Benzene

Goldstein, Bernard D.; Witz, Gisela

doi:10.1002/9780470442890.ch13

Cited by 6 publications

(6 citation statements)

References 180 publications

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“…That is probably due to improper or poor displacement of indoor air with the influx of fresh air. Other studies have shown that benzene is absorbed mainly through skin and lungs; after being distributed into the tissues, benzene in the blood remains in equilibrium with that in expired air [24]. Data presented in this work suggest that, although automobile MCs do face exposure to several solvents during various maintenance tasks, they are relatively much less exposed to organic solvents than PNs.…”

Section: Discussionmentioning

confidence: 57%

Hematological Evidence of Occupational Exposure to Chemicals and Other Factors among Auto-Repair Workers in Rawalpindi, Pakistan

Kamal

Malik

2012

Osong Public Health and Research Perspectives

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ObjectivesOccupational exposure to aromatic solvents causes many serious health hazards to workers, especially if an ambient environment increases the exposure during routine working hours. This study was conducted on two related groups, i.e., automobile mechanics (MCs) and automobile spray painters (PNs), with an effort to analyze effects of chemical exposure on hematological parameters, keeping a focus on environmental parameters and workers’ personal behavioral characteristics that could be held responsible for increasing exposure risk.MethodsA preliminary survey of various chemicals used in these places was done, and 78 blood samples were collected from three groups (control, n = 24; mechanics, n = 25; painters, n = 29). Demographic features of workers were recorded through a short questionnaire.ResultsResults showed that mean red blood cell (RBC) count was lower both in MCs [t(51) = 2.38, p < 0.021, r = 0.32] and in PNs [t(47) = 2.12, p < 0.03, r = 0.29], whereas mean hemoglobin (Hb) was significantly lower in MCs [t(51) = 2.5, p = 0.017, r = 0.33]. Combined data for exposed groups for smokers (SMs) versus nonsmokers (NSs) showed that SMs had a significantly lower number (RBC count: t(52) = 2.28, p < 0.027, r = 0.25; Hb count: t(52) = 2.71, p < 0.009, r = 0.30] of these parameters than NSs, even compared to the control group. Moreover, logistic regression results showed that smoking is a significant predictor of reduction in RBC and Hb counts, besides occupational exposure and work experience to a little extent among exposed workers. Mean white blood cell count [t(47) = 2.63, p < 0.01, r=0.35], mean corpuscle volume [t(47)= –2.82, p = 0.007, r = 0.29], and packed cell volume [t(47)= –2.28, p = 0.027, r = 31] were higher exclusively in painters, which could be related to exposure to benzene in addition to isocyanate.ConclusionIt appeared that workplace exposure may be complex due to interaction of multiple factors and PNs face much more exposure to isocyanate and aromatic solvents than MCs, which had significant effects on their hematopoiesis. Smoking enhances exposure risk manifolds, and among MCs it showed combined effects along with occupational exposure. There is a need to create awareness among these workers to adopt self-safety measures during routine tasks and also of a separate study to elucidate actual occupational exposure among them, eliminating confounding factors.

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Section: Discussionmentioning

confidence: 57%

Hematological Evidence of Occupational Exposure to Chemicals and Other Factors among Auto-Repair Workers in Rawalpindi, Pakistan

Kamal

Malik

2012

Osong Public Health and Research Perspectives

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“…The elucidation of the pathways of benzene metabolism and their relation to benzene toxicity is the subject of extensive research (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). (£,£)-Muconic acid, 1 in Scheme I, has long been recognized as one of the metabolic products (1), and its presence in urine is widely used as a marker of benzene exposure (12).…”

Section: Introductionmentioning

confidence: 99%

Energetics of the metabolic production of (E,E)-muconaldehdye from benzene via the intermediates 2,3-epoxyoxepin and (Z,Z)- and (E,Z)-muconaldehyde: Ab initio molecular orbital calculations

Greenberg¹,

Bock²,

George³

et al. 1993

Chem. Res. Toxicol.

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To assess the feasibility of the pathway set out in the title, we have carried out ab initio molecular orbital calculations of the energies of cisoid- and transoid-2,3-epoxyoxepin and the eZzZz-, eZeZz-, eEeZz-, eEeEz-, and eEeEe-conformers of muconaldehyde at the MP2/6-31G* (frozen core, valence orbitals active) level with full geometry optimization using the split-valence RHF/6-31G* basis set. Including thermal energies, derived from vibrational frequencies obtained at the RHF/6-31G*//RHF/6-31G* level, reaction energies (that would correspond to gas phase data at 298 K) have been evaluated. The muconaldehyde conformers are lower in energy than the epoxyoxepin, i.e., are formed exothermically, and in accord with experiment, the Z,Z-conformers are less stable than the E,Z, and the E,Z less stable than the E,E. In addition, we have characterized the transition state for the fission of the C-O bond in the epoxy ring and the C-O bond in the oxepin ring of transoid-2,3-epoxyoxepin, thereby generating (eZzZz)-muconaldehyde. With an activation energy of 16.5 kcal mol-1 the half-life of the epoxyoxepin is very short at the temperatures employed in the experiments, less than 1 min, which explains why it has not been detected. To gain some insight into the isomerization about the carbon-carbon double bonds in the muconaldehyde conformers, we have examined the possible involvement of 2-formyl-2H-pyran and cyclobutene-3,4-dicarboxaldehyde as intermediates. In model reactions simulating the microsomal monooxygenase system, the formation of benzene oxide and of the epoxyoxepin are found to be very favorable exothermic processes.

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“…Causal inferences could be established in the absence of mechanistic understanding by consistent differences in response according to intensity of exposure to a specific agent, a mixture, or a marker of the mixture. Specific toxicants were associated with specific adverse effects, such as in occupational and environmental exposures to lead (Pb) associated with neuropathy (Fischbein and Hu, ; Grant, ), mercury (Hg) associated with neurotoxicity (Goldman, ; Grandjean and Nielsen, ), carbon monoxide (CO) as a cause of hypoxia and ischemic heart disease (Kleinman, ), benzene (C 6 H 6 ) as a cause of hepatic and bone marrow defects and of leukemia (Goldstein and Witz, ), silica (Si) associated with silicosis (Jalloul and Banks, ), and asbestos fibers associated with asbestosis, lung cancer, and mesothelioma (Rom, ; Lippmann, ). Similarly, for some general population exposures to complex mixtures, it was shown that there were exposure‐intensity related excesses of lung cancer and cardiac mortality in humans for passive cigarette smoke exposures (Samet et al., ) and for coal smoke–related community air pollution (Thurston et al., ), although, in these cases, the specific constituents within the mixtures that caused the effects are not yet adequately known.…”

Section: Introductionmentioning

confidence: 99%

Inhalation Toxicology Methods: The Generation and Characterization of Exposure Atmospheres and Inhalational Exposures

Chen

Lippmann

2015

CP Toxicology

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In this review, we outline the need for laboratory-based inhalation toxicology studies, the historical background on adverse health effects of airborne toxicants, and the benefits of advance planning for the building of analytic options into the study design to maximize the scientific gains to be derived from the investments in the study. We then discuss methods for: 1) the generation and characterization of exposure atmospheres for inhalation exposures in humans and laboratory animals; 2) their delivery and distribution into and within whole-body exposure chambers, head-only exposure chambers, face-masks, and mouthpieces or nasal catheters; 3) options for on-line functional assays during and between exposures; and 4) options for serial non-invasive assays of response. In doing so, we go beyond exposures to single agents and simple mixtures, and include methods for evaluating biological responses to complex environmental mixtures. We also emphasize that great care should be taken in the design and execution of such studies so that the scientific returns can be maximized both initially, and in follow-up utilization of archived samples of the exposure atmospheres, excreta, and tissues collected for histology.

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Benzene

Cited by 6 publications

References 180 publications

Hematological Evidence of Occupational Exposure to Chemicals and Other Factors among Auto-Repair Workers in Rawalpindi, Pakistan

Hematological Evidence of Occupational Exposure to Chemicals and Other Factors among Auto-Repair Workers in Rawalpindi, Pakistan

Energetics of the metabolic production of (E,E)-muconaldehdye from benzene via the intermediates 2,3-epoxyoxepin and (Z,Z)- and (E,Z)-muconaldehyde: Ab initio molecular orbital calculations

Inhalation Toxicology Methods: The Generation and Characterization of Exposure Atmospheres and Inhalational Exposures

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