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

1 Rapid turnover soft tissue pool: ­T 1/ days; blood, liver, kidney, CNS 2 Slow turnover skeletal pool: ­T 1/ 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 Storage & Distribution

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 poisoning Sources

Lead in waterLead 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 Water

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 Environmental lead exposure Paint

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

Case 1: 68  g/g lead i.e. 6.8 % 76  g/g mercury i.e. 7.6 % 12  g/g arsenic i.e. 1.2 % i.e % heavy metals Case 2: 50  g/g lead i.e. 5.0 % 39  g/g mercury i.e. 3.9 % i.e. 8.9 % heavy metals Ayurvedic Traditional Remedies

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

Blood lead concentration (µg/L) Children: <400 Adults: < >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 Mild anaemiaSevere 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 NilMuscle pain Hypertension, nephrotoxicity, lowered Vit D metabolism Hypertension, nephrotoxicity, lowered Vit D metabolism

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 –  100 µg/l blood lead   IQ 2.5 points

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,  ALA

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) Management of 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 - 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 µg/l : Remove from source, repeat level 1 month µg/l : Remove from source : DMSA only if persists at this level µg/l : Remove from source : DMSA chelation >700µg/l : Remove from source : Urgent EDTA chelation (with BAL if encephalopathy)

Treatment guidelines Adults µg/l : Remove from source (??) : Repeat level 3-6 mths µg/l : Remove from source (?) : Repeat level 1-2 mths µg/l : Remove from source : DMSA chelation IF symptomatic >700µg/l : Remove from source : DMSA chelation : EDTA if neurological features