Lead Poisoning

THRESHOLD LIMIT VALUE (TLV/TWA): 0.15 MG/M3 ( PPM)
TOXICITY: LD50 (IPR-RAT)(MG/KG) - 630

Children

Approximately 434,000 U.S. children aged 1-5 years have blood lead levels greater than the CDC recommended level of 10 micrograms of lead per deciliter of blood.
Lead poisoning can affect nearly every system in the body. Because lead poisoning often occurs with no obvious symptoms, it frequently goes unrecognized. Lead poisoning can cause learning disabilities, behavioral problems, and, at very high levels, seizures, coma, and even death.
The major source of lead exposure among children is lead-based paint and lead-contaminated dust found in deteriorating buildings.
Lead-based paints were banned for use in housing in 1978. However, many housing units have deteriorated leaded paint and elevated levels of lead-contaminated house dust.These dwellings are homes to one or more young children.
Other sources of lead poisoning are related to:
hobbies (making stained-glass windows)
work (recycling or making automobile batteries)
drinking water (lead pipes, solder, brass fixtures, valves can all leach lead)
home health remedies (arzacon and greta, which are used for upset stomach or indigestion; pay-loo-ah, which is used for rash or fever).

Lead encephalopathy is a life-threatening complication of lead poisoning that can occur in young children who have very high BLLs (blood-lead level) >70--100 µg/dL.
Nonspecific symptoms (e.g., lethargy, sporadic vomiting, and constipation) can occur at BLLs >50--70 µg/dL and may precede the abrupt onset of frank encephalopathy characterized by persistent vomiting, ataxia, altered consciousness, coma, and seizures. Anemia with basophilic stippling also suggest lead poisoning.
However, symptoms or signs cannot be used to reliably diagnose or exclude lead poisoning; a BLL must be measured whenever lead poisoning is suspected.
In young children, BLLs >70 µg/dL or elevated BLLs with symptoms suggesting encephalopathy require prompt inpatient treatment with chelating agents to rapidly reduce BLLs. Providing appropriate intensive care for children with encephalopathy can prevent death, although severe permanent brain damage can occur despite treatment .

Reference :
"Fatal Pediatric Lead Poisoning"
CDC:Centers for Disease Control and Prevention
Atlanta, Georgia.

Adults

There can be a difference in neurologic manifestations or sequelae between an adult exposed to lead as an adult, and an adult exposed as a child when the brain was developing. Childhood neurologic effects, including possibly ADHD, may persist into adulthood. Other than this, many of the neurologic symptoms experienced by children may also be experienced by lead-exposed adults, although the thresholds tend to be higher. Lead encephalopathy may occur at extremely high BLLs, e.g., 460 µg/dL (Kehoe 1961). Precursors of encephalopathy, such as dullness, irritability, poor attention span, muscular tremor, loss of memory, and hallucination, may occur at lower BLLs. Less severe neurologic and behavioral effects have been documented in lead-exposed workers with BLLs ranging from 40 to 120 µg/dL. These effects include malaise; forgetfulness; irritability; lethargy; impaired concentration; depression and mood changes; increased nervousness; headache; fatigue; impotence; decreased libido; dizziness; weakness; and paresthesia; as well as diminished reaction time, visual motor performance, hand dexterity, IQ scores, and cognitive performance (ATSDR 1999). There is also some evidence that lead exposure may affect adults’ postural balance and peripheral nerve function (ATSDR 1997a, 1997b; Arving et al. 1980; Haenninen et al. 1978; Hogstedt et al. 1983; Mantere et al. 1982; Valciukas et al. 1978). Slowed nerve conduction and forearm extensor weakness (wrist drop), as late signs of lead intoxication, are more classic signs in workers chronically exposed to high lead levels.

Reference :
"Case Studies in Environmental Medicine
Lead Toxicity "
ASTD:Agency for Toxic Substances and Disease Registry.