Table 1.

Characteristics of TCE metals with the influence of these metals on living organisms.

Metal	General Description	Impact	Ref
Germanium	widely distributed in the body and its accumulation and retention in the organs depending on the chemical form of germanium. no definite evidence for the mutagenicity of germanium but under certain conditions it inhibits the mutagenic activity of other substances.	causes toxic effects in humans. organic compounds destroy cancer cells and reveal antineoplastic properties in human. inorganic forms (especially when inhaled) may be toxic in high doses.	[6,13,14]
Thallium	very toxic. its salts are considered to be the most toxic compounds known. toxicity of Tl has not been greatly studied, but its harmful impact has been observed on both humans and animals.	contents of Tl in most mammalian tissues <200 µg kg−1. increased level, at 500 µg kg–1 (in the skin) is easily absorbed through the skin. ingested and inhaled Tl is also harmful to organisms. general exposure has been observed in the population living in the vicinity of a cement plant (discharges high-Tl containing dust). other Tl sources: coal combustion, roasting of sulfide concentrates, and manufacturing of Tl-containing products.	[6,14]
Tellurium	has no biological role. all its compounds are highly toxic. considered to be a teratogenic agent, however, acute poisoning is rare.	workers exposed to 0.5 to <10 µg Te m–3 have a garlic-like odor (a symptom of the Te intoxication). permissible exposure limits for Te in inhaled air vary for different compounds, from 0.1 mg m–3 for elemental and dioxide Te, to 10 mg m–3 for telluride compounds.	[14]