Development of a method to determine workers' personal exposure levels to glyphosate.

OBJECTIVES: We aimed to develop a method to determine workers' personal exposure levels to N-(phosphonomethyl)glycine (glyphosate) for their risk assessments. METHODS: The proposed method was assessed as follows: recovery, stability of samples on storage, method limit of quantification, and reproducibility. Glyphosate in air was sampled using an air-sampling cassette containing a glass fiber filter. Ultrapure water was used to extract glyphosate from sampler filters. After derivation with 9-fluorenylmethyloxycarbonyl chloride, samples were analyzed by high-performance liquid chromatography using a fluorescence detector. RESULTS: Spiked samples indicated an overall recovery of 101%. After 7 days of storage at 4°C, recoveries were approximately 100%. The method limit of quantification was 0.060 µg/sample. Relative standard deviations representing overall reproducibility, defined as precision, were 1.4%-1.8%. CONCLUSIONS: The method developed in this study allows 4-h personal exposure monitoring of glyphosate at 0.250-500 µg/m3 . Thus, this method can be used to estimate worker exposure to glyphosate.

Assessment of dermal exposure to N,N-dimethylacetamide in spray workers by combining personal exposure monitoring, biological monitoring, and glove permeation monitoring: A pilot study.

OBJECTIVES: We assessed dermal exposure to N,N-dimethylacetamide (DMAC) in a spray worker by utilizing a combination of personal exposure monitoring, biological monitoring, and glove permeation monitoring. We also determined the protective effects of chemical protective gloves (CPGs). METHODS: Surveys with and without CPG usage were performed on different days. In the survey with CPG usage, the worker had worn leather gloves over the CPG. Personal exposure monitoring and glove permeation monitoring were performed using 3M Organic Vapor Monitor 3500 and PERMEA-TEC Pads respectively. Urinary concentration of DMAC and its metabolites (N-methylacetamide [NMAC], N-hydroxymethyl-N-methylacetamide [DMAC-OH], S-(acetamidomethyl) mercapturic acid [AMMA]) were measured in the before-shift and end-of-shift samples collected from the worker. RESULTS: Personal exposure DMAC concentration in the survey with CPG usage (0.32 ppm) was twice that in the survey without CPG usage (0.15 ppm). However, urinary concentrations of DMAC-OH and AMMA in the end-of-shift samples in the survey with CPG usage (DMAC-OH, 0.74 mg/g creatinine; AMMA, 0.10 mg/g creatinine) were lower than those in the survey without CPG usage (DMAC-OH, 1.27 mg/g creatinine; AMMA, 0.24 mg/g creatinine). Urinary concentrations of DMAC and NMAC were below the limit of detection in all samples. DMAC concentrations in PERMEA-TEC Pads that were used in the surveys with and without CPG usage were in the range of 0.3-2.1 µg/sample and 16.4-1985.2 µg/sample respectively. CONCLUSIONS: The combination of CPG usage and leather gloves was effective in preventing dermal exposure to DMAC.

Evaluation of the ceiling levels of ortho-phthalaldehyde exposure among health care workers engaged in endoscope disinfection: A new methodology using video-exposure monitoring.

OBJECTIVES: The present study aimed to develop a method for measuring the ceiling level of ortho-phthalaldehyde (OPA) exposure and evaluate the ceiling levels of OPA exposure among health care workers who handle disinfectant solutions containing OPA for the disinfection of endoscopes. METHODS: The study consisted of a preliminary survey and main survey. In the preliminary survey, processes involving high-concentration exposure to OPA were identified by video-exposure monitoring (VEM). In the main survey, the ceiling levels of OPA exposure for high-concentration exposure processes identified from the results of the preliminary survey were determined using a measuring method combining sampling using a 2,4-dinitrophenylhydrazine-silica cartridge and analysis by high-performance liquid chromatography tandem mass spectrometry. RESULTS: In the preliminary survey, seven processes involving high-concentration exposure to OPA were identified by VEM. The duration of each process was short, lasting from 20 seconds to a few minutes. In the main survey, the OPA concentrations for the identified high-concentration exposure processes ranged from 1.18 to 4.49 ppb, which markedly exceeded the threshold limit value ceiling (TLV-C) of 0.1 ppb recommended by the American Conference of Governmental Industrial Hygienists. CONCLUSIONS: The method for measuring the ceiling level of OPA exposure was established using VEM and the highly sensitive method of chemical analysis; and we successfully evaluated the ceiling levels of OPA exposure among health care workers engaged in endoscope disinfection. This approach can also be applied to other chemical substances with recommended TLV-Cs, and important information for reducing exposure can thus be obtained.

Simple and reliable method to simultaneously determine urinary 1- and 2-naphthol using in situ derivatization and gas chromatography-mass spectrometry for biological monitoring of naphthalene exposure in occupational health practice.

OBJECTIVES: The aim of this study was to develop and validate a simple and reliable gas chromatography-mass spectrometry (GC-MS) method to simultaneously determine urinary 1-naphthol (1-NAP) and 2-naphthol (2-NAP) for biological monitoring of occupational exposure to naphthalene. METHODS: NAPs were derivatized in situ with acetic anhydride after enzymatic hydrolysis, extracted with n-hexane, and analyzed using GC-MS. Validation of the proposed method was conducted in accordance with US Food and Drug Administration guidance. A final validation was performed by analyzing a ClinChek® -Control for phenolic compounds. RESULTS: The linearity of calibration curves was indicated by a high correlation coefficient (>0.999) in the concentration range 1-100 µg/L for each NAP. The limits of detection and quantification for each NAP were 0.30 and 1.00 µg/L, respectively. The recovery was 90.8%-98.1%. The intraday and interday accuracies, expressed as the deviation from the nominal value, were 92.2%-99.9% and 93.4%-99.9%, respectively. The intraday and interday precision, expressed as the relative standard deviation, was 0.3%-3.9% and 0.4%-4.1%, respectively. The ClinChek® values obtained using our method were sufficiently accurate. CONCLUSIONS: The proposed method is simple, reliable, and appropriate for routine analyses, and is useful for biological monitoring of naphthalene exposure in occupational health practice.

Development of a measurement method to determine the ceiling exposure concentration of ortho-phthalaldehyde handling workers.

OBJECTIVES: The purpose of this research was to develop and validate an analytical method for rapid determination of the exposure of workers to ortho-phthalaldehyde (OPA) at the ceiling threshold concentration. METHODS: A 2,4-dinitrophenylhydrazine (DNPH)-silica cartridge was chosen as a sampler. OPA collected by the DNPH-silica cartridge was subsequently extracted with 5 mL of acetonitrile. A 50-µL aliquot of phosphoric acid/acetonitrile solution (2%, v/v) was added to 950 µL of the extraction solution and allowed to stand for 30 minutes at room temperature. This solution was then analyzed by high-performance liquid chromatography tandem mass spectrometry. The basic characteristics of the proposed method, such as recovery, repeatability, limit of quantification, and storage stability of the samples, were examined. RESULTS: The overall recoveries of OPA from OPA-spiked DNPH-silica cartridges were 93.6%-100.1% with relative standard deviations, representing the repeatability, of 1.5%-10.8%. The limit of quantification was 0.165 ng/sample. The recovery of OPA from DNPH-silica cartridges after 5 days of storage in a refrigerator exceeded 95%. CONCLUSIONS: The proposed method enabled the determination of the OPA concentration corresponding to the Threshold Limit Value-Ceiling of 0.1 ppb recommended by the American Conference of Governmental Industrial Hygienists, with a minimum sampling time of 18 seconds (corresponding to a sampling volume of 300 mL at 25°C and 1 atm). Thus, this method will be useful for estimating worker exposures to OPA.

Acetoaceto-o-Toluidide Enhances Cellular Proliferative Activity in the Urinary Bladder of Rats.

Acetoaceto-o-toluidide (AAOT) is made from ortho-toluidine (OTD) and is used for the synthesis of pigments. A report of occupational urinary bladder carcinomas in Japanese workers chronically exposed to OTD and AAOT has recently been published. OTD is a well-known human urinary bladder carcinogen; however, little is known about the toxicity and the carcinogenicity of AAOT. The aim of the present study is to evaluate the toxic effects of AAOT on urinary bladder epithelium. In vitro, the cytotoxicities of AAOT and OTD were evaluated in rat (MYP3) and human (1T1) urothelial cells. The LC50 of AAOT was higher than that of OTD in both MYP cells and 1T1 cells. In vivo, 6-week-old male and female F344 rats were fed diets supplemented with 0%, 1.5%, or 3% AAOT for 4 weeks. Incidences of simple hyperplasia, cell proliferative activity, and γ-H2AX expression, which is a novel marker for the prediction of carcinogenicity, were significantly increased in a dose-dependent manner in the bladder urothelium of male and female rats administered AAOT. Furthermore, in male and female rats administered AAOT, the major urine metabolite of AAOT was OTD. These results demonstrate that AAOT has proliferation-enhancing activity and suggest that OTD metabolized from AAOT may play a pivotal role in the deleterious effects of AAOT in rats. The results of the present study also indicate that AAOT, like other carcinogenic aromatic amines, is likely to be a human bladder carcinogen.

Direct methyl esterification with 2,2-dimethoxypropane for the simultaneous determination of urinary metabolites of toluene, xylene, styrene, and ethylbenzene by gas chromatography-mass spectrometry.

OBJECTIVES: The purpose of this study was to develop a simple and accurate gas chromatography-mass spectrometry (GC-MS) method for simultaneous determination of four urinary metabolites from four organic solvents, that is, hippuric acid (HA) from toluene, methylhippuric acid (MHA) from xylene, and mandelic acid (MA) and phenylglyoxylic acid (PGA) from styrene or ethylbenzene for biological monitoring. METHODS: The four metabolites were directly methyl-esterified with 2,2-dimethoxypropane and analyzed using GC-MS. The proposed method was validated according to the US Food and Drug Administration guidance. The accuracy of the proposed method was confirmed by analyzing a ClinChek® -Control for occupational medicine (RECIPE Chemicals +Instruments GmbH). RESULTS: Calibration curves showed linearity in the concentration range of 10-1000 mg/L for each metabolite, with correlation coefficients >0.999. For each metabolite, the limits of detection and quantification were 3 mg/L and 10 mg/L, respectively. The recovery was 93%-117%, intraday accuracy, expressed as the deviation from the nominal value, was 92.7%-103.0%, and intraday precision, expressed as the relative standard deviation (RSD), was 1.3%-4.7%. Interday accuracy and precision were 93.4%-104.0% and 1.2%-9.5%, respectively. The analytical values of ClinChek obtained using the proposed method were sufficiently accurate. CONCLUSIONS: The proposed method is a simple and accurate which is suitable for routine analyses that could be used for biological monitoring of occupational exposure to four organic solvents.

Development of a method for monitoring personal exposure to benzyl violet 4B and direct blue 15 in workplace air.

OBJECTIVES: The purpose of this research was to develop a method for monitoring personal exposure to benzyl violet 4B (BV) and direct blue 15 (DB) in workplace air for risk assessment. METHODS: We evaluated the utility of the proposed method by examining the following: recovery; method limit of quantification; reproducibility; and storage stability of the samples. RESULTS: An air sampling cassette containing a glass fiber filter was chosen as the sampler. BV and DB were extracted from the sampler filters with a solution of water and methanol (7:3, v/v) and then analyzed by a high-performance liquid chromatograph equipped with a photo-diode array detector. The overall recoveries from spiked samplers were 94-102% and 94-99% for BV and DB, respectively. The recovery after seven days of storage at 4°C exceeded 95%. The method limits of quantification were 0.250 and 1.25 µg/sample for BV and DB, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.6-4.1% and 0.8-2.9% for BV and DB, respectively. CONCLUSIONS: The proposed method enables 4 h personal exposure monitoring of BV and DB at concentrations of 1-2,000 µg/m3 for BV and 5-2,000 µg/m3 for DB, with a 240 l sampling. Thus, the proposed method is useful for estimating worker exposure to BV and DB.

Evaluation of urinary cyclohexanediols and cyclohexanol as biomarkers of occupational exposure to cyclohexane.

OBJECTIVES: The aim of the present study was to comparatively evaluate the usefulness of urinary cyclohexanediols (CHdiols-U) and cyclohexanol (CHol-U) as biomarkers of occupational exposure to cyclohexane (CH). METHODS: Sixteen subjects (14 men and 2 women) were exposed to CH during proof-printing work. Personal exposure monitoring was conducted during the whole shift on the last working day of the week. The time-weighted average level of exposure to CH (CH-A) was measured using a diffusive sampler. Two urine samples were collected from each worker at different times during the same week: a baseline urine sample (before the first shift of the working week, after a 5-day holiday with no CH exposure) and an end-of-shift urine sample (after the last shift of the same working week, the same day personal exposure monitoring was conducted). CH-A, CHdiols-U and CHol-U were determined using a gas chromatograph-flame ionization detector. RESULTS: The CH-A concentrations ranged from 4.5 to 60.3 ppm, with a geometric mean (GM) of 18.1 ppm. The GMs and ranges (in parenthesis) of the creatinine (cr)-corrected end-of-shift 1,2-CHdiol-U, 1,4-CHdiol-U and CHol-U concentrations were 12.1 (4.1-36.6), 7.5 (2.4-20.1) and 0.4 (0.2-1.0) mg/g cr, respectively. Both CHdiols-U at the end of the shift were significantly correlated with CH-A (correlation coefficients for 1,2-CHdiol-U and 1,4-CHdiol-U of 0.852 and 0.847, respectively). No correlation was observed between CH-A and CHol-U. CONCLUSIONS: CHdiols-U at the end of the last shift of the working week are suitable biomarkers of occupational exposure to CH, but CHol-U is not suitable.

Comparison of the exposure-excretion relationship between men and women exposed to organic solvents.

OBJECTIVES: The present study was initiated to examine if application of the same biological occupational exposure limits (BOELs) for organic solvents is applicable across the sexes. METHODS: A survey was conducted in 69 micro-scale enterprises in a furniture-producing industrial park. In practice, 211 men and 52 women participated in the survey. They worked in a series of production process, and were exposed to solvent vapor mixtures. The exposure intensities were monitored with two types of diffusive samplers, one with carbon cloth (for solvents in general) and the other with water (for methyl alcohol) as adsorbents. Solvents in the adsorbents and head-space air from urine samples were analyzed with capillary FID-GC. The measured values were subjected to linear regression analysis followed by statistical evaluation for possible sex-related differences in slopes. RESULTS: Essentially no significant difference was detected between men and women in regression line parameters including slopes. Possible differences in the cases of acetone and toluene were discussed and excluded. CONCLUSIONS: With the exceptions for acetone and toluene, the present study did not detect any clear differences between men and women. In examinations of past reports, no support for the observed differences was found. The present findings deserve further study so that a solid conclusion can be formed.

A method for routine analysis of urinary 4,4'-methylenebis (2-chloroaniline) by gas chromatography-electron capture detection.

OBJECTIVES: The purpose of this study was to develop a simple and cost-effective method for the determination of urinary 4,4'-methylenebis (2-chloroaniline) (MBOCA) by gas chromatography-electron capture detection (GC-ECD) for biological monitoring of occupational exposure to MBOCA. METHODS: MBOCA was prepared by liquid-liquid extraction after alkaline hydrolysis, derivatized with N-methyl-bis (trifluoroacetamide) and then analyzed using GC-ECD. The proposed method was validated in accordance with the US Food and Drug Administration guidance. RESULTS: The calibration curve showed linearity in the range 1-100 µg/l, with a correlation coefficient of >0.999. The limits of detection and quantification were 0.3 µg/l and 1 µg/l, respectively. The recovery was 94-99%. Intraday accuracy, expressed as the deviation from the nominal value, was 90.5-100.3%, and intraday precision, expressed as the relative standard deviation, was 0.3-2.4%. Interday accuracy and precision were 87.8-100.2% and 0.3-4.1%, respectively. CONCLUSIONS: The proposed method is a simple and cost-effective method suitable for routine analyses and could be useful for biological monitoring of occupational exposure to MBOCA.

Combined effects of working hours, income, and leisure time on suicide in all 47 prefectures of Japan.

This study describes an ecological study that evaluated the combined effects of working hours, income, and leisure time on suicide in all 47 prefectures of Japan. In men, the age-adjusted rate of suicide (per 100,000 population) was significantly correlated with working hours (r=0.587, p<0.0001) as well as significantly and negatively correlated with income (r=-0.517, p=0.0002) and times for the leisure activities of self-education (r=-0.447, p=0.0016) and hobbies (r=-0.511, p=0.0002). In addition, a stepwise multiple regression analysis identified time for leisure social activities as a determining factor in suicide rate, even after adjusting for working hours and income. However, the impact of time for leisure social activities on suicide rate was smaller than that of working hours and income. In contrast, none of these factors affected suicide rate in women. These results suggest that increasing leisure time may be useful for preventing suicide among men in Japan.

Determination method for p-Phenylazoaniline and 2-methyl-4-(2-tolylazo)aniline in workplace air by high-performance liquid chromatography.

OBJECTIVES: The purpose of this research was to develop a method for the simultaneous determination of p-Phenylazoaniline (also called 4-aminoazobenzene, AAB) and 2-methyl-4-(2-tolylazo)aniline (also called o-aminoazotoluene, AAT) in workplace air for risk assessment. METHODS: The characteristics of the proposed method, such as recovery, limit of quantitation, reproducibility and storage stability of the samples were examined. RESULTS: An air sampling cassette containing two sulfuric acid-treated glass fiber filters was chosen as the sampler. The AAB and AAT were extracted from the sampler filters by methanol and then analyzed by a high-performance liquid chromatograph equipped with a photo-diode array detector. The overall recoveries from spiked samplers were 77-98 and 85-98% for AAB and AAT, respectively. The recovery after 5 days of storage in a refrigerator exceeded 96%. The overall limits of quantitation were 5.00 and 2.50 µg/sample for AAB and AAT, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.6-1.8 and 0.5-2.2% for AAB and AAT, respectively. CONCLUSIONS: The proposed method enables 4-h personal exposure monitoring of AAB and AAT at concentrations of 21 to 2,000 µg/m3 for AAB and 10 to 2,000 µg/m3 for AAT, respectively. The proposed method is useful for estimating worker exposure to AAB and AAT.

Development of an analytical method for the determination of arsenic in urine by gas chromatography-mass spectrometry for biological monitoring of exposure to inorganic arsenic.

OBJECTIVES: The purpose of this study was to develop an analytical method for the simultaneous determination of inorganic arsenic [As(III) and As(V)] and monomethylarsonic acid (MMA) in urine by gas chromatography-mass spectrometry (GC-MS) for the biological monitoring of exposure to inorganic arsenic. METHODS: Arsenic compounds (after reduction of arsenic to the trivalent state) were derivatized with 2,3-dimercapto-1-propanol and then analyzed using a GC-MS. The proposed method was validated according to the US Food and Drug Administration guidelines. The accuracy of the proposed method was confirmed by analyzing Standard Reference Material (SRM) 2669 (National Institute of Standards and Technology). RESULTS: Calibration curves showed linearity in the range 1-100 µg/l for each of the arsenic species, with correlation coefficients of >0.999. For each of the arsenic species, the limits of detection and quantification were 0.2 µg/l and 1 µg/l, respectively. The recoveries were 96-100%, 99-102% and 99-112% for As(III), As(V) and MMA, respectively. Intraday accuracy and precision were 82.7-99.8% and 0.9-7.4%, respectively. Interday accuracy and precision were 81.3-100.0% and 0.8-9.9%, respectively. The analytical values of SRM 2669 obtained by the proposed method were sufficiently accurate. CONCLUSIONS: The proposed method overcame the disadvantages of high-performance liquid chromatography with inductively coupled plasma mass spectrometry. It was a robust, selective and cost-effective method suitable for routine analyses and could be useful for the biological monitoring of occupational exposure to inorganic arsenic.

Sequential extraction of inorganic arsenic compounds and methyl arsenate in human urine using mixed-mode monolithic silica spin column coupled with gas chromatography-mass spectrometry.

A sequential analytical method was developed for the detection of arsenite, arsenate, and methylarsenate in human urine by gas chromatography-mass spectrometry (GC-MS). The combination of a derivatization of trivalent arsenic compounds by 2,3-dithio-1-propanol (British antilewisite; BAL) and a reduction of pentavalent arsenic compounds (arsenate and methylarsenate) were accomplished to carry out the analysis of arsenic compounds in urine. The arsenic derivatives obtained using BAL were extracted in a stepwise manner using a monolithic spin column and analyzed by GC-MS. A linear curve was observed for concentrations of arsenic compounds of 2.0 to 200 ng/mL, where the correlation coefficients of calibration curves were greater than 0.996 (for a signal-to-noise (S/N) ratio >10). The detection limits were 1 ng/mL (S/N > 3). Recoveries of the targets in urine were in the range 91.9-106.5%, and RSDs of the intra- and interday assay for urine samples containing 5, 50, and 150 ng/mL of arsenic compounds varied between 2.95 and 13.4%. The results from real samples obtained from a patient suspected of having ingested As containing medications using this proposed method were in good agreement with those obtained using high-performance liquid chromatography with inductively coupled plasma mass spectrometry.

Determination method for mono- and diethanolamine in workplace air by high-performance liquid chromatography.

OBJECTIVES: The purpose of this research was to develop a simultaneous determination method for monoethanol-amine (MEA) and diethanolamine (DEA) in workplace air for risk assessment. METHODS: The characteristics of the proposed method, such as recovery, quantitation limit, reproducibility and storage stability of the samples, were examined. RESULTS: An air sampling cassette containing two sulfuric acid-treated glass fiber filters was chosen as the sampler. The MEA and DEA were extracted from the sampler filters, derivatized with 9-fluorenylmethyloxycarbonyl chloride and then analyzed by a high-performance liquid Chromatograph equipped with a fluorescence detector or photo-diode array detector. The overall recoveries from spiked samplers were 86-99 and 88-99% for MEA and DEA, respectively. The recovery after 5 days of storage in a refrigerator exceeded 95%. The overall limits of quantitation were 0.750 and 0.100 jug/sample for MEA and DEA, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.3-1.6 and 0.4-5.7% for MEA and DEA, respectively. CONCLUSIONS: The proposed method enables 4-h personal exposure monitoring of MEA and DEA at concentrations equaling 1/3,000-2 times the threshold limit value-time-weighted average (TLV-TWA: 3 ppmfor MEA, 1 mg/m(3) for DEA) adopted by the American Conference of Governmental Industrial Hygienists and also by the Japan Society for Occupational Health. The method is useful for estimating worker exposure to MEA and DEA.