Chronic toxic encephalopathy in a painter exposed to mixed solvents

Molecular evidence of the amelioration of toluene induced encephalopathy by human breast milk mesenchymal stem cells

Toluene was widely used volatile organic compound that accumulates in tissues with high lipid content. Stem cells have been proposed as an increasingly attractive approach for repair of damaged nervous system, we aimed to evaluate the ability of breast milk mesenchymal stem cells (MSc) to ameliorate toluene-induced encephalopathy. Sixty adult male albino rats were assigned to 3 groups, control, toluene, and toluene/breast milk-MSc. Neurological assessment was evaluated as well as serum levels of glial fibrillary acidic protein (GFAP), tumor necrosis factor-alpha (TNF-α), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), tissue dopamine and oxidative markers. Gene expression of peroxisome Proliferator-Activated Receptor-Gamma (PPAR-ɣ), nuclear factor-kappaB (NF-kB), and interleukin-6 (IL-6) were evaluated. Moreover, histological and immunohistochemical investigation were done. Results revealed that toluene caused cerebral injury, as evidenced by a significant increase in serum GFAP, TNF-α, malondialdehyde (MDA) and nitric oxide (NO), a significant decrease in serum NGF, tissue dopamine and oxidative markers, besides, a non-significant change in VEGF. Toluene also caused changes in normal cerebral structure and cellular degeneration, including a significant decrease in the total number of neurons and thickness of frontal cortex. Meninges showing signs of inflammation with inflammatory cell infiltration and exudation, a significant decrease in MBP immunoreactivity, and increase in the percent of high motility group box protein-1 (HMGB1) positive cells. PPAR- ɣ, NF-kB, and IL-6 gene expression were all considerably elevated by toluene. These changes were greatly improved by breast milk MSc. Therefore, we conclude that breast milk MSc can attenuate toluene-induced encephalopathy.

Major component causing neurological toxicity in acute glufosinate ammonium poisoning: determination of glufosinate, 1-methoxy-2-propanol, and ammonia in serum and cerebrospinal fluid

OBJECTIVE

To determine the primary contributor to neurotoxicity in patients with glufosinate ammonium (GLA) poisoning, by quantifying glufosinate, 1-methoxy-2-propanol, and ammonia in serum and the cerebrospinal fluid (CSF).

MATERIALS AND METHODS

We collected and analysed data from confirmed cases of GLA poisoning between May 2018 and August 2020. Based on the occurrence of neurological complications (mental change, seizure, and central apnoea), patients were assigned to one of two groups: those with complications (NCx) and without (non-NCx) complications. Concentrations of glufosinate, 1-methoxy-2-propanol (1M2P), and ammonia were measured in the serum upon admission and during hospital stay. The concentrations of all these substances were again measured in the CSF following a decline in the mental status or seizure (NCx group) or on the day after hospitalisation (non-NCx group).

RESULTS

Of the 20 patients included, ammonia levels in the serum and CSF at onset of altered sensorium in the NCx group (n = 16) were significantly higher than those at one day after hospitalisation in the non-NCx group (n = 4) (p = 0.011 in serum, p = 0.047 in CSF), with its concentration in the CSF being higher than that in the serum in 15/16 cases. The concentration of 1M2P was similar in the serum and CSF (8/16), but the concentrations of glufosinate (7/16) was lower in the CSF than in the serum. In the non-NCx group (n = 4), only ammonia was detectable.

CONCLUSIONS

Among patients with GLA poisoning, increased CSF ammonia was significantly correlated with neurological complications.

Water-stable Cd(ii)/Zn(ii) coordination polymers as recyclable luminescent sensors for detecting hippuric acid in simulated urine for indexing toluene exposure with high selectivity, sensitivity and fast response

Three novel Cd(ii)/Zn(ii) coordination polymers (CPs), namely [Cd(L)(BPDC)_0.5H₂O]·0.5H₂O (1), [Zn₂(L)₂(BPDC)]·2H₂O (2) and [Cd₂(L)(BTC)H₂O]·3H₂O (3) (L = 4-(tetrazol-5-yl)phenyl-4,2':6',4''-terpyridine, H₂BPDC = 4,4'-biphenyldicarboxylic acid, and H₃BTC = 1,3,5-benzenetricarboxylic acid), have been successfully synthesized and characterized. CP 1 and CP 2 display new two-dimensional double-layered honeycomb frameworks containing uncoordinated nitrogen atoms from pyridine and tetrazole rings, which can easily form hydrogen bonds with various analytes. CP 3 exhibits a 3D framework also with uncoordinated nitrogen atoms from pyridine and tetrazole rings. The fluorescence explorations indicate that CPs 1-3 exhibit strong blue luminescence and excellent chemical stability under a relatively wide range of pH conditions. It is worth noting that CPs 1-3 can quantitatively detect hippuric acid (HA), which is a metabolite of toluene in human urine, with high selectivity, sensitivity, fast response and relatively low detection limits. Moreover, the sensing mechanism of CPs 1-3 for HA can mainly be ascribed to fluorescence resonance energy transfer (FRET). CPs 1-3 could be ideal candidates as HA sensors in human urine samples for practical applications. Notably, to the best of our knowledge, we report for the first time Cd(ii)/Zn(ii)-based luminescent sensors for detecting HA in simulated urine.

An aggravated return-to-work case of organic solvent induced chronic toxic encephalopathy

Background

Organic solvent-induced chronic toxic encephalopathy (CTE) is known as a non-progressive disorder that does not progress after diagnosis. The authors present a case those symptoms worsened after continued exposure to organic solvent after returning to work. Because such a case has not been reported in South Korea to the best of our knowledge, we intend to report this case along with literature review.

Case presentation

A 59-year-old man, who performed painting job at a large shipyard for 20 years, was receiving hospital treatment mainly for depression. During the inpatient treatment, severe cognitive impairment was identified, and he visited the occupational and environmental medicine outpatient clinic for assessing work relatedness. In 1984, at the age of 27, he began performing touch-up and spray painting as a shipyard painter. Before that he had not been exposure to any neurotoxic substances. In 2001, at the age of 44, after 15 years of exposure to mixed solvents including toluene, xylene and others, he was diagnosed with CTE International Solvent Workshop (ISW) type 2A. After 7 years of sick leave, he returned to work in 2006. And he repeated return-to-work and sick leave in the same job due to worsening of depressive symptoms. He had worked four times (2006–2010, 2011–2011, 2011–2011, 2016–2017) for a total of 5 years as a shipyard painter after first compensation. During the return-to-work period, the mean values of the mixed solvent index ranged from 0.57 to 2.15, and except for a one semiannual period, all mean values were above the standard value of 1. We excluded other diseases that can cause cognitive impairment like central nervous system diseases, brain injury, psychological diseases and metabolic diseases with physical examinations, laboratory tests, and brain image analysis. And finally, throughout neuropsychological tests, an overall deterioration in cognitive function was identified compared to 2002, and the deterioration types was similar to that often shown in the case of CTE; thus a diagnosis of CTE (ISW) type 3 was made.

Conclusion

This case is showing that CTE can go on with continued exposure to mixed solvents. Appropriate “fitness to work” should be taken to prevent disease deterioration especially for the sick leave workers.

Voice and speech signs and symptoms in individuals exposed to chemical agents: an analysis of medical records

ABSTRACT Objective: to identify voice and speech signs and symptoms in patients exposed to chemical agents. Methods: an exploratory and descriptive study analyzing the data from the medical records of patients who sought health services at a toxicology outpatient clinic located in Southeastern Brazil. Results: a total of 139 medical records were obtained, 75 being selected. Twelve of the records selected contained data regarding voice and speech symptoms, including hoarseness (3), loss of voice (2), chronic throat inflammation (1), sore throat (1), secretion and burning in the throat (1), dry throat and mouth (1), lump in the throat associated with difficulty in swallowing (1), difficulty in articulating words (1), and difficulty in verbal expression (1). Diseases capable of causing phono-articulatory problems were detected in 6 cases. These symptoms affected individuals with occupational exposure to different substances, particularly community health agents (7) and pesticide applicators (7). Conclusion: individuals exposed to chemical substances experienced voice and speech problems, either due to a possible irritation caused by chemical agents or due to diseases developed during or after the exposure.

Amyotrophic lateral sclerosis-A case report and mechanistic review of the association with toluene and other volatile organic compounds

Unmasking of latent neurodegenerative disease has been reported following exposure to chemicals that share one or more mechanisms of action in common with those implicated in the specific disease. For example, unmasking of latent Parkinson's disease (PD) has been associated with exposure to anti-dopaminergic agents, while the progression of pre-existing mild cognitive impairment and unmasking of latent Alzheimer's disease has been associated with exposure to general anesthetic agents which promote Aβ protein aggregation. This literature review and clinical case report about a 45-year-old man with no family history of motor neuron disease who developed overt symptoms of a neuromuscular disorder in close temporal association with his unwitting occupational exposure to volatile organic compounds (VOCs) puts forth the hypothesis that exposure to VOCs such as toluene, which disrupt motor function and increase oxidative stress, can unmask latent ALS type neuromuscular disorder in susceptible individuals.

Occupational Health and the Visual Arts: An Introduction

OBJECTIVE

Occupational hazards in the visual arts often involve hazardous materials, though hazardous equipment and hazardous work conditions can also be found. Occupational health professionals are familiar with most of these hazards and are particularly qualified to contribute clinical and preventive expertise to these issues.

METHODS

Articles illustrating visual arts health issues were sought and reviewed. Literature sources included medical databases, unindexed art-health publications, and popular press articles.

RESULTS

Few medical articles examine health issues in the visuals arts directly, but exposures to pigments, solvents, and other hazards found in the visual arts are well described. The hierarchy of controls is an appropriate model for controlling hazards and promoting safer visual art workplaces.

CONCLUSIONS

The health and safety of those working in the visual arts can benefit from the occupational health approach. Sources of further information are available.

Occupation and the risk of chronic toxic leukoencephalopathy

Among the hundreds of environmental insults capable of inducing nervous system injury, a small number can produce clinically significant damage to the brain white matter. The use of magnetic resonance imaging (MRI) in affected individuals has greatly illuminated this previously obscure area of neurotoxicology. Toxic leukoencephalopathy has acute and chronic forms, in both of which cognitive dysfunction is the major clinical manifestation. Chronic toxic leukoencephalopathy (CTL) has been most thoroughly described in individuals with intense and prolonged exposure to leukotoxins, but the consequences of lesser degrees of exposure are not well understood. Rare cases of CTL have been reported in workers exposed to culpable leukotoxins, but study of this syndrome is hindered by many confounds such as uncertain level of toxin exposure, the presence of multiple toxins, vague dose-response relationship, comorbid medical or neurologic disorders, psychiatric illness, and legal issues. The risk of CTL in workers is low, although it is not possible to determine quantitative risk estimates. More knowledge can be expected with the application of advanced MRI techniques to the assessment of workers who may have been exposed to known or potential leukotoxins. Preventive measures for avoiding workplace CTL will be informed by clinical assessment involving the use of advanced neuroimaging and neuropsychologic evaluation in combination with accurate measurement of leukotoxin exposure.

Recyclable lanthanide-functionalized MOF hybrids to determine hippuric acid in urine as a biological index of toluene exposure

A lanthanide-functionalized MOF with extremely high water tolerance was developed as a fluorescent probe for hippuric acid (HA) in urine which is considered as the biological indicators of toluene exposure. For the first time, the urinary HA was detected by fluorescence spectrometry based on a recyclable Ln-MOF sensor.

Heterogeneous electrochemical immunoassay of hippuric acid on the electrodeposited organic films

By directly coordinating hippuric acid (HA) to the ferrate (Fe) as an electron transfer mediator, we synthesized a Fe-HA complex, which shows a good electrochemical signal and thus enables the electrochemical immunoanalysis for HA. We electrodeposited organic films containing imidazole groups on the electrode surface and then bonded Ni ion (positive charge) to induce immobilization of Fe-HA (negative charge) through the electrostatic interaction. The heterogeneous competitive immunoassay system relies on the interaction between immobilized Fe-HA antigen conjugate and free HA antigen to its antibody (anti-HA). The electric signal becomes weaker due to the hindered electron transfer reaction when a large-sized HA antibody is bound onto the Fe-HA. However, in the presence of HA, the electric signal increases because free HA competitively reacts with the HA antibody prior to actual reaction and thus prevents the HA antibody from interacting with Fe-HA at the electrode surface. This competition reaction enabled an electrochemical quantitative analysis of HA concentration with a detection limit of 0.5 μg mL(-1), and thus allowed us to develop a simple and rapid electrochemical immunosensor.

Recovery from central nervous system changes following volatile substance misuse

This review examines cognitive, neurological, and neuroanatomical recovery associated with abstinence from volatile substance misuse (VSM). Articles describing functional or structural brain changes longitudinally or cross-sectional reports comparing current and abstinent users were identified and reviewed. A significant lack of empirical studies investigating central nervous system recovery following VSM was noted. The few case reports and group studies identified indicated that cognitive and neurological impairments appear to follow a progression of decline and progression of recovery model, with the severity of impairment related to the duration and severity of misuse, blood lead levels among leaded petrol misusers, and the duration of abstinence for recovery. By contrast, severe neurological impairment known as lead encephalopathy from sniffing leaded petrol occurred as more catastrophic or abrupt damage to cerebellar processes that may never fully recover. Neuroanatomical damage may not recover even with prolonged abstinence.

Neuropsychological health in F-111 aircraft maintenance workers

OBJECTIVE

To contrast subjective and objective measures of neuropsychological health in F-111 aircraft Deseal/Reseal maintenance personnel, against two appropriate comparison groups.

METHODS

Exposed and comparison participants completed a postal questionnaire which included a validated memory questionnaire and additional questions relating to possible cognitive symptoms. They also underwent a comprehensive neuropsychological assessment and screening for a past or current disturbance of mood. Multiple linear or logistic regression was conducted for each outcome using exposure group and potential confounders as explanatory variables.

RESULTS

There was a strong and consistent excess of self-reported cognitive problems among the exposed group relative to the comparison groups including a 2.8-4.3-fold increase in self-reported symptoms of forgetfulness, loss of concentration and difficulty finding the right word. On detailed neuropsychological testing, the exposed group performed significantly worse than comparisons on tests of psychomotor speed, executive functioning, and new learning/memory. These findings could not be accounted for by disturbances of mood or other potential confounders.

CONCLUSIONS

There was a strong and consistent increase in self-reported cognitive problems among the exposed, and small but significant exposure-specific differences on objective tests of cognitive functioning. The findings are consistent with the development of adverse neuropsychiatric changes related to occupational exposure to solvents.

Neurobehavioral performance in workers exposed to toluene

Toluene is widely used in adhesive, printing, painting and petroleum industries in many countries. This study was conducted to examine the effect of chronic exposure to toluene below 100ppm on neurobehavioral performance using a computerized neurobehavioral test battery that emphasizes simple instructions and practice prior to testing. The Behavioral Assessment and Research System (BARS) with Korean language instructions was administered to 54 workers from three different industries: oil refinery, gravure printing, and rubber boat manufacturing. The battery consisted of the following tests: Digit Span (DS), Simple Reaction Time (SRT), Selective Attention (SAT), Finger Tapping (FT), and Symbol Digit (SD). Urine was collected at the end-of-shift to analyze urinary hippuric acid to assess exposure level to toluene. Based on the previous air toluene level, workers were divided into three groups: Low (21 workers, less than 10ppm), Moderate (13 workers, 20-30ppm) and High (20 workers, 70-80ppm) exposure status. Analysis of Covariance (ANCOVA) adjusting for age, education and work duration as covariates, was performed to examine the relationship between the neurobehavioral performance and the exposure groups. Poorer performance of the High exposure group was found on FT-preferred (F=7.034, p=0.002) and SAT latency (F=11.710, p=0.000). Age showed a significant correlation with SD (r=0.417, p=0.002) and SAT number correct (r=-0.460, p=0.000). Years of education and work duration were not significantly correlated with any items. This study supports that toluene exposure below 100ppm is associated with neurobehavioral changes and that high-level toluene exposure could cause not only attention and concentration, but also motor performance deficits.

Relationship between lipophilicity of C6-10 hydrocarbon solvents and their ROS-inducing potency in rat cerebellar granule cells

We have studied the effects of aliphatic, alicyclic, and aromatic C6-10 solvents on the formation of reactive oxygen species (ROS) in rat cerebellar granule cell cultures. ROS formation was assessed by monitoring oxidation of 2',7'-dichlorofluorescin (DCFH) to the fluorescent compound 2',7'-dichlorofluorescein (DCF). We found that aromatic solvents with C > 7, and aliphatic and alicyclic solvents with C > or = 7 induce ROS formation in rat cerebellar granule cells in vitro. The response increased with increasing solvent concentration. The potency of the compounds within each homologous group seemed to be correlated to their octanol water partition-coefficients. The aromatic solvents were generally less efficient in inducing ROS formation than the aliphatic and the alicyclic compounds.

Neuropsychological dysfunction, mood disturbance, and emotional status of munitions workers

The objective of this study was to compare the neuropsychological function, emotional status, visual function, and illness prevalence of 265 former munitions plant workers (M age = 56.7 years, M years of education = 12.07; 201 African American, 64 White) exposed to organic solvents for an average of 17.03 years with that of a group of 77 unexposed controls (M age = 51.3 years, M years of education = 13.07; 30 African American, 47 White). Neuropsychological tests were selected from the World Health Organization Neurobehavioral Core Test Battery, Wechsler Adult Intelligence Scale-III (WAIS-III), and Wechsler Memory Scale-III (WMS-III) and also included the Brief Symptom Inventory, Profile of Mood States, Beck Anxiety Inventory, and Beck Depression Inventory. Vision tests included the Lanthony d-15 color vision, the Vistech Contrast Sensitivity, and the Snellen. The exposed group showed greater deficits than the controls in verbal learning (WMS-III Logical Memory I Learning Slope and Word Lists I Recall), visuomotor tracking speed (Cancellation H, WAIS-III Digit Symbol-Coding) and psychomotor function (Dynamometer and Grooved Pegboard), and dysfunction in emotional status, illness prevalence, and visual function. African American workers reported higher levels of exposure than Whites. Exposure relations demonstrated increased neuropsychological dysfunction with increased exposure.

Impairment of colour vision in workers exposed to organic solvents

OBJECTIVES

To investigate loss of colour vision related to exposure to solvents and the role of three enzyme polymorphisms in modifying the risk in exposed workers.

METHODS

A sample was studied of 68 male dockyard workers and 42 male community controls with and without neuropsychological symptoms from a previous cross sectional study. Indices of cumulative and intensity based exposure to solvents were calculated for all subjects. Alcohol, drug, and smoking histories were obtained. Colour vision was tested by Lanthony D15d colour vision test. Genotype of glutathione S-transferase M1 and T1 and N-acetyltransferase 2 polymorphisms were determined.

RESULTS

The relation between impairment of colour vision and exposure to solvents was investigated with multiple regression techniques. Increasing annual exposure to solvents was significantly associated with reduced colour vision (p=0.029). Impairment of colour vision was not associated with neuropsychological symptoms as measured by the Q16 solvent symptom questionnaire. No significant association was found between acquired impairment of colour vision and genetic polymorphisms when GSTM1, GSTT1 or NAT2 phenotypes were included in the analyses.

CONCLUSIONS

Exposure to mixed solvents is associated with impairment in colour vision, the risk increases with increasing exposure. The risk of impairment of colour vision was not altered in this study by the presence of different GSTM1, GSTT1 or NAT2 polymorphisms.