Otoneurologic disturbances caused by solvent pollution

Surface analysis and thermal behavior of the functionalized cellulose by glutaric anhydride through a solvent-free and catalyst-free process

According to the 12 principles of green chemistry, surface functionalization was performed using glutaric anhydride under solvent-free and catalyst-free conditions. FTIR spectra and DS analyses demonstrated the functionalization of HCl-hydrolyzed cellulose. The influence of two parameters, i.e., the glutaric anhydride concentration and the reaction time, on the functionalization of HCl-hydrolyzed cellulose was investigated. Protocol efficiency was studied by a degree of substitution (DS). It was found that higher concentrations of glutaric anhydride cause an enhancement of DS to 0.75 and 0.87 for GA3-12 and GA9-12, respectively. In addition, the longer reaction time increased zeta potential from -12.2 ± 1.7 for G9-6 to -34.57 ± 2.2 for GA9-12. Morphology analysis by SEM showed a decrease in fiber length for the functionalized cellulose. DSC profiles confirmed dehydration at a range of 17 to 134 °C. A glass transition was revealed at -30 to -20 °C for all studied samples. The fusion, the depolymerization of cellulose chains, the cleavage of glycosidic linkages, and the decomposition of the crystalline parts of cellulose occur at 195 to 374 °C. Therefore, an efficient and greener process was developed to functionalize the HCl-hydrolyzed cellulose by glutaric anhydride, a safe and non-toxic anhydride, in the absence of the solvent and catalyst.

Self-reported hearing performance in workers exposed to solvents

OBJECTIVE: To compare hearing performance relating to the peripheral and central auditory system between solvent-exposed and non-exposed workers. METHODS: Forty-eight workers exposed to a mixture of solvents and 48 non-exposed control subjects of matched age, gender and educational level were selected to participate in the study. The evaluation procedures included: pure-tone audiometry (500 - 8,000 Hz), to investigate the peripheral auditory system; the Random Gap Detection test, to assess the central auditory system; and the Amsterdam Inventory for Auditory Disability and Handicap, to investigate subjects' self-reported hearing performance in daily-life activities. A Student t test and analyses of covariance (ANCOVA) were computed to determine possible significant differences between solvent-exposed and non-exposed subjects for the hearing level, Random Gap Detection test and Amsterdam Inventory for Auditory Disability and Handicap. Pearson correlations among the three measures were also calculated. RESULTS: Solvent-exposed subjects exhibited significantly poorer hearing thresholds for the right ear than non-exposed subjects. Also, solvent-exposed subjects exhibited poorer results for the Random Gap Detection test and self-reported poorer listening performance than non-exposed subjects. Results of the Amsterdam Inventory for Auditory Disability and Handicap were significantly correlated with the binaural average of subject pure-tone thresholds and Random Gap Detection test performance. CONCLUSIONS: Solvent exposure is associated with poorer hearing performance in daily life activities that relate to the function of the peripheral and central auditory system.

Auditory dysfunction associated with solvent exposure

Background

A number of studies have demonstrated that solvents may induce auditory dysfunction. However, there is still little knowledge regarding the main signs and symptoms of solvent-induced hearing loss (SIHL). The aim of this research was to investigate the association between solvent exposure and adverse effects on peripheral and central auditory functioning with a comprehensive audiological test battery.

Methods

Seventy-two solvent-exposed workers and 72 non-exposed workers were selected to participate in the study. The test battery comprised pure-tone audiometry (PTA), transient evoked otoacoustic emissions (TEOAE), Random Gap Detection (RGD) and Hearing-in-Noise test (HINT).

Results

Solvent-exposed subjects presented with poorer mean test results than non-exposed subjects. A bivariate and multivariate linear regression model analysis was performed. One model for each auditory outcome (PTA, TEOAE, RGD and HINT) was independently constructed. For all of the models solvent exposure was significantly associated with the auditory outcome. Age also appeared significantly associated with some auditory outcomes.

Conclusions

This study provides further evidence of the possible adverse effect of solvents on the peripheral and central auditory functioning. A discussion of these effects and the utility of selected hearing tests to assess SIHL is addressed.

Balance system assessment in workers exposed to organic solvent mixture

OBJECTIVE

The aim of this study was to assess the balance and vestibular systems in healthy workers exposed to low concentrations of organic solvent mixtures.

METHODS

The study groups comprised 60 workers exposed to mixture of organic solvents and 110 reference workers. All subjects performed static posturography and electronystagmography (ENG).

RESULTS

In posturography, abnormal reaction time was more frequent and statistically longer in solvent-exposed group. Also, worse results of movement coordination parameters were observed in this group. The ENG square waves and abnormal optokinetic results were more common in exposed group. Mean caloric response was shorter in the exposed group. Negative relationship was found between time of caloric response and cumulative toluene concentration.

CONCLUSIONS

Balance abnormalities in solvent-exposed workers indicated subclinical damage, mainly of central part of vestibular system and body-movement coordination. It would not be reasonable to exclude the vestibular hyporeactivity.

Organic solvents and hearing loss: The challenge for audiology

Organic solvents have been reported to adversely affect human health, including hearing health. Animal models have demonstrated that solvents may induce auditory damage, especially to the outer hair cells. Research on workers exposed to solvents has suggested that these chemicals may also induce auditory damage through effects on the central auditory pathways. Studies conducted with both animals and humans demonstrate that the hearing frequencies affected by solvent exposure are different to those affected by noise, and that solvents may interact synergistically with noise. The present article aims to review the contemporary literature of solvent-induced hearing loss, and consider the implications of solvent-induced auditory damage for clinical audiologists. Possible audiological tests that may be used when auditory damage due to solvent exposure is suspected are discussed.

Chemobrain: a translational challenge for neurotoxicology

Neurotoxicity is a frequent accompaniment of cancer chemotherapy, and held by many oncologists to be the major dose-limiting side effect. It appears in many forms, but attracted attention during the past decade primarily because of complaints by patients of impaired cognitive function they have labeled as "chemobrain". Neuropsychological testing confirmed the validity of these complaints and has generated a substantial literature examining different aspects of cognitive impairment in various clinical populations undergoing a variety of treatments. Cognitive impairment is far from the only manifestation of neurotoxicity induced by chemotherapy, however. It alters sensory function and motor function as well. A critical need for patients is a suite of methods that will enable clinicians to trace the onset and progression of neurotoxicity so as to guide and balance decisions about the course of chemotherapy. This commentary describes some of the potential methods and encourages neurotoxicologists to enlist their unique skills in the service of these needs.

Occupational exposure to chemicals and sensory organs: a neglected research field

The effect of industrial chemicals on the sensory perception of exposed workers has received scant attention from the medical community to date, and the scientific literature is mainly limited to some case-reports or isolated studies. Possible explanations for this include the complexity of sensory perception, and the lack of agreement among researchers on methods for testing large groups of subjects. Nevertheless, some published studies showed that vision, hearing and olfactory function can be affected by various industrial metals and solvents, and some data exist also for touch and taste. This review discusses the main industrial chemicals involved. The pathogenesis of the toxicity of chemicals to sensory perception may be related to an action on receptors, nerve fibers, and/or the brain; probably, different pathogenetic mechanisms are involved. One of the main problems in this research field is that most of the studies to date evaluated the effect of a single industrial chemical on a single sense: as an example, we know that styrene exposure can impair smell and also hearing and vision but we have little idea whether different senses are impaired in the same worker, or whether each impairment is independent. In addition, workers are frequently exposed to different chemicals: co-exposure may have no effect, or result in both an increase or a decrease of the effect, as was observed for hearing loss, but studies on this aspect are largely insufficient. Research shows that both occupational and environmental exposure to industrial chemicals can affect sense organs, and suggests that the decline of perception with age may be, at least partly, related to this exposure. Nevertheless, available evidence is incomplete, and is largely inadequate for an estimation of a "safe" threshold of exposure. Good quality further research in this field is needed. This is certainly complex and demands adequate resources, but is justified by the ultimate result: the possibility to prevent an avoidable part of the decline in sensory function with age.

Thinner abuse alters optokinetic nystagmus parameters

BACKGROUND

Deliberate self-inhalation of solvents such as thinner is a recognized problem in underdeveloped countries, with chronic abuse resulting in neurological impairment. In this article, we use electronystagmography (ENG) to study optokinetic nystagmus abnormalities (OKN) that may be induced by thinner consumption.

METHODS

Twenty-five patients exposed to thinner for 5-20 years, in an irregular fashion of consumption, were recruited from a toxicologic center. Twenty-five control subjects were invited to participate as volunteers matched by age (+/-2 years) and gender. At the time of evaluation, all had abstained from intoxicants for at least 4 weeks. ENG recordings were performed by clinicians masked to the patient's group. Clockwise and counterclockwise stimulation were performed at 20 and 40 degrees /sec.

RESULTS

None of the patients showed spontaneous nystagmus during the test period. Differences between thinner abusers and controls on clockwise and counterclockwise OKN on number of beats of nystagmus elicited on the 40 degrees /sec velocity were identified. The thinner abusers group showed a lesser number of nystagmus (p level was 0.02 and 0.005, respectively).

CONCLUSIONS

The present results confirm the sensibility of OKN as an early marker of solvent abuse. These results were obtained in middle-term chronic exposure to solvent mixtures and are in favor of both cortical and brainstem dysfunction.

MR imaging in solvent-induced chronic toxic encephalopathy

PURPOSE

To use MR to examine patients with CNS symptoms indicating +chronic intoxication.

MATERIAL AND METHODS

Thirty-two subjects exposed to industrial solvents for 5 to 28 years and 40 age-matched, healthy controls were examined.

RESULTS

All patients showed decreased signal in the basal ganglia on T2-weighted images. In 11 of the patients the white matter showed diffuse hyperintensity with loss of the grey-white matter discrimination and with distinct periventricular hyperintensities in 5 of the patients. The controls had no pathological changes in the brain.

CONCLUSION

Although the relatively small number of patients may obscure the significance, findings observed on T2-weighted images were patchy periventricular hyperintensities and hypointensities in the basal ganglia. Fast spin-echo is a good technique with fast acquisition of images with true spin-echo contrast features.

Auditory and vestibular functions after single or combined exposure to toluene: a review

Toluene is a widely used organic solvent, heavily employed in many manufacturing industries. Recently, evidence has begun to accumulate on the deleterious effect of toluene exposure has on the auditory and vestibular systems. Although little published information exists regarding these effects, the reported findings indicate a need for further investigation. The results of such investigations may dramatically affect occupational hearing conservation practices and legislation. Both human and animal studies will be summarized in discussing the effects of toluene alone or in combination with noise or other chemicals. Gaps in scientific knowledge are highlighted to assist future research.