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LEAD POISONING. Lead poisoning Absorption. 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 poisoning Storage & Distribution.

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lead poisoning absorption
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 poisoning storage distribution
Lead poisoningStorage & Distribution
  • Rapid turnover soft tissue pool:
    • T1/2 30-40 days; blood, liver, kidney, CNS
  • Slow turnover skeletal pool:
    • T1/2 10-20 years; 75% - 90% in skeletal pool
    • Chronic exposure results in a steady state distribution between bone and blood

Excretion: Renal (90%) and biliary (10%)

    • Maximum excretion is ~ 3.5µg/kg/day
    • If intake > 3.5 µg/kg/day accumulation will occur
lead poisoning sources
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

Lead poisoningSources
environmental lead exposure water
Environmental lead exposureWater
  • Lead in water:
    • Largely from lead pipes/solderings/fittings
    • Water lead contamination from ground lead has occurred in Nepal
    • WHO max water lead content: 10µg/l
      • ~ 20-30% UK homes exceed this limit
environmental lead exposure paint
Environmental lead exposurePaint
  • Pre 1960’s up to 40% lead in paint
    • rapid drying, weather resistance, colouring
  • Domestic paint now <0.06% lead (600ppm)
  • BUT leaded paint remains in many homes
    • walls, furniture, toys
  • Lead exposure from paint:
    • sanding, heat stripping, flaking, pica
    • contamination of carpets/curtains, dust
ayurvedic traditional remedies
Ayurvedic Traditional Remedies
  • Numerous reports of lead, mercury, thallium, arsenic poisoning from Ayurvedic (& Chinese) remedies
  • 40% of the >6000 medicines in Ayurveda contain at least one heavy metal
  • Thought by practitioners to have therapeutic properties and/or to increase the efficacy of other herbal contents
  • Used most commonly for chronic disorders and so there is a greater risk of heavy metal accumulation
ayurvedic traditional remedies1
Ayurvedic Traditional Remedies
  • Case 1: 68 mg/g lead i.e. 6.8 %

76 mg/g mercury i.e. 7.6 %

12 mg/g arsenic i.e. 1.2 %

i.e. 15.5 % heavy metals

  • Case 2: 50 mg/g lead i.e. 5.0 %

39 mg/g mercury i.e. 3.9 %

i.e. 8.9 % heavy metals

clinical features of lead poisoning
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 sequelae
slide10

Blood lead concentration (µg/L)

Children: <400

Adults: <400

400-500

400-600

500-700

600-1000

>700

>1000

GI Tract

Nil

±Abdominal pain

±Constipation

Abdominal pain,

constipation,

weight loss,

loss of appetite

Abdominal colic, vomiting

Blood

Subclinical inhibition of RBC enzymes

Subclinical inhibition of RBC enzymes

Mild anaemia

Severe anaemia

CNS

Effects on IQ in children?

Mild fatigue,

irritability,

slowed motor neurone conduction

Fatigue,

poor concentration

[Peripheral neuropathy]

Encephalopathy

- delirium

- ataxia

- fits

- coma

Other

Nil

Muscle pain

Hypertension,

nephrotoxicity,

lowered Vit D metabolism

Hypertension,

nephrotoxicity,

lowered Vit D metabolism

low level lead poisoning and children s iq
Low level lead poisoning and children’s IQ
  • There have been many studies
    • 5 prospective, 14 cross-sectional
  • The problem is allowing for multiple confounders
  • Three published metanalyses
    • 100µg/l blood lead

  IQ 2.5 points

diagnosis of lead poisoning
Diagnosis of Lead Poisoning
  • Blood lead is the best test (normal <100µg/l)
  • Other bloods
    • FBC (film), U&E, LFT, Ca, Vit D, Ferritin
  • Radiology
    • AXR ?lead in gut
    • Long bone XR in children
  • Other tests much less reliable
    • Urine lead - variable, more useful for organic lead
    • RBC Zn protoporphyrin, Urine coproporphyrin, dALA
management of lead poisoning
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
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 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 !!
treatment guidelines children
Treatment guidelinesChildren

100-240µg/l : Remove from source, repeat level 1 month

250-440µg/l : Remove from source

: DMSA only if persists at this level

450-690µg/l: Remove from source

: DMSA chelation

>700µg/l : Remove from source

: Urgent EDTA chelation

(with BAL if encephalopathy)

treatment guidelines adults
Treatment guidelinesAdults

100-400µg/l: Remove from source (??)

: Repeat level 3-6 mths

400-500µg/l : Remove from source (?)

: Repeat level 1-2 mths

450-690µg/l: Remove from source

: DMSA chelation IF symptomatic

>700µg/l : Remove from source

: DMSA chelation

: EDTA if neurological features