Toluene Diisocyanate Concentration Research Articles

A synergistic effect of MXene/MWCNT enables self-healable and low percolation elastomer sensor: A combined experiment and all-atom molecular dynamics simulation

Flexible conductive composites have garnered significant interest as wearable strain sensors due to their potential in diverse application fields, such as next-generation robotics automation, electronic skin, and human body detection. Nevertheless, the practical usage scenarios often entail tear and fracture, posing a persistent challenge to their performance stability. Consequently, there exists a pressing demand to engineer conductive composites that not only exhibit flexibility, stretchability, and sensing capabilities but also demonstrate effective self-healing properties. This pursuit presents a formidable task, considering the complex requirements imposed on the materials. This study presents a novel methodology for fabricating a conductive silicone elastomer composite. The approach involves the initial utilization of an excess of amino-capped Polydimethylsiloxane (PDMS) to undergo a reaction with Toluene diisocyanate (TDI) and Isoflurane diisocyanate (IPDI), leading to the formation of amino-capped polyurea (TPU). Subsequently, the self-healing elastomer IPDI/TDI/TA (ITT) is synthesized through chain expansion with Terephthalaldehyde (TA) in tetrahydrofuran (THF). To complement the experimental investigations, all-atom molecular dynamics (AAMD) simulations are employed to develop a comprehensive model elucidating the mechanical characteristics and self-healing capabilities of the elastomers. To introduce hybrid fillers into the elastomer composite, MXenes are electrostatically modified with L-glutamine (negatively charged), while multi-walled carbon nanotubes (MWCNTs) are modified with cetyltrimethylammonium bromide (positively charged). These modified fillers self-assemble in water and are subsequently combined with the aforementioned rubber THF solution after drying. Through ultrasonication and drying, the ITT elastomers/MXene/MWCNT composite is successfully prepared. The formation of hydrogen bonds and dynamic imine bonds is verified using FT-IR and AAMD simulations. By maintaining a fixed ratio of TA to PDMS, we observe a positive correlation between TDI concentration and the fracture strength of the ITT elastomer, while the elongation at break decreases with increasing TDI. Furthermore, the successful modification of MXene and MWCNT is confirmed through FT-IR, XRD, and zeta potential measurements, and the resulting composites exhibit significant electrical conductivity and self-healing properties. Tensile and electrochemical measurements demonstrate that the composite possesses promising characteristics suitable for sensor applications, and its mechanical and electrical properties can recover after self-healing. Notably, the resulting composites exhibit a very low conductivity threshold (3.5 wt%). The composite system exhibits desirable tensile properties and efficient self-healing ability due to the reversibility of multiple hydrogen and imine bonds. Overall, this study aims to introduce a novel elastomer-based composite that possesses excellent properties in terms of self-healing, stretchability, sensing capability and flexibility.

Preparation and characterization of pesticide Fosthiazate‐loaded microcapsules for controlled release system

AbstractPreparation of Fosthiazate (FTZ)‐loaded microcapsules with controlled release was attempted by the interfacial polymerization using toluene diisocyanate (TDI) and triethylenetetramine (TETA) as monomers. The effects of the monomer concentration and the monomer concentration ratio on characteristics of the microcapsules such as size, shell thickness and release behavior in water and in soil were studied. In the study, FTZ was successfully encapsulated into a polyurea resin, and the characterization revealed that the microcapsule shell became thicker proportionally to the applied monomer concentration. The release rate of FTZ from the microcapsules in water was mostly proportional to the ratio of the surface area to the shell thickness of the microcapsules, and the release rate fitted the first‐order kinetic model. On the one hand, when TDI concentration was low or the monomer concentration ratio was high, the release rate was significantly increased owing to the formation of insufficient microcapsule shell and the coarseness of the shell. Moreover, the slower the release rate in water was, the higher residual ratio of FTZ in soil could be maintained. However, it was also observed that the release rate in soil was faster than that in water. It is suggested that the constant replacement of water around the microcapsules accelerated the release rate, or the microcapsule particles migrated through the soil. These results indicated that FTZ‐loaded microcapsules with controlled release were able to be prepared. In addition, basic findings about the relationship and the difference between the release behaviors of FTZ‐loaded microcapsules in water and in soil were obtained.

Exposure to Toluene Di-isocyanate and Respiratory Effects in Flexible Polyurethane Foam Industries in Western India.

Background:Flexible foam industry largely uses 2,4 and 2,6 Toluene di-isocyanate as main raw materials and chronic exposure to its result in occupational asthma. The exposure to di-isocyanates might be higher due to the usage of obsolete technology, hand-mixing methods and working in confined spaces with insufficient local exhaust ventilation systems in developing countries. Exposure studies in flexible foam industries have not been done in developing countries.Objective:The present cross-sectional study was conducted to evaluate toluene di-isocyanate (TDI) exposures and respiratory health of the workers working in the seven flexible polyurethane foam industries located in Western India during 2010-2013.Method:A total of 128 personal air samples collected and evaluated for total TDI concentration using improved Occupational Safety and Head Administration method number 42. Then 194 workers were covered for complete clinical examination and spirometry for assessing respiratory health.Results:In all, 17.83% of air samples exceeded the ACGIH TWA-TLV of 0.005 ppm for TDI. Though only 11 (5.6%) workers had respiratory complaints, the spirometry revealed that 19 (9.8%) and four (2.1%) had restrictive and obstructive type of pulmonary function impairment, respectively.Conclusion:The TWA concentration of TDI exceeded at raw material storage, mixing, foaming, block cutting and curing areas in four out of seven industries even in the presence of local exhaust systems. The respiratory health effect is less when compared to exposure to TDI, suitable preventive and control measures were suggested based on the study findings to the stakeholders to prevent the increase of respiratory health effects.

Involvement of Innate Lymphoid Cells and Dendritic Cells in a Mouse Model of Chemical-induced Asthma

PurposeExposure to low concentrations of toluene diisocyanate (TDI) leads to immune-mediated chemical-induced asthma. The role of the adaptive immune system has already been thoroughly investigated; nevertheless, the involvement of innate immune cells in the pathophysiology of chemical-induced asthma is still unresolved. The aim of the study is to investigate the role of innate lymphoid cells (ILCs) and dendritic cells (DCs) in a mouse model for chemical-induced asthma.MethodsOn days 1 and 8, BALB/c mice were dermally treated (20 µL/ear) with 0.5% TDI or the vehicle acetone olive oil (AOO; 2:3). On days 15, 17, 19, 22 and 24, the mice received an oropharyngeal challenge with 0.01% TDI or AOO (1:4). One day after the last challenge, airway hyperreactivity (AHR) to methacholine was assessed, followed by an evaluation of pulmonary inflammation and immune-related parameters, including the cytokine pattern in bronchoalveolar lavage fluid, lymphocyte subpopulations of the lymph nodes and their ex vivo cytokine production profile, blood immunoglobulins and DC and ILC subpopulations in the lungs.ResultsBoth DC and ILC2 were recruited to the lungs after multiple airway exposures to TDI, regardless of the prior dermal sensitization. However, prior dermal sensitization with TDI alone results in AHR and predominant eosinophilic airway inflammation, accompanied by a typical type 2 helper T (Th2) cytokine profile.ConclusionsTDI-induced asthma is mediated by a predominant type 2 immune response, with the involvement of adaptive Th2 cells. However, from our study we suggest that the innate ILC2 cells are important additional players in the development of TDI-induced asthma.

Thymic stromal lymphopoietin (TSLP) and Toluene-diisocyanate-induced airway inflammation: Alleviation by TSLP neutralizing antibody

Toluene-diisocyanate (TDI) is mainly used in the manufacturing process of polyurethane foams, and is a potent inducer of occupational asthma characterized by airway inflammation and airway hyperreactivity. Thymic stromal lymphopoietin (TSLP) plays an important role in the development of asthma, and correlating with the differentiation of Th2 and Th17 cells. However, the role of TSLP in TDI-induced asthma remains unclear. In this study, 96 TDI-exposed workers as well as a mouse model of TDI-induced asthma were investigated. The air exposure assessment result of TDI in the workplace showed that workers were exposed to inhalation of a very high concentration of TDI, approximately 8 times the recommended level, leading to a decrease in pulmonary function and an increase in inflammatory cells, as well as TSLP and IgE levels in the supernatant of sputum obtained from exposed workers. In order to further investigate the role of TSLP in the pathogenesis of TDI-induced asthma, a mouse model of TDI-induced asthma was also employed. Histopathological analysis of mouse lung and bronchus showed an obvious infiltration of inflammatory cells around the bronchus. The levels of inflammatory cells, IFN-γ, IL-4 and IL-17 in bronchoalveolar lavage fluid (BALF), the expression levels of TSLP protein and ROR-γt and IL-17 mRNA in mouse lung tissues were also significantly increased. However, after treatment with TSLP neutralizing antibody (TSLP-Ab), the degree of pulmonary and bronchial inflammation in mice was significantly alleviated, and the levels of inflammatory cells, IFN-γ, IL-4 and IL-17 in BALF, and the expression levels of ROR-γt and IL-17 mRNA in lung tissue were significantly decreased. Our data shows that TSLP plays an important role in the pathogenesis of TDI-induced asthma, and that TSLP-Ab can effectively alleviate TDI-induced airway inflammation of asthma.

Evaluation of chemical-specific IgG antibodies in male workers from a urethane foam factory

BackgroundPlastic resins are complex chemicals that contain toluene diisocyanate (TDI) and/or trimellitic anhydride (TMA), which cause occupational allergies (OA), including respiratory allergies. Serum IgGs against TDI and TMA have been suggested as potential markers of the exposure status and as exploring cause of OA. Although TDI-specific IgG has been examined for suspected OA, TMA-specific IgG is not commonly evaluated in a urethane foam factory. This study therefore investigated both TDI- and TMA-specific IgGs in suspected OA patients and to evaluate the usefulness of the measurement of multiple chemical-specific IgG measurement for practical monitoring.MethodsBlood samples were collected from two male workers who developed respiratory allergies supposedly caused by occupational exposure to TDI and/or TMA for the presence of TDI- and TMA-specific IgGs. In addition, blood samples from 75 male workers from a urethane foam factory, along with 87 male control subjects, were collected in 2014 and tested for the same IgGs in 2014. The presence and levels of TDI- and TMA-specific serum IgGs were measured using dot blot assays.ResultsWe found that controls had mean concentrations of TDI- and TMA-specific IgGs of 0.98 and 2.10 μg/mL, respectively. In the two workers with respiratory allergies, the TDI-specific IgG concentrations were 15.6 and 9.51 μg/mL, and TMA-specific IgG concentrations were 4.56 and 14.4 μg/mL, which are clearly higher than those in controls. Mean concentrations of TDI- and TMA-specific IgGs in the factory workers were 1.89 and 2.41 μg/mL, respectively, and are significantly higher than those of the controls (P < 0.001 and P < 0.026 for TDI- and TMA-specific IgGs, respectively).ConclusionThe workers suspected of OA showed an evidently high level of TDI- and TMA-specific IgG, and these levels in workers at the urethane foam factory were also significantly higher than those in controls. In conclusion, the measurement of TDI- and TMA-specific IgG among workers using plastic resins is helpful to monitor their exposure status.

Preparation and formation mechanism of porous polyurea by reaction of toluene diisocyanate with water and its application as adsorbent for anionic dye removal

A novel and easy one-step protocol for preparation of a new porous material, polyurea (PPU), is reported, which is accomplished through a precipitation polymerization of toluene diisocyanate (TDI) in mixed solvent of H2O-acetone without need for surfactant and porogen. Effects of TDI concentration, mechanical stirring, solvent composition and TDI addition rate on PPU structure are studied. Surface morphology and pore structure of PPU are characterized by scanning electron microscopy and Hg intrusion. Chemical structure of the PPU polymer is investigated using NMR, XRD and FTIR. Mechanism of pore formation is discussed. The obtained PPU is used as adsorbent for anionic dyes adsorption investigation. Two anionic dyes, remazol brilliant blue R and acid fuchsine, are tested. The results indicate that the as-prepared PPU is of high performance in dye adsorption and recycled use. This study provided therefore a facile route to the preparation of a novel and attractive adsorbent candidate for removal of anionic dyes from wastewaters.

Preparation and characterization of composite NF membrane from a graft copolymer of trimethylallyl ammonium chloride onto chitosan by toluene diisocyanate cross-linking

A novel positively charged composite NF membrane was prepared using a copolymer graft of trimethylallylammonium chloride onto chitosan (GCTACC) as the top selective layer, a poly(acrylonitrile (PAN) ultrafiltrationmembrane as the support layer and toluene diisocyanate (TDI) as the cross-linking reagent. The effects of membranepreparation conditions on membrane performance were investigated such as TDI concentration, GCTACCconcentration, etc. The observation from scanning electron microscopy suggested the composite structure of theresultant NF membrane. At 20 and 30 L.h −1 of cycling flow, the permeability of pure water was 14.1 kg.h −1.m −2.MPa −1. The order of rejection to different salt solutions was MgCl 2> MgSO 4> NaCl > Na 2SO 4, revealing thecharacteristic of positively charged NF membranes.

Underestimation of toluene diisocyanate concentration using long-term sampling with 1-(2-methoxyphenyl) piperazine impregnated filters

Occupational exposure to toluene diisocyanate (TDI) is a known occupational hazard and the occupational exposure limits in air are very low. One of the most common methods to monitor exposure to isocyanates is to sample air through filters impregnated with 1-(2-methoxyphenyl) piperazine (2MP). In one earlier field study it was found that long-term sampling with 2MP-filters underestimated the exposure compared with consecutive short-term samples of TDI. The aim of this study was to confirm that finding in a controlled atmosphere in the laboratory. A test atmosphere of 2,4-TDI or 2,6-TDI was generated in a small test chamber and parallel long-term samples and consecutive short-term samples were collected. A total of 159 filters were exposed. The long-term samples collected significantly lower amounts of TDI than the sum of the short-term samples. For a 4-h sampling, the air levels were calculated to underestimate the exposure for 2,4-TDI by a factor of 1.4 and for 2,6-TDI by a of factor 1.3. The calculated underestimation was lower than earlier reported.

Measurement of 2,4-toluene diisocyanate concentrations by different samplers

The standard sampling methods for toluene diisocyanate (TDI) only collect total TDI without separating the aerosol and gas phases. There are few other samplers, such as the dual filter, triple filter and annular denuder systems (ADS), which are able to sample the aerosol and gas phases simultaneously. This field study was conducted at two workplaces to access the total 2,4-TDI and the gaseous and aerosol TDI concentrations by different samplers simultaneously. In addition to the standard sampling time of 15 min, sampling was done for 30 and 60 min to study the effect of sampling time on the measured 2,4-TDI concentrations. Test results at two workplaces show that gas-phase 2,4-TDI is the predominant species and the aerosol phase concentration is very small. The measurements using various samplers show that the sampling time influences the sampled TDI concentration considerably which may be due to reaction of TDI with water vapor and polyo in the sampling process. It is evident that as sampling time increases the TDI concentration decreases. Laboratory test was also conducted using pure gas-phase 2,4-TDI to confirm the sampling time effect on the measured concentrations found in the field study.

Eosinophil infiltration in airways of mice exposed to toluene diisocyanate.

Toluene diisocyanate (TDI) is a chemically reactive low-molecular-weight compound widely used in industries as a polymerizing agent in the production of polyurethanes. TDI has been reported as one of the most important causes of occupational asthma. Clinical investigations have shown that asthma is an inflammatory disorder of the airways and is referred to as chronic eosiniopilic bronchitis . Evidence has shown that activation of selected T cells with subsequent eosinophil recruitment and secretion of eosinophil-derived mediators may contribute to both epithelial cell damage and airway hyperresponsiveness. Our previous study showed that a 5-day exposure to 1.35 ppm TDI vapor resulted in airway inflammatory responses characterized by marked infiltration of eosinophils in central and peripheral airways of an asthmatic mouse model, but the infiltration of eosinophils in the airways of animals exposed to different concentrations of TDI in different time courses is unknown. To address this problem, in the present study, mice were exposed to three doses of TDI, and the infiltration of eosinophils was determined at three different stages of exposure under each respective concentration.

Respiratory response to toluene diisocyanate depends on prior frequency and concentration of dermal sensitization in mice.

Occupational asthma is the principal cause of work-related respiratory disease in the industrial world. In the absence of satisfactory models for predicting the potential of low molecular weight chemicals to cause asthma, we verified that dermal sensitization prior to intranasal challenge influences the respiratory response using toluene diisocyanate (TDI), a known respiratory sensitizer. BALB/c mice received TDI or vehicle (acetone/olive oil) on each ear on three consecutive days (days 1, 2, and 3; 0.3 or 3% TDI) or only once (day 1, 1% TDI). On day 7, the mice received similar dermal applications of vehicle or the same concentration of TDI as before ("boost"). On day 10, they received an intranasal dose of TDI (0.1%) or vehicle. Ventilatory function was monitored by whole body plethysmography for 40 min after intranasal application, and reactivity to inhaled methacholine was assessed 24 h later. Pulmonary inflammation was assessed by bronchoalveolar lavage and histology. Mice that received an intranasal dose of TDI without having received a prior dermal application of TDI did not exhibit any ventilatory response or inflammatory changes compared to vehicle controls. In contrast, mice that had received prior application(s) of TDI, even if only on day 7, exhibited the following: ventilatory responses, compatible with bronchoconstriction, immediately after intranasal application with TDI; enhanced methacholine responsiveness 24 h later; and pulmonary inflammation characterized by neutrophils. This was, however, not the case in mice that received the highest dermal amount of TDI (3% on days 1, 2, and 3). These findings suggest that respiratory response to TDI depends on prior frequency and concentration of dermal sensitization in mice.

Respiratory Effects of Toluene Diisocyanate in the Workplace: A Discussion of Exposure-Response Relationships

Toluene diisocyanate (TDI) is an important industrial intermediate used in manufacturing flexible polyurethane (PUR) foams, surface coatings, cast elastomers, sealants, and adhesives. In this review long-term trends in workplace exposures to TDI are assessed in both the producing and using industries, and respiratory health effects of TDI are evaluated in relation to workplace TDI concentrations. The key respiratory health effects associated with repeated or long-term TDI exposure are bronchial asthma and an accelerated rate of decline in lung function. In the early years of the industry, annual incidence rates of occupational asthma (OA) due to TDI ranged from 1% to as high as 5 to 6%, depending on the extent of engineering and work practice controls in the various workplaces. Since the mid-1970s, annual OA incidence rates have been <1%, where 8 h TDI concentrations have been maintained below 5 ppb as determined by personal monitoring, even where short-term TDI concentrations above 20 ppb and less frequently above 40 ppb were routinely detected. In these latter settings, there is evidence that the majority of OA cases may be attributable to TDI concentrations well above 20 ppb associated with overexposure incidents. Further study is needed regarding the role of such incidents in inducing respiratory sensitization. Cross-sectional and longitudinal studies of lung function have indicated that continued exposure after development of work-related respiratory symptoms can lead to transient or accelerated fixed declines in forced expiratory volume in 1 sec (FEV1). These findings are congruent with the FEV1 declines demonstrated in general population studies of persons with persistent bronchial hyperresponsiveness or nonoccupational asthma. More recent longitudinal studies in settings with ongoing medical surveillance have provided no consistent evidence of accelerated FEV1 loss among employees exposed up to 5 ppb TDI on an 8 h time-weighted average basis.

Occupational Asthma, Lung Function Decrement, and Toluene Diisocyanate (TDI) Exposure: A Critical Review of Exposure-Response Relationships

An extensive amount of clinical/epidemiological literature exists regarding the effects of toluene diisocyanate (TDI) exposure on respiratory health. This review presents an evaluation and synthesis of that literature with an emphasis on assessing exposure-response relationships in the workplace. The key respiratory disorders examined are bronchial asthma and an accelerated decline in lung function. In the early years of the industry, annual incidence rates of TDI-induced occupational asthma (OA) were as high as 5-6 percent. In settings where mean TDI concentrations have been maintained below 5 ppb based on 8-hr personal samples, OA incidence rates have declined to < 1 percent annually. Recent data also suggest that overexposure incidents may play an important role in inducing OA, particularly in work environments engineered to minimize routine ambient air concentrations. Fourteen studies were reviewed that examined lung function decrement. Early studies from the 1960s and 1970s provided evidence of transient or fixed lung function loss (measured as a decline in forced expiratory volume in one second [FEV1]) during periods of ongoing exposure among employees experiencing high rates of work-related symptoms of OA. Such findings would not be unexpected in that modest FEV1 declines have been demonstrated in general population studies of persons with bronchial hyperresponsiveness or persistent non-occupational asthma. More recent workplace studies have provided no consistent evidence of accelerated FEV1 loss among employees exposed up to 5 ppb TDI (8-hr TWA) even with documented routine short-term TDI concentrations exceeding 20 ppb TDI.

Toluene diisocyanate concentration investigation among TDI-related factories in Taiwan and their relations to the type of industry.

To determine nationwide 2,4- and 2,6-toluene diisocyanates (TDI) concentrations among polyurethane (PU) resin, PU foam, and other TDI-related industries in Taiwan. The ratios of 2,4-/2,6-TDI and the noncarcinogenic risk among these three industries were also investigated. Personal and fixed-area monitoring of TDI concentrations as well as questionnaires were performed for 26 factories in Taiwan. The modified OHSA 42 method was applied in sampling and analysis. Noncarcinogenic hazard index was estimated for these three industries based on the average concentration measurements. Significant differences of TDI concentrations were found among the three industry categories. For personal monitoring, PU foam was found to have the highest TDI levels [18.6 (+/-33.6) and 22.1 (+/-42.3) ppb for 2,4- and 2,6-TDI], Others average [8.3 (+/-18.9) and 10.2 (+/-17.2) ppb], and PU resin lowest [2.0 (+/-3.5) and 0.7 (+/-1.2) ppb]. The estimated average hazard indices were found to be 310-3310. A substantial percentage of airborne TDI concentrations among in Taiwan industries exceeded current TDI occupational exposure limit, and significant difference of TDI levels were found among the three industry categories. The control remedy for the tasks of charging and foaming should be enforced with the highest priority. A separate 2,6-TDI exposure standard is warranted.

Community exposure assessment and intervention effectiveness at Trinity American Corporation, Glenola, North Carolina.

This case study was a critical investigation of the analytical methodology and exposure assessment components of an intervention that led to the closure of a polyurethane foaming plant in Glenola, N.C., where plant neighbors reported a wide range of adverse health effects. Resident complaints and reports of nuisance odors and health effects persisted for many years, coming to a head in late 1995 and early 1996. Central to state and federal agency activities was the determination of the concentrations of air contaminants including toluene diisocyanate (TDI) at the plant fence line to establish an empirical foundation for resident complaints. Well over 2000 air concentration measurements were collected in the 18-month period prior to intervention and plant closure in September 1997. Results showed that flawed methodology, including poor quality assurance and improper interpretation of the data, may have led to improper conclusions and the inappropriate closing of this facility. Agency data did not show that ambient air concentrations of TDI at the plant fence line exceeded any required or recommended concentration limit. Furthermore, the identity and concentration of other air contaminants were not thoroughly investigated. Key lessons learned are that such interventions must be based on well-designed and executed exposure assessments. Resultant risk determinations must be based on sound science and methods.

Reactive bonding of natural rubber to metal by a nitrile–phenolic adhesive

AbstractThe mechanism of adhesive bonding of rubber to metal using an interlayer of bonding agent (adhesive) is discussed with respect to various physical and chemical events such as adsorption at the metal surface, chemical crosslinking within the adhesive, interdiffusion, and formation of interpenetrating networks at the rubber–adhesive interface. An investigation on the peel strength of a natural rubber (NR)–adhesive–metal joint, made by vulcanization bonding using nitrile–phenolic adhesive containing various concentrations of toluene diisocyanate–nitrosophenol (TDI–NOP) adduct, is presented. A single‐coat adhesive, consisting of a p‐cresol phenol formaldehyde resin, nitrile rubber (NBR), and vulcanizing agents in methyl ethyl ketone solvent, was selected for the study. Considerable improvement in the peel strength was obtained by the incorporation of TDI–NOP adduct into the nitrile–phenolic adhesive. The peel strength increases as the concentration of TDI–NOP adduct in the adhesive composition increases, then levels off with a transition from interfacial failure to cohesive tearing of rubber. The peel strength improvement is believed to be attributed to the interfacial reactions between the bonding agent and natural rubber, when TDI–NOP adduct is incorporated. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 81: 2597–2608, 2001

Health Information in Material Safety Data Sheets for a Chemical Which Causes Asthma

OBJECTIVE: To assess the quality of health information on material safety data sheets (MSDS) for a workplace chemical that is well known to cause or exacerbate asthma (toluene diisocyanate, TDI). DESIGN: We reviewed a random sample of 61 MSDSs for TDI products produced by 30 manufacturers. MEASUREMENTS AND MAIN RESULTS: Two physicians independently abstracted data from each MSDS onto a standardized audit form. One manufacturer provided no language about any respiratory effects of TDI exposure. Asthma was listed as a potential health effect by only 15 of the 30 manufacturers (50%). Listing asthma in the MSDS was associated with higher toluene diisocyanate concentrations in the product (P<.042). Allergic or sensitizing respiratory reactions were listed by 21 manufacturers (70%). CONCLUSIONS: Many MSDSs for toluene diisocyanate do not communicate clearly that exposure can cause or exacerbate asthma. This suggests that physicians should not rely on the MSDS for information about health effects of this chemical.

Health information in material safety data sheets for a chemical which causes asthma.

To assess the quality of health information on material safety data sheets (MSDS) for a workplace chemical that is well known to cause or exacerbate asthma (toluene diisocyanate, TDI). We reviewed a random sample of 61 MSDSs for TDI products produced by 30 manufacturers. Two physicians independently abstracted data from each MSDS onto a standardized audit form. One manufacturer provided no language about any respiratory effects of TDI exposure. Asthma was listed as a potential health effect by only 15 of the 30 manufacturers (50%). Listing asthma in the MSDS was associated with higher toluene diisocyanate concentrations in the product (P <.042). Allergic or sensitizing respiratory reactions were listed by 21 manufacturers (70%). Many MSDSs for toluene diisocyanate do not communicate clearly that exposure can cause or exacerbate asthma. This suggests that physicians should not rely on the MSDS for information about health effects of this chemical.

Construction and evaluation of an aerosol generating apparatus for combustion products from polyurethane foam.

A system has been constructed and evaluated for generating aerosols from combustion or pyrolysis of various cross-linked polymers. The system consists of an aerosol generator and an aerosol chamber with a sampling compartment designed for various samplers and sampling probes. A geared electric motor assembly is used to lower a polymer strip into the controlled atmosphere of a quartz-lined furnace. The polymer used in this investigation was a polyurethane foam (PUF) based on toluene diisocyanate (TDI). Combustion of the PUF was conducted in filtered air at a temperature of 300 degrees C. The particle number concentration of the generated aerosol was measured by light scattering in the particle size range from 0.1 micron to greater than 5 microns. Air samples were collected periodically in impinger flasks using dibutylamine (DBA) in toluene as derivatization reagent. The TDI-DBA derivatives from the impinger samples were analyzed with high performance liquid chromatography. The aerosol generating system was found to generate a stable, reproducible, and predictable concentration of particles and TDI monomer. Three partial least squares models were created to evaluate the generator. The investigated responses were the TDI concentration, the particle number concentration, and the stability of the particle number concentration during the generating process. The factor with most impact on the concentrations of the generated aerosol was found to be the interaction between linear feeding rate of the polymer strip and the flow rate of combustion gas. For stability the linear feeding rate was the most important.