Membrane fluidity does not explain how solvents act on the middle-ear reflex

The Global Prevalence of Noise Induced Hearing Impairment Among Industrial Workers: A Systematic Review and Meta-Analysis

Noise is one of the harmful health factors in industrial sites. Hearing impairments are one of the most common occupational diseases in a wide range of industries. The aim of this study is to determine the general prevalence of noise-induced hearing disorders among industrial workers and to homogenize the results of different studies in this field. In this systematic review and meta-analysis study, the keywords of Occupational Noise, Hearing Impairment, Workers, Industry in Science Direct, PubMed, Scopus, Web of Science and Google Scholar databases without any lower time limit and until March 2022. Details of the identified studies were then transferred into the EndNote reference management software. Subsequently, duplicate studies were eliminated, and the remaining studies were evaluated in accordance with the inclusion and exclusion criteria and through the three remaining phases of PRISMA i.e., screening, eligibility, and inclusion. To analyze the eligible studies, the random effects model was used, and the heterogeneity of the studies was assessed using the I2 index. In a review of 69 studies with a sample size of 3,552,888 people, the overall prevalence of hearing impairment among industrial workers was 28.8% (95% CI 26.2%-31.6%). The highest prevalence of hearing impairments was reported among agricultural and fishery workers with 45.7% (95% CI 35.1%-56.7%), and the highest prevalence of hearing impairment among industrial workers was found in the continent of Africa with 46.2% (95% CI 37.4%-55.2%). Due to the higher prevalence of hearing impairments among men, the elderly and in developing countries, it is necessary to establish pertinent laws and regulations in order for workers to use appropriate personal protective equipment (PPE) and mandate employers to provide hearing protection programs.

Occupational noise-induced hearing loss in China: a systematic review and meta-analysis

OBJECTIVE

Most of the Chinese occupational population are becoming at risk of noise-induced hearing loss (NIHL). However, there is a limited number of literature reviews on occupational NIHL in China. This study aimed to analyse the prevalence and characteristics of occupational NIHL in the Chinese population using data from relevant studies.

DESIGN

Systematic review and meta-analysis.

METHODS

From December 2019 to February 2020, we searched the literature through databases, including Web of Science, PubMed, MEDLINE, Scopus, the China National Knowledge Internet, Chinese Sci-Tech Journal Database (weip.com), WanFang Database and China United Library Database, for studies on NIHL in China published in 1993-2019 and analysed the correlation between NIHL and occupational exposure to noise, including exposure to complex noise and coexposure to noise and chemicals.

RESULTS

A total of 71 865 workers aged 33.5±8.7 years were occupationally exposed to 98.6±7.2 dB(A) (A-weighted decibels) noise for a duration of 9.9±8.4 years in the transportation, mining and typical manufacturing industries. The prevalence of occupational NIHL in China was 21.3%, of which 30.2% was related to high-frequency NIHL (HFNIHL), 9.0% to speech-frequency NIHL and 5.8% to noise-induced deafness. Among manufacturing workers, complex noise contributed to greater HFNIHL than Gaussian noise (overall weighted OR (OR)=1.95). Coexposure to noise and chemicals such as organic solvents, welding fumes, carbon monoxide and hydrogen sulfide led to greater HFNIHL than noise exposure alone (overall weighted OR=2.36). Male workers were more likely to experience HFNIHL than female workers (overall weighted OR=2.26). Age, noise level and exposure duration were also risk factors for HFNIHL (overall weighted OR=1.35, 5.63 and 1.75, respectively).

CONCLUSIONS

The high prevalence of occupational NIHL in China was related to the wide distribution of noise in different industries as well as high-level and long-term noise exposure. The prevalence was further aggravated by exposure to complex noise or coexposure to noise and specific chemicals. Additional efforts are needed to reduce occupational noise exposure in China.

A potent, minimally invasive and simple strategy of enhancing intracellular targeted delivery of Tat peptide-conjugated quantum dots: organic solvent-based permeation enhancer

Targeted delivery of nanomaterials to specific intracellular locations is essential for the development of many nanomaterials-based biological applications. Thus far the targeting performance has been limited due to various intracellular transport barriers, especially intracellular vesicle trapping. Here we report the application of permeation enhancers based on organic solvents in small percentage to enhance the intracellular targeted delivery of nanomaterials. Previously permeation enhancers based on organic solvents and ionic liquids have been used in overcoming biological transport barriers at tissue, organ, and cellular levels, but this strategy has so far rarely been examined for its potential in facilitating transport of nanometer-scale entities across intracellular barriers, particularly intracellular vesicle trapping. Using the cell nucleus as a model intracellular target and Tat peptide-conjugated quantum dots (QDs-Tat) as a model nanomaterial-based probe, we demonstrate that a small percentage (e.g. 1%) of organic solvent greatly enhances nucleus targeting specificity as well as increasing endocytosis-based cellular uptake of QDs. We combine vesicle colocalization (DiO dye staining), vesicle integrity (calcein dye release), and single-particle studies (pair-correlation function microscopy) to investigate the process of organic solvent-enhanced vesicle escape of QDs-Tat. The organic solvent based vesicle escape-enhancing approach is found to be not only very effective but minimally invasive, resulting in high vesicle escape efficiency with no significant disruption to the membrane integrity of either intracellular vesicles or cells. This approach drastically outperforms the commonly used vesicle escape-enhancing agent (i.e., chloroquine, whose enhancement effect is based on disrupting vesicle integrity) in both potency and minimal invasiveness. Finally, we apply organic solvent-based targeting enhancement to improve the intracellular delivery of the anticancer drug doxorubicin (DOX).

Use of the kurtosis statistic in an evaluation of the effects of noise and solvent exposures on the hearing thresholds of workers: An exploratory study

The aim of this exploratory study was to examine whether the kurtosis metric can contribute to investigations of the effects of combined exposure to noise and solvents on human hearing thresholds. Twenty factory workers exposed to noise and solvents along with 20 workers of similar age exposed only to noise in eastern China were investigated using pure-tone audiometry (1000-8000 Hz). Exposure histories and shift-long noise recording files were obtained for each participant. The data were used in the calculation of the cumulative noise exposure (CNE) and CNE adjusted by the kurtosis metric for each participant. Passive samplers were used to measure solvent concentrations for each worker exposed to solvents over the full work shift. Results showed an interaction between noise exposure and solvents for the hearing threshold at 6000 Hz. This effect was observed only when the CNE level was adjusted by the kurtosis metric.