A German chemist Clemens A. Winkler first isolated Germanium in 1886 from the mineral argyrodite. Germanium (Ge) is a semiconducting metal from Group IVA of the periodic table, and it forms a series of hydrides. Interest in the organogermanium compounds has centered on their antimicrobial activity and the fact that their mammalian toxicity is lower than the corresponding derivatives of tin or lead. Today, germanium is used in the computer industry (as resistors on computer chips), in fiber optics, solar applications, and metallurgy, and has also been used in supplements and for chemotherapy agents. The inorganic compound, Ge tetrachloride, has been shown to cause skin and eye irritation, and inhalation of high exposure concentrations can cause necrosis of the tracheal mucosa, bronchitis, and interstitial pneumonitis. In recent years, germanium nanoparticles (NPs) have received increased attention as a favorable alternative to II–VI and IV–VI semiconductor materials. It was found that GE nano length imogolites persisted in the lungs of tested animals and promoted genotoxicity, sustained inflammation, and fibrosis.
The Bronze Age began approximately 3500 BCE with the discovery that alloying tin (Sn) with easily smelted soft copper made it harder and stronger. Tin and copper are important for the manufacture of numerous commercially valuable products including electrical conductors, piping, and antimicrobial agents. Tin is a solid, unreactive metal in Group IVA of the periodic table and has the largest number of stable isotopes of any element. Tin also has many unstable isotopes with half‐lives ranging from 2.2 min to 105 years. The physical and chemical properties of tin and some of its compounds are provided. Organotins, such as tributyltin (TBT) and trimethyltin (TMT) compounds, have drawn much attention because of their toxicity and wide range of adverse effects in experimental animals and in humans. Laboratory research has demonstrated that tributyltin is an endocrine disruptor in mammals, affects the immune system, is reported to be teratogenic, and is a reproductive and developmental toxicant. Occupational exposure to trimethyltin has been shown to increase the risk of kidney stones among TMT‐exposed workers.
Copper (Cu) is in Group IB of the periodic table. The electrical conductivity and malleability of copper are important commercial properties of the metal. Exposure to copper can occur from environmental sources such as food, water from copper pipes, and soil ingestion near copper smelting operations. The adverse health effects associated with copper production may be due to the sulfur oxides generated during smelting or because of the impurities, such as arsenic and antimony. Results from numerous experimental studies support the position that reactive oxygen species (ROS)‐generated oxidative damage plays an important role in Cu toxicity. Copper processing workers were found to have had significantly lower pulmonary function parameter test results, significantly increased serum levels of malondialdehyde, and their total antioxidative capacity and glutathione concentrations were significantly lower than controls. Also, based on the comet assay, it was found that significant DNA damage occurred in leukocytes among the copper processing workers. Copper nanoparticles are being used in a wide range of applications. Experimental studies in animals have reported that inhalation of Cu NPs was shown to cause the increased deposition of copper in the lung and liver and an undesired modulation of immune system response. Inhalation of Cu NPs in rats resulted in dose‐dependent lung inflammation and cytotoxicity, and histopathology examinations of the lungs revealed alveolitis, bronchitis, and vacuolation of the respiratory epithelium and emphysema. In a study of the hemolytic effects of copper oxide (CuO) nanoparticles and bulk CuO in human red blood cells, it was demonstrated that CuO NPs caused toxic hemolytic effects in a concentration‐dependent manner and that the CuO NPs effectively destroy human red blood cells in comparison to bulk CuO.
