Heavy Metal Toxicity

Original Editors - Chase Almgren from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Chase Almgren, Lucinda hampton, Kim Jackson, Admin, Elaine Lonnemann, 127.0.0.1, Wendy Walker and WikiSysop  

Introduction

Heavy metal (HM) toxicity is a generic term for an above average level of metal in the blood which may result in undesirable side-effects. Humans are exposed to HMs through inhalation, ingestion, or contact with the skin. Environmental pollution with HMs can result in contamination of air, water, sewage, seawater, waterways, and can accumulate in plants, crops, seafood, and meat and indirectly affect humans. Some occupations have increased risk for particular HMs exposure and toxicity.

Accumulating evidence suggests that all age groups and organs are susceptible to metal induced toxicity, although the impact on the central nervous system is more severe and long-lasting in both developing and adult human brain. There are no clinically proven treatments to those affected by heavy metal toxicity.

Heavy metal (HM) toxicity is underestimated in the community.

Heavy metals can affect the nervous, pulmonary, cardiovascular, renal, skin, reproductive, and skeletal systems in varying degrees.

Heavy metals cause harm to proteins like enzymes, DNA, membrane lipids, and disrupt normal cellular functions.

Young children are affected more than adults.

Affected pregnant women can pass on the toxic HMs to the developing fetus and produce much harm.

The toxicity of HMs can be acute and chronic.

Etiology

HMs are dense, naturally occurring elements that cause health hazards by accumulation in the environment and living beings.

1. The common list of non-essential HM that cause toxicity includes Arsenic (As), Cadmium (Cd), Lead (Pb), Mercury (Hg)
2. Those essential to humans in trace quantities for various cellular activities include: Cobalt (Co), Copper (Cu), chromium (Cr), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se) and Zinc (Zn).

Exposure to HMs can be natural or occupational.

Epidemiology

HM toxicity is worldwide.

1. The incidence and magnitude of the toxicities of individual HMs vary with the geographical location, natural soil content, habits, customs, location of industries, regulatory measures to contain pollution, healthcare facilities to detect HM toxicity, and individual factors like nutritional status, and genetics.
2. When an HM is released into the air, water, or soil, it can be absorbed by plants, crops, consumed by cattle and fish, and finally, end up in humans to complete the food chain.
3. Industrial and workplace exposure can result in HM toxicity by inhalation, ingestion, or skin contact.

Lead Toxicity

File:Lead.jpg

Pure Lead

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.  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.  Lead particles may also travel through the air during older house renovation projects
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).  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.  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.

Arsenic Toxicity

File:Arsenic.jpg

Arsenic

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

Mercury Toxicity

Mercury exposure can be in the forms of inhalion, ingestion, or topically through the skin.  Common sources of mercury are fish (the number one cause of toxicity), emissions from coal burning plants, medical waste and from mines.  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.

File:Mercury.jpg

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.

Common signs and symptoms of heavy metal toxicity:

• 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
• Ataxia

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:

• 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
• Schizophrenia
• Thyroid Disorders

Medications

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

Systemic Involvement

Systemic involvement varies between heavy metals.

Lead systemic involvement

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

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

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

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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