Potential toxicity and safety evaluation of nanomaterials for the respiratory system and lung cancer

Our plain-English summary of Potential toxicity and safety evaluation of nanomaterials for the respiratory system and lung cancer, by T. Vlachogianni, K. Fiotakis, S. Loridas, et al (Lung Cancer, 2013).

The study

• Authors: T. Vlachogianni, K. Fiotakis, S. Loridas, S. Perdicaris, A. Valavanidis
• Journal: Lung Cancer
• Published: 2013;4:71-82
• Type of article: Review
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Engineered nanomaterials (ENMs) are a diverse group of materials finding increasing use in manufacturing, computing, food, pharmaceuticals, and biomedicine due to their very small size and exceptional properties. Health and safety concerns for ENMs have forced regulatory agencies to consider preventive measures and regulations for workers' health and safety protection. Respiratory system toxicity from inhalable ENMs is the most important concern to health specialists. In this review, we focus on similarities and differences between conventional microparticles (diameters in mm and μm), which have been previously studied, and nanoparticles (sizes between 1 and 100 nm) in terms of size, composition, and mechanisms of action in biological systems. In past decades, respirable particulate matter (PM), asbestos fibers, crystalline silicate, and various amorphous dusts have been studied, and epidemiological evidence has shown how dangerous they are to human health, especially from exposure in working environments. Scientific evidence has shown that there is a close connection between respirable PM and pulmonary oxidative stress through the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). There is a close connection between oxidative stress in the cell and the elicitation of an inflammatory response via pro-inflammatory gene transcription. Inflammatory processes increase the risk for lung cancer. Studies in vitro and in vivo in the last decade have shown that engineered nanoparticles (ENPs) at various doses can cause ROS generation, oxidative stress, and pro-inflammatory gene expression in the cell. It is assumed that ENPs have the potential to cause acute respiratory diseases and probably lung cancer in humans. The situation regarding chronic exposure at low doses is more complicated. The long-term accumulation of ENPs in the respiratory system cannot be excluded. However, at present, exposure data for the general public regarding ENPs are not available.

In plain English

This article was a narrative review, not new research. The authors discussed research on engineered nanomaterials, a diverse group of materials that includes nanoparticles 1 to 100 nanometers in size. They compared these with larger particles studied in workplaces, such as asbestos, crystalline silica and particulate matter. The article did not say how studies were chosen. Citing other work, the authors stated that there was positive evidence of increased lung cancer risk from long-term workplace exposure to asbestos, especially crocidolite (blue asbestos), and that this risk multiplied substantially with smoking. They noted that carbon nanotubes raised safety concerns similar to asbestos. A 2009 review they cited reported mesotheliomas in rats and mice given carbon nanotubes intraperitoneally (into the abdomen). The authors reported laboratory studies showing nanoparticles can generate reactive oxygen species, oxidative stress and inflammation. A 2011 review they cited found only about 50% of in vitro genotoxicity studies positive. The authors stated there was little evidence of cancer effects of engineered nanoparticles in humans. They concluded that the data, though very incomplete, were adequate to alert scientists to future health and safety problems for workers and consumers.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: narrative review of published literature (no stated search method)
• Who was studied: No study population of its own. The review discussed published laboratory (in vitro), animal (in vivo) and some epidemiological studies. The number of studies reviewed is not given.
• Exposure: Engineered nanomaterials, a diverse group that includes nanoparticles 1 to 100 nm in size (such as titanium dioxide, carbon nanotubes, fullerenes, metal and metal oxide nanoparticles, zinc oxide, silver and gold). These were compared with conventional particles including asbestos fibers, crystalline silica and particulate matter.
• Main results:
  • Citing other studies, the authors stated that long-term occupational exposure to asbestos fibers, especially blue asbestos (crocidolite), carries positive evidence of increased lung cancer risk, and that this risk multiplies substantially with tobacco smoking
  • Citing other studies, the authors noted some similarities between the disease-causing properties of multi-walled carbon nanotubes and those of asbestos fibers
  • A 2009 review cited by the authors reported mesotheliomas in rats and mice after carbon nanotubes were applied intraperitoneally
  • The authors reported that experimental studies showed engineered nanoparticles can increase formation of reactive oxygen and nitrogen species, causing oxidative stress and inflammation
  • A 2011 review cited by the authors found that only about 50% of in vitro genotoxicity studies of nanomaterials were positive
  • The authors stated there is little evidence of carcinogenic effects of engineered nanoparticles in humans
• The authors' conclusion: The authors concluded that the toxicological data on engineered nanoparticles, although very incomplete, are adequate to alert scientists to future health and safety problems for workers and consumers. They also stated it is assumed that these particles have the potential to cause acute respiratory diseases and probably lung cancer in humans.
• Limitations the authors state:
  • The authors stated that exposure data for the general public regarding engineered nanoparticles are not available
  • The authors stated that the situation for chronic low-dose exposure is more complicated
  • The authors stated that few recent animal studies have addressed a cancer endpoint for engineered nanoparticles

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Crystalline, Silicate, Oxidative Stress, Reactive Oxygen Species (ROS), Reactive Nitrogen Species (RNS).

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