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Persistent chemicals, classification table

The use of the older restricted version of the Pauli principle has persisted, however, and is routinely employed to develop the electronic version of the periodic table. Modern chemistry appears to be committing two mistakes. Firstly, there is a rejection of the classical chemical heritage whereby the classification of elements is based on the accumulation of data on the properties and reactions of elements. Secondly, modem chemistry looks to physics with reverence and the false assumption that therein lies the underlying explanation to all of chemistry. Chemistry in common with all other branches of science appears to have succumbed to the prevailing tendency that attempts to reduce everything to physics (11). In the case of the Pauli principle, chemists frequently fall short of a full understanding of the subject matter, and... [Pg.13]

The availability of reliable measurements or estimates of water solubility, octanol-water partition coefficient, bioconcentration factor, rate constants and the like allows one to make qualitative judgements or, through the use of mathematical simulation models such as EPA s EXAMS (19), quantitative calculations of environmental distribution and persistence. In the qualitative use, Swann and coworkers (20) classified chemical mobility in soil based upon reversed-phase HPLC retention data which in turn is related to S. The approximate water solubility equivalents in this first-estimate classification, with chemical examples, are in Table II. This classification holds for chemicals whose primary adsorption in soil is to organic matter, and excludes those chemicals (such as paraquat) which bind ionically to the soil mineral fraction. A recent tabulation of pesticides found in groundwater had 11 entries, 8 of which represented compounds with water solubilities in excess of 200 ppm with the remaining three falling in the range of 3.5 to 52 ppm (21). [Pg.96]

In 1968, the classification of pesticides depending on their degree of hazard was proposed for the purposes of hygienic selection, and was modified in 1987. In addition to the WHO classiflcation it covers the chemical assessment for both concordance with the LD50 and criteria such as cumulation, persistence, carcinogenicity, embryotoxicity, and ability to cause allergy (see Table 19.1). [Pg.289]

The periodic table of the elements is perhaps the most natural system of classification in the whole of science. Whereas biological classification is continually debated, the classification of the chemical elements is far more clear-cut as a result of the periodic table, although some disagreements still persist. [Pg.329]


See other pages where Persistent chemicals, classification table is mentioned: [Pg.176]    [Pg.747]    [Pg.747]    [Pg.415]    [Pg.148]    [Pg.23]    [Pg.14]    [Pg.9]    [Pg.334]   


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