Biochemical investigations into the mutagenic potential of 8-oxo-2'-deoxyguanosine using nucleotide analogues.

8-Oxo-2'-deoxyguanosine (OdG) is an abundant DNA lesion produced during oxidative damage to DNA. It can form relatively stable base pairs with both dC and dA that mimic natural dG:dC and dT:dA base pairs, respectively. Thus, when in the template strand, OdG can direct the insertion of either dCTP or dATP during replication, the latter of which can lead to a dG → T transversion. The potential for OdG to cause mutation is dependent on the preference for dCTP or dATP insertion opposite OdG, as well as the ability to extend past the resulting base pairs. The C2-amine and C8-oxygen could play major roles during these reactions since both would lie outside the Watson-Crick cognate base pairs shape in the major groove when OdG base pairs to dA and dC, respectively, and both have the ability to form strong interactions, like hydrogen bonds. To gain a more generalized understanding of how the C2-amine and C8-oxygen of OdG affect its mutagenic potential, the incorporation opposite and extension past seven analogues of dG/OdG that vary at C2 and/or C8 were characterized for three DNA polymerases, including an exonuclease-deficient version of the replicative polymerase from RB69 (RB69), human polymerase (pol) ß, and polymerase IV from Sulfolobus solfataricus P2 (Dpo4). Based on the results from these studies, as well as those from previous studies with RB69, pol ß, Dpo4, and two A-family polymerases, the influence of the C2-amine and C8-oxygen during each incorporation and extension reaction with each polymerase is discussed. In general, it appears that when the C2-amine and the C8-oxygen are in the minor groove, they allow OdG to retain interactions that are normally present during insertion and extension. However, when the two groups are in the major groove, they each tend to form novel active site interactions, both stabilizing and destabilizing, that are not present during insertion and extension with natural DNA.

Evaluation of novel synthetic conditioning polymers for shampoos.

Cationic polymers have traditionally been used in shampoo formulations to impart conditioning properties to hair. In this study, commercial synthetic cationic polymers were investigated using coacervate formation, objective wet comb analysis, silicone deposition and panel studies to determine structure function properties with the goal of developing novel conditioning polymers. New polymers were synthesized and, based on criteria determined in the first part of the study, found to have marginal improvement over existing synthetic cationic conditioning polymers. A novel experimental polymer developed for a different industry was also investigated for conditioning properties. This polymer showed significant enhancement of silicone deposition over current commercial polymers, including cationic guar, even at significantly reduced silicone and polymer concentrations. The experimental polymer exhibited parity or improvement over benchmark polymers in panel studies, and similar performance to other synthetic polymers in objective wet comb studies.

High throughput workflow for coacervate formation and characterization in shampoo systems.

Cationic cellulosic polymers find wide utility as benefit agents in shampoo. Deposition of these polymers onto hair has been shown to mend split-ends, improve appearance and wet combing, as well as provide controlled delivery of insoluble actives. The deposition is thought to be enhanced by the formation of a polymer/surfactant complex that phase-separates from the bulk solution upon dilution. A standard characterization method has been developed to characterize the coacervate formation upon dilution, but the test is time and material prohibitive. We have developed a semi-automated high throughput workflow to characterize the coacervate-forming behavior of different shampoo formulations. A procedure that allows testing of real use shampoo dilutions without first formulating a complete shampoo was identified. This procedure was adapted to a Tecan liquid handler by optimizing the parameters for liquid dispensing as well as for mixing. The high throughput workflow enabled preparation and testing of hundreds of formulations with different types and levels of cationic cellulosic polymers and surfactants, and for each formulation a haze diagram was constructed. Optimal formulations and their dilutions that give substantial coacervate formation (determined by haze measurements) were identified. Results from this high throughput workflow were shown to reproduce standard haze and bench-top turbidity measurements, and this workflow has the advantages of using less material and allowing more variables to be tested with significant time savings.

Use of limb movement sensors as indicators of the level of everyday physical activity in chronic congestive heart failure.

The level of everyday physical activity of patients with chronic congestive heart failure (CHF) may be an important reflection of their quality of life. Everyday physical activity is difficult to measure objectively, and may not relate to exercise capacity determined by laboratory exercise testing. A light-weight sensor worn on the wrist or ankle, which provides a cumulative record of limb movement, was evaluated. The sensor counted reliably when tested in a laboratory rig and during treadmill exercise. In 20 young normal subjects, hourly movement scores showed the expected diurnal rhythm. Twenty-four-hour movement scores in 30 patients with stable CHF were lower than in 20 age-matched control subjects (p less than 0.005). Movement scores in CHF correlated with a standard questionnaire scale assessing everyday physical activity (R = +0.72, p less than 0.001). Consecutive daily scores varied widely, but wrist and ankle scores were correlated (R greater than +0.7, p less than 0.05 in each subject), suggesting true day-to-day differences in activity rather than variability in the recording method. Recording for 5 to 6 consecutive days provides a reliable estimate of mean 24-hour movement score for a subject, and mean 24-hour scores were reproducible when subjects were retested after 8 weeks. There was a weak correlation between movement scores and exercise capacity as measured by peak oxygen consumption during maximal treadmill exercise (R = +0.42, p = 0.01). Quality-of-life score correlated with movement scores (R = +0.53, p less than 0.002) but not with peak oxygen consumption (R = +0.36; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Glutaraldehyde permeation: choosing the proper glove.

Six different gloves were tested with five different aqueous glutaraldehyde formulations to determine each glove's resistance to permeation. When tested against 2% or 3.4% glutaraldehyde solutions, nitrile rubber, butyl rubber, a synthetic surgical glove, and polyethylene were each impermeable for at least 4 hours. The two latex gloves tested showed glutaraldehyde breakthrough at 45 minutes. When the latex gloves were doubled, the time to first breakthrough increased to 3 to 4 hours. With 50% glutaraldehyde, only butyl rubber and nitrile rubber were impermeable for extended periods. The surgical synthetic glove had breakthrough at 1 hour, whereas polyethylene and the two latex gloves had breakthrough in less than 1 hour.

Evaluation of Roche Diagnostics ONLINE DAT II, a new generation of assays for the detection of drugs of abuse.

A new generation of ONLINE assays has been developed that offers improved performance and enhanced ease of use. This family of assays is being applied to both the COBAS INTEGRA and Roche/Hitachi line of analyzers. The four ONLINE DAT II assays that were evaluated included cocaine (benzoylecgonine) (BE), methadone (MDN), opiates (OP), and tetrahydrocannabinol (THC). The BE assay has a dual cutoff (150/300 ng/mL) with a dynamic range from 0 to 5000 ng/mL. The MDN assay has a cutoff of 300 ng/mL with a dynamic range from 0 to 2000 ng/mL. The opiates assay has a 300 ng/mL cutoff with a 0 to 2000 ng/mL range and a 2000 ng/mL cutoff with a 0 to 8000 ng/mL range. The THC assay has 20, 50, and 100 ng/mL cutoffs with 0 to 100, 0 to 300, and 0 to 300 ng/mL dynamic ranges, respectively. The ranges of the intra-assay precision (coefficients of variation for n = 20) run in the semiquantitative mode are 2.3-7.5% for BE, 2.0-3.8% for MDN, 1.9-4.2% for OP, and 3.9-5.2% for THC. The intra-assay qualitative precision for all of the assays as calculated from absorbance values is generally higher than that of the intra-assay semiquantitative precision at the cutoff. The qualitative precision ranges between 0.4% and 3.1%. The standard curve stability defined for the COBAS INTEGRA systems for these reagents ranges from 35 to 68 days. The clinical sensitivity and specificity were compared to the OnLine generation I and CEDIA immunoassays, as well as gas chromatography-mass spectrometry (GC-MS). The results indicate that for each assay, the sensitivity and specificity were the same or greater when compared to the other two immunoassay technologies. The results of each assay also correlated very well (> 99%) when compared with GC-MS.

Superficial vascularity of temporomandibular joint retrodiskal tissue: an element of the internal derangement process.

Superficial vascular changes in the retrodiskal tissue are an aspect of the remodeling process during progressive anterior displacement of the temporomandibular joint (TMJ) disk. The salient portion of the remodeled retrodiskal tissue (RRT) is contained in a 3 x 3 grid of arthroscopic fields in the superior joint space, plus the tympanic portion of the remodeled retrodiskal tissue. A four-level vascularity classification system gives a statistically significant association between superficial avascularity of the remodeled retrodiskal tissue and progressive stages of disk derangement. In particular, simultaneous avascularity in both the tympanic remodeled retrodiskal tissue and the central arthroscopic field occurs with severe disk displacement without reduction. Analyses are based on 16 microscopic studies, 25 magnetic resonance imaging and tomographic imaging studies, and 26 arthroscopic studies.

Geometric considerations of disk repositioning procedures.

One approach to treatment of internal derangements of the temporomandibular joint (TMJ) is surgical remodeling and repositioning of the disk and its attachments. Nine joints exhibiting disk displacements (four histological series and five magnetic resonance imagining (MRI) series) were studied to analyze the geometrical and mechanical implications of surgical repositioning. In the central tomographic plane, for example, these cases would have required repositioning the disk 6.9 mm posteriorly (+/- 3.3 mm), removing 5.2 mm (+/- 1.6 mm) of remodeled retrodiskal tissue, and trimming 2.1 mm (+/- 2.0 mm) of disk. This suggests that from gross geometric considerations alone, there is not sufficient viable joint tissue to recommend disk repositioning as a routine procedure.

The correct use of glutaraldehyde in the healthcare environment.

When using and handling glutaraldehyde-based instrument sterilants, it is important to employ appropriate industrial hygiene practices such as wearing the proper personal protective equipment and installing environmental controls. Every healthcare worker who uses glutaraldehyde, or any disinfectant, should be well trained and knowledgeable about the properties of the material(s), their potential harmful effects, and the cleaning/disinfecting procedures of the healthcare facility and infection control department. Appropriate gloves, gowns, and eye protection should be available and worn. If necessary, additional ventilation should be installed to keep glutaraldehyde vapor concentrations below the Threshold Limit Value (TLV), and respiratory protective equipment should be available for emergency situations. Finally, all employees should be aware of spill clean up procedures, which should include written instructions. By keeping employees well trained and informed and by utilizing good industrial hygiene practices, the chances of overexposure to glutaraldehyde-based instrument sterilants will be minimized, and working conditions will be comfortable and safe.

Toxicological, medical and industrial hygiene aspects of glutaraldehyde with particular reference to its biocidal use in cold sterilization procedures.

Aqueous solutions of > or =5% glutaraldehyde (GA) are of moderate acute peroral toxicity and those of < or =2% are of slight toxicity. By single sustained skin contact, aqueous GA solutions of > or =45% are of moderate acute percutaneous toxicity, those of 25% are of slight toxicity and those of or =5%. Primary skin irritation depends on the duration and contact site, occlusion and solvent. By sustained contact, the threshold for skin irritation is 1%, above which erythema and edema are dose related. With 45% and higher, skin corrosion may occur. There is a low incidence of skin sensitizing reactions, with an eliciting threshold of 0.5% aqueous GA. However, GA is neither phototoxic nor photosensitizing. Subchronic repeated exposure studies by the peroral route show only renal physiological compensatory effects, secondary to reduced water consumption. Repeated skin contact shows only minor skin irritant effects without systemic toxicity. By subchronic vapor exposure, effects are limited to the nasal mucosa at 1.0 ppm, with a no-effect concentration generally at 0.1 ppm. There is no evidence for systemic target organ or tissue toxicity by subchronic repeated exposure by any route. A chronic drinking water study showed an apparent increase, in females only, of large granular cell lymphocytic leukemia but this was not dosage related. This is most likely the result of a modifying effect on the factor(s) responsible for the expression of this commonly occurring rat neoplasm. A chronic (2-year) inhalation toxicity/oncogenicity study showed inflammatory changes in the anterior nasal cavity but no neoplasms or systemic toxicity. In vitro genotoxicity studies--bacterial mutagenicity, forward gene mutation (HGPRT and TK loci), sister chromatid exchange, chromosome aberration, UDS and DNA repair tests--have given variable results, ranging from no effect through to weak positive. In vivo genotoxicity studies--micronucleus, chromosome aberration, dominant lethal and Drosophila tests--generally have shown no activity but one mouse intraperitoneal study showed bone marrow cell chromosome aberrations. Developmental toxicity studies show GA not to be teratogenic, and a two-generation study showed no adverse reproductive effects. Percutaneous pharmacokinetic studies showed low skin penetration, with lowest values measured in vitro in rats and human skin. Overexposure of humans produces typical sensory irritant effects on the eye, skin and respiratory tract. Some reports have described an asthmatic-like reaction by overexposure to GA vapor. In most cases this resembles reactive airways dysfunction syndrome, and the role of immune mechanisms is uncertain. Local mucosal effects may occur if medical instruments or endoscopes are not adequately decontaminated. Protection of individuals from the potential adverse effects of GA exposure requires that there be adequate protection of the skin, eyes and respiratory tract. The airborne concentration of GA vapor should be kept below the recommended safe exposure level (e.g. the threshold limit value) by the use of engineering controls. Those who work with GA should, through a training program, be aware of the properties of GA, its potential adverse effects, how to handle the material safely and how to deal with accidental situations involving GA. If effects develop in exposed workers, the reasons should be determined immediately and corrective methods initiated. (c) 2001 John Wiley & Sons, Ltd.

The resolvase protein from the transposon Tn21.

The tac promoter was inserted into Tn21 upstream of the tnpR gene and the resultant plasmid was used to generate substantial amounts of resolvase. This protein was purified to homogeneity. The protein was characterized by amino acid sequence studies (which showed that an open-reading frame previously identified by DNA sequencing had been correctly assigned to the tnpR gene) and by molecular weight measurements (which demonstrated that the only active for of the protein in solution was dimeric). Pure Tn21 resolvase catalysed site-specific recombinations between directly repeated res sites from Tn21 or Tn1721 but not from Tn3 nor on inverted res sites from Tn21.

Site-specific recombination and topoisomerization by Tn21 resolvase: role of metal ions.

The resolvase from the transposon Tn21 catalyses site-specific recombination between the two res sites on its DNA substrate both in the absence and presence of Mg2+ ions. This contrasts with reports on the resolvase from gamma-delta (Tn1000) and on other recombinational proteins that are homologous to Tn21 resolvase but which need Mg2+ for their activity. Magnesium ions could enhance the activity of Tn21 resolvase, as did a number of other cations but some metal ions such as Ni2+ inhibit recombination. The metal ions are not directly involved in the catalytic process but probably affect recombination by altering the conformation of the DNA. Tn21 resolvase relaxes its DNA substrate in the presence and in the absence of Mg2+, and also in ionic conditions that inhibit recombination. Hence, the topoisomerization reflects an activity of resolvase that is distinct from recombination. However, the two activities are functions of the same DNA-protein complex. The complex contains about 6 molecules of the resolvase dimer per molecule of DNA.

Inactivation and injury of pressure-resistant strains of Escherichia coli O157 and Listeria monocytogenes in fruit juices.

AIMS: To investigate methods for inactivating a pressure-resistant strain of Escherichia coli O157 in fruit juices. METHODS AND RESULTS: Cells of a pressure-resistant strain of E. coli O157 (C9490) were exposed to pressures of between, 0.1 and 500 MPa for 5 min in orange, apple or tomato juice. Treatment at 500 MPa achieved an immediate reduction of 5 log units in apple juice (pH 3.5) and tomato juice (pH 4.1), but only about a 1-2 log10 reduction in orange juice (pH 3.8). The greater level of inactivation in tomato juice than in orange juice of lower pH was due to the presence of low levels (0.7%) of salt in the tomato juice. With the type-strain of E. coli (ATCC 11775) and Listeria monocytogenes NCTC 11994, similar levels of inactivation were achieved at pressures 200 MPa lower. Following storage of pressure-treated orange juice at 4 degrees C for 24 h or 25 degrees C for 3 h, the level of inactivation of E. coli O157 strain C9490 increased to 4.4 or > 7 log10 units, respectively. CONCLUSION: Treatment at 500 MPa may be insufficient to achieve a '5D' reduction in counts of pressure-resistant strains of E. coli, but subsequent death during storage substantially increases process lethality. SIGNIFICANCE AND IMPACT OF THE STUDY: Commercially-practicable pressure processes can be used to inactivate even the most pressure-and acid-resistant strains of E. coli O157, provided that processing and subsequent storage conditions are carefully optimized.

Radiological evaluation of bone status in the jaw and in the vertebral column in a group of women.

Vertebral bone mineral content was determined in a group of 56 women, ages 30-62. These measurements were compared with the status of supporting bone in the jaws (alveolar, molar and bicuspid) and with gingival health. There was a significant decline in vertebral bone mineral content from the pre- to post-menopausal group. Molar and bicuspid measurements were highly correlated. There was some association between lumbar bone mineral content and molar bone status for postmenopausal women. For postmenopausal women, the cases of greatest percent bone loss in alveolar crest were associated with lower lumbar bone mineral content. Gingival health did not confound the bone status measurements. The 56 subjects did not exhibit the degree of reduction in bone density that is observed in the general population. Further investigation using these radiographic techniques may reveal a link between substantial bone loss in the jaw and moderate to severe bone loss in the lumbar vertebrae.

Facial muscle reanimation using the trigeminal motor nerve: an experimental study in the rabbit.

Surgical repair of facial nerve deficits may be marred by lack of muscle control and donor region paresis. Using New Zealand white rabbits, a study was undertaken to evaluate facial muscle reanimation with a donor source not previously used: the motor division of the trigeminal nerve. The results were compared with the severed facial nerve and hypoglossal-facial coaptation. An atrophy scale was calibrated for facial muscles of the rabbit. Clinical, electromyographic, and histomorphometric findings confirmed that the trigeminal nerve was a suitable donor source. The neurorrhaphy produced an exponential rate of repair.

Inhaled bronchodilators increase maximum oxygen consumption in chronic left ventricular failure.

Bronchoconstriction is seen at rest in patients with chronic heart failure, and may contribute towards exercise limitation. To investigate the effect of bronchodilator agents on exercise capacity, 10 patients (mean age 60 years, range 39-72) in New York Heart Association class II and III heart failure, underwent symptom-limited maximal exercise testing after inhalation of nebulized salbutamol (5 mg), ipratropium bromide (500 micrograms) or placebo delivered on separate days in a randomized, double-blinded study. There was an increase in forced expiratory volume in one second from pre-treatment to after nebulizer, 2.28 +/- 0.20 to 2.38 +/- 0.19 l (P < 0.05) with salbutamol, and 2.27 +/- 0.21 to 2.37 +/- 0.21 l (P < 0.05) with ipratropium bromide. There was an increase in maximal oxygen consumption after salbutamol 17.9 +/- 1.3 ml.kg-1.min-1 (P < 0.05) and ipratropium bromide 17.0 +/- 1.4 ml.kg-1.min-1 (P < 0.05), compared with placebo 16.3 +/- 1.4 ml.kg-1.min +/- 1. Peak minute ventilation during exercise also increased after salbutamol 52.8 +/- 4.5 l.min-1 (P < 0.05), compared with placebo 46.1 +/- 3.1 l.min-1. The small but significant increase in exercise capacity in chronic heart failure following bronchodilator agents implies that a degree of bronchoconstriction is present in these patients and contributes to exercise limitation.

Inactivation of glutaraldehyde by reaction with sodium bisulfite.

The microbiocidal activity of glutaraldehyde was inactivated by reaction with sodium bisulfite via formation of a proposed glutaraldehyde-bisulfite complex. High-performance liquid chromatography (HPLC) analysis of 2% (0.2M) alkaline glutaraldehyde indicated complete loss of glutaraldehyde at a 2.2:1 molar ratio of sodium bisulfite to glutaraldehyde. Neither 1.7% (0.17 M) sodium bisulfite alone nor the glutaraldehyde-bisulfite complex was microbiocidal when tested against Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, and Polybac Polyseed BOD seed inoculum. Bacterial inhibition tests indicated that the glutaraldehyde-sodium bisulfite complex had no effect on the growth of sewage microorganisms at concentrations as high as 50-100 ppm (5 x 10(-4)-1 x 10(-3) M), with an IC50 of 230-440 ppm (2.3 x 10(-3)-4.4 x 10(-3) M), based on glutaraldehyde concentration. A 28-close bottle test showed a 5-d biodegradation of 48% and 51%, and a 15-d biodegradation of 57% and 63% for 3:1 and 2.2:1 bisulfite to glutaraldehyde molar ratios, respectively. Acute aquatic toxicity testing with Daphnia magna demonstrated an LC50 of 41-109 ppm (4.1 x 10(-4)-10.9 x 10(-4) M) and a no-observed-effect concentration (NOEC) of 16 ppm (1.6 x 10(-4) M) for the proposed glutaraldehyde-bisulfite complex (based on glutaraldehyde concentration), approximately 10-fold higher than found for glutaraldehyde alone, indicating that the proposed glutaraldehyde-bisulfite complex is less toxic to the environment than glutaraldehyde.

Short-stepping gait in severe heart failure.

BACKGROUND: Patients with severe chronic heart failure seem to take shorter steps than healthy controls when walking on a treadmill and when walking freely along a corridor. In healthy individuals the pattern of walking affects the oxygen cost of exercise, and so this observation might be relevant to the limitation of exercise in heart failure. METHOD: Length of stride was analysed as stride/stature index in 15 controls, 10 patients with moderate heart failure, 10 patients with severe heart failure, and 10 patients with angina, walking at a constant speed/stature index. RESULTS: The stride/stature index was 0.64 in the controls in patients with New York Heart Association (NYHA) class II heart failure, and in patients with angina. It was 0.49 in patients with NYHA class III heart failure. In the patients with heart failure the stride/stature index correlated with exercise capacity determined as peak oxygen consumption VO2max (R = +0.62, p < 0.005). When healthy controls walked in time to a metronome adjusted to decrease their stride/stature index to approximately that seen in severe heart failure steady-state oxygen consumption increased by a mean of 15%. CONCLUSIONS: The length of stride is reduced in severe heart failure, and when healthy controls adopt this gait the oxygen cost of walking is increased. A short-stepping gait may contribute to the limitation of exercise capacity in heart failure.

Abnormal diastolic filling patterns in chronic heart failure--relationship to exercise capacity.

Abnormal patterns of diastolic ventricular filling are well recognized in chronic heart failure, but their relationship to the severity of heart failure is not known. The present study evaluates the relationship of diastolic filling indices to the severity of heart failure and to exercise capacity. In 40 patients with chronic heart failure secondary to ischaemic left ventricular impairment, exercise capacity was measured as peak oxygen consumption (VO2max) by progressive treadmill exercise. Left ventricular function was assessed by M-mode and Doppler echocardiographic indices. Peak aortic velocity correlated weakly with VO2max (R = +0.38, P less than 0.05). VO2max did not correlate with other systolic indices, including mean aortic acceleration, time to peak velocity, or isovolumic contraction time. VO2max correlated with the mitral inflow E/A ratio (R = -0.57, P less than 0.005) and with the Doppler estimate of isovolumic relaxation time (R = -0.48, P less than 0.01). Two distinct patterns of diastolic filling were observed: subjects with mild-to-moderate heart failure (NYHA grade II, VO2max 15-20 ml.kg-1.min-1) had abnormally low E/A ratios and long isovolumic relaxation times, whereas those with severe heart failure (NYHA grade III-IV, VO2max less than 12 ml.kg-1.min-1) had abnormally high E/A ratios and short isovolumic relaxation times. Different patterns of abnormal diastolic filling with different degrees of severity of heart failure may explain some of the previous controversy as to the prevalence of abnormal diastolic function in chronic heart failure. Exercise capacity in chronic heart failure appears more closely related to abnormalities of diastolic filling pattern than to indices of systolic function.

Laboratory and hospital evaluation of four personal monitoring methods for glutaraldehyde in ambient air.

Four industrial hygiene monitoring methods were studied in the laboratory and in a hospital to evaluate their effectiveness in measuring glutaraldehyde concentrations in ambient air. The sampling devices evaluated included a silica gel tube, a direct reading handheld glutaraldehyde meter, a DNPH- (2,4-dinitrophenylhydrazine) impregnated passive diffusion badge, and a DNPH-impregnated filter cassette. The accuracy and precision of the different methods were determined in the laboratory. The methods were evaluated using dynamically generated glutaraldehyde air concentrations over the range of 0.05-0.4 ppm. The badge, silica gel tube, and filter cassette methods were found to be accurate under controlled laboratory conditions. The handheld meter did not respond to the glutaraldehyde test atmospheres. The methods were compared in a hospital environment. During the hospital study the performance of the handheld meter could not be demonstrated because the concentrations of glutaraldehyde were below or only slightly above the manufacturer's stated 0.03 ppm limit of detection. Statistically significant differences were found between the badge, silica gel tube, and filter cassette methods, but the differences were small enough to be acceptable for industrial hygiene monitoring.