Heavy metal poisoning

Heavy Metal Poisoning

Lead poisoningAbsorption

• Skin:- little/no absorption

• Inhalation (<1µm): - dust or lead fumes - absorb 50-70%

• Oral: - adults absorb 10% - children absorb 40-50%- increased absorption if low Fe, Ca

Lead poisoningSources

Occupational

• Lead smelters• Painter/decorators• Battery manufacturers• Stain-glass workers• Jewellery makers• Bronze workers etc...

Environmental• paint (walls, furniture, toys)• water• food• air (petrol, industry), dust/soil

Other• traditional remedies (Ayruvedic)

• surma & kohl cosmetics• lead shot• lead glazed ceramics• foreign body ingestion

e.g. curtain/fishing weight, snooker chalk

Clinical features of lead poisoning

• Results in variable effects on many systems

• The effects are well established at high levels

• Infants/children get symptoms at lower levels

• Treatable, but can cause chronic sequel

Diagnosis of Lead Poisoning• Blood lead is the best test (normal <100µg/l)

• Other bloods FBC (film)

Management of Lead Poisoning

• IDENTIFY & REMOVE from SOURCE

• Treat coexisting iron (& calcium) deficiency

• Consider the use of chelation therapy

- Good data for benefit with blood lead >450µg/l (children)

Chelating agents for lead poisoning

1. EDTA - Sodium calcium edetate

2. DMSA - Dimercaptosuccinic acid

3. BAL - Dimercaprol - IM for severe toxicity only, particularly encephalopathy

4. Penicillamine - no longer recommended

EDTA and DMSA• EDTA - Sodium Calcium Edetate

IV for severe toxicity, particularly encephalopathy Well tolerated, <1% nephrotoxicity

• DMSA - 2,3dimercaptosuccinic acid

The oral agent of choice for lead poisoning Given as a 19 day course Well tolerated The main problem is foul taste and smell !!

MERCURY

Mercury (Hg)

Speciation (chemical/physical forms) of Hg:

•elemental (Hg0)•inorganic (mercurous, Hg1+ or mercuric, Hg2+)•organic (methyl-, ethyl-, or phenylmercury)

Sources:• Liquid form

medical and environmental measuring devisesdisc batteriesfluorescent light bulbsdental amalgam

• Vapor formburning fossil fuelsmanufacturing, processing, and mining

Pink Disease

AcrodyniaSigns and Symptoms:•Painful hands and feet•Pink (dusky progression) color to hands and feet• Profuse sweating•Profuse salivation•Photophobia

ARSENIC

Arsenic (As)• Chemistry:

• extremely complex because it can exist in metallic form, can be in trivalent and pentavalent state (charge of 3+ or 5+), and can be organic or inorganic

• widely distributed in nature (variety of forms)

• Sources:• smelting of gold, silver, copper, lead and zinc ores• combustion of fossil fuels• agricultural uses as herbicides and fungicides• cigarette smoke• occupational: largest source is manufacture of pesticides and herbicides

• Environmental fate:• found in surface and groundwater through runoff• accumulates in plants if soil conditions are right• bioaccumulates in aquatic ecosystems (so fish consumption is a source)

Sources of As• Eating food, drinking water, or breathing air containing arsenic.

• Herbal medicines (India/Pakistan Ayurvedic” remedies• Breathing contaminated workplace air. • Breathing sawdust or burning smoke from wood treated with arsenic. • Living near uncontrolled hazardous waste sites containing arsenic. • Living in areas with unusually high natural levels of arsenic in rock.

Arsenic Toxicity• organic arsenicals>inorganic

arsenicals>metallic forms• trivalent>pentavalent• acute: severe abdominal pain, fever, cardiac

arrhythmia • chronic: muscle weakness and pain, gross

edema, gastrointestinal disturbances, liver and kidney damage, swelling of peripheral nerves (neuritis), paralysis• liver injury: jaundice• peripheral vascular disease - blackfoot

disease• chronic drinking water exposure in

Taiwan and Chile• cancer (skin, lung. Maybe other organs)

Arsenic Toxicity• skin disease:

• keratosis of palms and soles, and hyperpigmentation

Arsenic detection and treatment

• What would cause you to suspect As toxicity?

• What tests could you do to detect exposure or effects?• Mee's lines: white lines on fingernails

can be used to determine chronology of exposure

• What could you prescribe for treatment?• Gastric lavage, activated charcoal• Hemodialysis• BAL chelation

• WWII

We see things not as they are, but as we are conditioned to see them. What ever they said, what ever they did, we assume it as same as what we thought but not based on empathy~