Dr. Dalia El-ShafeiAss.Prof of Occupational

Medicine

What is Lead?

Lead is a blush gray metallic element which occurs naturally (in small amounts) in the earth’s crust.

It is dense, hence its use as a ballast, ammunition, or radiation shield.

Lead is insoluble in water, but some salts are soluble.

  Lead is a soft, malleable poor metal. It is also countedas one of the heavy metals.It is sometimes found free innature, Although lead makesup only about 0.0013% of the earth's crust, it is not consideredto be a rare element since it is easily mined

and refined.

What Is Plumbun?

Plumbing is derived from plumbun, Latin

for lead

Significant Health Characteristics of Lead

Lead has a low melting point and can easily be aerosolized by heating.Lead can be formed into organic compounds by some organisms, and some organic compounds (such as “leaded gasoline”) have industrial uses.

Lead poisoning is a medical condition caused by increased levels of the heavy metal lead in the body, and this can interfere with a variety of body processes and causes toxicity to many organs and tissues.

It’s also called plumbism, colica Pictonum or saturnism

What is lead poisoning???

"Lead makes the mind give way."

Ancient Awareness

GreekDioscerides - 2nd BC

LEADInlet to the body:

Through inhalation of dust & fumes. Also, ingestion & absorption through the skin (by organic compounds) may occur.

How can the human be exposed to lead??

1 -Occupational exposure:- is the main cause of lead poisoning in

adults, as in lead miners and smelters, plumbers glass manufacturers,

construction workers …etc.

2 -Paints:- is the main cause of lead Poisoning in children. Many of the children display pica, so even a small

amount of a lead-containing product can contain hundreds of milligrams

of lead.

3 -Soil:- is the main cause of lead poisoning in the agricultural areas.

By eating food grown in an contaminated soil.

4 -Water:- Lead from the soil oratmosphere can end up in surface water and groundwater. It is also potentially in drinking water.

5 -Lead containing products -:Like plastic toys, bottles, cans……etc.

6 -Hunting:- Animals which are hunted are at high risk of exposure because of the bullets which may contain lead.

• Breast feeding is also considered as an important route of lead exposure because of the presence of the lead in the affected female milk.

All children under the age of 6 years old. People living in old houses are at great

risk. People work in industries. Pregnant woman & developing baby.

Who is at high risk?

Lead in Jewelry

Lead in Environment

Metabolism:A- Distribution in the body:- Bound to RBCs, membranes.- Precipitate in bone, teeth.- Exist in the plasma.B- Excretion:- Almost via the kidney.- Small amount excreted through bile.- Sweat and milk.

What are the Normal levels of lead??

Adults:Less than 20 micrograms/dL of lead in the blood

Children:Less than 5 micrograms/dL of lead in the blood

Agency Blood Lead Levels

60

40

3025

2015

10

20

10

20

30

40

50

60

Bloo

d Le

ad (u

g/dl

)

CDC1960

CDC1973

CDC1975

CDC1985

WHO1986

EPA1986

CDC1990

CDC2006?

Agency and Year

Acceptable Childhood Blood Lead Levels

Prevention: By the triad of:a) Engineering control measures.b) Good industrial hygiene.c) Regular clinical examination and investigation.Treatment of lead poisoning:a) Identification of source of lead poisoning.b) Removal from exposure.c) Chelation therapy for symptomatic patient with blood lead level more than 100 microgram/ dl.d) Chelation is performed under strict medical supervision by giving the patient injections of calcium ethylene dianine tetra acetic acid (Ca EDTA) and/ or oral penicillamine.

Occupational Exposure Levels

OSHA PEL 0.05 mg/m3, 8-h TWA

NIOSH REL 0.10 mg/m3, 10-h TWA;

ACGIH TLV 0.05 mg/m3, 8-h TWA

Medical Surveillance for Adult Workers

When: Exposure above “action level” >30 days/yr

What: Triggers periodic exams & biologic monitoring (including blood level)

Removal threshold: 50 µg/dl (repeated) or 60 µg/dl once.

Repeat testing: Monthly, depending on lead level

Adult Return to Work Lead poisoned workers can return to the

workplace when blood lead is <40 µg/dl. Symptomatic workers can remain out of

the workplace at lower levels. Workers whose blood lead is near 40 µg/dl

are most likely to be able to remain in the workplace if they can perform modified duty without lead exposure.

The Key to “Treatment”of Lead Poisoning

Remove from exposure, or otherwise preventexposure.

Workplace Home Substitution MoveEngineering Identify and AbatePersonal ProtectionWork PracticesJob Placement

Chelation

Not a decision to be taken lightly Requires close monitoring Inefficient process, typically reducing

body burden only 1 - 2 % Chelating agents may not significantly

reduce tissue levels, esp. in CNS

Adult Chelation Therapy

Indicated for symptomatic Pb toxicity Generally less effective Never a substitute for control of exposure Unethical to give chelation for prophylaxis Indications for chelation depend on

symptoms and BPb (g/dl), not BPb alone

C/P Blood Lead Level (µg/dl)

Chelation

Encephalopathy Any level BAL + EDTA“High dose”

Symptomatic > 100 BAL + EDTA“low dose”

Mild symptoms 70 -100 Succimer

Asymptomatic < 70 Medical removal