Environmental causes of disease. A50-A52

Question 1

A/50. Effects of tobacco and air pollution

The toxins contained in tabacco

Associated risks of tabacco smoking

Answer 1

Components

• Tar
• Polycyclic aromatic hydrocarbons
• Nicotene
• Carbon Monoxide
• Formaldehyde
• Nitrogen oxides
• Nitrosamine

Major effects of smoking: Carcinogenic, Lung, Vascular, Cardiac, GI effects, Fetal effects.

1. Cancers: all of the respiratory tracts, and also pancrase, urinary and bladder.
   
   • Lung cancer
   • Oral
   • Esophageal
   • Laryngeal
   • Pancreatic
   • Urinary
   • Bladder
2. Lung effects
   
   1. ​Causes 90% cancers in the lung
   2. Directly irritates the mucosa, and promotes opportunistic infections, thus causing:
   3. Chronic Bronchitis
   4. Emphysema, and lung fibrosis
   5. COPD
   6. Chronic dry cough
   7. Brochiectasis
   8. Smoking associated interstitial lung diseases:
      
      1. Involve large accumulation of macrophages and lymphocytes, inside the alveolar space
      2. Respiratory bronchiolitis
      3. Desquamative interstitial pneumonia (DIP)
3. Vascular effects
   
   1. Is a direct major modifiable risk factor for atherosclerosis.
   2. Also promotes hypertension, another risk factor. and also its own source of problems.
4. GI effects
   
   • Erosions of the GI mucosa
   • Aggravates Crohns disease
   • Soothes Ulcerative collitis
5. Major effects on a fetus
   
   1. CO causes general fetal hypoxia
   2. Increased spontaneous abortions
   3. Mental impairments
   4. impaired fetal growth.

Question 2

A/50. Effects of tobacco and air pollution

Air pollution, outdoor air pollution

Answer 2

Outdoor air pollution:

1. Carbon monoxide
   
   • ​​doesn’t irritate the lungs, but causes hypoxia
2. Ozone
   
   • ​Caused by sunlight reacting with car exhaust.
   • Generates some free radicals and damages the lung.
3. Nitrogen Oxide​
4. Lead poisoning
5. Sulfur dioxide
   
   • ​​irritate resp mucosa
   • especially irritating to asthmatic patients
6. Acid aerosols - Produced by coal and oil burning power plants
   
   • ​​irritates the mucosa
   • increases respiratory infections in children
   • especially irritating to asthmatics
7. Particles in the air
   
   1. ​especially industrial, coal/oil burning power plants
   2. metals may be in these
   3. Particles are the main pathologic outdoor pollutant, causing macrophage uptake, and macrophage death, then fibrosis. (like in coal miners pneumoconiosis)

Question 3

A/50. Effects of tobacco and air pollution

Indoor air pollution

Answer 3

1. From smoking tabacco indoors, and its second hand toxins
2. Carbon monoxide
3. Nitrogen dioxide
4. Asbestos
5. Smoke from wood burning fires
6. Radon
7. Bioaerosols, containing infectious particles, ie from aire conditioners.

Question 4

A/51. Effects of alcohol

Answer 4

Toxic effects of alcohol, are from ethanol, and acetaldehyde, and some ROS production by CYP2E1** when metabolising ethanol.

Aldehyde dehydrogenase is slower than alcohol dehydrogenase, so acetaldehyde builds up.

The high NADH/NAD ratio also inhibits glycolysis, promotes FA synthesis, may limit ATP availability.

Acute toxicities of alcohol:

• Directly may cause gastritis and ulceration
• CNS depressant effects
• Severe alcohol poisoning can depress CNS so much as to cause respiratory arrest, unconciousness, death.

Chronic toxicites:

• Fatty liver, progressing to cirrhosis
• Gastritis, Ulceration
• Ruptured ulcers or erosion down to vessels may cause intense GI bleeding.
• Peripheral neuropathies, CNS atrophy.
• Wernicke-Korsakoff syndrome
  
  • Ataxia
  • Vision changes
• Increased LDL, atherosclerosis
• Myocardial injury, and congestive cardiomyopathy causing eccentric hypertrophy
• Acute or Chronic Pancreatitis
• Fetal alcohol syndrome during pregnancy
• oral, esophageal, stomach, and liver cancer, as well as breast cancer in females.

Question 5

A/52. Injury produced by ionizing radiation and physical agents

Injury by ionizing radiation

Answer 5

Ionizing radiation are high energy particles that can knock electrons out of atoms, creating ions.

• X-rays,
• gamma-rays
• alpha beta praticle beams.

Causes:

1. DNA damage, carcinogeneis/apoptosis
2. Vascular Damage, leading to
3. Fibrosis
4. Shrinkage of the lymph nodes and spleen.
5. Lymphopenia, leukocytopenia, thrmbocytopenia

Generate free radicals and free electrons. the free radicals can produce further reactions and may generate new free radicals, lipid peroxidations.

It is especially dmaging to DNA, and is mutagenic, carcinogenic.

Biological effect depends on:

• Sensitivity, replication rate of the tissue.
  
  • Radiation is more damaging to bone marrow/testes/GI mucosa, not very damaging to post-mitotic regions like the brain or heart.
  • Intermediatel ydamaging to endothelial cells.
• Vascular damage
• Hypoxia
• Field size
• Rate of delivery, continuous vs non-continuous exposure, non-cancer cells can repair themselves more effeciently than cancer cells during times in between exposure.

High dose total body irradiation can cause acute radiation poisoning/syndrome, which damages the GI, hematopoeitic systems greatly, and also impairs the CNS.