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Many gases have toxic properties, which are often assessed using the LC 50 (median lethal concentration) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or permanent injury), and/or exposure limits (TLV, TWA/PEL, STEL, or REL) determined by the ACGIH professional association.
This is the list of extremely hazardous substances defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. § 11002). The list can be found as an appendix to 40 CFR 355. [1] Updates as of 2006 can be seen on the Federal Register, 71 FR 47121 (August 16, 2006). [2]
Palytoxin, PTX [3] or PLTX [4] is an intense vasoconstrictor, [1] and is considered to be one of the most poisonous non-protein substances known, second only to maitotoxin in terms of toxicity in mice. [5] Palytoxin is a polyhydroxylated and partially unsaturated compound (8 double bonds) with a long carbon chain.
P. toxica contains palytoxin, one of the most poisonous substances known. [9] This zoanthid is not the only member of its genus to contain the toxin; that distinction is shared by P. tuberculosa. The latter species has a seasonal cycle, varying in toxicity at different times of year, whereas P. toxica is equally toxic all year round. [10]
The man, however, has since recovered and left the hospital. It's strongly suspected the two were poisoned by aconite, an alkaloid toxin found in the raw roots and flowers of its namesake plant.
The botulinum toxin as the most toxic substance known has an LD 50 value of 1 ng/kg, while the most non-toxic substance water has an LD 50 value of more than 90 g/kg; a difference of about 1 in 100 billion, or 11 orders of magnitude. As with all measured values that differ by many orders of magnitude, a logarithmic view is advisable.
Biologically speaking, any substance, if given in large enough amounts, is poisonous and can cause death. For instance, several kilograms worth of water would constitute a lethal dose. Many substances used as medications—such as fentanyl—have an LD 50 only one order of magnitude greater than the ED50. An alternative classification ...
The term "environmental toxin" can sometimes explicitly include synthetic contaminants [26] such as industrial pollutants and other artificially made toxic substances. As this contradicts most formal definitions of the term "toxin", it is important to confirm what the researcher means when encountering the term outside of microbiological contexts.