Worker Safety in the Rare Earth Elements Recycling Process From the Review of Toxicity and Issues

Although the rare earth elements (REEs) recycling industry is expected to increase worldwide in high-tech industry, regulations for worker safety have yet to be established. This study was conducted to understand the potential hazard/risk of REE recycling and to support the establishment of regulations or standards. We review the extensive literature on the toxicology, occupational safety, and health issues, and epidemiological surveys related to the REEs, and propose suitable management measures. REE recycling has four key steps such as collection, dismantling, separation, and processing. In these processes, hazardous substances, such as REEs-containing dust, metals, and chemicals, were used or occurred, including the risk of ignition and explosion, and the workers can be easily exposed to them. In addition, skin irritation and toxicities for respiratory, nervous, and cardiovascular systems with the liver toxicity were reported; however, more supplementary data are needed, owing to incompleteness. Therefore, monitoring systems concerning health, environmental impacts, and safety need to be established, based on additional research studies. It is also necessary to develop innovative and environment-friendly recycling technologies, analytical methods, and biomarkers with government support. Through these efforts, the occupational safety and health status will be improved, along with the establishment of advanced REE recycling industry.

Reproductive Toxic Chemicals at Work and Efforts to Protect Workers' Health: A Literature Review

A huge number of chemicals are produced and used in the world, and some of them can have negative effects on the reproductive health of workers. To date, most chemicals and work environments have not been studied for their potential to have damaging effects on the workers' reproductive system. Because of the lack of information, many workers may not be aware that such problems can be related to occupational exposures. Newly industrialized countries such as Republic of Korea have rapidly amassed chemicals and other toxicants that pose health hazards, especially to the reproductive systems of workers. This literature review provides an overview of peer-reviewed literature regarding the teratogenic impact and need for safe handling of chemicals. Literature searches were performed using PubMed, Google Scholar, and ScienceDirect. Search strategies were narrowed based on author expertise and 100 articles were chosen for detailed analysis. A total of 47 articles met prespecified inclusion criteria. The majority of papers contained studies that were descriptive in nature with respect to the Medical Subject Headings (MeSH) terms and keywords: “reproductive and heath or hazard and/or workplace or workers or occupations.” In the absence of complete information about the safe occupational handling of chemicals in Republic of Korea (other than a material safety data sheet), this review serves as a valuable reference for identifying and remedying potential gaps in relevant regulations. The review also proposes other public health actions including hazard surveillance and primary prevention activities such as reduction, substitution, ventilation, as well as protective equipment.

Quantitative Analysis of Exosomes From Murine Lung Cancer Cells by Flow Cytometry

In vivo studies regarding biochemical, molecular biological, and histopathological changes in cancer tissues have been widely performed by the administration of carcinogens in rodents. In these established methods, dissection of the animal following sacrifice must be carried out. Exosomes are cell-derived vesicles that are present in all body fluids and these vesicles have specific roles within cells. Thus, much attention is given to the clinical application of exosomes that can possibly be used for prediction and therapy and as biomarkers related to cancer. To develop a new tool for monitoring in vivo genetic alterations, as a result of carcinogenesis, without the need for frequent euthanasia, we performed quantitative measurement of exosomes in Mlg2908 murine lung fibroblasts and LA-4 and KLN 205 murine lung cancer cells using fluorescence-activated cell sorting. We detected an increase in CD63-specific exosomes in LA-4 lung cancer cells. This result is able to be applied to the classification of cancer-specific proteins and miRNA as diagnostic markers.

A Review on Mutagenicity Testing for Hazard Classification of Chemicals at Work: Focusing on in vivo Micronucleus Test for Allyl Chloride

Chemical mutagenicity is a major hazard that is important to workers' health. Despite the use of large amounts of allyl chloride, the available mutagenicity data for this chemical remains controversial. To clarify the mutagenicity of allyl chloride and because a micronucleus (MN) test had not yet been conducted, we screened for MN induction by using male ICR mice bone marrow cells. The test results indicated that this chemical is not mutagenic under the test conditions. In this paper, the regulatory test battery and several assay combinations used to determine the genotoxic potential of chemicals in the workplace have been described. Further application of these assays may prove useful in future development strategies of hazard evaluations of industrial chemicals. This study also should help to improve the testing of this chemical by commonly used mutagenicity testing methods and investigations on the underlying mechanisms and could be applicable for workers' health.

Biologically Hazardous Agents at Work and Efforts to Protect Workers' Health: A Review of Recent Reports

Because information on biological agents in the workplace is lacking, biological hazard analyses at the workplace to securely recognize the harmful factors with biological basis are desperately needed. This review concentrates on literatures published after 2010 that attempted to detect biological hazards to humans, especially workers, and the efforts to protect them against these factors. It is important to improve the current understanding of the health hazards caused by biological factors at the workplace. In addition, this review briefly describes these factors and provides some examples of their adverse health effects. It also reviews risk assessments, protection with personal protective equipment, prevention with training of workers, regulations, as well as vaccinations.

Oxidative DNA Damage from Nanoparticle Exposure and Its Application to Workers' Health: A Literature Review

The use of nanoparticles (NPs) in industry is increasing, bringing with it a number of adverse health effects on workers. Like other chemical carcinogens, NPs can cause cancer via oxidative DNA damage. Of all the molecules vulnerable to oxidative modification by NPs, DNA has received the greatest attention, and biomarkers of exposure and effect are nearing validation. This review concentrates on studies published between 2000 and 2012 that attempted to detect oxidative DNA damage in humans, laboratory animals, and cell lines. It is important to review these studies to improve the current understanding of the oxidative DNA damage caused by NP exposure in the workplace. In addition to examining studies on oxidative damage, this review briefly describes NPs, giving some examples of their adverse effects, and reviews occupational exposure assessments and approaches to minimizing exposure (e.g., personal protective equipment and engineering controls such as fume hoods). Current recommendations to minimize exposure are largely based on common sense, analogy to ultrafine material toxicity, and general health and safety recommendations.

Toxicological Evaluations of Rare Earths and Their Health Impacts to Workers: A Literature Review

In concert with the development of new materials in the last decade, the need for toxicological studies of these materials has been increasing. These new materials include a group of rare earths (RE). The use of RE nanotechnology is being considered in some green applications, to increase their efficiency by using nano-sized RE compounds, and therefore hazard evaluation and risk assessment are highly recommended. This review was conducted through an extensive contemplation of the literatures in toxicology with in vitro and in vivo studies. Major aspects reviewed were the toxicological evaluations of these elements and metallic compounds at the molecular and cellular level, animal and human epidemiological studies and environmental and occupational health impacts on workers. We also discuss the future prospect of industries with appliances using RE together with the significance of preventive efforts for workers' health. To establish a safe and healthy working environment for RE industries, the use of biomarkers is increasing to provide sustainable measure, due to demand for information about the health risks from unfavorable exposures. Given the recent toxicological results on the exposure of cells, animals and workers to RE compounds, it is important to review the toxicological studies to improve the current understanding of the RE compounds in the field of occupational health. This will help to establish a sustainable, safe and healthy working environment for RE industries.

Subchronic Inhalation Toxicity Study of n-pentane in Rats

OBJECTIVES: This study was conducted in order to obtain information concerning the health hazards that may result from a 13 week inhalation exposure of n-pentane in Sprague-Dawley rats. METHODS: This study was conducted in accordance with the Organization for Economic Co-operation and Development (OECD) guidelines for the testing of chemicals No. 413 'Subchronic inhalation toxicity: 90-day study (as revised in 2009)'. The rats were divided into 4 groups (10 male and 10 female rats in each group), and were exposed to 0, 340, 1,530, and 6,885 ppm n-pentane in each exposure chamber for 6 hour/day, 5 days/week, for 13 weeks. All of the rats were sacrificed at the end of the treatment period. During the test period, clinical signs, mortality, body weights, food consumption, ophthalmoscopy, locomotion activity, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were assessed. RESULTS: During the period of testing, there were no treatment related effects on the clinical findings, body weight, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, relative organ weight, and histopathological findings. CONCLUSION: The no-observable-adverse-effect level (NOAEL) of n-pentane is evaluated as being more than 6,885 ppm (20.3 mg/L) in both male and female rats. n-pentane was not a classified specific target organ toxicity in the globally harmonized classification system (GHS).

Evaluation of the Genetic Toxicity of Cyclopentane and Ammonium Nitrate: In vitro Mammalian Chromosomal Aberration Assay in Chinese Hamster Ovary Cells

OBJECTIVES: In this study, the in vitro mammalian chromosomal aberration (CA) assay was conducted to gain additional information concerning the hazards associated with the use of cyclopentane and ammonium nitrate. While these two chemicals had already been tested by many methods, they had not been studied in the CA test. METHODS: The assay was performed using the ovarian infantile cell (CHO-K1 cell), by the direct method (-S9) and by the metabolic activated method (+S9 mix). RESULTS: Using the direct method, the 7 dosages in a 48 hour treatment group did not show that the frequency of CA is proportion to the dosage addition. The frequency of CA is not proportion to the dosage addition for a 6 hour treatment using the metabolic activated method. CONCLUSION: From these findings, it was decided that the 2 chemicals do not induce chromosomal aberrations under the tested conditions.

Effect of Nano-sized Carbon Black Particles on Lung and Circulatory System by Inhalation Exposure in Rats

OBJECTIVES: We sought to establish a novel method to generate nano-sized carbon black particles (nano-CBPs) with an average size smaller than 100 nm for examining the inhalation exposure risks of experimental rats. We also tested the effect of nano-CBPs on the pulmonary and circulatory systems. METHODS: We used chemical vapor deposition (CVD) without the addition of any additives to generate nano-CBPs with a particle size (electrical mobility diameter) of less than 100nm to examine the effects of inhalation exposure. Nano-CBPs were applied to a nose-only inhalation chamber system for studying the inhalation toxicity in rats. The effect on the lungs and circulatory system was determined according to the degree of inflammation as quantified by bronchoalveolar lavage fluid (BALF). The functional alteration of the hemostatic and vasomotor activities was measured by plasma coagulation, platelet activity, contraction and relaxation of blood vessels. RESULTS: Nano-CBPs were generated in the range of 83.3-87.9 nm. Rats were exposed for 4 hour/day, 5 days/week for 4 weeks to 4.2 x 10(6), 6.2 x 10(5), and 1.3 x 10(5) particles/cm3. Exposure of nano-CBPs by inhalation resulted in minimal pulmonary inflammation and did not appear to damage the lung tissue. In addition, there was no significant effect on blood functions, such as plasma coagulation and platelet aggregation, or on vasomotor function. CONCLUSION: We successfully generated nano-CBPs in the range of 83.3-87.9 nm at a maximum concentration of 4.2 x 10(6) particles/cm3 in a nose-only inhalation chamber system. This reliable method can be useful to investigate the biological and toxicological effects of inhalation exposure to nano-CBPs on experimental rats.

A Study of Micronucleus Induction with Methyl Formate and 2-Methylbutane in Bone Marrow Cells of Male ICR Mice

OBJECTIVES: We investigated the genotoxicity of two chemicals, methyl formate and 2-methylbutane, using male ICR mice bone marrow cells for the screening of micronucleus induction. Although these two chemicals have already been tested numerous times, a micronucleus test has not been conducted and the amounts used have recently been increased. METHODS: 7 week male ICR mice were tested at dosages of 250, 500, and 1,000 mg/kg for methyl formate and 500, 1,000, and 2,000 mg/kg for 2-methlybutane, respectively. After 24 hours of oral administration with the two chemicals, the mice were sacrificed and their bone marrow cells were prepared for smearing slides. RESULTS: As a result of counting the micronucleated polychromatic erythrocyte (MNPCE) of 2,000 polychromatic erythrocytes, all treated groups expressed no statistically significant increase of MNPCE compared to the negative control group. There were no clinical signs related with the oral exposure of these two chemicals. CONCLUSION: It was concluded that the two chemicals did not induce micronucleus in the bone marrow cells of ICR mice, and there was no direct proportion with dosage. These results indicate that the two chemicals have no mutagenic potential under each study condition.