Effectiveness and safety of apixaban and rivaroxaban for acute venous thromboembolism therapy in patients with extremes in bodyweight.

OBJECTIVES: To investigate the association of extremes in bodyweight (EBW) and outcomes in patients with acute venous thromboembolism (VTE). Recurrent VTE, major bleeding, and clinically relevant non-major bleeding were compared between patients with bodyweight <60 kg, 60-120 kg, and >120 kg. METHODS: Consecutive patients enrolled in the Mayo Clinic VTE Registry (03/28/2013-8/31/2019) with acute VTE were followed prospectively. Patient status was assessed in person, by mailing a written questionnaire, or by a scripted phone interview. RESULTS: Among 2577 patients with weight ranging from 27.0 kg to 263.2 kg, 2123 (82%) had a bodyweight between 60 and 120 kg, 223 (8.7%) had bodyweight < 60 kg, and 230 (8.9%) had bodyweight >120 kg. Patients with bodyweight <60 kg treated with DOACs had higher 3- and 6-month incidence of major bleeding compared to the bodyweight 60-120kg group (4.4% vs 1.1%, P = .03, and 4.4% vs 1.4%, P = .05, respectively). Patients with bodyweight >120 kg and cancer on rivaroxaban had higher VTE recurrence compared to bodyweight 60-120kg group (P = .01). CONCLUSIONS: Treatment of acute VTE is associated with a higher incidence of bleeding in patients with bodyweight <60 kg. A higher VTE recurrence rate occurred only in cancer patients with bodyweight >120 kg on rivaroxaban.

Adverse Events and Mortality in Anticoagulated Patients with Different Categories of Pulmonary Embolism.

OBJECTIVE: To determine whether the pulmonary embolism (PE) categories of massive, submassive, PE with no right ventricle dysfunction (NRVD), and subsegmental only (SSO) adequately predict clinical outcome. METHODS: Patients treated for acute PE (March 1, 2013, through July 31, 2019) were followed forward prospectively to compare venous thromboembolism (VTE) recurrence, all-cause mortality, major bleeding, and clinically relevant nonmajor bleeding (CRNMB) across 4 PE categories. RESULTS: Of 2703 patients with VTE, 1188 (44%) had PE, of which 1021 (85.9%) completed at least 3 months of therapy or had clinical outcomes precluding further treatment (27 with massive, 217 submassive, 557 NRVD, and 220 SSO PE). One patient with massive, 8 with submassive, 23 with NRVD, and 5 with SSO PE had recurrent VTE (3.90, 5.33, 5.36, and 3.66 per 100 person-years, respectively; P=.84). There were 3 deaths in massive, 27 in submassive, 140 in NRVD, and 34 in SSO PE groups (11.59, 17.37, 31.74, and 24.74 per 100 person-years, respectively; P=.02); when adjusted for cancer, the relationship was no longer significant (P=.27). One patient with massive, 5 with submassive, 22 with NRVD, and 5 with SSO PE had major bleeding (3.90, 3.31, 5.24, and 3.75 per 100 person-years, respectively; P=.66). Similar cumulative rates for CRNMB were observed (P=.87). Three-month rates of VTE recurrence, death, major bleeding, and CRNMB did not differ by PE category. CONCLUSION: In the setting of anticoagulation therapy with maximal standardization and evidence-based practice, there is no evidence of a difference between PE categories and outcomes. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT03504007.

Comparison of apixaban to rivaroxaban and enoxaparin in acute cancer-associated venous thromboembolism.

To provide direct comparison between apixaban and rivaroxaban in patients with acute cancer-associated venous thromboembolism (Ca-VTE), consecutive patients treated with apixaban, rivaroxaban, or enoxaparin at Mayo Thrombophilia Clinic (March 1, 2013 to January 31, 2018)) were followed prospectively. The primary effectiveness outcome was venous thromboembolism (VTE) recurrence, and the secondary was mortality. The primary safety outcome was major bleeding, the secondary clinically relevant safety outcome was non-major bleeding (CRNMB), and the third a composite of major and CRNMB. There were 750 patients treated for acute Ca-VTE with apixaban (n = 224), rivaroxaban (n = 163), and enoxaparin (n = 363) within 14 days of diagnosis and for at least 3 months, or until study event. Recurrent VTE was diagnosed in 11 receiving apixaban, 7 receiving rivaroxaban (apixaban vs rivaroxaban hazard ratio (HR) 1.31, 95% confidence interval (95% CI) 0.51-3.36) and 17 in the enoxaparin receiving group (apixaban vs enoxaparin HR 1.14, 95% CI: 0.54, 2.42 and rivaroxaban vs enoxaparin HR 0.85, 95% Cl: 0.36, 2.06). There were 82 deaths in apixaban, 74 rivaroxaban (apixaban vs rivaroxaban HR 1.67, 95% Cl: 1.20, 2.33) and 171 in enoxaparin group (rivaroxaban vs enoxaparin HR 0.73, 95% Cl: 0.56, 0.96). Major bleeding occurred in 11 apixaban, 12 rivaroxaban (apixaban vs rivaroxaban HR 0.73, 95% Cl: 0.32, 1.66) and 21 enoxaparin group (apixaban vs enoxaparin HR 0.89, 95% Cl: 0.43, 1.84 and rivaroxaban vs enoxaparin HR 1.23, 95% Cl: 0.61, 2.50). The CRNMB rate was higher in rivaroxaban compared to apixaban (P = .03) and LMWH (P = .01) groups. Recurrence of VTE and major bleeding were similar in apixaban, rivaroxaban, and enoxaparin groups. Rivaroxaban was associated with higher CRNMB but lower mortality compared to apixaban and enoxaparin.

Apixaban and Rivaroxaban in Patients With Acute Venous Thromboembolism.

OBJECTIVE: To compare the clinical efficacy and safety of apixaban with those of rivaroxaban for the treatment of acute venous thromboembolism (VTE). PATIENTS AND METHODS: Consecutive patients enrolled in the Mayo Thrombophilia Clinic Registry (between March 1, 2013, and January 30, 2018) and treated with apixaban or rivaroxaban for acute VTE were followed forward in time. The primary efficacy outcome was VTE recurrence. The primary safety outcome was major bleeding; the second safety outcome was clinically relevant nonmajor bleeding (CRNMB); and the third was a composite of major bleeding or CRNMB. RESULTS: Within the group of 1696 patients with VTE enrolled, 600 (38%) were treated either with apixaban (n=302, 50%) or rivaroxaban (n=298, 50%) within the first 14 days of VTE diagnosis and who completed at least 3 months of therapy or had a study event. Recurrent VTE was diagnosed in 7 patients (2.3%) treated with apixaban and in 6 (2%) treated with rivaroxaban (adjusted hazard ratio [aHR], 1.4; 95% CI, 0.5-3.8). Major bleeding occurred in 11 patients (3.6%) receiving apixaban and in 9 patients (3.0%) receiving rivaroxaban (aHR, 1.2; 95% CI, 0.5-3.2). Clinically relevant nonmajor bleeding was diagnosed in 7 patients (2.3%) receiving apixaban and in 20 (6.7%) receiving rivaroxaban (aHR, 0.4; 95% CI, 0.2-0.9). The rates of composite major bleeding or CRNMB were similar (aHR, 0.6; 95% CI, 0.3-1.2). Most study events occurred in patients with cancer. CONCLUSION: In the setting of a standardized, guideline-directed, patient-oriented clinical practice, the efficacy and safety of apixaban and rivaroxaban for the treatment of acute VTE were comparable.

Rivaroxaban and Apixaban for Initial Treatment of Acute Venous Thromboembolism of Atypical Location.

OBJECTIVES: To assess the outcome of direct oral anticoagulants (DOACs), specifically Xa inhibitors: rivaroxaban and apixaban, for the treatment of venous thromboembolism (VTE) of atypical location (VTE-AL), portal, mesenteric, hepatic, splenic, gonadal, renal, and cerebral veins, prospectively collected data of Mayo Thrombophilia Clinic Registry were used. METHODS: Patients with acute VTE-AL treated with DOACs, enrolled between March 1, 2013, and February 1, 2017, were compared with patients with VTE of typical location (VTE-TL: deep vein thrombosis of extremities and/or pulmonary embolism) receiving DOACs and with patients with VTE-AL treated with enoxaparin. RESULTS: Out of 623 patients with acute VTE receiving the study drug within 14 days of diagnosis, there were 63 with VTE-AL: 36 on DOAC, 23 on enoxaparin, and 4 on warfarin; 352 received DOAC for VTE-TL. The VTE-AL treated with DOAC/enoxaparin included the following: splanchnic (26/22), ovarian (8/2), renal (3/5), and cerebral veins (1/1), respectively. Recurrence rate (per 100 person-years) for the VTE-AL group receiving DOAC was 7.3, which was not different when compared with those for VTE-TL (2.4; P=.13) and VTE-AL groups receiving enoxaparin (23.7; P=.37). Major bleeding rate in the VTE-AL group receiving DOAC was not different compared with those for VTE-TL (7.2 vs 3.0; P=.26) and VTE-AL groups on enoxaparin (22.4; P=.31). Mortality was higher in the VTE-AL group on DOAC compared with the VTE-TL group (21.45 [95% CI, 7.87-46.69] vs 8.26 [95% CI, 5.35, 12.20]; P=.03). All patients with VTE-AL with events had cancer. CONCLUSION: The VTE recurrence and bleeding rates for rivaroxaban and apixaban used in VTE-AL are not different from those in patients with VTE-TL and similar to that for enoxaparin.

Efficacy and Safety of Rivaroxaban in Patients with Venous Thromboembolism and Active Malignancy: A Single-Center Registry.

OBJECTIVE: The purpose of this study is to evaluate the efficacy and safety of rivaroxaban in patients with venous thromboembolism and active malignancy, given the paucity of clinical data with the use of direct Xa inhibitors in this high-risk population. PATIENTS AND METHODS: Consecutive patients treated with rivaroxaban for deep vein thrombosis or pulmonary embolism, enrolled into Mayo Thrombophilia Clinic Direct Oral Anticoagulants Registry between March 1, 2013, and April 30, 2015, were followed prospectively to evaluate the efficacy and safety of this therapy. RESULTS: Of the 404 venous thromboembolism patients in the registry, 296 received rivaroxaban and had at least 3 months of follow-up. Of these, 118 (40%) had active malignancy (51% female, mean age 66 ± 10 years) and 178 had no cancer (47% female, mean age 55 ± 15 years). The 3 most common cancer locations were genitourinary (23.6%), gastrointestinal (20.3%), and lung (13.5%). There was no difference in venous thromboembolism recurrence between the malignant (3.3%) and the nonmalignant (2.8%) venous thromboembolism groups (P = .533). Borderline higher rates for major bleeding (P = .06) and nonmajor clinically relevant bleeding (P = .08) were observed in patients with cancer. CONCLUSIONS: The "real world" effectiveness and safety of rivaroxaban is similar for venous thromboembolism patients with and without active malignancy.

Determination of isocyanic acid in air.

A method is presented for the determination of isocyanic acid (ICA), HNCO, in air samples as a di-n-butylamine (DBA) derivative. The method is based on sampling in midget impinger flasks containing 10 ml of 0.01 mol l-1 DBA in toluene. Quantification was made using liquid chromatography (LC) and electrospray mass spectrometry (MS) monitoring positive ions. The instrumental detection limit for the LC-MS was 10 fmol of ICA-DBA. ICA was generated by thermal decomposition of urea. A standard solution containing the DBA derivatives of ICA was prepared by collecting the emitted ICA in an impinger flask containing DBA. ICA in the reference solution was characterised by LC and time-of-flight (TOF) MS and quantified by LC chemiluminescent nitrogen detection (LC-CLND). The instrumental detection limit for the LC-CLND was 1 ng of nitrogen. ICA was emitted during thermal degradation of PFU resins and polyurethane (PUR) lacquers, from car metal sheets. ICA was the most dominant isocyanate and in PUR coating up to 8% of the total weight was emitted as ICA and for PFU resins up to 14% was emitted as ICA. When air samples were collected in an iron foundry during casting in sand moulds with furan resins, concentrations of ICA in the range 50-700 micrograms m-3 were found in the working atmosphere.

Exposure biomarkers and risk from gluing and heating of polyurethane: a cross sectional study of respiratory symptoms.

OBJECTIVES: To define the relation between exposure to polyurethane (PUR) glue, biomarkers of exposure and effect, and work related symptoms that occur at least once a week. METHODS: In a cross sectional study, 152 workers and 14 clerks in a factory with exposure to sprayed and heated PUR glue containing 4, 4'-diphenylmethane (MDI) or 1,6-hexamethylene (HDI) di-isocyanate were examined with gas chromatography-mass spectrometry (GC-MS) for metabolites of MDI in plasma (P-MDX) and urine (U-MDX), 2,4- and 2, 6-toluene di-isocyanate (TDI; P-TDX, U-TDX) and HDI in plasma and urine, specific serum IgG (S-IgG-MDI, S-IgG-HDI, and S-IgG-TDI, respectively) and IgE (S-IgE-MDI). Work related symptoms of the eyes and airways (nose or lower airways, or both), and lung function were also evaluated. RESULTS: P-MDX was detected in 65% of the workers, U-TDX in 47%, HDX in none. Three per cent were positive for S-IgE-MDI, 33% for S-IgG-MDI, 32% for S-IgG-TDI, and 12% for S-IgG-HDI. A few clerks had metabolites, and some had antibodies. Most metabolites and immunoglobulins were slightly correlated-for example, P-MDX v S-IgG-MDI: r(s)=0.21. Workers who heated glue had increased P-MDX (odds ratio (OR)=12 for a value above the median) and S-IgG-MDI (OR=3.7), sprayers P-2,4-TDX (OR=6.2) and P-2,6-TDX (OR=16). Twenty six per cent of the workers had work related symptoms of the airways, 21% from the nose, 11% from the lower airways. Spraying of glue increased the risk of work related symptoms and slightly decreased lung function. U-MDX was associated with work related symptoms from the airways (OR=3.7) and P-2,6-TDX with work related symptoms from the lower airways (OR=6.6). S-IgG-MDI was related to work related symptoms from the airways (OR=2.6). CONCLUSIONS: There were relations between exposures to sprayed and heated PUR glue based on MDI and HDI, concentrations of metabolites of MDI and TDI in plasma and urine, specific IgG serum antibodies against MDI, TDI, and HDI, and work related symptoms.

Airborne thermal degradation products of polyurethene coatings in car repair shops.

A methodology for workplace air monitoring of aromatic and aliphatic, mono- and polyisocyanates by derivatisation with di-n-butylamine (DBA) is presented. Air sampling was performed using midget impinger flasks containing 10 ml of 0.01 mol l(-1) DBA in toluene and a glass-fibre filter in series after the impinger flask, thereby providing the possibility of collecting and derivatising isocyanates in both the gas and particle phases. Quantification was made by LC-MS, monitoring the molecular ions [MH]+. Air samples taken with this method in car repair shops showed that many different isocyanates are formed during thermal decomposition of polyurethane (PUR) coatings. In addition to isocyanates such as hexamethylene (HDI), isophorone (IPDI), toluene (TDI) and methylenediphenyl diisocyanate (MDI), monoisocyanates such as methyl (MIC), ethyl (EIC), propyl (PIC), butyl (BIC) and phenyl isocyanate (PhI) were found. In many air samples the aliphatic monoisocyanates dominated. During cutting and welding operations, the highest levels of isocyanates were observed. In a single air sample from a welding operation in a car repair shop, the highest concentrations found were: MIC, 290; EIC, 60; PIC, 20; BIC, 9; PhI, 27; HDI, 105; IPDI, 39; MDI, 4; and 2,4-TDI and 2,6-TDI 140 microg m(-3). Monitoring the particle size distribution and concentration during grinding, welding and cutting operations showed that ultrafine particles (< 0.1 microm) were formed at high concentrations. Isocyanates with low volatility were mainly found in the particle phase, but isocyanates with a relatively high volatility such as TDI, were found in both the particle and gas phases.

Determination of complex mixtures of airborne isocyanates and amines. Part 5. Determination of low molecular weight aliphatic isocyanates as dibutylamine derivatives.

A method is presented for the determination of low molecular weight aliphatic isocyanates, methyl isocyanate (MIC), ethyl isocyanate (EIC), propyl isocyanate (PIC) and butyl isocyanate (BIC), as their dibutylamine (DBA) derivatives. The method is based on sampling in midget impinger flasks containing 10 ml of 0.01 mol l-1 DBA in toluene (as in Parts 1-4 in this series). The samples are analysed using liquid chromatography-electrospray mass spectrometry (LC-ESP-MS) or gas chromatography-mass spectrometry using chemical ionisation with ammonia, monitoring positive ions (GC-PCI). Quantification was effected by monitoring the molecular ions MH+. Aliquots of 10 ml of toluene solutions containing 0.01 mol l-1 DBA were spiked with 0.03-0.85 microgram of MIC-, EIC-, PIC- and BIC-DBA. The correlation coefficients for LC-ESP-MS were in the range 0.9952-0.9999 (n = 14). The repeatability (RSD) was in the range 0.37-1.2% (0.12-0.34 microgram ml-1, n = 10). The instrumental detection limit for MIC was about 15 micrograms l-1, which corresponds to about 0.5 microgram m-3 in a 15 l air sample. The correlation coefficients for GC-PCI were in the range 0.9913-0.9990. The repeatability (RSD) was in the range 1.1-4.9% (0.12-0.34 microgram ml-1, n = 10). The instrumental detection limit for MIC was about 0.2 microgram l-1, which corresponds to about 0.05 microgram m-3 in a 15 l air sample. Using electron ionisation, the instrumental detection limit for MIC was about 10 micrograms l-1. No derivatisation reaction losses were seen when the derivatization reaction between PIC and DBA took place in the presence of morpholine, propylamine, ethanol, phenol and water. When mineral wool with a phenol-formaldehyde-urea resin was thermally degraded, 0.1% m/m of MIC was released. In air samples taken on top of a new electric oven insulated with mineral wool, MIC was found in the range 0.1-3 mg m-3. No MIC in air was found from a pre-heated oven.

Workers exposed to thermal degradation products of TDI- and MDI-based polyurethane: biomonitoring of 2,4-TDA, 2,6-TDA, and 4,4'-MDA in hydrolyzed urine and plasma.

The aim of the study was to investigate biomarkers of exposure to thermal degradation products of 2,4- and 2,6-toluene diisocyanate (TDI)- and 4,4'-methylenediphenyl diisocyanate (MDI)-based polyurethane and the toxicokinetics of these products. Blood and urine were collected from 15 factory workers exposed to thermal degradation products of MDI-based polyurethane glue and TDI-based flexible foam. Four of these workers were also studied during an exposure-free period. Urine and plasma were analyzed after acidic hydrolysis and the concentrations of the isocyanates' corresponding amines, 2,4-, 2,6-toluenediamine (TDA), and 4,4'-methylenedianiline (MDA), were determined as derivatives of pentafluoropropionic anhydride by gas chromatography using chemical ionization mass spectrometry monitoring negative ions. Urinary elimination rates were in the range of < 0.01-5.7 micrograms of 2,4-TDA per hour, < 0.01-3.5 micrograms of 2,6-TDA per hour, and < 0.01-1.6 micrograms of 4,4'-MDA per hour. Plasma levels were in the range of < 0.1-5.5 ng of 2,4-TDA per mL, < 0.1-2.3 ng of 2,6-TDA per mL, and < 0.1-45 ng of 4,4'-MDA per mL. The urinary half-lives of 4,4'-MDA for four of the workers were found to be 59, 61, 73, and 82 hours. The half-lives of 4,4'-MDA in plasma were 10, 14, 16, and 22 days. Elimination rate peaks of 2,4-TDA, 2,6-TDA, and 4,4'-MDA in urine varied during and between workdays. The individual variation in plasma concentrations of 2,4-TDA, 2,6-TDA, and 4,4'-MDA with time was small, but between individuals the variation was great.

Determination of complex mixtures of airborne isocyanates and amines. Part 3. Methylenediphenyl diisocyanate, methylenediphenylamino isocyanate and methylenediphenyldiamine and structural analogues after thermal degradation of polyurethane.

A method is presented for the determination of isocyanates in polymeric methylenediphenyl diisocyanate (MDI) and related compounds formed during the thermal decomposition of polyurethane (PUR). Derivatization of isocyanates was performed in impinger flasks containing dibutylamine (DBA) with the formation of urea derivatives. Compounds containing amine groups were then derivatized with ethyl chloroformate (ET to give urethane derivatives. Reversed-phase liquid chromatography, with a gradient flow rate of 40 milligrams min-1 and mass spectrometry in the electrospray mode monitoring positive ions was studied. Injection volumes of up to 10 milligrams of the sample were made possible by using column focusing. 1,5-Naphthyldiisocyanate-DBA and 1,5-naphthyldiamine-ET derivatives were used as internal standards. Virtually linear calibration curves were obtained for 4,4'-MDI-DBA and 4,4'-methylenediphenyldiamine-ET (MDA-ET) and the correlation coefficients were 0.9952-0.9964 (n = 14). The precision for five injections of samples spiked with 4,4'-MDA-ET, and 4,4'-MDI-DBA ar concentrations of 50 nmol ml-1 was 2.76 and 2.55%, respectively. The instrumental detection limit, defined as three times the noise, was 4 fmol of MDI-DBA and 50 fmol of MDA-ET injected. In chromatograms of polymeric MDI derivatized with diethylamine, dipropylamine and DBA, the presence of several structural isomers and analogues in polymeric MDI was demonstrated. In the chromatograms of thermal decomposition products of MDI-PUR, in addition to isocyanates, related amino isocyanates and amines were also observed.

Air and biological monitoring of toluene diisocyanate in a flexible foam plant.

Comparative air measurements of toluene diisocyanate (TDI) were performed in a 5.6 m3 standard atmosphere and at a TDI flexible foam plant. Air samples were collected in midget impinger flasks containing 9-(N-methyl-amino-methyl)-anthracene (MAMA) in toluene and on 13-mm glass-fiber filters impregnated with MAMA and glycerol analyzed by LC-UV and with filter-tape instruments. In the laboratory study the average amounts of the TDI-MAMA derivatives determined were higher for filters compared to impingers when tested at concentrations between 16 and 150 micrograms/m3 (n = 29). At the TDI foaming plant the amount of TDI-MAMA collected on the filters compared with impingers showed higher TDI values at low concentrations and lower values at higher concentrations. The same was seen for the filter-tape measurements, but for two samples at very low concentrations the response was much lower. The average air concentration was 29.8 micrograms/m3 (12.5-79.9; n = 12). The highest exposure peak measured was approximately 3 mg TDI/m3. 2,4- and 2,6-toluene diamine (TDA) in urine (U-TDA) and in plasma (P-TDA) from four exposed workers and one volunteer were determined after strong acid hydrolysis as their pentafluoro-propionic anhydride derivatives using gas chromatography-mass spectrometry. The ions monitored were the M-20 ions (M = molecular weight) of the TDA and trideuterium labeled TDA as the internal standard. The P-TDA among the workers varied between 1-38 micrograms/L and between 7-24 micrograms/L for 2,4- and 2,6-TDA, respectively. The individual plasma levels among the workers over the 3-day periods varied between 7-73%. For the volunteer, P-TDA reached a maximum about 24 hours after the last exposure. The half-time of P-TDA for the volunteer was about 10 days. The urine levels (U-TDA) varied greatly with time and exposure. High peaks were found during or shortly after the exposure. No clear correlation between air levels of TDI measured with the filter-tape instruments and levels of TDA in hydrolyzed urine and plasma was seen, but the U-TDAMax followed the exposure in time as measured with the filter-tape instruments.

Albumin adducts in plasma from workers exposed to toluene diisocyanate.

Desalted plasma from a 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6-TDI) exposed worker at a factory producing flexible polyurethane foam was separated and fractionated into 200 fractions using ion-exchange chromatography followed by a gel-filtration separation and fractionation into 59 fractions. The corresponding amines (to the isocyanates), 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA), were determined in each fraction after sulfuric acid hydrolysis as pentafluoropropionic anhydride derivatives by capillary gas chromatography and chemical ionisation mass spectrometry monitoring negative ions. The ion exchange fractions containing TDA (81-115) were added together and the solution was separated and fractionated on the gel-filtration column. The fractions 81-115 contained 84 and 72% of 2,4- and 2,6-TDA, respectively, as compared to the unfractionated plasma. The gel filtration fractions 22-27 contained 107 and 119% of 2,4- and 2,6-TDA, respectively, as compared to the amounts in the ion exchange fractions (81-115). Agarose gel-electrophoresis and electroimmunoassay demonstrated that albumin, 2,4- and 2,6-TDA co-eluted in both ion-exchange and gel-filtration chromatography. Quantitative determination of albumin, 2,4- and 2,6-TDA also demonstrated that these components co-eluted using albumin-immunosorption chromatography. In addition, studies of affinity isolated IgG revealed that this fraction was devoid of 2,4- and 2,6-TDA. These results indicate that albumin is the major receptor molecule for 2,4- and 2,6-TDI in blood plasma and that these isocyanates form covalent bondings with albumin.

Biomarkers in hydrolysed urine, plasma and erythrocytes among workers exposed to thermal degradation products from toluene diisocyanate foam.

Blood and urine samples were collected from six workers and two volunteers exposed to thermal degradation products from toluene diisocyanate (TDI)-based polyurethane (PUR) before and during the summer vacation. Air samples were collected on filters impregnated with 9-(N-methylaminomethyl)anthracene. The concentrations of the amines corresponding to 2,4- and 2,6-TDI, i.e., 2,4- and 2,6-toluenediamine (TDA), were determined in urine (U-TDA), plasma (P-TDA) and erythrocytes (E-TDA) after acid hydrolysis as pentafluoropropionic anhydride derivatives by GC-MS. Among the workers urinary elimination phases were seen. The estimated medians of the urinary half-lives were for the slow phase 18 d for 2,4-TDA and 19 d for 2,6-TDA. P-2,4-TDA ranged between 2.5 and 19 ng ml-1 and P-2,6-TDA between 4.4 and 30 ng ml-1. The estimated median of the half-lives in plasma were 7.8 d for 2,4-TDA and 9.6 d for 2,6-TDA. E-2,4-TDA ranged between 0.5 and 6.6 ng g-1 and E-2,6-TDA between 1.2 and 14 ng g-1. A significant linear relationship was found between the mean P-TDA and the mean E-TDA. Linear relationships were observed between the mean daily U-TDA and P-TDA and E-TDA. Virtually linear relationships were obtained for P-TDA and E-TDA and the TDI air levels. Proteins from lysed erythrocytes were separated and fractionated by gel filtration. 'TDI'-modified proteins were found in six out of a total of 80 fractions (fractions 51-56). These co-eluted completely with the haemoglobin (UV, 415 nm). Fractions 51-56 contained 89% of the applied amounts of 2,4-TDA and 81% of 2,6-TDA.

Biomarkers of exposure, antibodies, and respiratory symptoms in workers heating polyurethane glue.

OBJECTIVES: The pathogenic basis of respiratory disorders associated with isocyanates are still obscure. One reason for this is the lack of good estimates of human exposure. In this study exposure was estimated by measurement of isocyanate metabolites in biological samples. METHODS: In a factory using isocyanate based polyurethane (PUR) glue, isocyanate concentrations in air were measured by liquid chromatography. Samples from 174 employees were analysed for metabolites of 4,4'-methylene diphenyl diisocyanate (MDI) in plasma (P-MDX) and urine (U-MDX). After hydrolysis, 4,4'-methylenedianiline was measured by gas chromatography-mass spectrometry (GC-MS). The employees were screened for work related respiratory symptoms and tested for specific immunoglobulin E (IgE) and IgG antibodies directed against isocyanate conjugated to human serum albumin. RESULTS: The time weighted isocyanate concentrations in air were low (MDI < 0.2-7; hexamethylene diisocyanate (HDI) < 0.1-0.7; 2,6-toluene diisocyanate (TDI) < 0.1 microgram/m3). All subjects had detectable P-MDX and U-MDX. There were significant associations between the estimates of exposure to thermal degradation products of an MDI based glue and P-MDX (range < or = 0.10-5.5 micrograms/l); and U-MDX (< or = 0.04-5.0 micrograms/g creatinine); in cases of heavy exposure. P-MDX and U-MDX were associated with each other (r = 0.64; P = 0.0001), work related symptoms (P-MDX: P = 0.03; Mann-Whitney U test), and serum concentrations of MDI specific IgG antibodies (r = 0.26; P = 0.0007). Unexpectedly, high P-MDX and U-MDX concentrations were also encountered in workers cutting textile (P-MDX 2.4-4.5 micrograms/l; U-MDX 0.81-3.8 micrograms/g creatinine); the reason is still unknown. Equally unexpected, there were significant negative associations between P-MDX and liver function tests. CONCLUSIONS: The results clearly show the value of biomarkers for isocyanate exposure; in particular, P-MDX is useful. Further, these results show the risk connected with thermal degradation of PUR.

Toxicokinetics of 2,4- and 2,6-toluenediamine in hydrolysed urine and plasma after occupational exposure to 2,4- and 2,6- toluene diisocyanate.

OBJECTIVES: To assess the toxicokinetics of 2,4- and 2,6- toluenediisocyanate (TDI) in chronically exposed subjects. METHODS: Blood and urine, from 11 workers at two flexible foam polyurethane production plants, were sampled. By gas chromatography-mass spectrometry (GC-MS) 2,4- and 2,6-toluene diamine (TDA) were measured as pentafluoropropionic anhydride (PFPA) derivatives after acidic hydrolysis of plasma (P-TDA, ng/ml) and urine (U-TDA, microgram/h). RESULTS: In one of the plants the P-2,4-TDA concentrations were 0.4-1 ng/ml before a four to five week holiday and 0.2-0.5 ng/ml afterwards. The corresponding values for P-2,6-TDA were 2-6 and 0.5-2 ng/ml respectively. In the other plant the P-2,4-TDA concentrations were 2-23 ng/ml before the holiday and 0.5-6 ng/ml afterwards and the P-2,6-TDA concentrations were 7-24 ng/ml before and 3-6 ng/ml afterwards. The P-2,4-TDA concentrations were 2-24 ng/ml before a 12 day holiday, and 1-14 ng/ml afterwards. The corresponding values for P-2,6-TDA were 12-29 and 8-17 ng/ml, respectively. The urinary elimination rates (U-TDA, microgram/h) for 2,4-TDA before the holiday were 0.04-0.54 and 0.02-0.18 microgram/h afterwards. The corresponding values for 2,6-TDA were 0.18-0.76 microgram/h before and 0.09-0.27 microgram/h after the holiday. The half life in urine ranged between 5.8 and 11 days for 2,4- and 2,6-TDA. The differences in exposure were reflected by the P-TDA concentrations. The mean half life in plasma was 21 (range 14-34) days for 2,4-TDA and 21 (16-26) days for 2,6-TDA. The TDI air concentrations varied between 0.4 and 4 micrograms/m3 in one plant and in the other between 10 and 120 micrograms/m3. CONCLUSIONS: The half life in plasma of chronically exposed workers for 2,4-and 2,6-TDA was twice as long as for volunteers with short term exposure. An indication of a two phase elimination pattern in urine was found. The first phase was related to the more recent exposure and the second, much slower one was probably related to release of TDA in urine from TDI adducts in the body.

MDA in plasma as a biomarker of exposure to pyrolysed MDI-based polyurethane: correlations with estimated cumulative dose and genotype for N-acetylation.

The object of this study was to investigate whether exposure of pipe-layers to thermal degradation products of diphenylmethane diisocyanate (MDI) could be assessed by analysing 4,4-methylenedianiline (MDA) in hydrolysed plasma and urine, and whether the genotype for N-acetylation affected these biomarker levels. Blood and urine samples were drawn from 30-pipe-layers who had been welding polyurethane (PUR) insulated pipes during the preceding 3 months. MDA in hydrolysed plasma and urine was determined with a gas chromatography-mass spectrometry technique, and genotype for N-acetylation was analysed with a polymerase chain reaction technique. MDA in plasma was detected in 18 of the 30 pipe-layers. Their plasma concentrations of MDA varied from 0.05 to 8.48 micrograms/l. There was a significant negative correlation between time since last welding of PUR-insulated pipes and P-MDA (rs = 0.50, P = 0.005). There was also a significant positive correlation between the estimated number of welded PUR-insulated pipes during the preceding 3 months and P-MDA (rs = 0.68, P = < 0.001). No significant association between genotype of N-acetylation and P-MDA was observed in a multiple regression analysis when adjustment was made for the estimated cumulative exposure to thermal degradation products of MDI. MDA in urine was detected in only four of the 30 pipe-layers. These four subjects had been welding PUR pipes on the same day as the sampling, or on the day before. The present results indicate the spot plasma samples analysed for MDA may give a rather good estimate of exposure to MDI during the preceding months. P-MDA, but not U-MDA, therefore seems to be a useful biomarker of long-term exposure to MDI. The individual N-acetylation capacity did not affect the plasma levels of MDA.

Analysis of the reactivity of [14C]toluene diisocyanate (TDI) in an isolated, perfused lung model.

An isolated, perfused, guinea pig lung model was used to investigate the molecular events which occur when a 14C-labeled TDI vapor reaches the airways. Exposure concentrations of 0.2 and 0.7 ppm were tested. Perfusate composition included: Krebs Ringer buffer only, as well as buffer containing either guinea pig serum albumin, human serum albumin, or diluted guinea pig plasma. Radioactivity was detected in the perfusate within minutes of exposure, and following a delay, increased linearly. The rate of uptake was dependent on TDI concentration and the composition of the perfusate. Biochemical characterization of the state of the 14C-labeled material in the perfusate was performed. The distribution between low and high molecular weight reaction products was determined by molecular sieve fractionation and varied as a function of perfusate composition but no variability was observed as a function of time during the 45 min of exposure. An increase in nucleophile concentration in the perfusate was associated with both a higher percentage of conjugated products (from 15% with buffer only to 45% with diluted guinea pig plasma) and an increase in the rate of TDX uptake (from 0.5 microns Eq/min with buffer alone to 0.1 micrograms Eq/min with diluted GPSA as perfusate at 0.7 ppm). GC-MS analysis of the samples for free TDA, before and after acid hydrolysis, showed that the low molecular weight product(s), which represented from 55-85% of the circulating radioactivity, was composed of hydrolyzable and non-hydrolyzable conjugates and metabolites with approximately 4% of the label associated with free TDA. Although the distribution between high and low molecular weight species varies, this result is analogous to the findings from in vivo studies and suggests that the isolated, perfused lung (IVPL) system may be a useful tool in investigating the molecular mechanisms of isocyanate-induced disease and metabolic activity of the lung.

Urinary cotinine in children and adults during and after semiexperimental exposure to environmental tobacco smoke.

Urinary cotinine (U-cotinine) as a biomarker of environmental tobacco smoke exposure was evaluated in 14 children (age 4-11 y) and in 7 adults who were exposed to environmental tobacco smoke at an air nicotine level of 110 mg/m3 for 2 h in a bus. Nicotine in air and U-cotinine were measured by gas chromatography/mass spectrometry before, during, and after the experiment. U-cotinine rose rapidly to a maximum after a median of 6 h following the end of exposure; remained at an apparent plateau for half a day; and then decreased exponentially, with a mean half-time of 19 h (95% confidence interval 18-20 h; no significant difference between children and adults). The maximum U-cotinine was higher in the children (mean = 22 mg/l) than in the adults (13 mg/l; p = .005); decreased with age among the children (r = -.74; p = .002); and increased as the estimated inhaled nicotine dose increased. Therefore, the findings of the present study showed that young children had higher U-cotinine than adults at the same experimental environmental tobacco smoke exposure, probably because they had a higher relative nicotine dose because of a higher relative ventilation rate, and possibly also because of metabolic differences; the elimination rate did not differ. The long half-time makes U-cotinine a good biomarker of environmental tobacco smoke exposure; the time of sampling is not very critical. Dilution-adjusted concentrations should be employed, and in children, preferably by density correction. A certain urinary cotinine level indicates a lower environmental tobacco smoke exposure in a small child than in an adult.