Lead Cas No. 7439-92-1

Lead

Cas No. 7439-92-1

Potential sources and exposure

For the general population, exposure to lead (Pb) occurs by eating foods that

contain lead, inhalation of outdoor/household dust, incidental ingestion of soil

and lead paint, and through the consumption of lead in drinking water. Through

atmospheric deposition, lead enters the environment. Lead can be translocated

from the soil into plants. Lead may enter prepared foods when food is prepared

in improper glazed pottery and ceramic dishes. Drinking water from acidic water

supplies may contain lead which enters through the distribution system (lead

pipes, solder, and brass faucets). Household dust may contain lead that is

attributed to the outdoor lead in soil and the weathering of lead-based paints.

Most childhood lead exposures result from inhaling lead paint dust, eating soil or

dust that contains lead, and drinking water containing lead.

Physical and chemical properties

Property

Value

Molecular weight

207.2 g/mol

Toxicity

Toxic effects resulting from chronic lead exposures are well documented and

many have been associated with particular blood-lead levels. Preschool aged

children develop symptoms of lead intoxication at lower blood lead levels than

do adults. Lead is particularly harmful to the developing brain and nervous

system of young children and fetuses (Center for Disease Central (CDC) 1991).

Research has shown that adverse effects of lead on the developing nervous

system occur at blood-lead levels as low as 10-15 ug/dL. The recommended

target level for blood lead in children is 10 ug/dl. Children with a consistent

blood-lead level of 15-19 ug/dL can suffer adverse effects such as mild to

moderate decrease in IQ, increase in hearing thresholds, shortened attention

span, and learning and behavioral difficulties. Children with blood-lead levels

between 20-69 ug/dL are considered "lead poisoned." Depending upon the age

of the child, blood-lead level and duration of exposure may exhibit speech

delays, hyperactivity, regression of recently acquired skills, irritability, and

change in appetite. The gastrointestinal system is one of the earliest to show

symptoms of acute lead intoxication with colic (acute abdominal pain)

considered a consistent early symptom of lead poisoning. Lead encephalopathy

can result from blood-lead levels greater than 100 ug/dL and is characterized by

irritability, loss of memory, and ability to concentrate, delirium, hallucinations,

cerebral edema, and coma (ATSDR 1992).

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Appendix D Toxicological Profiles