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 sulfide forms metallic black cubic crystals. It is used in glazing earthenware, as a friction additive in clutch facings and disc brakes. It is also used in photoconductive cells, infrared detectors, transistors, humidity sensors in rockets, catalysts for removing mercaptans from petroleum distillates, mirror coatings to limit reflectivity, high temperature solid-film lubricants, and in blue lead pigments. Lead sulfide quantum dots have biomedical applications. ANIMAL STUDIES: Lead sulfide may deposit as a thin line along the gingival margin. This line appears blue to black and is called a Burtonian line. It is characteristic of chronic lead poisoning. A case of chronic lead poisoning with lead sulfide presented clinically with abdominal crampoid pain, encephalopathy (manifested as anxiety and irritability), a Burtonian gingival border and microcytic sideropenic anemia. ANIMAL STUDIES: Lead sulfide was found to have a low bioavailability in rat at repeated doses and thus did not result in overt toxicity. In rats, deposits of a black/brown pigment were recognized in the lung 12 weeks after the intratracheal administration of lead sulfide in dosages of 15 or 30 mg, with cells exhibiting a light foam reaction. A black/brown pigment was deposited nodularly 12 weeks after the administration of lead sulfide in a dosage of 50 mg. In rats PbS nanoparticles showed high neurotoxicity, while a possible mechanism was suggested to be due to the calcium homeostasis disorder which was caused by the abnormal calcium transportation. Lead sulphide was found mutagenic at the HPRT locus, in V79 cells, at concentrations that do not induce SCE.
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,如铅/
A3; Confirmed animal carcinogen with unknown relevance to humans. /Lead and and inorganic compounds, as Pb/
Biosynthesis of nanoparticles using microorganisms has attracted a lot of attention in recent years as this route has the potential to lead to synthesis of monodisperse nanoparticles. Here, we report the intracellular synthesis of stable lead sulfide nanoparticles by a marine yeast, Rhodosporidium diobovatum. The PbS nanoparticles were characterized by UV-visible absorption spectroscopy, X-ray diffraction (XRD) and energy dispersive atomic spectroscopy (EDAX). UV-visible absorption scan revealed a peak at 320 nm, a characteristic of the nanosize range. XRD confirmed the presence of PbS nanoparticles of cubic structure. Crystallite size as determined from transmission electron microscopy was found to be in the range of 2-5 nm. Elemental analysis by EDAX revealed the presence of particles composed of lead and sulfur in a 1:2 ratio indicating that PbS nanoparticles were capped by a sulfur-rich peptide. A quantitative study of lead uptake through atomic absorption spectrometry revealed that 55% of lead in the medium was accumulated in the exponential phase, whereas a further 35% was accumulated in the stationary phase; thus, the overall recovery of PbS nanoparticles was 90%. The lead-exposed yeast displayed a marked increase (280% over the control) in nonprotein thiols in the stationary phase. /PbS nanoparticles/
Data obtained from a feeding study in rats /showed that/ lead uptake into rat femurs was highly dependent on the chemical form of lead administered. Bioavailability was highest for lead acetate, intermediate for lead oxide, and lowest for lead sulfide and Alaskan mixed ore concentrate. This uptake was linearly related to dose over the range studied.
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
在禁食条件下,人体对硝酸铅、硫化铅和铅胱氨酸的吸收率在16%到53%之间。
... Under fasting conditions /in humans/ absorption of lead nitrate, lead sulfide, and lead cysteine ranged from 16 to 53%.
/In rats/, absorption of sulfide, chromate, naphenate, and octoate were absorbed at only 44-67% the rate of absorption for lead acetate. ... Update of lead into the femurs of rats was highest for lead acetate, intermediate for lead oxide, and lowest for lead sulfide and a mixture of Alaskan ore concentrate.
The lead sulfide (PbS) in galena is insoluble and absorption from the lung is limited; however, in the stomach, some lead sulfide may be converted to slightly soluble lead chloride which may then be absorbed in moderate quantities.
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