Germanium exposure

Germanium tetrafluoride produces hydrogen fluoride in aqueous acidic solutions. Hydrogen fluoride is toxic and very corrosive. The OSHA permissible exposure limit (17) and the American Conference of Governmental Industrial Hygienists (ACGIH) TLV for fluoride is 2.5 mg/m of air (18). 

High exposure levels of germanium salts may disturb the water balance leading to dehydration, hemoconcentration, decrease in blood pressure and hypothermia, without showing gross tissue damage7. 

The mesoporous forms of germanium that derive from the above chemistry are very air sensitive and rapidly convert to germanium suboxides GeOx upon exposure in air for a short time (<1 min). This is expected since almost all Ge atoms of the framework lie at or near the surface and the Ge-Ge bond is susceptible in oxidation. The formation of GeOx involves the conversion of Ge-Ge bonds to Ge-O-Ge moieties and seems to be a homogeneous process. This causes a systematic blue-shift of the energy band gap, possibly due to the size-confinement effect. 

Fig. 6. Energy levels at a germanium surface (a) before and (b) after exposure...

Despite the range of hydrides present, hydride termination by HF etching stabilizes the surface against oxidation and maintains surface ordering for further wet chemistry. Hydride-terminated germanium shows no oxidation after exposure to ambient... 

Electron transfer from the germanium analog of 1, (PMePhGe) , to photoexcited Cgo in benzene-acetonitrile solution has also been investigated by 532 nm laser flash photolysis10. The transient absorption band at 730 nm which appears immediately after laser exposure is attributed to 3Cgo (2). With the decay of 3Cgo (2), the intensities of the... 

At a gum arabic concentration of 1.0% (w v), polysaccharide was detected at the Ge surface within the first minute of exposure to the flowing solution as shown in the first spectrum (T 0 min) in Figure 7. The intensities of both the protein and polysaccharide bands then rose rapidly in a 15-min period of time as shown in Figure 6. The 1070 cm 1 polysaccharide band plateaued at 14.7 mAU after 30 min whereas the Amide II band stabilized at 12.5 mAU after approximately 2 hr. The intensity of the 1070 cm 1 polysaccharide band dropped rapidly when Milli-Q water was pumped through the flow cell. A 90% decrease in the 1070 cm 1 band intensity occurred over the 4-hr rinse period. The final intensity of this band was not significantly different from the intensity observed when gum arabic was adsorbed onto germanium at a concentration that was 10 times less. The protein was more firmly bound to the IRE surface as indicated by the Amide II band intensity which dropped less than 10% during the rinse period. Only 15% less protein remained firmly attached to the Ge IRE when it was adsorbed from a gum arabic solution concentration of 0.1% as compared to 1%. Experiments to study adsorption of proteins and polysaccharides on copper and nickel are not yet complete, but appear to show similar trends. 

In contrast to germanium the exposure of mankind to tin and lead was much earlier and not so dramatic18-21,28. These two elements belong to the seven main elements known to ancient man40. Up to the seventeenth century, tin and lead were often confused, as is witnessed by their Latin names, i.e. Plumbum album, Plumbum candidum (Sn) and Plumbum nigrum (Pb). Tin was known in countries of the Near East at least from the middle of the third millennium BC. Lead became known to the Egyptians at the same time as iron and silver, and very probably earlier than tin19,28. 

Occupational exposure to inorganic germanium compounds can cause slightly impaired renal function (2). However, severe nephrotoxic reactions have been described, and it has become clear that these can occur both with inorganic and organic germanium compounds (SEDA-21, 235). 

C, 220 °C, and 300 °C. Two samples of each type of material were exposed simultaneously. One of each sample type was covered with a screen during exposure. Each exposure was to 50,000 pulses of the hyperthermal O-atom beam, and included a screened Kapton H reference sample. The O-atom fluence was on the order of 1020 O-atoms cm-2. The nominal O-atom translational energy of each exposure was 5.2 eV, and the 0/02 ratio in the beam was 0.65 0.35. For the 25 °C exposure, the films (which were not cast on substrates) were placed in the sample holder. For the higher temperature exposures, the films were cast on germanium discs that were in contact with a controlled heating block during the exposures, and were equilibrated to the desired temperature. 

The general population takes up germanium mainly from food, and the daily intake can vary between 0.4 and 3.5 mg (Schroeder and Balassa 1967, Swennen etal. 2000). Ysart etal. (1999) reported about a daily total dietary exposure of only 0.004 mg in the UK population. Values will depend on the provenance of food and potential industrial contaminants. Inhalation is a potential hazard of occupational exposure (Rods and Buchet 2001). Dust containing up to 7 mg m has been found in the production of Ge monocrystals (Gerber, 1988). 

Although the general toxicity of Ge is low, exposure to germanium can lead to intoxication symptoms in flora, fauna, and humans. Ge products (elixirs, supplements) present a potential human health hazard (Tao and Bolger 1997). 

Roels ha and Buchet JP (2001) Determination of germanium in urine and its usefulness for biomonitoring of inhalation exposure to inorganic germanium in the occupational setting. J Environ Monit 3 67-73. 

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