute OSHA excursion limit for asbestos of 1 f/cc. This study adds to the available data regarding chrysotile exposure potential during maintenance on overhead cranes.

Evaluation of the Safety and Efficacy of Hand Sanitizer Products Marketed to Children Available during the COVID-19 Pandemic.

Hand sanitizer use in the United States (U.S.) increased after the SARS-CoV-2 outbreak. The U.S. Food and Drug Administration (FDA) released temporary manufacturer guidance, changing impurity level limits for alcohol-based hand sanitizers (ABHSs). Since the guidance took effect, the FDA has recommended against using these hand sanitizers due to concerns over safety, efficacy, and/or risk of incidental ingestion. To address current gaps in exposure characterization, this study describes a survey of ABHSs marketed to children available in the U.S., as defined by several inclusion criteria. A subset of ABHSs (n = 31) were evaluated for ethanol and organic impurities using a modified FDA method. Products with detectable impurity levels were compared to the FDA's established interim limits. Seven children's products had impurity levels exceeding the FDA's recommended interim limits, including benzene (up to 9.14 ppm), acetaldehyde (up to 134.12 ppm), and acetal (up to 75.60 ppm). The total measured alcohol content ranged from 52% to 98% in all hand sanitizers tested, ranging from 39% below, and up to 31% above, the labeled concentration. Future studies should confirm impurity contamination sources. A risk assessment could determine whether dermal application or incidental ingestion of impurity-containing hand sanitizers pose any consumer risk.

Evaluation of a wearable consumer noise measurement device in a laboratory setting.

Exposure to noise occurs throughout daily life and, depending on the intensity, duration, and context, can lead to hearing loss, disturbed sleep, decreased academic achievement, and other negative health outcomes. Recently, smartwatches that use the device's onboard microphone to measure noise levels were released. This study evaluated the accuracy of these smartwatches in a controlled laboratory setting. For broadband pink noise, a total of 11 441 measurements were collected. The results showed that, on average, the smartwatch reported 3.4 dBA lower than the reference system on average. For the octave-band, a total of 18 449 measurements were collected. The smartwatch measured lower than the reference microphone from the 125 Hz to 1000 Hz octave bands, were somewhat in agreement at 2000 Hz, measured higher sound pressure levels than the reference microphone at 4000 Hz, and then lower at 8000 Hz. Despite not meeting the ANSI criteria for sound level meters, in some cases, these smartwatches still provide a reasonable degree of accuracy and have the potential for use in studies that require the measurement of personal noise exposure over an extended period.

Potential airborne asbestos exposures in dentistry: a comprehensive review and risk assessment.

Chrysotile was formerly used in the manufacture of casting ring liner (CRL) and periodontal dressing powder (PDP). The purpose of this study was to describe the potential for airborne asbestos exposure among dental professionals who may have used these products and to assess their risk of asbestos-related disease (ARD). Task-specific exposure data associated with CRL and PDP were identified and compared to regulatory standards for asbestos and health-based benchmarks. Personal airborne fiber concentrations ranged from 0.008-3.5 f/cc by PCM (duration: 3-420 minutes) for CRL (tearing, placement), and from <0.0044-<0.297 f/cc by PCM (duration: 5-28 minutes) for PDP (mixing). Eight-hour time-weighted average (TWA) exposures were calculated using the reported task-based airborne fiber concentrations and associated sampling durations. For CRL tasks, the upper-bound calculated 8-hour TWA of 0.022 f/cc (tearing, placement) did not exceed regulatory standards for asbestos (≥0.1 f/cc). All samples collected during the mixing of PDP resulted in non-measurable fiber concentrations. The greatest estimated cumulative asbestos exposure for dental professionals using CRL (tearing, placement) of 0.33 f/cc-years is well below "best estimate", published chrysotile no-observed-adverse-effect-levels (NOAEL) for ARD (lung cancer = 89-168 f/cc-years; pleural mesothelioma = 208-415 f/cc-years). As such, the use of asbestos-containing CRL and/or PDP is not expected to pose an increased risk of ARD among dental professionals. This conclusion is consistent with the lack of an increased risk of ARD reported in epidemiological studies of these occupations.

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.

Assessing and managing the risks of COVID-19 in the workplace: Applying industrial hygiene (IH)/occupational and environmental health and safety (OEHS) frameworks.

As businesses attempt to reopen to varying degrees amid the current coronavirus disease (COVID-19) pandemic, industrial hygiene (IH) and occupational and environmental health and safety (OEHS) professionals have been challenged with assessing and managing the risks of COVID-19 in the workplace. In general, the available IH/OEHS tools were designed to control hazards originating in the workplace; however, attempts to tailor them specifically to the control of infectious disease outbreaks have been limited. This analysis evaluated the IH decision-making framework (Anticipate, Recognize, Evaluate, Control, and Confirm ("ARECC")) as it relates to biological hazards, in general, and to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), specifically. Available IH/OEHS risk assessment and risk management tools (e.g. control banding and the hierarchy of controls) are important components of the ARECC framework. These conceptual models, however, were primarily developed for controlling chemical hazards and must be adapted to the unique characteristics of highly infectious and virulent pathogens, such as SARS-CoV-2. This assessment provides an overview of the key considerations for developing occupational infection control plans, selecting the best available controls, and applying other emerging tools (e.g. quantitative microbial risk assessment), with the ultimate goal of facilitating risk management decisions during the current global pandemic.

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.

Breast Cancer Characteristics Associated with 2D Digital Mammography versus Digital Breast Tomosynthesis for Screening-detected and Interval Cancers.

Purpose To determine whether the rates and tumor characteristics of screening-detected and interval cancers differ for two-dimensional digital mammography (DM) versus digital breast tomosynthesis (DBT) mammography. Materials and Methods Consecutive screening mammograms from January 2009 to February 2011 (DM group, before DBT integration) and from January 2013 to February 2015 (DBT group, after complete DBT integration) were reviewed. Cancers were considered screening detected if diagnosed within 365 days of a positive screening examination and interval if diagnosed within 365 days of a negative screening examination. Z tests were used to compare cancers on DM versus DBT examinations. Results A total of 948 breast cancers were diagnosed after 78 385 DM and 76 896 DBT examinations. Although the overall rate of screening-detected cancers was similar with DM and DBT (5.0 vs 5.0 per 1000 examinations, P = .98), a higher proportion of screening-detected cancers were invasive rather than in situ with DBT (74.2% [287 of 387] vs 66.0% [260 of 394], P = .01). There were no significant differences in tumor characteristics, including size at pathologic examination, grade, hormone receptor status, and nodal status, between the screening-detected invasive cancers on DM versus DBT (P = .09-.99). The rate of interval cancers was similar with DM and DBT (1.1 vs 1.1 per 1000 examinations, P = .84). Compared with symptomatic interval cancers, magnetic resonance imaging-detected interval cancers were more likely to be minimal cancers. Conclusion The overall rates of screening-detected and interval cancers are similar with DM and DBT, but a higher proportion of screening-detected cancers are invasive rather than in situ with DBT. © RSNA, 2017.

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.

Supplementary dataset for child and adult exposure and health risk evaluation following the use of metal- and metalloid-containing costume cosmetics sold in the United States.

The data presented in this article are related to the research article entitled "Child and adult exposure and health risk evaluation following the use of metal- and metalloid-containing costume cosmetics sold in the United States" [1]. This article describes the concentration of metals and metalloids contained in various cosmetic products such as body paint, lipstick and eye shadow, the relative percent deviation of two analyses performed on the products and the physico-chemico properties of the metals and metalloids used in the SkinPerm model presented in the aforementioned article.

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.

Child and adult exposure and health risk evaluation following the use of metal- and metalloid-containing costume cosmetics sold in the United States.

Costume cosmetics (lipstick, body paints, eyeshadow) were analyzed for metals using inductively coupled plasma mass spectrometry (ICP-MS). Sb was detected in all samples (range: 0.12-6.3 mg/kg; d.f. 100%), followed by Pb (<0.15-9.3 mg/kg), Ni (<0.20-6.3 mg/kg), Co (<0.5-2.0 mg/kg); with d.f. 80% each, Hg (<0.00015-0.0020 mg/kg; d.f. 50%) and As (0.53 mg/kg, d.f. 10%). Ingestion and dermal exposures were estimated for child- and adult-intermittent and adult-occupational users. Adult-occupational users exceeded the U.S. EPA Reference Dose (RfD) for Sb and the CA Proposition 65 maximum allowable dose level (MADL) for Pb was exceeded for all user scenarios. The Pb dose from body paint was sufficient to raise blood lead levels (BLL) in all user scenarios above baseline BLLs from 0.2 µg/dL to 1.9 µg/dL per the Adult Lead Model (ALM) and child Integrated Exposure Uptake Biokinetic (IEUBK) blood Pb models. Change in BLL was less than 1 µg/dL amongst the child and adult-intermittent users, the benchmark change in BLL developed for health risk assessments for children. Adult-occupational users exceeded the CA Proposition 65 NSRL intake value of 15 µg/day, which corresponds to an increase of 1.2 µg/dL above baseline levels using ALM. Exposure of occupational users of costume cosmetics should be evaluated further to prevent unnecessary metal exposure.

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.

Airborne asbestos take-home exposures during handling of chrysotile-contaminated clothing following simulated full shift workplace exposures.

The potential for para-occupational, domestic, or take-home exposures from asbestos-contaminated work clothing has been acknowledged for decades, but historically has not been quantitatively well characterized. A simulation study was performed to measure airborne chrysotile concentrations associated with laundering of contaminated clothing worn during a full shift work day. Work clothing fitted onto mannequins was exposed for 6.5 h to an airborne concentration of 11.4 f/cc (PCME) of chrysotile asbestos, and was subsequently handled and shaken. Mean 5-min and 15-min concentrations during active clothes handling and shake-out were 3.2 f/cc and 2.9 f/cc, respectively (PCME). Mean airborne PCME concentrations decreased by 55% 15 min after clothes handling ceased, and by 85% after 30 min. PCM concentrations during clothes handling were 11-47% greater than PCME concentrations. Consistent with previously published data, daily mean 8-h TWA airborne concentrations for clothes-handling activity were approximately 1.0% of workplace concentrations. Similarly, weekly 40-h TWAs for clothes handling were approximately 0.20% of workplace concentrations. Estimated take-home cumulative exposure estimates for weekly clothes handling over 25-year working durations were below 1 f/cc-year for handling work clothes contaminated in an occupational environment with full shift airborne chrysotile concentrations of up to 9 f/cc (8-h TWA).

Naturally occurring diacetyl and 2,3-pentanedione concentrations associated with roasting and grinding unflavored coffee beans in a commercial setting.

Over the last decade, concerns have been raised about potential respiratory health effects associated with occupational exposure to the flavoring additives diacetyl and 2,3-pentanedione. Both of these diketones are also natural components of many foods and beverages, including roasted coffee. To date, there are no published studies characterizing workplace exposures to these diketones during commercial roasting and grinding of unflavored coffee beans. In this study, we measured naturally occurring diacetyl, 2,3-pentanedione, and respirable dust at a facility that roasts and grinds coffee beans with no added flavoring agents. Sampling was conducted over the course of three roasting batches and three grinding batches at varying distances from a commercial roaster and grinder. The three batches consisted of lightly roasted soft beans, lightly roasted hard beans, and dark roasted hard beans. Roasting occurred for 37 to 41 min, and the grinding process took between 8 and 11 min. Diacetyl, 2,3-pentanedione, and respirable dust concentrations measured during roasting ranged from less than the limit of detection (

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.

Dose-response relationships for blood cobalt concentrations and health effects: a review of the literature and application of a biokinetic model.

Cobalt (Co) is an essential component of vitamin B(12). As with all metals, at sufficiently high doses, Co may exert detrimental effects on different organ systems, and adverse responses have been observed in animals, patients undergoing Co therapy, and workers exposed to respirable Co particulates. Although blood Co concentrations are postulated to be the most accurate indicator of ongoing Co exposure, little is known regarding the dose-response relationships between blood Co concentrations and adverse health effects in various organ systems. In this analysis, the animal toxicology and epidemiology literature were evaluated to identify blood Co concentrations at which effects have, and have not, been reported. Where necessary, a biokinetic model was used to convert oral doses to blood Co concentrations. Our results indicated that blood Co concentrations of 300 µg/L and less have not been associated with adverse responses of any type in humans. Concentrations of 300 µg/L and higher were associated with certain hematological and reversible endocrine responses, including polycythemia and reduced iodide uptake. Blood Co concentrations of 700-800 µg Co/L and higher may pose a risk of more serious neurological, reproductive, or cardiac effects. These blood concentrations should be useful to clinicians and toxicologists who are attempting to interpret blood Co concentrations in exposed individuals.