The key characteristics of cardiotoxicity for the pervasive pollutant phenanthrene.

The key characteristic (KCs) framework has been used previously to assess the carcinogenicity and cardiotoxicity of various chemical and pharmacological agents. Here, the 12 KCs of cardiotoxicity are used to evaluate the previously reported cardiotoxicity of phenanthrene (Phe), a tricyclic polycyclic aromatic hydrocarbon (PAH), and major component of fossil fuel-derived air pollution. Phe is a semi-volatile pollutant existing in both the gas phase and particle phase through adsorption onto or into particulate matter (PM). Phe can translocate across the airways and gastrointestinal tract into the systemic circulation, enabling body-wide effects. Our evaluation based on a comprehensive literature review, indicates Phe exhibits 11 of the 12 KCs for cardiotoxicity. These include adverse effects on cardiac electromechanical performance, the vasculature and endothelium, immunomodulation and oxidative stress, and neuronal and endocrine control. Environmental agents that have similarly damaging effects on the cardiovascular system are heavily regulated and monitored, yet globally there is no air quality regulation specific for PAHs like Phe. Environmental monitoring of Phe is not the international standard with benzo[a]pyrene being frequently used as a proxy despite the two PAH species exhibiting significant differences in sources, concentration variations and toxic effects. The evidence summarised in this evaluation highlights the need to move away from proxied PAH measurements and develop a monitoring network capable of measuring Phe concentration. It also stresses the need to raise awareness amongst the medical community of the potential cardiovascular impact of PAH exposure. This will allow the production of mitigation strategies and possibly the development of new policies for the protection of the societal groups most vulnerable to cardiovascular disease.

Phosphorylation state of pyruvate dehydrogenase and metabolite levels in turkey skeletal muscle in normal and pale, soft, exudative meats.

1. Turkey production has increased dramatically as genetic selection has succeeded in increasing body weight and muscle yield to fulfil increasing consumer demand. However, producing fast-growing, heavily muscled birds is linked to increased heat stress susceptibility and can result in pale, soft, exudative (PSE) meat. Previous studies indicated that pyruvate dehydrogenase kinase 4 (PDK4) is significantly reduced in PSE samples, suggesting this as a candidate gene associated with the development of this problem.2. The objective of this study was to determine whether pre-market thermal challenge results in PSE meat as a result of differential expression of PDK4. Two genetic lines of turkeys were used in this study; the Randombred Control Line 2 (RBC2) and a commercial line. Turkeys were exposed to a pre-market thermal challenge of 12 h at 35°C followed by 12 h at 27°C for 5 d. Birds were slaughtered and processed according to industry standards. Pectoralis major samples were categorised as PSE or normal based on marinade uptake and cook loss indicators. In the first experiment, the relative expression of pyruvate dehydrogenase (PDH) and the phosphorylation state of PDH in normal and PSE turkey meat were analysed by western blotting. In the second experiment, the same samples were used to measure metabolite levels at 5 min post-mortem, comparing the normal to the PSE samples.3. The results of the first experiment showed that PSE samples had significantly lower total PDH (P = 0.029) compared to normal meat. However, there was no significant difference in the degree of phosphorylation of sites 1, 2 or 3. In the second experiment, there were no significant differences in glycogen, lactate, glycolytic potential or ATP when comparing PSE to control samples.4. These results suggested that a reduction in PDK4 expression alone does not explain the development of PSE meat.

Muscle from grass- and grain-fed cattle differs energetically.

Insufficient acidification results in dark, firm, and dry beef. While this defect is often indicative of a stress event antemortem, muscle tissue may change in response to feeding regime. Longissimus dorsi muscle samples from 10 grain-fed and 10 grass-fed market weight, angus-crossbred beef cattle were collected postmortem. Lower (P < .05) L* and a* values were recorded for steaks from grass-fed cattle. Higher (P < .05) ultimate pH values were noted in lean of grass-fed cattle compared to grain-fed cattle, yet differences in lactate, glycogen and glucose were not detected. Further, increased (P < .05) ultimate pH values and lower (P < .05) lactate accumulations were noted when samples from grass-fed cattle were subjected to an in vitro glycolysis system. Muscle from grass-fed beef possessed nearly two-fold more (P < .05) succinate dehydrogenase and (P < .001) myoglobin than that of grain-fed cattle. These data show lean from grass-fed beef has greater enzymes reflective of oxidative metabolism and suggest dark lean from grass-fed cattle may be a function of more oxidative metabolism rather than a stress-related event antemortem.

Chronic activation of AMP-activated protein kinase increases monocarboxylate transporter 2 and 4 expression in skeletal muscle.

Acute activation of AMP-activated protein kinase (AMPK) increases monocarboxylate transporter (MCT) expression in skeletal muscle. However, the impact of chronic activation of AMPK on MCT expression in skeletal muscle is unknown. To investigate, MCT1, MCT2, and MCT4 mRNA expression and protein abundance were measured in the longissimus lumborum (glycolytic), masseter (oxidative), and heart from wild-type (control) and AMPK γ3 pigs. The AMPK γ3 gain in function mutation results in AMPK being constitutively active in glycolytic skeletal muscle and increases energy producing pathways. The MCT1 and MCT2 mRNA expression in muscle was lower ( < 0.05) from both wild-type and AMPK γ3 animals compared to other tissues. However, in both genotypes, MCT1 and MCT2 mRNA expression was greater ( < 0.05) in the masseter than the longissimus lumborum. The MCT1 protein was not detected in skeletal muscle, but MCT2 was greater ( < 0.05) in muscles with an oxidative muscle phenotype. Monocarboxylate transporter 2 was also detected in muscle mitochondria and may explain the differences between muscles. The MCT4 mRNA expression was intermediate among all tissues tested and greater ( < 0.05) in the longissimus lumborum than the masseter. Furthermore, MCT4 protein expression in the longissimus lumborum from AMPK γ3 animals was greater ( < 0.05) than in the longissimus lumborum from wild-type animals. In totality, these data indicate that chronic AMPK activation simultaneously increases MCT2 and MCT4 expression in skeletal muscle.

Muscle characteristics only partially explain color variations in fresh hams.

Fresh hams display significant lean color variation that persists through further processing and contributes to a less desirable cured product. In an attempt to understand the underlying cause of this color disparity, we evaluated the differences in muscle characteristics and energy metabolites across semimembranosus (SM) muscles differing in color variation. The L* (lightness) and a* (redness) values were highest and lowest (P<0.001), respectfully in the most caudal aspects of the muscle while the ultimate pH was the lowest (P<0.001). Correspondingly, this region possessed highest (P<0.01) glycolytic potential (GP) and lactate dehydrogenase (LDH) levels but did not differ in the amount of myoglobin or myosin heavy chain type I isoform. These data show that differences in muscle may contribute to ham color variation but suggest other factors may mitigate or exacerbate these variances.

Pectoralis major muscle of turkey displays divergent function as correlated with meat quality.

Fresh turkey meat color is determined by many factors that include muscle fiber type composition and heme protein concentrations. These factors either are affected by or influence biochemical events occurring postmortem. Deviations in the processing environment also can result in aberrant fresh meat quality and may ultimately change the quality characteristics of further processed products. Our objective was to describe the underlying cause and significance of the two-toning color defect in fresh turkey breast. In the first experiment, pectoralis major muscles were collected, classified as single- or two-toned, and analyzed using image processing to characterize fresh turkey color. Samples from the large and small lobes of the pectoralis major muscle were collected for pH, glycolytic intermediates, protein abundance, mRNA expression, and quality characteristics. In the second experiment, time from stun to exsanguination was tested as a promoter of fresh turkey color. Results from the first experiment showed that the turkey breast possesses two distinct lobes. The large lobe had greater (P < 0.05) glycolytic potential, lactate content, lactate dehydrogenase (LDH) abundance, and centrifugal drip loss, while pH, myoglobin mRNA expression, and soluble protein levels were lower (P < 0.05) compared to the small lobe. Results from the second experiment showed that reducing time from stun to exsanguination enhanced (P < 0.05) fresh turkey color by mitigating the differences between the two lobes. Our results also showed that birds exsanguinated first had greater (P < 0.05) muscle pH values and body temperatures. These results show inherent differences in breast muscle and processing conditions interact to establish variations in fresh turkey color.

BAP guidelines on the management of weight gain, metabolic disturbances and cardiovascular risk associated with psychosis and antipsychotic drug treatment.

Excess deaths from cardiovascular disease are a major contributor to the significant reduction in life expectancy experienced by people with schizophrenia. Important risk factors in this are smoking, alcohol misuse, excessive weight gain and diabetes. Weight gain also reinforces service users' negative views of themselves and is a factor in poor adherence with treatment. Monitoring of relevant physical health risk factors is frequently inadequate, as is provision of interventions to modify these. These guidelines review issues surrounding monitoring of physical health risk factors and make recommendations about an appropriate approach. Overweight and obesity, partly driven by antipsychotic drug treatment, are important factors contributing to the development of diabetes and cardiovascular disease in people with schizophrenia. There have been clinical trials of many interventions for people experiencing weight gain when taking antipsychotic medications but there is a lack of clear consensus regarding which may be appropriate in usual clinical practice. These guidelines review these trials and make recommendations regarding appropriate interventions. Interventions for smoking and alcohol misuse are reviewed, but more briefly as these are similar to those recommended for the general population. The management of impaired fasting glycaemia and impaired glucose tolerance ('pre-diabetes'), diabetes and other cardiovascular risks, such as dyslipidaemia, are also reviewed with respect to other currently available guidelines.These guidelines were compiled following a consensus meeting of experts involved in various aspects of these problems. They reviewed key areas of evidence and their clinical implications. Wider issues relating to primary care/secondary care interfaces are discussed but cannot be resolved within guidelines such as these.

Thermogelling bioadhesive scaffolds for intervertebral disk tissue engineering: preliminary in vitro comparison of aldehyde-based versus alginate microparticle-mediated adhesion.

Tissue engineering of certain load-bearing parts of the body can be dependent on scaffold adhesion or integration with the surrounding tissue to prevent dislocation. One such area is the regeneration of the intervertebral disc (IVD). In this work, poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to generate an injectable polymer that can form covalent bonds with tissue upon contact. However, the presence of the reactive aldehyde groups can compromise the viability of encapsulated cells. Thus, liposomes were encapsulated in the blend, designed to deliver the ECM derivative, gelatin, after the polymer has adhered to tissue and reached physiological temperature. This work is based on the hypothesis that the discharge of gelatin will enhance the biocompatibility of the material by covalently reacting with, or "end-capping", the aldehyde functionalities within the gel that did not participate in bonding with tissue upon contact. As a comparison, formulations were also created without CS aldehyde and with an alternative adhesion mediator, mucoadhesive calcium alginate particles. Gels formed from blends of PNIPAAm-g-CS and CS aldehyde exhibited increased adhesive strength compared to PNIPAAm-g-CS alone (p<0.05). However, the addition of gelatin-loaded liposomes to the blend significantly decreased the adhesive strength (p<0.05). The encapsulation of alginate microparticles within PNIPAAm-g-CS gels caused the tensile strength to increase twofold over that of PNIPAAm-g-CS blends with CS aldehyde (p<0.05). Cytocompatibility studies indicate that formulations containing alginate particles exhibit reduced cytotoxicity over those containing CS aldehyde. Overall, the results indicated that the adhesives composed of alginate microparticles encapsulated in PNIPAAm-g-CS have the potential to serve as a scaffold for IVD regeneration.

Altered AMP deaminase activity may extend postmortem glycolysis.

Postmortem energy metabolism drives hydrogen accumulation in muscle and results in a fairly constant ultimate pH. Extended glycolysis results in adverse pork quality and may be possible with greater adenonucleotide availability postmortem. We hypothesized that slowing adenonucleotide removal by reducing AMP deaminase activity would extend glycolysis and lower the ultimate pH of muscle. Longissimus muscle samples were incorporated into an in vitro system that mimics postmortem glycolysis with or without pentostatin, an AMP deaminase inhibitor. Pentostatin lowered ultimate pH and increased lactate and glucose 6-phosphate with time. Based on these results and that AMPK γ3(R200Q) mutated pigs (RN⁻) produce low ultimate pH pork, we hypothesized AMP deaminase abundance and activity would be lower in RN⁻ muscle than wild-type. RN⁻ muscle contained lower AMP deaminase abundance and activity. These data show that altering adenonucleotide availability postmortem can extend postmortem pH decline and suggest that AMP deaminase activity may, in part, contribute to the low ultimate pH observed in RN⁻ pork.

Effects of AMP-activated protein kinase (AMPK) signaling and essential amino acids on mammalian target of rapamycin (mTOR) signaling and protein synthesis rates in mammary cells.

Regulation of mammary protein synthesis potentially changes the relationships between AA supply and milk protein output represented in current nutrient requirement models. Glucose and AA regulate muscle protein synthesis via cellular signaling pathways involving mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK). The objective of this study was to investigate the effects of essential AA (EAA) and acetate or glucose on mTOR and AMPK signaling pathways and milk protein synthesis rates. A bovine mammary epithelial cell line, MAC-T, was subjected to different media containing 0 or 3.5 mmol/L EAA concentrations with 0 or 5 mmol/L acetate or 0 or 17.5 mmol/L glucose in 2 separate 2 × 2 factorial studies. In a separate set of experiments, lactogenic bovine mammary tissue slices were subjected to the same treatments except that the low EAA treatment contained a low level of EAA (0.18 mmol/L). Supplementation of EAA enhanced phosphorylation of mTOR (Ser2448) and eukaryotic initiation factor 4E binding protein 1 (4EBP1, Thr37/46), and reduced phosphorylation of eukaryotic elongation factor 2 (eEF2, Thr56) in MAC-T cells. Concentration of ATP and phosphorylation of AMPK increased and decreased, respectively, in the presence of EAA in MAC-T cells. Acetate, EAA, or glucose numerically reduced AMPK phosphorylation by about 16% in mammary tissue slices. Provision of EAA increased phosphorylation of mTOR and 4EBP1, intracellular total EAA concentration, and casein synthesis rates in mammary tissue slices, irrespective of the presence of acetate or glucose in the medium. Phosphorylation of mTOR had a marginally negative association with AMPK phosphorylation, which was positively related to eEF2 phosphorylation. Casein synthesis rates were positively and more strongly linked to mTOR phosphorylation than the negative link between eEF2 phosphorylation and casein synthesis rates. A 100% increase in mTOR phosphorylation was associated with an increase in the casein synthesis rate of 0.74%·h(-1), whereas a 100% increase in eEF2 phosphorylation was related to a decline in the casein synthesis rate of 0.33%·h(-1). Although AMPK phosphorylation was responsive to cellular energy status and had a negative effect on mTOR-mediated signals in bovine mammary epithelial cells, its effect on milk protein synthesis rates appeared to be marginal compared with the mTOR-mediated regulation of milk protein synthesis by EAA.

Exploring the unknowns involved in the transformation of muscle to meat.

Meat quality development, or the transformation of muscle to meat, involves a myriad of biochemical pathways that are largely well-studied in living muscle tissue. However, these pathways are less predictable when homeostatic ranges are violated. In addition, there is far less known about how various management or environmental stimuli impact these pathways, either by substrate load or altered cellular environment. Likewise, it is largely accepted that oxygen plays little to no role in the conversion of muscle to meat, as anaerobic metabolism predominates in the muscle tissue. Even so, the oxygen tension within the tissues does not fall precipitously at exsanguination. Therefore, transition to an anaerobic environment may impact energy metabolism postmortem. Antemortem handling, on the other hand, clearly impacts meat quality development, yet the exact mechanisms remain a mystery. In this paper, we will attempt to review those factors known to affect postmortem energy metabolism in muscle and explore those areas where additional work may be fruitful.

Incidence and costs of severe hypoglycaemia requiring attendance by the emergency medical services in South Central England.

AIMS: The aim was to estimate the incidence of severe hypoglycaemia requiring emergency ambulance assistance, its management and associated costs. METHODS: A retrospective observational study used routinely collected data for a 1-year period from December 2009 to November 2010 from the South Central Ambulance Service National Health Service Trust, UK. The main outcome was episodes reported by ambulance personnel and costs were estimated from published data. RESULTS: During the 1-year study period, 398,409 emergency calls were received, of which 4081 (1.02%) were coded as hypoglycaemia. The overall numbers (and annual rate) of hypoglycaemia recorded among people ≥ 15 years with presumed diabetes was 3962 (2.1%), but for those aged 15-35 years was 516 (7.5%) and for those aged ≥ 65 years was 1886 (1.9%). Of those attended, 1441 (35.3%) were taken to hospital. The estimated total cost of initial ambulance attendance and treatment at scene was £553,000; if transport to hospital was necessary, the additional ambulance costs were £223,000 plus emergency department costs of £140,000; and the cost of primary care follow-up was estimated as £61,000. The average cost per emergency call was £263. The estimated annual cost of emergency calls for severe hypoglycaemia is £13.6m for England. CONCLUSIONS: Our estimates suggest prevalence of severe hypoglycaemia attended by the emergency services is high in younger age groups and lower for older age groups, although the absolute numbers of severe events in older age groups contribute substantially to the overall costs of providing emergency assistance for hypoglycaemia.

Postmortem titin proteolysis is influenced by sarcomere length in bovine muscle.

The calpain protease system, in particular, µ-calpain is involved in the disassembly of specific myofibrillar proteins, resulting in tenderization of meat postmortem. Given the size, complexity, and integral nature of titin to the structure of the sarcomere, it is plausible that the length of a sarcomere may alter the susceptibility of various domains of titin to cleavage by the calpains. Therefore, we hypothesized titin degradation differs in a sarcomere-length-dependent manner in beef. After slaughter, beef carcasses were split and sides were either suspended by the Achilles tendon (normal suspension, NS) or by the aitchbone (hip suspension, HS). Immediately after suspension, samples were dissected from the LM, psoas major (PM), and semitendinosus (STN) muscles to serve as 0-d controls. After 24 h, 4 steaks were removed from each muscle and randomly assigned to 1-, 4-, 7-, or 10-d aging treatments. After the assigned aging period, myofibrils were purified for determination of sarcomere length. Warner-Bratzler shear force analysis was also performed to evaluate differences in tenderness. Muscle proteins were solubilized and subjected to SDS-VAGE (vertical agarose gel electrophoresis) to evaluate titin degradation. Sarcomere lengths differed (P < 0.0001) between contralateral muscles of NS and HS carcasses. Quantification of SDS-VAGE gels revealed less (P < 0.05) intact titin in the PM muscle of NS carcasses at each aging period compared with the PM of HS carcasses. No significant differences (P > 0.05) were detected in the disappearance of intact titin among suspension methods in the LM or STN. These data demonstrate that suspension method alters proteolysis of titin and suggest an increase in sarcomere length may contribute to the susceptibility of titin to postmortem proteolysis in beef.

A field comparison of the IOM inhalable aerosol sampler and a modified 37-mm cassette.

This research focused on comparing a modified 37-mm (Mod37) sampling cassette with an IOM inhalable dust sampler. Paired IOM and Mod37 breathing-zone air samples were collected for workers engaged in corrosion control maintenance operations on several types of aircraft at several U.S. Air Force bases in the United States. Sampled operations included hand and power sanding, blow-down and wipe-down to remove dust, and spray finishing. The cassettes' interior surfaces were swabbed and the swabs combined with the filters for chromium analysis by NIOSH Method 7300. This approach utilized total chromium as a sensitive surrogate indicator of total aspirated mass. The influences of work location, work type, sample duration, and sampler type on measured concentration were evaluated using analysis of variance techniques. Only work type (process) was found to be a statistically significant predictor of measured concentration. The relationship between IOM- and Mod37-measured values for paired samples was evaluated by work type using linear regression techniques. Linear regressions showed that the modified 37-mm cassette over-samples aerosol by 35 percent compared to the IOM when a wide range of aerosol concentrations and compositions for divergent work tasks in multiple field locations are sampled. Interpretation of these results in light of previous results involving filter-only Mod37 analyses suggests that while the Mod37 has a higher aspiration efficiency than the IOM, substantial Mod37 wall losses result in underestimation of exposure when only the 37-mm filter is analyzed rather than filters plus wall swabs.

Erdheim-chester disease.

Erdheim-Chester disease (ECD) is a rare histiocytic infiltrative disease, characterized by long bone sclerosis. We describe two confirmed cases of ECD, both of which demonstrate non-malignant retroperitoneal and peri-renal infiltration causing dilatation of the upper renal tracts. The cases are illustrated with contrast studies, computed tomography (CT) and magnetic resonance imaging (MRI). Typical sclerosis of the long bones was apparent on radiography. Both cases have been treated conservatively to date.A brief review of the literature regarding the manifestations of ECD is included. In cases of non-malignant retroperitoneal infiltration, ECD should be considered as a diagnosis and radiographs of the long bones performed.

A comparison of solid sampler methods for the determination of hexamethylene-based isocyanates in spray-painting operations.

A polyurethane foam sponge impregnated with 1-(2-methoxyphenyl) piperazine in dimethylsulfoxide was mounted in both cassette and inhalable organic monitor samplers and these were then compared with a dual-filter cassette. The samplers were used for the collection of hexamethylene diisocyanate (HDI) monomer and oligomers during actual spray-painting operations. The dual filter cassettes were positioned on a mannequin. The polyurethane foam cassette (PUF CAS) and polyurethane foam inhalable organic monitor (PUF IOM) samplers were positioned on a cart in the same maximum overspray area. Data from this pilot study suggest that there is no significant difference (P < 0.05, n = 6) in the amount of HDI monomer obtained with the PUF IOM sampler when compared with the amount obtained from the dual filter cassette. The data also suggest that the PUF IOM sampler yields a higher amount of HDI oligomer than either the dual filter cassette or the PUF CAS sampler, neither of which exhibited a significant difference (P < 0.05, n = 6) from each other.

Metal exposure among abrasive blasting workers at four U.S. Air Force facilities.

Button Aerosol Samplers were used to monitor the personal exposure of workers performing abrasive blasting operations at four U.S. Air Force facilities. Inhalable aerosols containing 25 metals, including cadmium, lead, and chromium, were investigated. The Button Aerosol Sampler was chosen because of its ability to successfully withstand mechanical stress, prevent very large particles from collection, and protect the filter from overloading and shredding by rebound particles. In addition, previous studies have shown that the sampling efficiency of this personal Aerosol Sampler exhibits low sensitivity to the ambient air conditions and that it adequately follows the inhalability convention. Inductively coupled plasma (ICP) was used to analyze the collected samples for all 25 metals. In addition, visual absorption spectrophotometry (VAS) was used to analyze for hexavalent chromium because of the presence of strontium chromate. The collected samples yielded 8-hr time-weighted average (TWA) concentrations that were up to 250, 6, and 5 times higher than the permissible exposure limits (PELs) for cadmium, lead, and hexavalent chromium, respectively. Also, the chromium levels measured by the ICP and VAS exceeded the strontium chromate threshold limit value (TLV) by up to 640 and 950 times, respectively. No correlation was found between the ICP and VAS hexavalent chromium concentrations. The likely reasons of this were the presence of Cr (II) and (III) that cannot be detected by the VAS, and the chemical interference from iron and some other metals in the samples. The Button Aerosol Sampler was shown to be useful for the monitoring of workers' exposure to heavy metals during abrasive blasting operations.

Exposures to 1,6-hexamethylene diisocyanate during polyurethane spray painting in the U.S. Air Force.

1,6-Hexamethylene diisocyanate (HDI) exposures were measured during polyurethane enamel spray painting at four Air Force bases. Breathing zone samples were collected for HDI monomer and polyisocyanates (oligomers) using three sampling methods: NIOSH Method 5521, the Iso-Chek sampler, and the total aerosol mass method (TAMM). Exposures to HDI monomer are low when compared to current occupational exposure limits; the highest 8-hr time-weighted average (TWA) exposure found was 3.5 micrograms/m3, below the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 34 micrograms/m3. HDI oligomer levels were higher; mean task exposures indicated by either the Iso-Chek sampler or TAMM are above the Oregon ceiling limit of 1 mg/m3. Eight-hour TWA exposures, however, were much lower, with only one exceeding the Oregon standard of 0.5 mg/m3. Poor worker practices commonly observed during this study included: standing in downwind positions so paint overspray passed through breathing zones; spraying toward other painters; and using excessive paint spray gun air cap pressures. Workers should stand in upwind orientation relative to the aircraft being painted, causing overspray to move away from the painter's breathing zone; adjust their position to prevent spraying other painters or limit paint application to one worker at a time; and use air cap pressure gauges prior to spraying to limit spray gun air cap pressures and reduce paint overspray generation rates. These improved techniques will result in reduced worker exposures to isocyanates.

Comparison of sampling methods for monomer and polyisocyanates of 1,6-hexamethylene diisocyanate during spray finishing operations.

A comparison study of isocyanate sampling methods for 1,6-hexamethylene diisocyanate (HDI) monomer and HDI-based polyisocyanates was conducted in spray painting environments. This study compared the performance of the Iso-chek sampler against existing and proposed National Institute of Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) monitoring methods for HDI-based isocyanates. Six methods for monitoring HDI monomer and polyisocyanate levels were compared. Fifty-eight sampling sets were collected during spray painting of aircraft and aircraft parts at four U.S. Air Force bases. Impinger and cassette samplers were mounted side-by-side on a mannequin located in paint overspray areas. For HDI monomer sampling results, there were no significant differences between NIOSH 5521, NIOSH 5522, OSHA 42, MAP (the proposed NIOSH method), and the Iso-Chek. For HDI-based polyisocyanates, NIOSH 5522, NIOSH 5521, Iso-Chek, and the Total Aerosol Mass Method (TAMM) were significantly different from one another. There was no significant difference between MAP and the NIOSH 5522 polyisocyanate sampling results. This study suggests the Iso-Chek and MAP sampling methods compare favorably with established methods for monitoring in HDI spray painting environments and the Total Aerosol Mass Method provides a reasonable upper boundary for estimating HDI polyisocyanate concentrations. The results also reemphasize aerosol sampling physics and sampler geometries must be carefully considered and appropriate samplers used when measuring exposures in spray paint environments where particulates are of the inhalable size.