Corneal damage threshold induced by supercontinuum source: A further study

OBJECTIVES

Previous report shows that corneal spot size is an important influence factor on damage threshold induced by supercontinumm (SC) source. However, damage thresholds were determined for the spot size of only 0.37 mm due to the low output of the employed SC source at that time. The objectives of this study are to determine the lowest possible corneal damage threshold at a large corneal spot size using a more powerful SC source and provide data for the future possible refinements of laser safety standards.

MATERIALS AND METHODS

A series of experiments was conducted in the New Zealand white rabbit model to determine the corneal damage threshold induced by a 900-2000 nm SC source, with corneal 1/e beam diameter of about 1.2 mm. Slit-lamp biomicroscope was employed to reveal the corneal damage characteristics. By employing the action spectra determined through the analysis of current laser safety guidelines and standards, the effective damage threshold could be calculated.

RESULTS

The determined damage threshold given in terms of the peak radiant exposure for the exposure duration of 0.14 s was 44.3 J/cm2 . At threshold level, corneal damages involved the epithelium and the shallower stroma. The safety factor between the effective damage threshold and the corresponding maximum permissible exposure (MPE) was about 45.

CONCLUSIONS

Present corneal MPEs in the wavelength range of 700-1200 nm may be conservative and corneal damage thresholds for the infrared A wavelengths should be determined in future studies.

Electrolytic hydrogen-generating bottle supplies drinking water with free/combined chlorine and ozone repressed within safety standard under hydrogen-rich conditions

Hydrogen molecules have attracted attention as a new antioxidant, but are left to be confirmedly verified whether the oral administration is highly safe or not, concurrently with retention of abundant hydrogen. When electrolysis was performed for 10 minutes using a direct-current electrolytic hydrogen-water generating bottle with tap water, “residual free chlorine” concurrently upon the production of molecular hydrogen (444 μg/L) could be appreciably decreased from 0.18 mg/L to 0.12 mg/L as quantified by a N,N-diethyl-p-phenylenediamine-dye colorimetric method. Moreover, the total chlorine concentration (residual bound chlorine plus free chlorine) was estimated to be decreased from 0.17 mg/L to 0.11 mg/L. Although a merit of electrolytic hydrogen-generating bottles exists in electrolysis for periods as short as 10 minutes, the 30-minute electrolysis brought about the more abundant hydrogen (479 μg/L) together with an oxidation-reduction potential of –245 mV; even upon this long-term electrolysis, the gross amounts of chlorine, hypochlorous acid and chloramine were shown not to be increased (0.09–0.10 mg/L from 0.11 mg/L for tap water) as detected by orthotolidine colorimetry. Above-mentioned levels of diverse-type chlorines might fulfill the World Health Organization guideline for drinking water below 5 mg/L. In addition, the dissolved ozone upon electrolytic generation of hydrogen-water was below the detection limit (< 0.05 mg/L) or undetectable, which fulfilled the official safety standards in Japan and the USA for drinking water below 0.1 mg/L, as evaluated by three methods such as an electrode-type ozone checker, indigo dyeutilizing ozone detector capillaries and potassium iodide-based colorimetry. Importantly, even when half the amount of tap water was poured into the tank of the apparatus and electrolyzed, both the residual chlorine and ozone concentrations measured were also below the safety standard. Thus, major potently harmful substances, such as residual free/bound chlorine, or hypochlorous-acid/chloramine, respectively, and dissolved ozone, as the drinking hydrogen-water was direct-current-electrolytically generated, were estimated to be repressed within safety concentration ranges with achievements of abundant hydrogen generation.

Psychosocial Risk, Work-Related Stress, and Job Satisfaction among Domestic Waste Collectors in the Ho Municipality of Ghana: A Phenomenological Study

Domestic waste collectors play key roles in the collection and disposal of solid waste in Ghana. The work environment and conditions under which domestic waste collectors operate influence their job satisfaction ratings and health outcomes. This study investigated psychosocial risk factors, work-related stress and job satisfaction needs among municipal solid waste collectors in the Ho Municipality of Ghana. A phenomenological design was applied to collect data among 64 domestic waste collectors, 12 managers, and 23 supervisors of two waste companies in Ho Municipality, Ghana. Data were collected from June–August 2018 using in-depth interview and focus group discussion guides. Interviews were supplemented by field observations. Data were analyzed using inductive and deductive content procedures to form themes based on the study aim. Four themes emerged from the study. The study results revealed that domestic waste collector’s poor attitudes and safety behaviors such as not wearing personal protective equipment, poor enforcement of safety standards by supervisors and managers, and work-related stress caused by poor working environments impact negatively on domestic waste collector’s health and safety. Other factors such as poor enforcement of standard company regulations, poor work relations, non-clear work roles, lack of social protection to meet medical needs, poor remuneration, negative community perceptions of domestic waste collectors job, work environments, and workloads of domestic waste collectors were reported to negatively impact on work stress and job satisfaction needs. In conclusion, the findings are important in informing the necessary waste management policies aimed at improving decent work environments, as well as improving the health and well-being of domestic waste collectors in both the formal and informal sectors in Ghana.

Corneal Damage Effects Induced by a 770-2,500 nm Supercontinuum Light Source

BACKGROUND AND OBJECTIVES

Widespread applications of supercontinuum (SC) source lead to the possibility of ocular damages. However, the corneal damage effects induced by SC have not been explored before. The objectives of this study are to determine the rabbit corneal injury threshold for SC radiation and to examine whether the existing safety guidelines and standards are suitable for the hazard evaluation of this new kind of light source.

STUDY DESIGN/MATERIALS AND METHODS

A series of experiments was conducted in the New Zealand white rabbit model to determine the corneal damage thresholds induced by a 770-2,500 nm SC source, with a corneal 1/e beam diameter of 0.37 mm. Through slit-lamp biomicroscope, optical coherence tomography (OCT), and histopathology the corneal damage characteristics at the threshold level were revealed. By employing the action spectra determined through the analysis of safety guidelines and standards, the damage thresholds for SC source could be compared with the corresponding exposure limits.

RESULTS

The determined damage thresholds given in terms of the peak radiant exposure for exposure durations of 2.0 and 10.0 seconds were 2.1 × 10³ and 7.4 × 10³  J/cm² , respectively. At threshold level, corneal damages involved the epithelium and the shallower stroma, and no obvious changes could be found in the deep stroma, Descemet's membrane, and endothelium.

CONCLUSIONS

The exposure limits for the anterior parts of the eye in the wavelength range of 700-1,200 nm are overly conservative. The obtained results contribute to the knowledge base for the hazard evaluation of SC source. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Standardization of Care and Assistive Products Involving Robot Technology

An ongoing Japan-wide project for the development and deployment of care and assistive robotic devices is being followed by a program of standardizing some of the outcome technologies while focusing on safe usage. We examine the concept defining the required standard as robotic technology is introduced. Fundamentally, this involves the application of the existing safety standard for service robots used to improve the quality of life. We expect that this program will contribute to enhancing safety in device usage, and further expand the device market by constructing a structure for sharing roles of supporting both the manufacturers and users.

An Investigation of Health and Safety Measures in a Hydroelectric Power Plant

Background

Occupational risk management is known as a catalyst in generating superior returns for all stakeholders on a sustainable basis. A number of companies in Ghana implemented health and safety measures adopted from international companies to ensure the safety of their employees. However, there exist great threats to employees' safety in these companies. The purpose of this paper is to investigate the level of compliance of Occupational Health and Safety management systems and standards set by international and local legislation in power producing companies in Ghana.

Methods

The methodology is conducted by administering questionnaires and in-depth interviews as measuring instruments. A random sampling technique was applied to 60 respondents; only 50 respondents returned their responses. The questionnaire was developed from a literature review and contained questions and items relevant to the initial research problem. A factor analysis was also carried out to investigate the influence of some variables on safety in general.

Results

Results showed that the significant factors that influence the safety of employees at the hydroelectric power plant stations are: lack of training and supervision, non-observance of safe work procedures, lack of management commitment, and lack of periodical check on machine operations. The study pointed out the safety loopholes and therefore helped improve the health and safety measures of employees in the selected company by providing effective recommendations.

Conclusion

The implementation of the proposed recommendations in this paper, would lead to the prevention of work-related injuries and illnesses of employees as well as property damage and incidents in hydroelectric power plants. The recommendations may equally be considered as benchmark for the Safety and Health Management System with international standards.