II CHEMICAL EXPOSURE

• A.- Solids e.g.: dust, fumes, smoke, smog.

• B.- Liquids and vapors including mists and fogs.

• C.- Gases.

• Dusts are particular matter in a state of minute division arising from processes like grinding, crushing, blasting and drilling.

• Dusts are classified according to their physical nature or according to their effect on the body.

Organic dusts Plant origin such as ….. Animal origin………

Inorganic dusts such as……..

Lead Poisoning

• Sources:

• Battery industry.• Plumbing • Pipe sheets• Paints• Printing• Petroleum industry as tetraethyl lead (TEL) or

organic Lead.

Routes of absorption

• 1.- Through the lung: Lead fumes and dust can be absorbed nearly completely if inhaled through respiratory tract.

• 2.- Through digestive tract: Only 10% reaches the blood and tissues via this route. The rest are excreted through feces and some are absorbed through portal circulation to the liver to be excreted again with bile into the gastro-intestinal tract.

• 3.- Through skin: Organic lead can penetrate the

unbroken and normal skin rapidly to enter the body

Clinical symptoms & signs

• Gastro-intestinal tract:• Loss of appetite particularly in the morning• Metallic taste in the mouth.• Constipation is the rule, particularly before

attacks of colic.• Lead line: Occurs in the gums and buccal

mucosa and consists of minute particles of lead sulfide due to union between lead in blood and hydrogen sulfide formed by fermentation of food in the teeth pockets.

2:Lead colic:It occurs in approximately 80% of

cases and it may be severe to stimulate acute appendicitis. A very important point in differential diagnosis is that relief is often obtained by making firm pressure upon the abdomen..

• Pulse rate drops to 40 –50 per minute. Pulse is small and hard.

• Temperature usually subnormal but during the paroxysm blood pressure is usually elevated

• Neuromuscular SystemThere is tendency towards localization of lead palsy in overused and fatigued muscles and that the distribution of paralysis is related to functional groupings of muscles rather than to their nerve supply.

Usually the conditions start by a sensation of heaviness in the limbs especially in the morning then proceed to weakness of the affect muscles, which become fatigued readily and prematurely.

The paralysis usually begins in the extensor muscles of the fingers, at first in the right hand of the right-handed persons.

The condition is almost always bilateral although it may begin at first on one side and appear on the other side after a few days or weeks. Paralysis of hand and foot muscles may result in wrist drop and foot drop, however, this is rare nowadays.

Joints : arthralgia Genital System :Abortion in pregnant

females. Legislation forbidden the employment of women in occupations involving a lead hazard.

• Urinary System: Protienuria, coproporhynuria and chronic nephritis (lead nephritis) specially among young exposed persons.

• CirculatorySystem: Moderate hypertension.

• Hypochromic anaemia reduction in both HB% and RBCs, size.

• Punctate basophilia:Blue dots are found in the RBCs under Dark Ground illumination. A count of 10,000 or more per million RBCs in any worker is a suggestive evidence to suspend him temporarily from exposure to lead

Investigations

– Blood• a) hypochromic anaemia• b) stipped cells: more than 10,000

per million R.B.Cs.• c) lead in blood: more than 80

µg/100

• Urine

• a) Coproporphyrine in urine

• b) Al A (Amino levolenic acid)

More accurate and specific than coproporphyrine.

Management

• 1- Acute poisoning• Calcium gluconate 10 cc. 10% I.V.

repeated every 2 hrs until colic is relieved.

• Nitrites sublingually for colic.• Antispasmodics• Restoratives:- Iron compounds for

anemia

• Calcium• Thyroid extract• Vit B complex & B12.• Purgative enema for constipation

• 2- Chronic stage• The aim is to remove lead from

skeleton to blood in non-ionized form by giving chelating agent.

• a) Parenteral• Disodium calcium salts of Ethylene

Diamine tetra acetic acid (EDTA) • b) Oral route

Mozatil or penicillamine