TLV-TWA 0.15 mg/m3 as Pb (ACGIH and
MSHA), 0.05 mg (Pb)/m3 (OSHA); 10-h
TWA 0.1 mg(inorganic lead)/m3 (NIOSH).
物理描述:
Soft silver-bluish white to gray metal. (NTP, 1992)
颜色/状态:
Bluish-white, silvery, gray metal. Highly lustrous when freshly cut, tarnishes upon exposure to air. Cubic crystal structure.
气味:
None
味道:
Can not taste lead in water
蒸汽压力:
Vapor pressure (kPa) = 0.133 at 980 °C, 1.33 at 1160 °C, 13.33 at 1420 °C, 26.7 at 1500 °C, 53.3 at 1600 °C; Mohs' hardness = 1.5; latent head of vaporization = 860 J/g; specific heat = 130 J/kg-K; thermal conductivity = 34.7 W/n-K at 28 °C; latent heatof fusion = 25 J/g
Only 1 to 2% of ingested lead is absorbed from the GI tract because it can form rather insoluble compounds, even within the gut. Acid conditions favor dissolution of lead & its compounds.
In this paper, we tested the hypothesis that early life lead (Pb) exposure associated DNA methylation (5mC) changes are dependent on the sex of the child and can serve as biomarkers for Pb exposure. In this pilot study, we measured the 5mC profiles of DNA extracted from dried blood spots (DBS) in a cohort of 43 children (25 males and 18 females; ages from 3 months to 5 years) from Detroit. We found that the effect of Pb-exposure on the 5-mC profiles can be separated into three subtypes: affected methylation loci which are conserved irrespective of the sex of the child (conserved); affected methylation loci unique to males (male-specific); and affected methylation loci unique to females (female-specific). ... Blood spots from females show significantly higher numbers of differentially methylated clusters (DMCs) than males. Pb-dependent DNA methylation changes in females appear to be adaptive and protective in nature. Conserved regions show increase in DNA methylation around the transcription start site of Leptin (LEP), which is associated with the control of body mass. Increase in gene body DNA methylation of Lon-Peptidase 1 (LONP1) is an adaptive modification seen in females but not in males.
IDENTIFICATION AND USE: Lead is a bluish-white, silvery, gray metal. It is highly lustrous when freshly cut, but tarnishes upon exposure to air. Great quantities of lead are used in storage batteries. Lead is also used for cable covering, plumbing and ammunition. Lead is very effective as a sound and vibration absorber, and it is used as a radiation shield around X-ray equipment and nuclear reactors. HUMAN EXPOSURE AND TOXICITY: Lead affects the developing nervous system of children, and no safe blood lead level (BLL) in children has been identified. Elevated BLLs in childhood are associated with hyperactivity, attention problems, conduct problems, and impairment in cognition. Young children are at higher risk for environmental lead exposure from putting their hands or contaminated objects in their mouth. Although deteriorating lead paint in pre-1979 housing is the most common source of lead exposure in children, data indicate that > or =30% of children with elevated BLLs were exposed through a source other than paint. Take-home contamination occurs when lead dust is transferred from the workplace on employees' skin, clothing, shoes, and other personal items to their car and home. Recycling of used electronics (e-scrap) is a relatively recent source of exposure to lead. Lead is toxic by ingestion and inhalation of dust or fume. Cases of lead poisoning due to retained bullets are reported only rarely but represent potentially life-threatening reactions; almost all cases in USA have involved the dissolution of a single bullet over several months to more than 20 years. Bullets in joint spaces are more likely to cause toxic complications than are bullets lodged in soft tissues. Dissolution of lead from lead soldered joints in water pipes frequently occurs where water is soft or acidic. Thereby contributing to long-term chronic exposure to the general population. It appears that maternal milk might be a source of lead for the neonates, particularly when metal levels are elevated in the mother. Exposure to lead was associated with increased odds of sensitization to food allergens in adult but not in children. ANIMAL STUDIES: Lead particles have been well tolerated in the eyes of dogs and rats. Lead particles in the anterior chamber in rabbits became coated with purulent exudate and sometimes were extruded through the cornea at the limbus. In the vitreous humor in rabbits a similar purulent reaction was observed, causing the vitreous to shrink and the retina to separate. Twelve sheep were exposed to finely powdered metallic lead in their diet (doses, 0.5 to 16 mg/kg bw) during entire pregnancy; blood levels were about 0.4 mg/L, without resulting in death. Nine animals served as controls. Rate of lambing was 18% in exposed (27% abortions) and 100% in unexposed sheep (no abortions). No malformations were reported. Lead reduces resistance and increases mortality of experimental animals when infected with a broad range of bacterial and viral agents. Lead impairs antibody production in animals and generally decreases immunoglobin-producing cells. Lead powder suspended in corn oil was administered to male and female rats by stomach tube (10 mg twice/mo for 12 mo). Control rats were given corn oil by stomach tube according to same schedule. One lymphoma and 4 leukemias were found in 5/47 lead-treated rats; this did not differ significantly from the incidence of 3 lymphomas in 29 controls. ECOTOXICITY STUDIES: Lead exposure from ingestion of bullet fragments is a serious environmental hazard to eagles. Metallic lead is not toxic to birds except at very high dosage when administered in the form of powder. It is highly toxic to birds when given as lead shot. Studies have been conducted with nestling kestrels in which oral intubations were administered daily for the first 10 days post-hatching. A high mortality from metallic lead was observed with 525 mg/kg, reduced growth was observed with 125 mg/kg, and altered physiology was observed with 25 mg/kg. In geese chronically poisoned with lead shot, microscopic degenerative lesions appear in the myocardium before any ECG abnormalities are manifested. Lesions include upper GI impaction with plant materials, emaciation, distended gallbladder, flabby hemorrhagic heart, discolored friable liver, and enteritis. Lesions in mallard ducks given lead shot include destruction of proventricular epithelium, bone medullary osteocytes, and pectoral muscle cells. Renal proximal tubules contain intranuclear inclusions. Mallard ducks also may develop encephalopathy and peripheral neuropathy. Deer from the lead-polluted area showed higher lead levels in testis parenchyma, epididymal cauda and spermatozoa, lower values of acrosome integrity, higher activity of glutathione peroxidase and higher values of DNA fragmentation and stainability in sperm.
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/
Lead and lead compounds are reasonably anticipated to be human carcinogens based on limited evidence of carcinogenicity from studies in humans and sufficient evidence of carcinogenicity from studies in experimental animals. /Lead and Lead compounds/
... Two human volunteers were given (212)Pb intravenously. There was no lead in the feces during the first 24 hr, whereas the urine contained 4.42% of the dose. The figures for the second 24 hr, however, were 1.5% and 1.42%, respectively, which indicates that the fecal route may contribute as much as the urinary one to total excretion.
Recent studies on lead transport at the blood-brain barrier suggest that the blood-brain barrier is highly permeable to lead. The net influx of lead into the brain seems dependent upon two transport mechanisms that operate in opposite directions. A rapid influx of lead at the brain endothelium may occur by a passive transport mechanism involving a lead oxide species, whereas the outflow in the opposite direction that transports lead back into the capillary lumen may be via an active Ca2+ - ATP-dependent mechanism.
In animals, there is a positive correlation between tissue and dietary lead concentrations, although tissue concentrations are almost always lower. The distribution of lead within animals is closely associated with calcium metabolism. Lead shot is typically trapped in the gizzard of birds where it is slowly ground down resulting in the release of lead. The tetravalent organic form of lead is generally more toxic than the divalent inorganic form, and its distribution in organisms may not specifically follow calcium metabolism.
来源:Hazardous Substances Data Bank (HSDB)
安全信息
职业暴露等级:
D
职业暴露限值:
TWA: (8-hour) 0.050 mg/m3 [*Note: The REL also applies to other lead compounds (as Pb) -- see Appendix C.]
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