Analysis of 8-hydroxydeoxyguanosine among workers exposed to diesel particulate exhaust: comparison with urinary metabolites and PAH air monitoring

Oxidative DNA damage and repair, as measured by 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine and DNA samples were studied in association with work-related diesel exhaust exposure among garage and waste collection workers. Seasonal variations of the urinary 8-OHdG levels in pre- and two post-workshift urine samples of 29 exposed workers and 36 control persons were evaluated. The mean±SE levels of post-workshift 8-OHdG (μmol/mol crea) were 1.52±0.44 in winter and 1.61±0.33 in summer for the exposed workers, and 1.56±0.61 in winter and 1.43±0.49 in summer for the controls, respectively. No significant difference in the urinary 8-OHdG levels between exposed workers and control subjects in winter (p=0.923) and summer (p=0.350) was observed. A linear mixed model, adjusted for years of employment, age, ex/non-smoking and BMI, indicated no significant dose exposure-relationships between the urinary 8-OHdG and 15 PAH air concentrations nor between the 8-OHdG and 7 PAH monohydroxy-metabolites analyzed in the same workers. 8-OHdG was also analyzed in the mononuclear cell DNA of 19 exposed and 18 control subjects. The mean value of 8-OHdG/non-modified 2'-deoxyguanosine (8-OHdG/105 dG±SE) were 4.89±0.17 for the exposed and 4.11±0.16 for the control persons, which showed no correlation with the urinary 8-OHdG levels (r=0.01, n=28, P=0.96). The PAH exposure at workplaces was mainly composed of volatile compounds, particularly naphthalene, suggesting low exposure through the respiratory tract and a low effect of PAH in ROS induction.     

Immunohistochemical identification and localization of pancreatic polypeptide cells in the pancreas and gastrointestinal tract of the human fetus and adult man

Summary Pancreatic polypeptide (PP)-containing cells were detected by using anti-bovine PP (BPP) serum in the pancreas and gastrointestinal tract of human fetuses, premature infants and in the pancreas, antrum and jejunum of adult man obtained by biopsy from patients with normal gastroduodenal endoscopy. The localization was established by studying the distribution of PP cells in comparison to the distribution of glucagon-, somatostatin- and insulin cells. The first PP cells are seen in the pancreas at 10 weeks of gestation. They are located preferentially in the lower part of the head of the pancreas. The specificity of immunocytological reaction was ascertained by the inhibition of the reaction by bovine pancreatic polypeptide, glucagon and insulin did not modify the immunocytological reaction.     

An integrated approach to biomonitoring exposure to styrene and styrene-(7,8)-oxide using a repeated measurements sampling design

Abstract

The aim of this work was to investigate urinary analytes and haemoglobin and albumin adducts as biomarkers of exposure to airborne styrene (Sty) and styrene-(7,8)-oxide (StyOX) and to evaluate the influence of smoking habit and genetic polymorphism of metabolic enzymes GSTM1 and GSTT1 on these biomarkers. We obtained three or four air and urine samples from each exposed worker (eight reinforced plastics workers and 13 varnish workers), one air and urine samples from 22 control workers (automobile mechanics) and one blood sample from all subjects. Median levels of exposure to Sty and StyOX, respectively, were 18.2 mg m^?3 and 133 µg m^?3 for reinforced plastics workers, 3.4 mg m^?3 and 12 µg m^?3 for varnish workers, and <0.3 mg m^?3 and <5 µg m^?3 for controls. Urinary levels of styrene, mandelic acid, phenylglyoxylic acid, phenylglycine (PHG), 4-vinylphenol (VP) and mercapturic acids (M1+M2), as well as cysteinyl adducts of serum albumin (but not those of haemoglobin) were significantly associated with exposure status (controls相似文献   

Vitamin D induction of the human antimicrobial Peptide cathelicidin in the urinary bladder

The urinary tract is frequently being exposed to potential pathogens and rapid defence mechanisms are therefore needed. Cathelicidin, a human antimicrobial peptide is expressed and secreted by bladder epithelial cells and protects the urinary tract from infection. Here we show that vitamin D can induce cathelicidin in the urinary bladder. We analyzed bladder tissue from postmenopausal women for expression of cathelicidin, before and after a three-month period of supplementation with 25-hydroxyvitamin D3 (25D3). Cell culture experiments were performed to elucidate the mechanisms for cathelicidin induction. We observed that, vitamin D per se did not up-regulate cathelicidin in serum or in bladder tissue of the women in this study. However, when the bladder biopsies were infected with uropathogenic E. coli (UPEC), a significant increase in cathelicidin expression was observed after 25D3 supplementation. This observation was confirmed in human bladder cell lines, even though here, cathelicidin induction occurred irrespectively of infection. Vitamin D treated bladder cells exerted an increased antibacterial effect against UPEC and colocalization to cathelicidin indicated the relevance of this peptide. In the light of the rapidly growing problem of resistance to common urinary tract antibiotics, we suggest that vitamin D may be a potential complement in the prevention of UTI.     

Effects of arsenic exposure among semiconductor workers: a cautionary note on urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine

Arsenic is a notorious environmental toxicant and was found to cause oxidative stress in cultured cells and animals. However, little work has been done in human studies, especially for the population occupationally exposed to arsenic. In order to investigate the effect of occupational exposure to arsenic in oxidative stress, we measured urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) from 90 semiconductor workers including 50 exposed and 40 nonexposed subjects. A highly sensitive and specific isotope dilution LC-MS/MS method was used for quantification of 8-oxodGuo. The levels of inorganic arsenic (iAs3+, iAs5+), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in urine were determined by high-performance liquid chromatography-flow injection atomic absorption spectrometry (HPLC-FIAAS). Results showed that the mean urinary concentrations of total arsenic and 8-oxodGuo were significantly higher for exposed workers compared with the nonexposed workers. In addition, elevated urinary 8-oxodGuo concentrations of exposed workers were correlated with urinary levels of MMA (r = 0.44, P < 0.005) and the extent of primary methylation (the ratio of MMA to inorganic arsenic) (r = 0.40, P < 0.005). These findings suggested that occupational exposure to arsenic could result in the induction of oxidative stress. The presence and/or formation of MMA could play an important role in arsenic-involved injuries.     

Urinary mutagenicity tests in lead-exposed workers

Urinary mutagenic activity detected by the bacterial fluctuation assay, using Salmonella typhimurium TA98 and Escherichia coli WP2 uvrA with and without metabolic activation (S9 mix), was studied in a group of 21 workers exposed to inorganic lead and a control group of 22 non-occupationally exposed subjects. Occupational exposure to inorganic lead had no effect on urinary mutagenicity in the strains considered, with or without metabolic activation. In smokers (exposed and non-exposed), urinary mutagenic activity appeared to increase compared to non-smokers (exposed and non-exposed), only with Salmonella typhimurium TA98 in the presence of S9 mix.     

Modulation of adenylate cyclase in human keratinocytes by protein kinase C

Adenylate cyclase (ATP-pyrophosphate lyase (cyclizing); EC 4.6.1.1) in the human keratinocyte cell line SCC 12F was potentiated by 12-O-tetradecanoyl-phorbol-13-acetate (TPA), phorbol-12,13-diacetate, and 1,2-dioctanoylglycerol. Keratinocytes exposed to TPA showed a 2-fold enhancement of adenylate cyclase activity when assayed in the presence of isoproterenol or GTP. The half-maximal effective concentration (EC50) for both isoproterenol and GTP were unaltered by TPA treatment of the cells. Basal adenylate cyclase activity in membranes from TPA-treated cultures was also increased 2-fold relative to activity in control membranes. Potentiation of adenylate cyclase activity was dependent on the concentration of TPA to which the keratinocytes were exposed (EC50 for TPA = 3 nM). TPA actions on adenylate cyclase were maximal after 15 min of incubation of the cells with the compound, correlating well with the time course of translocation of protein kinase C (Ca2+/phospholipid-dependent enzyme) from cytosol to membrane. The action of cholera toxin on adenylate cyclase was additive with TPA. In contrast, pertussis toxin actions on adenylate cyclase were not additive with TPA. Treatment of control cells with pertussis toxin activated adenylate cyclase 1.5-fold, whereas cells exposed to pertussis toxin for 6 h followed by TPA for 15 min showed the same 2-fold increase in adenylate cyclase activity as observed in membranes from cells exposed to TPA without prior exposure to pertussis toxin. Pertussis toxin catalyzed ADP-ribosylation was increased 2-fold in membranes from SCC 12F cells exposed to TPA, indicating an increase in the alpha beta gamma form of Gi. These data suggest that exposure of human keratinocytes to phorbol esters increases adenylate cyclase activity by a protein kinase C-mediated increase in the heterotrimeric alpha beta gamma form of Gi resulting in decreased inhibition of basal adenylate cyclase activity.     

Cytogenetic monitoring of hospital workers exposed to low-level ionizing radiation

In the present study the cytogenetic effects in hospital workers exposed to low-level radiation were evaluated. Samples of peripheral blood were collected from 63 subjects working in radiodiagnostics and from 30 subjects, working in the same hospitals, who were used as controls. A higher number of cells with chromosome-type aberrations (CA) was observed in the exposed workers vs. the controls and the difference was statistically significant (p less than 0.05). No correlation was, on the contrary, found between CA and years of exposure. A significant difference was observed in the incidence of cells with CA between smokers and non-smokers, but in the control group only. In contrast, in the workers exposed to ionizing radiation, the frequency of cells with CA was very similar in smokers and non-smokers.     

Micronuclei in peripheral lymphocytes and exfoliated urothelial cells of workers exposed to 4,4′-methylenebis-(2-chloroaniline) (MOCA)

4,4′-Methylenebis-(2-chloroaniline) (MOCA) is used in the manufacture of polyurethane. The IARC classifies MOCA as a probable human carcinogen. Suggested changes to guidelines for health surveillance of MOCA-exposed workers in Australia include a reduction in acceptable levels of urinary MOCA to below 15 μmol/mol creatinine. Twelve male workers aged 24 and 42 years were recruited into this study from four work locations where MOCA is used. Exfoliated urothelial cells from prework urine samples on a midweek work day were assessed for micronucleus (MN) frequencies. Postwork urine samples were analysed for total MOCA. Blood samples collected on the same day were cultured for 96 h and cytochalasin-B-blocked cells were scored for MN. Eighteen male control subjects (23–59 years) provided corresponding urine and blood samples. Median urinary MOCA concentrations were 6.5 μmol/mol creatinine (range 0.4–48.6 μmol/mol creatinine) in postwork samples of MOCA-exposed workers. MOCA was not detected in urine of control workers. Mean MN frequencies were higher in urothelial cells and lymphocytes of MOCA workers (14.27±0.56 and 13.25±0.48 MN/1000 cells) than in controls (6.90±0.18 and 9.24±0.29 MN/1000 cells). The mean number of micronucleate cells was also higher in both tissues of exposed workers (9.69±0.32 and 8.54±0.14 MN cells/1000 cells) than in controls (5.18±0.11 and 5.93±0.13 MN cells/1000). There was no correlation between postwork urinary MOCA concentrations and MN frequencies in either tissue. This study suggests that exposures to MOCA in South Australia are similar to those of a decade ago and are at levels similar to those currently acceptable in Australia. These are associated with genotoxic effects in urothelial cells and peripheral blood lymphocytes. It may be prudent to reduce MOCA exposures in line with proposed guidance values.     

Determination of dihydroxynaphthalenes in human urine by gas chromatography-mass spectrometry

A gas chromatography-mass spectrometry (GC-MS) method was developed for measuring 1,2-dihydroxynaphthalene (1,2-DHN) and 1,4-dihydroxynaphthalene (1,4-DHN) in urine. The method involves enzymatic digestion of urinary conjugates to release the DHNs which were then analyzed as trimethylsilyl derivatives by GC-MS. For 1,2-DHN and 1,4-DHN, respectively, the assay limits of detection were 0.21 and 0.15 microg/l, the assay limits of quantitation were 0.69 and 0.44 microg/l, and the coefficients of variation were 14.7 and 10.9%. This method was successfully applied to determine urinary levels of 1,2-DHN and 1,4-DHN in coke workers (14 top workers and 13 side-bottom workers) and 21 matching control workers from the steel industry of northern China. The geometric mean (GM) levels of 1,2-DHN were approximately 100 and 30 times higher than those of 1,4-DHN in exposed and control subjects, respectively. The GM levels 1,2-DHN and 1,4-DHN were significantly higher for coke workers (1,2-DHN: top workers--552 microg/l, side-bottom workers--260 microg/l; 1,4-DHN: top workers--3.42 microg/l, side-bottom workers--3.56 microg/l) than for controls (1,2-DHN: 38.8 microg/l; 1,4-DHN: 1.21 microg/l) (por=0.623; p<0.0001). Also, levels of 1,2-DHN were significantly correlated with those of serum albumin adducts of l,2-naphthoquinone (rs=0.492, p=0.0004). These results indicate that 1,2- and 1,4-DHN are good biomarkers for assessment of naphthalene exposure in coke workers. Since the DHNs are precursors of the naphthoquinones, which have been implicated as toxic products of naphthalene metabolism, measurements of urinary DHNs may have toxicological significance.     

Changes in serum markers indicative of health effects in vineyard workers following exposure to the fungicide mancozeb: an Italian study

The aim of this study was to investigate the health effects induced by exposure to the fungicide mancozeb in Italian vineyard workers. Ninety-three Italian subjects entered the study - 48 vine-growers intermittently exposed to mancozeb and 45 healthy controls. The subjects were investigated three times: before the seasonal application of pesticides (T0), 30 days after the beginning of the application period (T30), and 45 days after T0 (T45). At T0 the comparison between agricultural workers and controls showed a higher prevalence of cold or flu symptoms, a statistically significant lower percentage of monocytes, higher absolute count of T lymphocytes, CD4 and natural killer cells, and lower plasma levels of IgA and IgM in workers. Such differences were not confirmed at T30 and T45. In fact at T30 in exposed workers, besides a significant increase of urinary ethylenethiourea, confirming mancozeb exposure, T lymphocytes, CD4 and natural killer cells, IgA and IgM returned to values comparable to those observed in controls. Moreover, no other differences in clinical signs, haematological, and immune parameters, such as the immune functional capability evaluated as a response to hepatitis B vaccination, was observed. Altogether the differences between exposed and controls were not consistently correlated to any clinical impairment and suggest that the seasonal application of mancozeb does not pose a significant health risk to exposed subjects.     

Occupational exposure to anaesthetic gases and urinary excretion of D-glucaric acid

In order to ascertain whether the urinary excretion of D-glucaric acid (DGA) might be a suitable biomarker of effect in monitoring workers exposed to anaesthetic gases, we measured DGA before and after an operating session (and, in some workers, before and after a 2-week vacation) in 229 workers of surgical units and in 229 controls. In the former, we also measured urinary levels of nitrous oxide (N₂O) and isofiurane after at least 4 h of exposure. For all subjects, information on age, smoking habits, daily intake of alcohol, coffee, and drugs, history of liver or kidney disease was collected. Study subjects were ranked according to: exposure (class 0: subjects not exposed; class 1: N₂     

Simultaneous determination of urinary CEA, ferritin and TPA in Egyptian bladder cancer patients.

Urinary carcinoembryonic antigen (CEA), ferritin (Fer) and tissue polypeptide antigen (TPA) were determined in 328 cases (106 with bladder cancer, 152 with non-malignant urinary tract disease and 70 healthy controls). CEA was determined by the kit supplied by Roche Diagnostica (CEA EIA Doumab 60), ferritin by the Tandem-E Fer kit supplied by Hybritech and TPA by the Prolifigen TPA-IRMA kit supplied by Sangtec Medical. The results of this work revealed that combined determination of urine CEA and Fer, CEA and TPA or Fer and TPA showed higher sensitivity than determination of the individual markers. There was no significant difference between combined and individual marker determination with respect to false positivity in non-malignant urinary tract diseases. At 97% specificity, the sensitivities of urine CEA, Fer and TPA were 82.1%, 71.7% and 90.6%, respectively, while combined urine CEA & Fer, CEA & TPA and Fer & TPA showed sensitivities of 92.5%, 99.1% and 98.1%, respectively. When the specificity was related to the entire non-cancer group (patients with benign urinary tract diseases and normal controls), some reduction in the sensitivities of the combined markers was noted compared to the normal group only. In conclusion, combined determination of urine markers is superior to determination of individual markers in the diagnosis of bladder cancer.     

Regulation of hexose transporters in chicken embryo fibroblasts: stimulation by the phorbol ester TPA leads to increased numbers of functioning transporters

As has been observed with many types of cultured cells, chicken embryo fibroblasts (CEF) when exposed to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) develop a 3- to 4-fold increase in hexose transport activity in 4 h. This increase in transport activity occurred despite a modest decline of 20% in [3H]leucine incorporation into acid insoluble fractions. Cycloheximide largely, but not completely, blocked the increase in transport activity during TPA exposure. The effects of TPA were somewhat similar to those of glucose starvation induced enhancement of hexose transport activity. Furthermore, with TPA there was no additive effect to that produced by glucose starvation. Plasma membrane enriched fractions were prepared from CEF treated with or without TPA. Membranes prepared from TPA exposed cells had a two-fold enhancement of stereospecific D-glucose transport activity as well as D-glucose inhibitable [3H]cytochalasin B binding as compared to the membranes from control CEF. There was no effect on transport when membranes were exposed to TPA in vitro. These results provide strong evidence that TPA exposure leads to an increase in the number of functioning transporters, an effect largely requiring protein synthesis.     

Comparative investigation of structural and gene somatic mutations in workers of nuclear chemical plants. I. A study of stable and unstable chromosome aberrations

A study of frequency of unstable chromosome aberrations in 50 workers of nuclear chemical plants in remote period after beginning or finishing professional contact with ionizing radiation was carried out. 14 persons from this cohort were mainly whole-body exposed to external gamma-rays and 36 were exposed to combined external and internal radiation from incorporated Pu nuclides. In results of this irradiating practically every subject had a chronical radiation sickness. In the 1-st group the frequency of unstable aberrations varied from 0.2 to 3.6 per 100 cells and exceeded reliably control level in 5 persons. In the 2-nd group the frequency of unstable aberrations varied from 0 to 11.6 per 100 cells and exceeded reliably control level in 20 examined workers. The FISH study of frequency of stable aberrations was performed in 13 subjects who were exposed to combined external and internal radiation. Total frequency of complete and incomplete translocations varied from 0.6 to 18.5 aberrations per genome per 100 cells and reliable exceeded control level in 9 subjects. Non-random participation in exchange rearrangements (translocations) was revealed for used set of chromosomes (2, 3 and 8).     

Potential health effects of exposure to carcinogenic compounds in incense smoke in temple workers

Incense smoke is a potential hazard to human health due to various airborne carcinogens emitted from incense burning. This study aimed to evaluate the potential health effects of exposure to benzene, 1,3-butadiene, and polycyclic aromatic hydrocarbons (PAHs) emitted from incense smoke in temple workers. Exposure and health risks were assessed through the measurement of ambient exposure as well as through the use of biomarkers of exposure and early biological effects. Ambient air measurement showed that incense burning generates significantly higher levels of airborne benzene (P<0.01), 1,3-butadiene (P<0.001) and total PAHs (P<0.01) inside the temples, compared to those of the control workplace. Temple workers were exposed to relatively high levels of benzene (45.90 microg/m(3)) 1,3-butadiene (11.29 microg/m(3)) and PAHs (19.56 ng/m(3)), which were significantly higher than those of control workers (P<0.001). The most abundant PAHs were chrysene, B[ghi]P, B[a]P, B[a]F and fluoranthene. Concentrations of B[a]P and B[a]P equivalents in air samples to which temple workers were exposed were 63- and 16-fold, higher, respectively, than those to which control subjects were exposed (P<0.001). Biomarkers of exposure to benzene (blood benzene and the urinary metabolites trans,trans-muconic acid and S-phenylmercapturic acid), 1,3-butadiene (urinary monohydroxy-butenyl mercapturic acid) and PAHs (1-hydroxypyrene) were all significantly higher in temple workers than those in control workers. DNA damage and DNA repair capacity were measured as biomarkers of early biological effects. Temple workers had a significant increase in DNA damage observed as a 2-fold increase in the levels of leukocyte 8-hydroxy-2'-deoxguanosine (8-OHdG) and DNA strand breaks (P<0.001). A significant reduction of DNA repair capacity in temple workers determined by the radiation challenge assay was also observed. These results indicate that exposure to carcinogens emitted from incense burning may increase health risk for the development of cancer in temple workers.     

Tumor markers (CEA, TPA and CA 19-9) in urine of bladder cancer patients

This study was carried out to evaluate the usefulness of determining urinary levels of carcinoembryogenic antigen (CEA), tissue-polypeptide antigen (TPA), and gastro-intestinal cancer antigen (Ca19-9) in addition to the usual diagnostic procedures for bladder cancer. Sixty-seven patients with transitional bladder cancer, 40 healthy controls and 20 patients with inflammatory diseases of the urinary tract were considered. All urine samples were obtained from patients with intact renal function and no urinary tract infection. TPA and Ca19-9 urinary levels in patients with G3 bladder tumors were significantly higher than in those with lower graded neoplasms. The sensitivity, specificity, and predictive value of a positive (PV+) or negative (PV-) test and the diagnostic accuracy were also evaluated. Ca19-9 was the best urinary marker for bladder cancer (sensitivity 71.6%, specificity 91.6%, PV+ 90.5%, PV- 74.3%, diagnostic accuracy 81%).     

Cytogenetic biomonitoring of carpet fabric workers using micronucleus frequency, nuclear changes, and the calculation of risk assessment by repair index in exfoliated mucosa cells

The micronucleus (MN) assay in exfoliated buccal cells is a minimally invasive method for monitoring genetic damage in human populations and is used as an indicator of genotoxic exposition, as it is associated with chromosome aberrations. In this study, we evaluated MN frequencies and other nuclear changes (NCs), such as karyorrhexis (KR), karyolysis (KL), broken egg (BE), and binucleus in buccal mucosa cells of 50 carpet fabric workers (25 smokers and 25 nonsmokers) and 50 healthy control subjects (25 smokers and 25 nonsmokers). Microscopic observation of 2000 cells per individual was performed in both workers and control subjects. In both the control group and the exposed group, for each person a repair index (RI) was calculated via the following formula: (KR+KL)/(BE+MN). The results showed a statistically significant increase in the frequency of MN in buccal epithelial cells of exposed group compared with control group. There is a significant difference between worker and control groups (p<0.001) for RI. We believe that the calculation of RI values, in addition to nuclear changes, presents a new approach in risk assessment in relation to occupational exposure.     

The relationship between tumor promoter binding and epstein-barr virus induction in human lymphoblastoid cell lines

The tumor promoter TPA (12-0-tetradecanoyl-phorbol-13-acetate) efficiently induces the synthesis of Epstein-Barr virus (EBV) antigens in EBV-genome-harboring human lymphoblastoid cells. We attempted to obtain information on the binding of TPA to cells and on the relationship between TPA-binding and EBV induction by the use of tritiated TPA (³H-TPA). Our data show: (1) In the absence of cells TPA can bind to serum completely within 60 minutes. (2) Cells can compete for a proportion of serum-bound TPA. (3) Binding of TPA to cells reaches equilibrium within 60 minutes and is higher at 37° than 0°C. In the absence of serum, the rate of binding is about twice as high as in the presence of serum. (4) Dissociation of TPA from cells also seems to be rapid. When the cells are incubated with cold TPA after prior treatment with ³H-TPA, followed by washing, a much higher rate of release of labeled TPA is observed than in cultures to which fresh medium is added exclusively. Dissociation is higher in the presence of serum than in the absence of it. If radiolabeled cells are analyzed after serial washing, the rate of cell-associated/noncell-associated radioactivity indicates that the proportion of molecules required for EBV induction is dissociated rapidly.     

Methylene bis (2-chloroaniline) (MbOCA): towards a biological monitoring guidance value

We report the development and validation of a high performance liquid chromatography method for the determination of methylene bis (2-chloroaniline) (MbOCA) and its labile conjugates in urine. The method has been in regular use for the biological monitoring of workers exposed to MbOCA for the past 11 years. Following the development of a biological monitoring strategy, and the introduction of a biological action level by the Health and Safety Commission in 1984, there has been a steady fall in the proportion of workers whose urinary results are above the action level. We conclude that, in the absence of reliable health-based data, a guidance value based on the use of the 90th percentile derived from monitoring a cross-section of the industry, can be used to interpret biological monitoring results. The measurement of urinary MbOCA is a practical non-invasive way of monitoring workers which can be useful in helping to control exposure.