化合物详情

ATMOSPHERIC FATE: In the atmosphere, lead most likely exists primarily as PbSO4 and PbCO3 and is deposited onto soil as lead sulfates and lead carbonates(1). Lead sulfate is a major species of lead in the atmosphere, either being emitted in that form or possibly being formed from the sulfide or other lead species with atmospheric SO2 and oxygen. Lead sulfate is expected to exist solely in the particulate phase in the ambient atmosphere, and will be subject to washout and gravitational settling. Transformations in the atmosphere to the carbonate and oxide may be expected(2).

Lead particulate matter emitted by motor vehicles, which is largely lead bromochloride and lead oxide with lesser amounts of the sulfate and phosphate salt, nonphotolytically degrade in the atmosphere. The sulfate concentration and water solubilities of the particulates is increased by irradiation(1). It has been suggested that sulfuric acid formed from the SO2 in the atmosphere or at the soil interface reacts with the lead particulate to form lead sulfate. This can also occur in soil in contact with groundwater(1).

The chemical composition of baghouse effluent from smelting and refining operations has been examined in one study which found that elemental lead composed 15-20% of the emissions in some cases; with PbS, PbSO4, and PbO.PbSO4 also being present(1). The form of lead in emissions from a lead smelter contained 41.2% of the lead as PbSO4, 48.8% as PbS and 10.1% as PbO(2). Bulk dust samples collected from different areas of a primary lead smelter contained lead in the ore storage area, sinter area, and the blast and dross furnace; lead particles emitted from the smelter would primarily be in the form of lead sulfur compounds, PbSO4, PbO.PbSO4, and PbS(3).

Lead sulfate occurs naturally in anglesite, one of three lead ores found in sufficient abundance to form mineable deposits(1). It also occurs in the mineral lanarkite, in which it is combined with PbO(2). Lead sulfate is a major component of more than 200 identified minerals(1).

The percent composition of airborne lead particles at a site near a road, 400 yds from a road, and at a rural site were, respectively: 2.2, 6.0 and 3.2 for PbSO4; and 1.0, 4.6 and 5.0 for PbO.PbSO4(1). An air filter containing particles with 2.3% lead, collected near a lead smelter, was rinsed so as to separate the Pb particles by density; the heavy and light fractions contained 61.5% and 7.8% of the original Pb, respectively, with 37% and 84% of these fractions being PbSO4(2).

Lead sulfate forms in lead storage batteries during the discharge cycle(1), and in the paste mixing process in the manufacture of lead storage batteries(2). Lead sulfate may be released into the environment during its manufacture, use and disposal, and especially in the disposal of lead storage batteries. Organic tetraalkyl lead compounds are emitted from automobiles primarily in the form of lead bromochloride, which is ultimately transformed to lead sulfate(3).

The principal form of lead from along roadsides is the sulfate salt(1). In a calcareous soil, PbSO4 and PbCO3 were shown to account for <5% of the total lead content, whereas in road side dust, PbSO4, elemental lead, Pb3O4, PbO.PbSO4 and 2PbCO3.Pb(OH)2 were present in high quantities(2).

People living in the vicinity of lead sources such as emissions from motor vehicles, mining operations, and smelters may be exposed to lead sulfate in soil; lead compounds may be converted to the sulfate in soil or at the air-soil interface. Limited data on speciation of atmospheric lead particles suggest that exposure to atmospheric lead sulfate will primarily result for people living close to stationary sources, such as smelters. This lead is primarily in airborne particulate matter that settles on plants and in water and may subsequently be ingested(1). Exposure may arise for people in contact with lead storage batteries(2).

The major constituents of sintering and blast furnace operations appear to be PbO.PbSO4 and PbSO4(1). In a study which identified lead compounds in the atmosphere, lead sulfate was listed, along with PbCO3 and 2PbBrCl.NH4Cl, as a major lead species(2). The chemical composition of baghouse effluent from smelting and refining operations contained 5% to ca. 100% PbSO4, and in one case, 70% PbO.PbSO4(3). The mining and smelting industry is geographically localized. The composition of airborne lead particulates in car exhaust was 0.1% PbSO4, which converted to the basic lead sulfate after standing(3).

Lead sulfate occurs in anglesite, one of three lead ores found in sufficient abundance as to form mineable deposits, and in the mineral lanarkite, in which it is combined with PbO. Lead sulfate forms in lead storage batteries during the discharge cycle. Lead sulfate's (or basic lead sulfates) manufacture and use in paints, pigments, and PVC stabilizers will result in its direct release to the environment. Lead sulfate may form naturally from lead and its compounds in the atmosphere and soil. Therefore, any source of lead emissions is a potential source of PbSO4. Speciation studies show that PbSO4 is a major lead compound in soil and air, especially near smelters. If released or deposited on soil, leaching is not expected under environmental conditions, however there is some evidence to...

Symptions of chronic lead poisoning include reduced cognitive abilities, nausea, abdominal pain, irritability, insomnia, metal taste in the mouth, excess lethargy or hyperactivity, chest pain, headache and, in extreme cases, seizures, comas, and death. There are also associated gastrointestinal problems, such as constipation, diarrhea, vomiting, poor appetite, weight loss, which are common in acute poisoning. (A2, L21)

Lead poisoning is usually treated with chelation therapy using DMSA, EDTA, or dimercaprol. (L21)

LD50: 300 mg/kg (Intraperitoneal, Guinea pig) (T57)

Lead is a neurotoxin and has been known to cause brain damage and reduced cognitive capacity, especially in children. Lead exposure can result in nephropathy, as well as blood disorders such as high blood pressure and anemia. Lead also exhibits reproductive toxicity and can results in miscarriages and reduced sperm production. (L21)

ACGIH Carcinogen - Confirmed Animal.

Oral (L136); inhalation (L136); dermal (L136)

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. (...

Chronic Inhalation: 0.05 mg/m3 (L134)

0.007 mg/kg (WHO) /Lead; from table/

2A, probably carcinogenic to humans. (L135)

LD50 Guinea pig ip 300 mg/kg

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Eight-mo-old dogs maintained on a high-fat-low-calcium diet were administered a mixture of lead chloride, lead bromide, and lead sulfate for prolonged periods at 4 different dose levels. Dogs on high levels of leads showed marked wt loss and gastrointestinal symptoms followed by death. Two dogs on low lead levels developed neurological signs. Radiological investigations showed radiopaque particles in 27% of abdominal radiographs and "lead lines" in the distal radius of 3 dogs. Highest tissue lead levels were found in bones followed by liver and kidney, brain and spinal cord.

A3; Confirmed animal carcinogen with unknown relevance to humans. /Lead, elemental, and inorganic compounds, as Pb/ American Conference of Governmental Industrial Hygienists TLVs and BEIs.