MEDICAL EFFECTS OF CARBON MONOXIDE

                           ON HUMANS AND ANIMALS

CO Exposure in Humans

  Once a person is aware of CO poisoning , it is often too late to escape.  According to Drill’s Pharmacology in Medicine, muscular and skeletal weakness is often severe enough to prevent escape from a hazardous situation, even though the individual can clearly sense that he is in danger. “This may in part be caused by the combination of CO with myoglobin, resulting in a degree of impairment of muscle cell metabolism.” (2)  Breathing in air contaminated with as little as 0.1 percent CO for an hour can be fatal. “A concentration of 0.5 percent CO may cause sudden death in a matter of minutes.  On the other hand, the more slowly a given degree of CO poisoning develops, the more persistent are the signs and symptoms associated with it.” (2) 

  Workers unloading dead animals from a gas chamber are exposed to low levels of the gas on a regular basis, which puts them at risk for a myriad of health problems.  They are also at risk when the machine leaks.  In several documented cases, workers have become sick from inhaling the gas. Two of these cases are in Reidsville and Clinton, North Carolina. Tragically, a worker died in Chattanooga, Tennessee in 2000, while unloading dead animals from the gas chamber there. (3)

    “A direct correlation has been claimed between CO level and symptoms of atherosclerotic diseases, intermittent claudation, angina, and myocardial infarction (heart attack).” (4)  According to the United States Department of Labor, CO health factors include headaches, tachypnea (abnormally fast breathing), nausea, weakness, dizziness, confusion, hallucinations, cyanosis, angina (chest pain), asphyxiation (suffocation), and syncope.  (5)

  The brain and heart are most sensitive to the hypoxic effects of CO exposure, because of their high demands for oxygen.  Many signs of CO exposure are related to the central nervous system, including nausea, headache, confusion, syncope, coma, seizures, and tachypnea.  Many patients experience delayed neurological deficits often following several days with no symptoms.   These symptoms can occur several weeks after exposure.  Delayed effects may include memory impairment, dementia, cerebellar ataxias, and dystonias.  “Deaths have been reported with very low CO levels.” (6)

  In a study by S.R. Thom, group of patients were acutely poisoned with CO.  Twenty three percent had persistent neurologic problems due to CO poisoning, which adversely affected their quality of life.  The study noted that loss of consciousness is not necessary for development of these symptoms. (7)  

  The outer brain surface is affected by CO exposure, resulting in effects on learning, judgement, speech, motor skills, intellectual capacity, and memory storage.  “Carbon monoxide poisoning can disrupt function in all areas of the cerebral cortex.”  (8,9)

  A study by S.D. Gale showed changes in neuropsychological function following CO poisoning.  “Ninety-three percent of the patients exhibited a variety of cognitive impairments, including impaired attention, memory, executive function, and mental processing speed.  Ninety-five percent of patients experienced affective changes including depression and anxiety.  Results from the imaging studies revealed that 38% of the patients had abnormal MRI scans, 67% had abnormal SPECT scans, and 67% had abnormal QMRI findings.” SPECT scans show changes in brain function following CO exposure. (10)

  CO Exposure in Animals 

   Most major humane organizations advocate a move toward more humane euthanasia for sheltered animals, citing the dangers and health effects of carbon monoxide.  The Humane Society of the United States says, “In order to be humane, every euthanasia technique must result in painless, rapid unconsciousness, followed by cardiac or respiratory arrest, and ultimately death.” Animals under four months of age have shown a resistance to hypoxia (oxygen deficiency), which means that it takes them longer to die.  It is unacceptable to use CO for animals who are old, sick injured, pregnant, or under four months of age.  Considering this, there must always be an acceptable backup method available. (11)  In many shelters in North Carolina, CO is used to euthanize all animals.      

   American Humane and the Animal Protection Institute consider carbon monoxide unacceptable for euthanasia. 

  The American Veterinary Medical Association confirms that animals exposed to CO suffer convulsions and muscular spasms.  While they still list it as an acceptable method, they stress “the primary responsibility of using the most rapid and painless euthanasia method possible under the circumstances.” (1) 

  In the 1983 study by Chalifoux and Dallaire, 18 dogs were euthanized with pure CO.  The animals were monitored for EEG, EKG, arterial blood pressure, heart rate, respiratory rate, and cortisol values.  They also noted behavior changes.  “Higher heart and respiratory rates during EEG modifications indicated stress.  Agitation and vocalization occurred for approximately 20 to 25 seconds.”  The study determined that this behavior can happen while the animals are conscious. (12)

  S.H. Cramlet studied the effects of CO on the heart of conscious dogs.  Each dog was exposed briefly  to 1,500 ppm of carbon monoxide.  He found significant increases in heart rate, ventricular pressure, and cardiac output. (13)  This indicates that the animals are under stress.

  According to John MacNeil, a molecular and research chemist, any rapid deprivation of oxygen causes severe angina pain, whether in humans or animals. MacNeil has witnessed dogs biting at their chests during CO euthanasia, which he believes is related to this pain.  He also notes that myocardial ischemia can occur, even in the absence of coronary disease. His knowledge of the effects of carbon monoxide gas chambers has motivated him to develop new euthanasia drugs. 

  Many witnesses of gas euthanasia have noticed animals crying out in distress, beating their heads against the wall of the gas chamber, fighting each other, and trying desperately to escape.  Photos from the Duplin County, North Carolina shelter show blood in the chamber after the euthanasia process, which should not be present after a peaceful death.  

  Considering the animals’ behavior, and the documentation of pain and suffering, carbon monoxide is deemed by many to be an unacceptable form of euthanasia. A society with high moral standards should not allow this barbaric treatment of our sheltered animals.  

Symptoms and Health Effects of Carbon Monoxide Poisoning

Angina (chest pain)

Myocardial infarction (heart attack)

Asphyxiation (suffocation)

Chemical anoxia

Tachypnea (abnormally fast breathing)

Syncope (light-headedness and fainting caused by insufficient blood supply to brain)

Teratogenic effects (causing abnormal embryonic growth processes)

Artherosclerotic diseases

Intermittent claudation

Dystonias

Malaise, flu-like symptoms, fatigue

Dyspnea on exertion

Lethargy

Confusion

Depression

Hallucinations

Agitation

Nausea

Vomiting

Diarrhea

Abdominal Pain

Headache

Drowsiness

Dizziness

Weakness

Visual disturbunce

Syncope

Seizure

Fecal and Urinary Incontinence

Memory loss

Gait disturbances

Bizarre Neurologic symptoms

Coma

Tachycardia

Hypertension/ Hypotension

Retinal hemorrhages

Pulmonary edema

Impaired judgement

Decreased cognitive ability

Tic disorders

Apraxia

Agnosia

Psychosis

Breathing difficulties

Cramps

Driving at night difficult

Emotional distress

Hypochondriasis

Hysteria

Irritability

Joint pain

Muscle twitches/ pain/ weakness

Panic attacks

Photophobia

Tremors

Vision blurred   (14, 15)

Footnotes 

1. 2000 Report of the AVMA Panel on Euthanasia, JAVMA, Vol. 218, No. 5, March 2001
2. Drill’s Pharmacology in Medicine, edited by Joseph R. DiPalma, M.D., Chapter 58.
3. The Tennessean.
4. T. W. Grace and F. W. Platt,  “Subacute Carbon Monoxide Poisoning:  Another Great Imitator”  JAMA, 1981.
5. United States Department of Labor, Safety and Health Topics: Carbon Monoxide, www.osha.gov/dts/chemicalsampling/data/CH_225600.html
6. Donald Elton, M.D.,  “Carbon Monoxide Poisoning.” Mid Carolina Medical Associates, www.midcarolina.org/papers/co.poisoning.html
7. S. R. Thom,  “Delayed Neurological Sequelae After Carbon Monoxide Poisoning.”, www.coheadquarters.com/Thom1.htm
8. Carbon Monoxide Headquarters, “Major Sites of Nervous System Damage,”  www.coheadquarters.com/codamage1.htm
9. Carbon Monoxide Headquarters, “Outer Brain Surface,” www.coheadquarters.com/coOuterBrain1.htm
10. S. D. Gates, “MRI, Quantitative MRI, SPECT, and Neuropsychological Findings Following Carbon Monoxide Poisoning,” 1999, www.coheadquarters.com/Gale1.htm
11. Humane Society of the United States, General Statement Regarding Euthanasia Methods for Dogs and Cats.
12. A. Chalifoux and A. Dallaire, “Physiologic and Behavioral Evaluation of CO Euthanasia of Adult Dogs,” National Library of Medicine, 1983.
13. S. H. Cramlet, “Ventricular Function Following Acute Carbon Monoxide Exposure,” Journal of Applied Physiology, 1975.
14. Guy Shochat, M.D., Michael Lucchesi, M.D., “Toxicity, Carbon Monoxide,” August 9, 2004, www.emedicine.com/EMERG/topic817.htm
15. Roy A. Myers et al, “Retrospective Brief Case Series,” 1998.

References

John MacNeil, Vortech Pharmaceuticals, Dearborn, Michigan.

Kim Loyd, Duplin Animal Response Team, Kenansville, North Carolina.

Peter MacQueen III, President, Eastern North Carolina Humane Society.

Sena Crutchley, North Carolina Voters for Animal Welfare.