Lead is absorbed following inhalation, oral, and dermal exposure. It is then distributed mainly to the bones and red blood cells. In the blood lead may be found bound to serum albumin or the metal-binding protein metallothionein. Organic lead is metabolized by cytochrome P-450 enzymes, whereas inorganic lead forms complexes with delta-aminolevulinic acid dehydratase. Lead is excreted mainly in the urine and faeces. (L136)
IDENTIFICATION AND USE: Lead dioxide is a dark-brown powder. It is used in electrodes in batteries; as oxidizing agent in manufacture dyes; as discharge in dyeing with indigo; manufacture rubber substitutes; with amorphous phosphorus as ignition surface for matches; pyrotechnics; manufacture pigments; in analytical chemistry. HUMAN EXPOSURE AND TOXICITY: Exposure can cause headache, irritability, and muscle and joint pain. Lead dioxide may damage the nervous system. Exposure may cause kidney and brain damage, and anemia. Repeated exposure to lead dioxide can cause lead poisoning. Symptoms include metallic taste, poor appetite, weight loss, colic, nausea, vomiting, and muscle cramps. Higher levels can cause muscle and joint pain, and weakness. High or repeated exposure may damage the nerves causing weakness, "pins and needles," and poor coordination in the arms and legs. Lead exposure increases the risk of high blood pressure. ANIMAL STUDIES: There are no data available.
Lead mimics other biologically important metals, such as zinc, calcium, and iron, competing as cofactors for many of their respective enzymatic reactions. For example, lead has been shown to competitively inhibit calcium's binding of calmodulin, interferring with neurotransmitter release. It exhibits similar competitive inhibition at the NMDA receptor and protein kinase C, which impairs brain microvascular formation and function, as well as alters the blood-brain barrier. Lead also affects the nervous system by impairing regulation of dopamine synthesis and blocking evoked release of acetylcholine. However, it's main mechanism of action occurs by inhibiting delta-aminolevulinic acid dehydratase, an enzyme vital in the biosynthesis of heme, which is a necesssary cofactor of hemoglobin. (T4, A20, A22, L136)
There is limited evidence in humans for the carcinogenicity of inorganic lead compounds. ... There is sufficient evidence in experimental animals for the carcinogenicity of inorganic lead compounds. There is sufficient evidence in experimental animals for the carcinogenicity of lead acetate, lead subacetate, lead chromate, and lead phosphate. There is inadequate evidence in experimental animals for the carcinogenicity of lead oxide and lead arsenate. ... There is inadequate evidence in experimental animals for the carcinogenicity of lead powder. Overall evaluation Inorganic lead compounds are probably carcinogenic to humans (Group 2A). /Inorganic lead compounds/
CLASSIFICATION: B2; probable human carcinogen. BASIS FOR CLASSIFICATION: Sufficient animal evidence. Ten rat bioassays and one mouse assay have shown statisticlly significant increases in renal tumors with dietary and subcutaneous exposure to several soluble lead salts. Animal assays provide reproducible results in several laboratories, in multiple rat strains with some evidence of multiple tumor sites. Short term studies show that lead affects gene expression. Human evidence is inadequate. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Sufficient. /Lead and Compounds (inorganic), Based on former classification system/
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌性证据
A3;已确认对动物有致癌性,但对人类的相关性未知。/铅和铅的无机化合物,如 Pb/
A3; Confirmed animal carcinogen with unknown relevance to humans. /Lead and and inorganic compounds, as Pb/
This solubility was studied in vitro for the six following metal oxides: Cd, Cr, Fe, Mn, Pb, Zn, by holding particle oxides in suspension into human plasma at 37 degrees C, during variable time. The experimentation was realized on particles which belong to two categories which sizes are 0.45-2 and 2-5 mu. The evolution of metal oxide dissolved level according to time have enabled exponential relation parameters to be calculated. These parameters translate the particle oxide dissolution into plasma and have permitted to classify metal oxide in decreasing solubility order: Cd, Zn, PbO, Fe2O3, Fe3O4, Mn, PbO2, Pb3O4 and Cr2O3.
1.周国泰,化学危险品安全技术全书,化学工业出版社,1997 2.国家环保局有毒化学品管理办公室、北京化工研究院合编,化学品毒性法规环境数据手册,中国环境科学出版社.1992 3.Canadian Centre for Occupational Health and Safety,CHEMINFO Database.1998 4.Canadian Centre for Occupational Health and Safety, RTECS Database, 1989
A process for producing alkylene carbonates which comprises reacting urea and glycols described by the general formula RCH(OH) CH.sub.2 OH; wherein R represents hydrogen or an alkyl group containing 1 to 4 carbons, using a catalyst containing zinc, magnesium, lead or calcium at reduced pressures. The alkylene carbonates are produced with high yield easily using raw materials which are comparatively inexpensive with a mild reaction that does not involve explosive or hazardous materials.
Process for preparing .beta.-lactam antibiotic substances useful as intermediate for various cephalosporin or penicillin derivatives, which comprises oxidation of 7-benzylideneaminocephem or 6-benzylideneaminopenam compounds capable of being converted to their quinoid forms by oxidation followed by reaction with lower alkanols.
Preparation of 4,4-disubstituted cyclohexadienones
申请人:Shell Oil Company
公开号:US04663487A1
公开(公告)日:1987-05-05
The invention provides a process for the preparation of 4,4-disubstituted cyclohexadienones of which at least one of the substituents is fluorine, which comprises reacting a compound of formula ##STR1## wheren X represents a hydrogen or halogen atom or an alkyl group, each R independently represents a halogen atom or an alkyl, alkoxy, or cyano or optionally substituted amino group, Z represents a hydrogen atom or an alkyl, acyl or aryloxycarbonyl group, and n is 0 to 4, with hydrogen fluoride and a Pb(IV) compound, in the presence of a compound which acts as a base towards HF.
Spectrofluorometric method and compounds that are of value for the method
申请人:Wallac Oy
公开号:US05216134A1
公开(公告)日:1993-06-01
A chelate formed between Eu.sup.3+, Tb.sup.3+, Dy.sup.3+ and Sm.sup.3+ and a compound having the formula ##STR1## where A.sub.1-6 are single carbon or nitrogen atoms; n=1 or 2; R.sub.1-6 is nothing when A is a nitrogen, and hydrogen or an organic group when A is a carbon; Z and Z' are selected among --N(CH.sub.2 CH.sub.2 COO.sup.-).sub.2, --N(CH.sub.2 COO.sup.-).sub.2, --N(CH.sub.2 OPO.sub.3.sup.2-).sub.2 and --N(CH.sub.2 PO.sub.3.sup.2-).sub.2 ;--species that --X--Y is a substituent replacing a hydrogen anywhere in the parent compound; and --X--Y represents an organic group containing no chelating heteroatom closer than four atoms from a chelating heteroatom in the parent compound and X is a stable bridge containing certain groups and Y is selected from (a) specified relative groups allowing coupling to other compounds and (b) residues of compounds participating in biospecific affinity reactions.
Aromatic compounds containing an .alpha.-fluoroalkyl or .alpha.,.alpha.-difluoroalkyl side chain are prepared by reacting selected aromatic compounds with a mixture of HF and a metal oxide which is PbO.sub.2 or NiO.sub.2 at -30.degree. to +80.degree. C. Exemplary is the conversion of 4-nitrotoluene to 4-(fluoromethyl)nitrobenzene and 4-(difluoromethyl)nitrobenzene.