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  2. List of highly toxic gases - Wikipedia

    en.wikipedia.org/wiki/List_of_highly_toxic_gases

    Highly Toxic: a gas that has a LC 50 in air of 200 ppm or less. [2] NFPA 704: Materials that, under emergency conditions, can cause serious or permanent injury are given a Health Hazard rating of 3. Their acute inhalation toxicity corresponds to those vapors or gases having LC 50 values greater than 1,000 ppm but less than or equal to 3,000 ppm ...

  3. Biological roles of the elements - Wikipedia

    en.wikipedia.org/wiki/Biological_roles_of_the...

    Highly toxic to humans in its elemental form. [11] iridium: 77: 1a: Due to its extreme rarity, iridium has no biological role. [11] The chloride is moderately toxic to humans. [11] iron: 26: 5: Essential to almost all living things, usually as a ligand in a protein; it is most familiar as an essential element in the protein hemoglobin. [11 ...

  4. Sulfur - Wikipedia

    en.wikipedia.org/wiki/Sulfur

    Though elemental sulfur is only minimally absorbed through the skin and is of low toxicity to humans, inhalation of sulfur dust or contact with eyes or skin may cause irritation. Excessive ingestion of sulfur can cause a burning sensation or diarrhea, [ 134 ] and cases of life-threatening metabolic acidosis have been reported after patients ...

  5. Metal toxicity - Wikipedia

    en.wikipedia.org/wiki/Metal_toxicity

    Many metals, particularly heavy metals are toxic, but some are essential, and some, such as bismuth, have a low toxicity. Metals in an oxidation state abnormal to the body may also become toxic: chromium(III) is an essential trace element, but chromium(VI) is a carcinogen. Only soluble metal-containing compounds are toxic.

  6. Organosulfur chemistry - Wikipedia

    en.wikipedia.org/wiki/Organosulfur_chemistry

    Organosulfur chemistry is the study of the properties and synthesis of organosulfur compounds, which are organic compounds that contain sulfur. [1] They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin.

  7. Hydrogen sulfide - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_sulfide

    100 ppm IDLH (NIOSH): immediately dangerous to life and health (the level that interferes with the ability to escape) 0.00047 ppm or 0.47 ppb is the odor threshold, the point at which 50% of a human panel can detect the presence of an odor without being able to identify it. [71] 10–20 ppm is the borderline concentration for eye irritation.

  8. Sulfur compounds - Wikipedia

    en.wikipedia.org/wiki/Sulfur_compounds

    Treatment of sulfur with hydrogen gives hydrogen sulfide.When dissolved in water, hydrogen sulfide is mildly acidic: [5] H 2 S ⇌ HS − + H +. Hydrogen sulfide gas and the hydrosulfide anion are extremely toxic to mammals, due to their inhibition of the oxygen-carrying capacity of hemoglobin and certain cytochromes in a manner analogous to cyanide and azide.

  9. Sulfur-reducing bacteria - Wikipedia

    en.wikipedia.org/wiki/Sulfur-reducing_bacteria

    Sulfur reduction metabolism is an ancient process, found in the deep branches of the phylogenetic tree. [15] Sulfur reduction uses elemental sulfur (S 0) and generates hydrogen sulfide (H 2 S) as the main end product. This metabolism is largely present in extreme environments where, especially in recent years, many microorganisms have been ...