Heavy Metal Poisoning

 

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Definition/Description

Heavy metal toxicity is a generic term for an above average level of metal in the blood which may result in undesirable side-effects.[1]  Many heavy metals are necessary for life, but may become toxic in large amounts. Authors argue what constitues a "heavy metal," but it's commonly referred to as any metal which could potentially cause human or environmental harm. 

List of Heavy Metals [2]

  • antimony
  • arsenic
  • bismuth
  • cadmium
  • cerium
  • chromium
  • cobalt
  • copper
  • callium
  • gold
  • iron
  • lead
  • manganese
  • mercury
  • nickel
  • platinum
  • silver
  • tellurium
  • thallium
  • tin
  • uranium
  • vanadium
  • zinc

Common heavy metal toxicities humans are exposed to are lead, arsenic, mercury, aluminum, iron and cadmium.

Lead Toxicity

Common sources of lead which may be harmful to humans are lead based paints, soldered around the rims of food cans (more common outside of the United States), plumbing, older bath tubs, and imported dishware.[1]  Though it is generally safe to use older bath tubs and imported dishware, scratching and chipping can extract the lead from these products.  Imported dishware may also have lead extracted through repeated microwave or dishwasher use, as well as frequent juices which are highly acidic.[1]  Lead particles may also travel through the air during older house renovation projects

Pure Lead

Precautions with young infants and children

Young children should be especially careful around lead based products as the minimal level to declare lead toxicity (10mg/dl) is smaller than that for adults(24mg/dl).[1]  Since the blood-brain barrier is unformed in infants, lead readily diffuses across.

Children and infants are commonly exposed to lead particles during floor activities, and through the hand-to-mouth stages of development.[1]  Risk factors which may predispose children to lead toxicity are (1) under age 6 (2) low income and (3)urban dwelling.

Adults and lead exposure

Adults are more likely to be exposed to lead during the renovation of old houses, manufacturing of brass, bullets, solder, stained-glass/ pottery designs, and frequent use of metallic wick candles. [1][2]

Arsenic Toxicity

Arsenic exposure may come from glass infiltrates, pesticides, wood preservatives, paints and during the process of smelting copper zinc, and lead.[1][2] 


Arsenic.jpg

Mercury Toxicity

Mercury exposure can be in the forms of inhalion, ingestion, or topically through the skin.[1]  Common sources of mercury are fish (the number one cause of toxicity), emissions from coal burning plants, medical waste and from mines.[2]  Another common source of mercury is through the food chain; one animal is exposed and passes it to the top of the food chain through ingestion. [1]

Mercury.jpg

Prevalence

Lead Prevalence

The prevalence of lead toxicity has been rated as high as 5.6% in a clinical study of 1 to 3 year olds.


Prevalence rates of mercury and arsenic were unable to be found.

Characteristics/Clinical Presentation

Characteristics of heavy metal poisoning are vague as patients will present depending on the route and level of exposure.  For instance, smaller levels of heavy metal exposure can cause minor irritations such as skin rashes and warts (arsenic), whereas large amounts may cause sudden death.[3]


Common signs and symptoms of heavy metal toxicity:[4]
  • Coated tongue
  • extreme fatigue
  • frequent colds and flus
  • insomnia
  • memory loss
  • metallic taste in mouth
  • muscle and joint pain
  • muscle twitching
  • night sweats
  • mood swings
  • sensitive teeth/gums
  • sensitivity to smells
  • skin irritations
  • hyperesthesias
  • neurological changes
    • Signs and symptoms are not limited to this list but these are commonly found among different heavy metals

Associated Co-morbidities

The following co-morbidities are not found with all types of heavy metal toxicity but are common:[4]

  • Attention Deficit Disorder
  • Alzheimer's disease
  • Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease)
  • Asthma
  • Arthritis
  • Autism Spectrum disorders
  • Auto-immune disorders
  • Candidiasis (Yeast Infection)
  • Chronic Fatigue Syndrome
  • Epilepsy
  • Fibromyalgia
  • Gulf War Syndrome
  • Hypertension
  • Insomnia
  • Infertility
  • Kidney disease
  • Liver disease
  • Multiple Sclerosis
  • Parkinson's Disease
  • Schizophrenia
  • Thyroid Disorders

Medications

Chelation therapy is commonly used to treat heavy metal poisoning.[5]  Chelating agents are introduced to the body orally, intravenously, transdermally, transdermally or by suppository.[4]  After binding to heavy metals, they are excreted from the body through urine.

Common Chelation Therapy Agents [4]
  • EDTA
  • DMPS
  • DMSA
Penicillamine (Brand names; Cuprimine, Depen)

This medication is generally used for Wilson's disease (excess copper in the body), rheumatoid arthritis, and kidney stone prevention, but can also be used to treat heavy metal toxicity.[6]

Diagnostic Tests/Lab Tests/Lab Values [4]

The most accurate test for heavy metal poisoning is a chelation challenge test.  This test involves a urinalysis over a 24 hour period after chelating agents are administered.  The chelation challenge test can identify which heavy metals are present.

A hair tissue mineral analysis (HTMA) may also be used to detect heavy metals.  The HMTA scans tissues of the body which can identify heavy metal and mineral levels up to 2 to 3 months prior.

Other common tests:

  • Complete Blood Count*
  • Urinalysis*
  • Hair analysis
  • The accuracy of these test isn't as reliable as the chelation challenge test or HTMA because they take a snapshot in time of what is in the body.

Systemic Involvement

Systemic involvement varies between heavy metals.

Lead systemic involvement [7]

Acute lead toxicity can cause gastrointestinal problems such as nausea, vomiting, loss of appetite, stomach cramps, and constipation.  It can also cause sleeping problems, fatigue, mood changes, headache, joint/muscle aches, anemia, and a decreased sexual drive.

Long term problems with lead exposure include nervous system, genitourinary system, and blood-forming system problems.  Chronic exposure to lead can lead to death. 

Arsenic systemic Involvement [3]

Long term effects of arsenic exposure include gross pigmentation with hyperkeratinization, wart formation, dermatitis, vasospasticity, Raynaud's phenomenon, decreased nerve conduction velocity, lung cancer, conjunctivitis, peripheral neuropathies, encephalopathy, laryngitis, bronchitis, rhinitis, and death.

 

Mercury systemic Involvement [8]

Short-term effects of mercury toxicity include lung damage, nausea, vomiting, diarrhea, hypertension, tachycardia, skin rashes, and eye irritation.  With chronic exposure to mercury, the nervous system is susceptible to damage.  Brain and kidney damage is common with high levels of mercury exposure.  Other common systemic side-effects are irritability, shyness, tremors, vision and hearing problems, and memory deficits. 

Physical Therapy Management (current best evidence)

Physical therapy has minimal effect on depleting heavy metals from the body.  There is no current "best evidence" for the treatment of patients with heavy metal toxicity. Physical therapy is aimed towards management of side effects and associated co-morbidities of heavy metal toxicity.


Since heavy metal toxicity includes many different types of toxicity, it may be important to ask patients questions such as

  1. Have you worked with any hazardous materials lately? Follow up question: How long were you exposed to these materials?
  2. Where do you work? Are there any chemicals or metals which are regulated for saftey reasons at work?
  3. How old is the house/apartment you live in? (older construction methods/ materials may contain metals which are currently regulated)
  4. Is your living situation located near any factories, power plants, construction sites? Have you been near any of these lately?
  5. Have you had any changes in diet involving and increased amount of a certain type of food?
  6. Is there anything you've been exposed to which is out of the ordinary in the past 6 months?


Management strategies for patients with heavy metal toxicity may include:

  • Cardiovascular re-conditioning
  • Desensitization for hyperesthesias
  • Range of motion deficits
  • Strengthening
  • Neuromuscular re-education
  • Balance and coordination
  • Chronic pain management



Case Reports/ Case Studies

Doleys DM, Crocker M, Patton D. Response of Patients with Chronic Pain to Exercise Quotas. PTJ 1982; 62: (8) 1111-1114

Electronic version: http://ptjournal.apta.org/content/62/8/1111.abstract?sid=3bf6b68e-2873-422f-9c24-892fc7342106


Protas EJ, Stanley RK, Jankovic J, MacNeill B.  Cardiovascular and metabolic responses to upper- and lower-extremity exercise in men with idiopathic parkinson's disease.  PTJ. 1996; 76 (1) 34-40
Electronic Version: http://ptjournal.apta.org/content/76/1/34.abstract?sid=a641eb6d-6460-4ee0-a2dc-e7b7154ef80d


Finlayson M, Plow M, Cho C.  Use of physical therapy services among middle-aged and older adults with multiple sclerosis. PTJ. 2010; (90) 1607-1618

Electronic Version: http://ptjournal.apta.org/content/90/11/1607.abstract?sid=16b0a2fd-9c6e-40b3-9a34-0cb203ca7731





add links to case studies here (case studies should be added on new pages using the case study template)

Resources for patients

Detoxification information:

http://www.evenbetterhealth.com/heavy-metal-poisoning.php

Toxicologic profile for Arsenic:

http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=22&tid=3#bookmark07

Toxicologic profile for Lead:

http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=22

Toxicologic profile for Mercury:

http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=24 

Recent Related Research (from Pubmed)

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References

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  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Goodman CC, Fuller KS. Pathology clinical implications for the physical therapist. 3rd ed. St. Louis: Saunders Elsevier, 2009
  2. 2.0 2.1 2.2 2.3 Life Extension. Heavy Metal Toxicity. http://www.lef.org/protocols/prtcl-156.shtml. Accessed: March 31, 2011.
  3. 3.0 3.1 Agency for toxic substances and disease registry. Toxicological profile for arsenic. http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=22&tid=3#bookmark07. Accessed: April 4, 2011
  4. 4.0 4.1 4.2 4.3 4.4 Even Better Health. Safe Detoxification for Heavy Metal Toxicity. http://www.evenbetterhealth.com/heavy-metal-poisoning.php. Accessed: April 4, 2011.
  5. American Heart Association. Chelation Therapy. http://www.americanheart.org/presenter.jhtml?identifier=4493. Accessed: April 4, 2011.
  6. Pubmed Health. Wilson’s Disease hepatolenticular degeneration. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001789/. Accessed: April 4, 2011.
  7. United States Department of Labor Occupational Safety and Health Administration. Safety and Health Topics Lead. http://www.osha.gov/SLTC/lead/. Accessed: April 4, 2011.
  8. Agency for toxic substances and disease registry. ToxFAQs for mercury. http://www.atsdr.cdc.gov/toxfaqs/TF.asp?id=113&tid=24. Accessed: April 4, 2011.