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Plehiers PM. Comment on "Detection of exposed phosgene in household bleach: development of a selective and cost-effective sensing tool" by S. Saha and P. Sahoo, Environ. Sci.: Processes Impacts, 2023, 25, 1144. Environ Sci Process Impacts 2024; 26:791-792. [PMID: 38516873 DOI: 10.1039/d3em00483j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
In the absence of an identified source of carbon, the reported formation of phosgene from bleach powder is questioned. Interferences and confounding effects other than those investigated by the authors may have led to artifactual results.
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de Kort P, Jensen E, Spence MW, Plehiers PM. Risk assessment-based verification of the CertiPUR TM limit values for toluene diamine and methylene dianiline in flexible polyurethane foam. Toxicol Ind Health 2024; 40:104-116. [PMID: 38166466 PMCID: PMC10851636 DOI: 10.1177/07482337231224514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 11/28/2023] [Accepted: 12/01/2023] [Indexed: 01/04/2024]
Abstract
Flexible polyurethane foams (PUF) are used in many consumer products. PUF may contain trace levels of aromatic diamine impurities that could represent a potential health risk. The risk associated with sleeping on a PUF mattress was evaluated. Toxicity benchmarks for sensitization and non-cancer endpoints were derived from the respective points-of-departure using standard assessment factors. For the cancer endpoints, toxicity benchmarks were derived from the 25th-percentile values of animal studies. Recently published emission and migration data allowed to link exposure with the CertiPURTM voluntary quality limits of ≤5 mg.kg-1 for 2,4-toluene diamine and 4,4'-methylene dianiline in PUF. Using conservative exposure scenarios, lifetime-average daily internal doses from the combined inhalation and dermal exposures were calculated. Margins of safety for non-cancer and sensitization endpoints were >104. The theoretical excess cancer risk was ≤1.5 × 10-7. It is concluded that sleeping on a mattress that satisfies the CertiPUR limit value does not pose undue risk to consumers.
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Affiliation(s)
| | | | - Mark W Spence
- International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
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Plehiers PM, Ward L, West RJ, Boegi C. Model-Assisted Interpretation of 4,4'-Methylene Dianiline Adsorption on Soils at Micromolar Concentrations. Environ Toxicol Chem 2023; 42:2580-2588. [PMID: 37638670 DOI: 10.1002/etc.5737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/09/2023] [Accepted: 08/22/2023] [Indexed: 08/29/2023]
Abstract
Adsorption kinetics and isotherms were determined for 4,4'-methylene dianiline (MDA) on five diverse soils at nominal concentrations of 0.01-1.0 mg L-1 (nominal soil loading 0.1-40 μg gs -1 ). The data were used to model the adsorption process based on the two-step mechanism that is characteristic of the adsorption of aromatic amines, consisting of a physical equilibrium between the aqueous phase and the soil organic matter and a chemical reaction between the adsorbed MDA and reactive sites in the soil organic matter. Generic parameters were determined that enabled application of the model to other soils, which was checked against previously published data for MDA adsorption. At the low concentrations evaluated, the adsorption process took place almost exclusively in the organic matter without the need to account for a separate ion exchange process with the soil mineral fraction. Physical adsorption was found to be mainly dependent on the protonation state of MDA and increased with decreasing pH of the soils. Because of the chemical reaction taking place, adsorption equilibrium constants (organic-carbon partition coefficient [KOC ]) normalized to the organic carbon content in the soil gradually increased with time; and it was demonstrated that, at steady-state conditions, values of log KOC > 3.5 can be expected for most any soil at conservatively estimated potential environmental MDA concentrations. Environ Toxicol Chem 2023;42:2580-2588. © 2023 SETAC.
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Affiliation(s)
| | - Lauren Ward
- International Isocyanate Institute, Mountain Lakes, New Jersey, USA
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Spence MW, Plehiers PM, George A, Hankett J. Methylene diphenyl diisocyanate occupational exposure data in industry (1998-2020): A descriptive summary from an industrial hygiene perspective. Toxicol Ind Health 2023:7482337231176604. [PMID: 37269111 PMCID: PMC10359961 DOI: 10.1177/07482337231176604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper provides an overview of airborne methylene diphenyl diisocyanate (MDI) concentrations in workplaces across North America and Europe. A total of 7649 samples were collected between 1998 and 2020 by producers of MDI during product stewardship activities at customer sites, primarily using validated OSHA or ISO sampling and analysis techniques. As would be expected from the low vapor pressure of MDI, 80% of the concentrations were less than 0.01 mg/m3 (1 ppb) and 93% were less than 0.05 mg/m3 (5 ppb). Respiratory protection is an integral part of Industrial Hygiene practices; therefore, its use was studied and summarized. While covering a variety of MDI applications, a large number of samples was obtained from composite wood manufacturing facilities, offering specific insight into potential exposures associated with different process sections and job types in this industry sector. Given the potential presence in industrial processes of MDI-containing dust or aerosols, future work should place increased emphasis on also investigating dermal exposure. The data reported in this paper provide valuable information for product stewardship and industrial hygiene purposes throughout the MDI-processing industry.
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Affiliation(s)
- Mark W Spence
- International Isocyanate Institute, Inc.-Mountain Lakes, NJ, USA
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Karlsson D, Spence MW, Plehiers PM. Emission and time-resolved migration rates of aromatic diamines from two flexible polyurethane foams. Toxicol Ind Health 2023; 39:298-312. [PMID: 37145999 DOI: 10.1177/07482337231172816] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Performing risk assessments (RA) on household use of flexible polyurethane (PU) foams requires access to reliable data about emission and migration of potential diamine impurities. A toluene diisocyanate (TDI) and a methylene diphenyl diisocyanate (MDI) based foam were thermally treated to enable measurements on samples with defined concentrations of the corresponding diamines, toluene diamine (TDA), and methylene dianiline (MDA). The thermally treated foams used for emission testing contained up to 15 mg.kg-1 of TDA and 27 mg.kg-1 of MDA. Those used for migration testing contained 5.1 mg.kg-1 of TDA and 14.1 mg.kg-1 of MDA. Stability of the thermally generated diamines was sufficient for testing over a 37-day period. Analytical techniques that did not decompose the polymer matrix were applied. Emission rates for TDA and MDA isomers were less than the limit of quantitation (LOQ) of 0.008-0.07 μg.m-2.h-1. Migration was studied using samples of the same thermally treated foams over a 35-day period. Quantifiable migration of MDA from the MDI-based foam was only observed on Days 1 and 2. From Day 3 onward, migration rates were less than the LOQ. Quantifiable migration of TDA from the TDI-based foam rapidly decreased with time and was only observed on Days 1 thru 3. From Day 4 onward, migration rates were less than the LOQ. Theoretically, the migration rate should be inversely proportional to the square root of time (t) as t-0.5. This relationship was confirmed by the experimental data and enables extrapolating migration values to more extended time periods to conduct RAs.
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Affiliation(s)
| | - Mark W Spence
- International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
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Plehiers PM. Letter to the Editor Regarding Tiwari and Raghavan, Indian J Occup Environ Med 2022;26:189-92. Indian J Occup Environ Med 2023; 27:190-191. [PMID: 37600644 PMCID: PMC10434800 DOI: 10.4103/ijoem.ijoem_22_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/22/2023] [Indexed: 08/22/2023] Open
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Welz O, Pfeifle M, Plehiers PM, Sure R, Deglmann P. Reaction of OH with Aliphatic and Aromatic Isocyanates. J Phys Chem A 2022; 126:9333-9352. [DOI: 10.1021/acs.jpca.2c06011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Oliver Welz
- BASF SE, Scientific Modelling − Quantum Chemistry, Group Research, Carl-Bosch-Straße 38, Ludwigshafen am Rhein67056, Germany
| | - Mark Pfeifle
- BASF SE, Scientific Modelling − Quantum Chemistry, Group Research, Carl-Bosch-Straße 38, Ludwigshafen am Rhein67056, Germany
| | - Patrick M. Plehiers
- International Isocyanate Institute Inc. (III), 333 Route 46 West, Suite. 206, Mountain Lakes, New Jersey07046, United States
| | - Rebecca Sure
- BASF SE, Scientific Modelling − Quantum Chemistry, Group Research, Carl-Bosch-Straße 38, Ludwigshafen am Rhein67056, Germany
| | - Peter Deglmann
- BASF SE, Scientific Modelling − Quantum Chemistry, Group Research, Carl-Bosch-Straße 38, Ludwigshafen am Rhein67056, Germany
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Plehiers PM, Skoglund R, Spence MW, Kiorpes AL. Concluding remarks. Toxicol Ind Health 2022; 38:653-654. [PMID: 36047298 DOI: 10.1177/07482337221107234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
| | | | - Mark W Spence
- 550512International Isocyanate Institute, Inc., Mountain Lakes, NJ, USA
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Plehiers PM, Skoglund R, Spence MW, Kiorpes AL. Editorial. Toxicol Ind Health 2022; 38:493-494. [PMID: 35731550 DOI: 10.1177/07482337221110408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | | | - Mark W Spence
- 550512International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
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West RJ, Burleson S, Gulledge T, Miller JW, Chappelle AH, Krieger S, Graham C, Snyder S, Simon G, Plehiers PM. Exploring structure/property relationships to health and environmental hazards of polymeric polyisocyanate prepolymer substances-2. Dermal sensitization potential in the mouse local lymph node assay. Toxicol Ind Health 2022; 38:556-577. [PMID: 35624531 DOI: 10.1177/07482337221089587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The sensitization potencies of twenty custom-designed monomer-depleted polymeric polyisocyanate prepolymer substances and their associated toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI) monomer precursors were investigated by means of the mouse Local Lymph Node Assay (LLNA). These polymeric prepolymers were designed to represent the structural features and physical-chemical properties exhibited by a broad range of commercial polymeric polyisocyanate prepolymers that are produced from the reaction of aromatic and aliphatic diisocyanate monomers with aliphatic polyether and polyester polyols. The normalization of LLNA responses to the applied (15-45-135 mM) concentrations showed that the skin sensitization potency of polymeric polyisocyanate prepolymers is at least 300 times less than that of the diisocyanate monomers from which they are derived. The sensitization potency of the prepolymers was shown to be mainly governed by their hydrophobicity (as expressed by the calculated octanol-water partition coefficient, log Kow) and surfactant properties. Neither hydrophilic (log Kow <0) nor very hydrophobic (log Kow >25) prepolymers stimulated lymphocyte proliferation beyond that of the dosing vehicle control. The findings of this investigation challenge the generally held assumption that all isocyanate (-N=C=O) bearing substances are potential skin (and respiratory) sensitizers. Further, these findings can guide the future development of isocyanate chemistries and associated polyurethane applications toward reduced exposure and health hazard potentials.
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Affiliation(s)
- Robert J West
- 550512International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
| | | | - Travis Gulledge
- Currently Burleson Research Technologies, StrideBio Inc, Durham, NC, USA
| | - Jason W Miller
- Environmental Analytics, Covestro LLC, Pittsburgh, PA, USA
| | - Anne H Chappelle
- 550512International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
| | - Shannon Krieger
- 5470Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, MI, USA
| | | | - Stephanie Snyder
- Environmental Analytics, Covestro LLC, Pittsburgh, PA, USA.,Product Safety and Regulatory Affairs, Covestro LLC, Pittsburgh, PA, USA
| | - Glenn Simon
- Simon Toxicology, LLC, Raleigh, NC, USA (Consultant to Vencorex US, Inc.)
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Abstract
By way of introduction to the special issue on d iisocyanates and their corresponding diamines, this brief overview presents, for the most commonly used diisocyanate monomers, a selection of physical-chemical properties that are relevant to exposure in the workplace and in the general environment, as well as a concise overview of diisocyanate reactions and some of their toxicological implications.
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Affiliation(s)
- Mark W. Spence
- International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
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Schupp T, Plehiers PM. Absorption, distribution, metabolism, and excretion of methylene diphenyl diisocyanate and toluene diisocyanate: Many similarities and few differences. Toxicol Ind Health 2022; 38:500-528. [PMID: 35301910 DOI: 10.1177/07482337211060133] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) are high production volume chemicals used for the manufacture of polyurethanes. For both substances, the most relevant adverse health effects after overexposure in the workplace are isocyanate-induced asthma, lung function decrement and, to a much lesser extent, skin effects. Over the last two decades many articles have addressed the reactivity of MDI and TDI in biological media and the associated biochemistry, which increased the understanding of their biochemical and physiological behavior. In this review, these new insights with respect to similarities and differences concerning the adsorption, distribution, metabolism, and excretion (ADME) of these two diisocyanates and the implications on their toxicities are summarized. Both TDI and MDI show very similar behavior in reactivity to biological macromolecules, distribution, metabolism, and excretion. Evidence suggests that the isocyanate (NCO) group is scavenged at the portal-of-entry and is not systemically available in unbound reactive form. This explains the lack of other than portal-of-entry toxicity observed in repeated-dose inhalation tests.
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Affiliation(s)
- Thomas Schupp
- 39002Münster University of Applied Sciences, Steinfurt, Germany
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Spence MW, Plehiers PM. Letter to the Editor concerning Gui et al.; Inception cohort study of workers exposed to toluene diisocyanate at a polyurethane foam factory. Am J Ind Med 2021; 64:1053-1054. [PMID: 34647334 DOI: 10.1002/ajim.23298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 04/14/2021] [Accepted: 09/22/2021] [Indexed: 11/10/2022]
Affiliation(s)
- Mark W. Spence
- International Isocyanate Institute, Inc. Mountain Lakes New Jersey USA
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Spence MW, West RJ, Plehiers PM. Letter to the editor regarding Cui et al., Microchemical Journal 160 (2021) 105722. Microchem J 2021. [DOI: 10.1016/j.microc.2021.106531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Plehiers PM, Chappelle AH, Spence MW. Practical learnings from an epidemiology study on TDI-related occupational asthma: Part II-Exposure without respiratory protection to TWA-8 values indicative of peak events is a good indicator of risk. Toxicol Ind Health 2020; 36:885-891. [PMID: 32945732 PMCID: PMC7750671 DOI: 10.1177/0748233720947203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The anonymized data of an epidemiology study on the incidence of toluene
diisocyanate (TDI)-related occupational asthma in three US-based TDI production
facilities have been reanalyzed to identify where to best focus exposure
reduction efforts in industrial practice in order to reduce the risk of
sensitization to TDI. In Part I, it was demonstrated that cumulative exposure is
not a good indicator of the risk of developing TDI-related occupational asthma.
In this Part II, an alternative model was developed based on net exposure
parameters (i.e. samples taken when no respiratory protection was used). A
statistically significant relationship was determined between asthma incidence
and the frequency of exposure to TDI levels indicative of peak events that are
expressed as time-weighted average-8 (TWA-8) values greater than 3 ppb during
which no respiratory protection was used. This relationship suggests a threshold
to induction of TDI-related asthma. The findings also highlight the importance
of a comprehensive program for controlling workplace atmosphere in the plant by
technical measures (e.g. selection of equipment, cleaning procedures) and
controlling exposure by organizational measures and situational awareness (e.g.
training, use of in-the-field direct reading indicators) during high potential
exposure scenarios (e.g. line breaking, spills) to encourage or enforce the
appropriate use of respiratory protection.
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Affiliation(s)
| | - Anne H Chappelle
- 550512International Isocyanate Institute, Inc. (III), Boonton, NJ, USA
| | - Mark W Spence
- 550512International Isocyanate Institute, Inc. (III), Boonton, NJ, USA
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Plehiers PM, Chappelle AH, Spence MW. Practical learnings from an epidemiology study on TDI-related occupational asthma: Part I-Cumulative exposure is not a good indicator of risk. Toxicol Ind Health 2020; 36:876-884. [PMID: 32862785 PMCID: PMC7750668 DOI: 10.1177/0748233720947202] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The anonymized data of an epidemiology study on incidence of toluene diisocyanate
(TDI)-related occupational asthma in three US-based TDI production facilities
have been reanalyzed to identify where to best focus exposure reduction efforts
in industrial practice to reduce the risk of sensitization to TDI. Since the
induction of sensitization has sometimes been attributed to cumulative exposure,
this relationship was examined first. Gross cumulative exposure values (i.e. not
taking into account whether respiratory protection was used or not) and net
cumulative exposure values (i.e. accounting for the use of respiratory
protection) per participant were calculated based on the duration of their study
participation and the average time-weighted average value of the exposure group
to which they belonged. These two sets of cumulative exposure data were compared
with asthma incidence using logistic regression. Incidence was zero among
workers who rarely come into contact with open plant systems (e.g. during
maintenance or spills). Notwithstanding, no statistically significant
relationship between asthma incidence and either gross or net cumulative
exposure could be determined. This is shown to be consistent with the results of
several other epidemiology studies on TDI-related occupational asthma. In
conclusion, cumulative exposure values are not a good indicator of the risk of
developing TDI-related occupational asthma.
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Affiliation(s)
| | | | - Mark W Spence
- 550512International Isocyanate Institute, Inc. (III), Boonton, NJ, USA
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Plehiers PM. Comment on "Isocyanic acid (HNCO) and its fate in the atmosphere: a review" by M. D. Leslie, M. Ridoli, J. G. Murphy and N. Borduas-Dedekind, Environ. Sci.: Processes Impacts, 2019, 21, 793. Environ Sci Process Impacts 2019; 21:2150-2152. [PMID: 31701116 DOI: 10.1039/c9em00403c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Can 1 ppb of isocyanic acid in air cause 100 μM in the blood stream? The impact of indoor and outdoor isocyanic acid (HNCO) levels may be of concern to human health. HNCO is well soluble in water but hydrolyzes rather slowly. Recently determined thermodynamic data and HNCO hydrolysis kinetics indicate that high blood levels might be reached. This data has been complemented with a brief assessment of kinetic information from the (bio)chemical and medical literature about carbamoylation reactions with proteins, indicating that other bodily elimination mechanisms cannot be ignored. Expected incremental blood levels corresponding to 1 ppbv HNCO in air are estimated to be in the low nM range. Acute toxic effects therefore seem unlikely, but chronic exposure to higher concentrations may still be of significance.
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