Transcript Heavy metal-Lead

Lead
Poisoning
P. K. was 7 years old in July 2005 when she was playing with
her new Polly Pocket toy, whose plastic clothes attached
to the doll with magnets.
The girl placed two of them between her lips so that her
hands would be free to affix the rest of the clothes, said
her mother.
A few days later, the girl complained of abdominal pain, but
her mother attributed it to the flu.
"When she started puking green, that's when I knew
something wasn't right," she said.
She was taken to a hospital, where a scan revealed that two
magnets -- each about the size of a watch battery -- had
lodged in her small bowel.
Surgery discovered the magnets had attached to each other,
separated only by a thin piece of tissue which caused two
holes in her intestines.
With the seepage into her body, came a massive infection.
"If I had waited a few more days, she would have died," May
said doctors had told her.
It required two weeks of hospitalization for treatment of her
infection and return trips to the doctor every few weeks for
months thereafter.
In all, the treatment cost about $40,000.
Toys are a source of danger!!!
Fisher-Price Recalls Licensed Character Toys Due
To Lead Poisoning Hazard
Hazard: Surface paints on the toys could contain
excessive levels of lead.
Manufactured in: China
What is Lead?!!
A soft, malleable metal that is chiefly obtained by the primary
smelting and refining of natural ores, or by the widespread
practice of recycling and secondary smelting of scrap lead
products.
One of the oldest chemical toxins. Lead fumes and sulphur
dioxide were probably amongst the first workplace health
and safety issues.
Reports of lead poisoning date to ancient Greece and high
levels of lead have been found in ancient Egyptian
mummies.
Artisans of lead-glazed pottery and stained glass were
particularly susceptible to poisoning until the advent of
improved workplace practices.
In the past, artists and craftsmen routinely wetted brushes
with their mouths, and as a result, accidentally ingested leadcontaining pigments from their tools and hands.
There are reports that lead poisoning may have contributed
to van Gogh's illness and madness and Nero probably went
mad from drinking excessive amounts of wine from pewter
vases.
How lead enters the body
Ingestion of lead compounds trapped in the upper
respiratory tract or introduced into the mouth on fingers,
food, tobacco, or other objects.
Large amount of lead is necessary to cause toxic
effects by this route and a long period of exposure is
usually necessary to produce symptoms.
Significant quantities of lead can be ingested from
stagnant water in pipes or water coolers with lead
solder.
Cases of paint ingestion have increased markedly.
Children are apparently attracted to the paint because of
the sweet taste of lead acetate found in these paints.
Inhalation of dust, fumes, mists or vapours.
In industry (e.g., smelting, battery production etc.),
inhalation is more common than ingestion.
Through the skin.
Most common in the case of organic compounds of lead
such as tetraethyl lead but it is not important for inorganic
forms of lead.
Symptoms of Toxicity
Abdominal discomfort , pain, loss of appetite, anaemia,
malaise and irritability.
Low levels of lead impair neurotransmission, the immune
system functions, and may increase systolic blood
pressure.
Muscle and joint pains/weakness and tremors.
Headache, dizziness and insomnia are frequently prominent.
Gastritis and liver changes are also usually present.
Lead encephalopathy (lead poisoning of the brain) is the
most severe but the rarest manifestation of lead poisoning.
Mechanism of Toxicity
Lead perturbs multiple enzyme systems. As in most heavy
metals, any ligand with sulfhydryl groups is vulnerable.
Perhaps the best-known effect is that on the production of
heme.
Lead interferes with the critical phases of the dehydration
of aminolevulinic acid and the incorporation of iron into the
protoporphyrin molecule; the result is a decrease in heme
production.
Because heme is essential for cellular oxidation, deficiencies
have far-reaching effects.
The effects of lead poisoning on the brain are manifold
and include delayed or reversed development,
permanent learning disabilities, seizures, coma, and
even death.
Lead is renally excreted, but the elimination rate varies,
depending on the tissue that absorbed the lead.
How and why are children at
risk?
Your children, particularly those under the age of four, often
play on the floor, and tend to put their hands in their
mouths. Children also tend to absorb lead more easily
than adults do because their metabolism is faster.
Lead affects the child's developing nervous system by
slowing development.
Children are particularly vulnerable up the age of six. The
effects include hearing impairment, behavioral problems
and a lessening of intelligence.
The signs of lead poisoning are difficult to distinguish
from normal childhood complaints and sometimes,
children show no symptoms at all.
When they do, the symptoms tend to be flu-like:
stomach cramps, irritability, loss of appetite and general
fatigue.
Because these symptoms are so general, it's best not to
rely on them as indicators of exposure.
Who else may be at risk?
Lead is also harmful to adults. They can suffer
from:
Difficulties during pregnancy.
Other reproductive problems (in both men and women)
High blood pressure , Kidney problems
Digestive problems
Nerve disorders
Memory and concentration problems
Muscle and joint pain
The minimum level of concern, according to the Centers for
Disease Control (CDC) in the US, is 10 micrograms per
deciliter of blood, expressed as 10ug/dL.
Drug Name
Dimercaprol (British antilewisite; BAL)
Description
The first chelator used in encephalopathic individuals.
Rapidly crosses the blood-brain barrier.
Is more effective at preventing lead from forming a ligand binding than
reversing it.
Usually used in combination with calcium disodium edetate.
Adverse effects are fever, pain at the injection site, nausea, vomiting,
headache, and sterile abscess formation.
In very severely poisoned patients, the dose is increased to 7 mg/kg
with great caution.
Adult Dose
3-5 mg/kg IM q4h
Pediatric Dose
Administer as in adults
Contraindications Documented hypersensitivity
Interactions
May form toxic complexes with iron, cadmium, and selenium; may
interfere with thyroid iodine accumulation
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not
studied in humans; may use if benefits outweigh risk to fetus
Precautions
Avoid concurrent iron therapy
Drug Name
Calcium EDTA (Calcium disodium edetate)
Description
Nearly the perfect chelator. Is water-soluble and can be used either
IV or IM.
Allows lead to be renally eliminated, is not metabolized, and has few
toxic effects.
When IM, the same daily dose is used, divided into 2-6 doses. Is
extremely irritating to muscle and intensely painful.
Lidocaine or procaine with the IM preparation lessens the pain.
Adult Dose
50-75 mg/kg/d IM/IV
Pediatric Dose
Administer as in adults
Contraindications Documented hypersensitivity
Interactions
IV incompatibility with amphotericin-B, D10W, and hydralazine
Pregnancy
B
Precautions
May cause hypertension, headache, eosinophilia, and fever; there is
controversy regarding possible mobilization of lead from bony
storage sites into the brain in the first 24 h; consider pretreating with
BAL; adequately hydrate
Since Pb may cause impairment of fluid balance and SIADH, it might
be prudent to avoid hypotonic fluids. Thus, the authors suggest using
normal saline to mix the IV CaNa2EDTA solution and carefully
monitoring fluid intake and output as well as serum electrolytes.
Drug Name
D-Penicillamine
Description
Hydrolysis product of penicillin approved for the treatment of Wilson
disease and cystinosis. Used as oral chelator of lead for 30 years but
has never been licensed for such by the FDA. Effective orally and has
few adverse effects.
Adult Dose
25-35 mg/kg PO divided
Pediatric Dose
Administer as in adults
Contraindication
s
Documented hypersensitivity
Interactions
None reported
Pregnancy
Precautions
C - May use if benefits outweigh risk to fetus
May cause GI irritation, Stevens-Johnson syndrome, nephrotic
syndrome, and neutropenia
Drug Name
Succimer (DMSA)
Description
In January 1991, became the only drug approved by the FDA
specifically for lead chelation in children and the only drug approved to
treat a specific laboratory test, a lead level higher than 45 mcg/dL.
Has been shown to be an effective oral chelator that produces
plumburesis, approaching that of the combination of CaNa2EDTA and
BAL. Not currently licensed for use in adults. Although experience
suggests that it is safe and effective, its use must be considered
carefully. Adults exposed from an occupational source must be
carefully excluded from further exposure.
Adult Dose
10 mg/kg PO q8h, days 1-5; 10 mg/kg PO q12h days 6-14
Pediatric Dose
Administer as in adults; has very low bioavailability and is very difficult
to administer; does not dissolve in water or juice; should be given on
empty stomach and can be dumped onto surface of applesauce in
teaspoon and immediately administered
Contraindication
Documented hypersensitivity
s
Interactions
None reported
Pregnancy
C
Precautions
May cause mild reversible liver enzyme elevations and rash
Drug Name
Dimerval (DMPS)
Description
Has received much attention worldwide but is not yet available in the
US except under special FDA IND permits. Has become DOC for most
heavy metal intoxications in Europe and Asia. Available in the oral
form and in a water-based parenteral form.
Adult Dose
No accepted dose established
Parenteral form comes as injectable form; one ampule contains 250
mg of active drug
Limited data suggest use of 250 mg q4h for 7 d, changing to 100 mg
oral capsules q6h until levels drop, then shifting to q12h, and then
weaning
Pediatric Dose
Administer as in adults
Contraindicatio
ns
Documented hypersensitivity
Interactions
None reported
Pregnancy
C
Precautions
Occasional shivering, fever, and skin rash are generally felt to be
reversible
Patient Education
All patients must be educated in lead avoidance. The
termination of exposure to lead is imperative.
A good substantial diet is important; lead absorption is
increased when a diet rich in fats is consumed. Also,
diets low in iron, calcium, and vitamin C increase the
likelihood of lead absorption and resultant lead
poisoning.
Dietary fiber helps promote good peristalsis and decreases
the opportunity for lead absorption; thus, at least 15 g of
dietary fiber are suggested for children each day.