TABLE 10-1 Selected Physical and Chemical Data on Elemental Lead

Synonyms and trade names

NA

CAS registry number

7439-92-1

Molecular formula

Pb

Atomic weight

207.2

Boiling point

1,740°C

Melting point

327.4°C

Flash point

NA

Density

11.34 g/cm3 at 20°C

Vapor pressure

1.77 mm Hg at 1000°C

Solubility

Salts have variable solubility in water; elemental lead is soluble in hot or concentrated mineral acids

Abbreviations: NA, not applicable or not available

Source: Data from Budavari et al. 1989.

case of organic forms of lead, dermal absorption (Bolger et al. 1996). Historically, elemental lead has been an important component of solder, brass, bronze, and other alloys. Lead is found in electric-cable insulation, and the oxide is found in some paints, inks, glass, crystal, plastics, textiles, and ceramics. At least half the elemental lead used worldwide is in lead-acid batteries (ATDSR 1999). Lead is present in stainless steel—such as that used in food-handling equipment and surfaces—as an unintentional contaminant at not more than 0.1% by weight (Precision Specialty Metals 2003; Nucor 2007). A variety of occupations are associated with lead exposure, including those involved in lead smelting, battery manufacturing, firing ranges, welding, construction, and demolition. Occupational exposure is often the most significant source of exposure of adults (Shannon 1998).

SUMMARY OF TOXICITY

The toxicology, epidemiology, and clinical presentation of lead intoxication have been reviewed (EPA 1986; ATSDR 1999). Lead is a cumulative poison that is poisonous in all forms, its elimination from the body is slow, and consequences of exposure are varied and can be severe (Gosselin et al. 1984). Generally, only 5-10% of ingested lead is absorbed from the adult human gastrointestinal tract. Lead may dissolve to an appreciable degree in the acid environment of the stomach, greatly increasing its absorption. Absorption of lead from the gastrointestinal tract is facilitated by the same mucosal transport proteins that mediate calcium transport (Fullmer 1992). Smaller lead particles are more readily absorbed from the gastrointestinal tract. In the blood, about 95% of



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