M.D By :Soltanioccupational medicine specialist

MercuryLead

Definitions

‘Metals’ originally included only gold, silver, copper, iron, lead, and tin.

Dense, malleable, lustrousConduct heat and electricity, cations

Many other elements since added to the list with some of these characteristics

‘Metalloids’ are elements with features intermediate between metals and non-metals. Example: arsenic

Periodic Table

‘Heavy metal’

A metal having an atomic weight greater than sodium, a density greater than 5 g/cm3

Some notion of toxicity Usually includes lead, cadmium and

mercury Many others may variably be added to list

Acute single exposures

bloodurine

time

Metal levels

exposure

Case Presentation

15-month old boy was treated with ampicillin for abdominal pain and diarrhea. The problem continued and the parent gave the child multiple doses of a Central American “home remedy” called azarcon. The child developed seizures. PE BP 103/68, P 94, RR 22, Tmax 98 F. Exam: listless, with poor motor tone. No neck stiffness, the heart, lungs and abdomen were unremarkable. Sz re-occurred. WBC 9.6 no anemia, Plts Nl, Lytes nl, UA nl Spinal tap was nl, with elevated opening pressure, cerebral edema was found on Cat Scan of the Head.

Case (cont)

The child was intubated, given lorazepam, fosphenatoin and phenobarbital without control of the Sz. An x-ray reveled a radiopaque image in the GI tract.

The child expired, despite aggressive supportive care.

What is azarcon?

Azarcon

Azarcon is a folk remedy that contains 85-96% lead tetroxide

Other lead containing remedies include Greta.

Case (cont.)

The child was found to have a blood lead level of 124 ug/dl., and died from lead encephalopathy.

Lead

Background:

The earliest toxicities

Lead have no function in human body

Soft , Malleable , Blue –gray , High density , Corrosion resistance

Some Sources of Lead Exposure

Battery manufacturing Chemical industry Construction workers

Welders Plastics industry

Jewelers Gasoline additives production Lead miners

Pigment manufacturing Pipe fitters

Pottery workers

Radiator repair Rubber industry products

Soldering of lead Solid waste production Printers

Occupational exposure

Casting bullets or fishing sinkers

Home remodeling Target shooting at firing ranges

Stained glass making

Lead soldering

Auto repair

Glazed pottery making

Hobbie

s

Some folk remedies Some "Health Foods"

Substance Use

Moonshine whiskey Ceramic ware

ToxicologyAbsorption

Respiratory (30 to 40 % ): dependent on: particle size

Solubility

respiratory volume

physiologic interindividual variation

Gastrointestinal systems: (10 to 15% ) adults < children

Skin : Inorganic lead is not absorbed Organic lead is well absorbed

Lead is carried bound to the RBC

Increased Absorption: deficient in calcium, iron, phosphorus or Zinc

Distribution : absorbed in bloodstream (ingestion or inhalation)

highest concentrations: in bone, teeth, liver, lungs, kidneys, brain and spleen .

Lead half-life: in blood 35 days

in soft tissue 40 days in bone 20 to 30 years

renal gastrointestinal

Excretion

sweatnails

excreted quite slowly from the body biologic half-life estimated at 10 years

accumulation in the body occurs easily

OSHA Lead Standards for Air and Blood

PEL: 50 µg per m3

Action level:

Medical removal from exposure: =>60 µg per dL

average of last three levels >=50 µg /dL

30 µg per m3

Neurological Effects

Health effects of lead

Gastrointestinal Effects

Heme Synthesis

Renal Effects Reproductive Effects

Other

Clinical Effects In Adults

Acute Inorganic Lead Toxicity Excessive exposure in brief period Acute lead poisoning syndrome .

Classic clinical findings : Abdominal colic Constipation

Fatigue CNS dysfunction

Acute encephalopathy Coma

Convulsions

In milder exposures : headaches personality changes

Chronic Inorganic Lead Toxicity Symptoms: Arthralgias

Headache

Weakness

Depression

Loss of libido

Impotence

Vague gastrointestinal difficulties

Late effects : Chronic renal failure

Hypertension

Gout

Chronic encephalopathy

Blood lead levels

AdultsChildren

10 g/dLHypertension may occur•Crosses placenta•Impairment IQ, growth•Partial inhibition of heme synthesis

20 g/dLInhibition of heme synthesisIncreased erythrocyte protoporphyrin

Beginning impairment of nerve conduction velocity

30 g/dL•Systolic hypertension•Impaired hearing()

Impaired vitamin D metabolism

40 g/dL•Infertility in males•Renal effects•Neuropathy•Fatigue, headache, abd pain

Hemoglobin synthesis inhibition

50 g/dLAnemia, GI sx, headache, tremor

Colicky abd pain, neuropathy

100 g/dLLethargy, seizures, encephalopathy

Encephalopathy, anemia, nephropathy, seizures

Range of Lead-induced Health Effects in Adults and Children

Childhood Lead Poisoning

Childhood lead poisoning is now defined as a blood lead level of 10 g/dl

Medical Examination of Lead-Exposed Workers

Medical and occupational history Attention to lead exposure history (occupational

and nooccupational) Personal and workplace hygiene

History of(GI, hematologic, renal, reproductive and neurologic) disorders

Blood pressure measurement

Physical examination

Attention to neurologic and hematologic abnormalities pulmonary evaluated

Blood testing Blood lead level

Zinc protoporphyrin or free erythrocyte protoporphyrin level Hemoglobin, hematocrit and peripheral smear

U/A with microscopic examination Supplementary laboratory tests as deemed clinically indicated

What Lead Levels are Considered Elevated in Adults?

B.L>80 μg/dL, serious, permanent health damage.

50 - 80 μg/dL, serious health damage.

30 - 50 μg/dL, health damage, even if no symptoms.

20-30 μg/dL, regular exposure. some evidence of potential physiologic problems .

1-20 μg/dL, lead is building up in the body.

Primary Prevention of Lead Poisoning

Engineering controls Personal protective equipment

Work practices Housekeeping activities to remove lead dust Personal hygiene practices Periodic inspection

Secondary prevention

All health care providers should be aware of (OSHA) Lead Standard.

If lead exposure is suspected, the patient's medical evaluation should include:An occupational and environmental history.Laboratory testing for blood lead and ZPP levels If elevated Ph/E includes:

1(lab testing : Hb,Hct, RBC indices, PBS, BUN,Cr,U/A ,pregnancy or male fertility

BLL>25 μg/dL shows :substantial exposure to lead increasing health effects

Tertiary prevention

Possible treatment :

Removal

Drug

Drug

DMSA:30 mg/kg/d for 5 day

20mg/kg/d for 20 day EDTA:25 mg/kg/d for 5 day BAL:25mg/kg/d for 6 dose deep IM D-penicillanin: BLL>45

CadmiumCadmium

What is Cadmium?

A metal most often encountered in earth’s crust combined with chlorine (cadmium chloride), oxygen (cadmium oxide), or sulfur (cadmium sulfide)

Exists as small particles in air, result of smelting, soldering or other high temp. industrial processes

By-product of smelting of zinc, lead, copper ores Used mainly in metal plating, producing

pigments, batteries, plastics and as a

neutron absorbent in nuclear reactors

Cadmium is used in batteries

Cadmium and Smelters/Mine

Sites Cadmium is a by-product of smelters Has been a concern at the Summitville

mine site in Colorado

Photo of Smelter

Exposure Sources - Tobacco

Tobacco smoke (a one pack a day smoker absorbs roughly 5 to 10 times the amount absorbed from the average daily diet)

Tobacco smoke is an important

source of cadmium exposure

Exposure Sources – By Mouth

Foods (only a small amount is absorbed) Itai Itai disease (cadmium contamination + diet low in

calcium & vitamin D) Cadmium a component of chuifong tokwan, sold illegally

as a miracle herb

Low levels are found in grains, cereals, leafy vegetables, and other basic foodstuffs

Biologic Fate Cadmium has no known beneficial function in

the human body Is transported in the blood bound to

metallothionein Greatest concentrations found in kidneys & liver Urinary excretion is slow Biologic half-life may be up to 30 yrs.

Why Is Cadmium a Health Hazard?

Affects lungs & kidneys 2o effects on skeletal system Binds to sulfhydryl groups, displacing other metals from

metalloenzymes, disrupting those enzymes Competes with calcium for binding sites on regulatory

proteins Lipid peroxidation has been demonstrated

Respiratory Effects

Acute inhalation may mimic metal fume fever Fever, chills & decreases in FVC and FEV1

Initial symptoms: flu-like symptoms Later: chest pain, cough, dyspnea Bronchospasm and hemoptysis may occur

Chronic inhalation MAY result in impairment of pulmonary function with reduction in ventilatory capacity

Renal Effects May cause tubular and glomerular

damage with resultant proteinuria May follow chronic inhalation or ingestion Latency period of ~10 yrs Nephropathy is progressive & irreversible

Skeletal Effects Bone lesions occur late in severe chronic

poisoningPseudofracturesOther effects of osteomalacia and

osteoporosisAppear to be secondary to increased urinary

calcium and phosphorus losses

Signs and Symptoms - Acute Food poisoning (ingestion) Bronchitis (inhalation) Interstitial pneumonitis (inhalation) Pulmonary edema (inhalation) A condition that mimics metal fume fever

Children who eat dirt (pica

behavior) are at risk

Evaluation Inhalation

Chest radiograph Chronic exposure

Renal tests Serum electrolytes, BUN, serum and urinary

creatinine, serum creatinine, cadmium in blood & urine, urinary protein

Other tests – CBC & LFTs

Direct Biologic Indicators

24 hour urine cadmium – reflects exposure over time an total body burden

Blood cadmium Cadmium in hair – not reliable

No quantitative relationship between hair cadmium levels and body burden

Indirect Biologic Indicators

Urinary ß2-microglobulin – evaluate urine

levels > 300 g/g creatinine Urinary RBP Urinary metallothionein (MT)

Treatment & Management

Acute Exposure No proven treatment

Supportive treatment includes fluid replacement, oxygen, mechanical ventilation. With ingestion, gastric decontamination by emesis or gastric lavage soon after exposure. Activated charcoal not proven effective

Chronic – Prevent further exposure

Mercury

Mercury

Occurs in three forms (elemental, inorganic salts, and organic compounds)

Contamination results from mining, smelting, and industrial discharges. Mercury in water can be converted by bacteria to organic mercury (more toxic) in fish.

Can also be found in thermometers, dental amalgams, fluorescent light bulbs, disc batteries, electrical switches, folk remedies, chemistry sets and vaccines.

Mercury - Exposure Elemental

liquid at room temperature that volatizes readily rapid distribution in body by vapor, poor in GI tract

Inorganic poorly absorbed in GI tract, but can be caustic dermal exposure has resulted in toxicity

Organic lipid soluble and well absorbed via GI, lungs and skin can cross placenta and into breast milk

Elemental Mercury At high concentrations, vapor inhalation

produces acute necrotizing bronchitis, pneumonitis, and death.

Long term exposure affects CNS. Early: insomnia, forgetfulness, anorexia,

mild tremor Late: progressive tremor and erethism (red

palms, emotional lability, and memory impairment)

Salivation, excessive sweating, renal toxicity (proteinuria, or nephrotic syndrome)

Dental amalgams do not pose a health risk.

Inorganic Mercury

Gastrointestinal ulceration or perforation and hemorrhage are rapidly produced, followed by circulatory collapse.

Breakdown of mucosal barriers leads to increased absorption and distribution to kidneys (proximal tubular necrosis and anuria).

Acrodynia (Pink disease) usually from dermal exposuremaculopapular rash, swollen and

painful extremities, peripheral neuropathy, hypertension, and renal tubular dysfunction.

Organic Mercury

Toxicity occurs with long term exposure and effects the CNS. Signs progress from paresthesias to ataxia,

followed by generalized weakness, visual and hearing impairment, tremor and muscle spasticity, and then coma and death.

Teratogen with large chronic exposure Asymptomatic mothers with severely affected

infants Infants appeared normal at birth, but

psychomotor retardation, blindness, deafness, and seizures developed over time.

Diagnosis and Treatment

Dx made by history and physical and lab analysis. Inorganic mercury can be measured in 24 hour urine collection; organic mercury is measured in whole blood.

The most important and effective treatment is to identify the source and end the exposure

Chelating agents (DMSA) may enhance inorganic mercury elimination. Dimercaprol may increase mercury concentration in the brain.

Mercury - Prevention

Many mercury compounds are no longer sold in the United States.

Elemental mercury spills: Roll onto a sheet of paper and place in

airtight container Use of a vacuum cleaner should be avoided

because it causes mercury to vaporize (unless it is a Hg Vac)

Consultation with environmental cleaning company is advised with large spills.

State advisories on public limit or avoid consumption of certain fish from specific bodies of water.

Questions?