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Published in Ken Addley, MCQs, MEQs and OSPEs in Occupational Medicine, 2023
This worker has significant silica exposure as well as a very significant smoking history. Long-term silica exposure and smoking have an additive effect on the risk of lung cancer development. Although significant chronic lung disease can lead to cachexia and pulmonary fibrosis can lead to clubbing, the presence of persistent haemoptysis is much more suggestive of a more sinister pathology.
Experimental Lung Carcinogenesis by Intratracheal Instillation
Published in Joan Gil, Models of Lung Disease, 2020
Silica, which has been known for a long time as a causative agent of silicosis, has been recently found to be carcinogenic to the lung of rats. Holland et al. (1983) showed lung tumors in 6 of 36 rats after 10 IT instillations of 7 mg/rat of quartz (Minu-U-Sil). In the experiment by Groth et al. (1986), rats developed lung tumors after a single IT instillation of 20 mg of quartz (Min-U-Sil or Novaculite). All 30 lung tumors in rats that received Min-U-Sil were adenocarcinomas. Twenty of 21 lung tumors in rats that received Novaculite were also adenocarcinomas, and 1 was a squamous cell carcinoma. After inhalation of 12 mg/m3 or 50 mg/m3 quartz (Min-U-Sil) for 24 months, rats developed lung tumors in the studies by Holland et al. (1986) and Dagle et al. (1986).
The respiratory system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Silicosis is defined as a fibrotic disease of the lungs caused by the inhalation of dust containing crystalline silicon dioxide. Its development depends on particle size, mineral form, and individual susceptibility. Most rocks contain silica, either in its free form (silicon dioxide) or combined as various silicates. Silica exists in crystalline and amorphous forms, the latter including flint and opal. The most common form of crystalline silica is quartz, seen in many rock types. Sandstone contains almost 100% quartz, and slate and shale up to 40%. Silica exposure occurs in quarrying, stone cutting, mining, sand blasting, and tunnelling.
Current status and prospect for future advancements of long-acting antibody formulations
Published in Expert Opinion on Drug Delivery, 2023
Puneet Tyagi, Garrett Harper, Patrick McGeehan, Shawn P Davis
Silica has attracted considerable interest in drug delivery in the recent past due to its advantageous properties, including biodegradability and biocompatibility [27,28]. Silica degrades in the body to silicic acid and is subsequently eliminated from the body via renal excretion [29]. Having been approved by the FDA as GRAS (generally regarded as safe), silica is a common ingredient in oral and topical formulations. In comparison to PLGA polymers, silica degradation does not create an acidic environment as silicic acid has the first pKa at 9.84 [30]. In one of our earlier studies, we reported a sustained release of an active mAb from a silica matrix formed by the polymerization of alkoxysilanes, Si(OR)4, using a technique known as the sol-gel process [31]. By changing the manufacturing process parameters, it is possible to vary the number of the OH groups and specific surface area (from a dense gel to highly porous), both influencing the biodegradation rate of silica. The matrix is slowly dissolved when in contact with body fluids. However, use for silica for injectable long-term therapy needs to be thoroughly investigated for potential side effects.
Persistent changes in expression of genes involved in inflammation and fibrosis in the lungs of rats exposed to airborne lunar dust
Published in Inhalation Toxicology, 2023
Ye Zhang, Michael Story, Samrawit Yeshitla, Xiaoyu Wang, Robert R. Scully, Corey Theriot, Honglu Wu, Valerie E. Ryder, Chiu-wing Lam
The Moon is covered by a thick layer of fine lunar dust (LD). During the Apollo missions, LD that adhered to the spacesuits of crewmembers was carried into the Apollo Lunar Modules and subsequently into the Commend Modules (CMs). On the return journeys, the microgravity environment caused some of the dust to dislodge and contaminate the breathing atmosphere of the CMs. As John Young, the commander of Apollo 16, noted, “…our feet and hands and our arms were all full of dust” (Wagner 2006). Some astronauts reported eye and throat irritation from exposures to LD (Wagner 2006). A flight surgeon experienced respiratory symptoms after inhaling some LD while unpacking spacesuits from stowage; this surgeon’s symptoms got progressively worse during additional exposures to LD after 2 subsequent missions (Scheuring et al. 2008). On Earth, occupational exposures to excessive amounts of respirable mineral particles, such as crystalline silica (SiO2), coal, and construction-related dusts, could pose major health threats to industrial workers. Environmental exposures to fine airborne particulate matter (PM2.5) over safety limits for prolong periods could pose a major health concern to general populations (Sanderson 1986; CDC 2022; EPA 2022).
The impact of empowerment and technology on safety behavior: evidence from mining companies
Published in International Journal of Occupational Safety and Ergonomics, 2022
Paola Ochoa Pacheco, Miguel Pina e Cunha, António Cunha Meneses Abrantes
According to the World Health Organization (WHO) [48], the environmental hazards in small and artisanal mining frequently not only influence degradation and contamination of the general environment but also have implications for the health and well-being of miners, surrounding communities and the global environment. Donoghue [49] highlighted five types of risks: physical, chemical, biological, ergonomic and psychosocial. Physical hazards include rock fall, fires, explosions, mobile equipment accidents, falls from height, entrapment and electrocution. Chemical hazards such as crystalline silica are a serious hazard in mining. Biological hazards refer to diseases such as malaria and dengue fever, which are common in mines, especially in tropical countries. The risks of ergonomic hazards derive from extensive manual handling. Psychosocial hazards include common effects on mining employees in remote locations due to their separation from their families and communities over long periods of time.