Environmental Pathology

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Air Pollution & Lung Impact - Smoggy Sicknesses

  • Key Air Pollutants & Sources:
    • Gases: Sulfur dioxide ($SO_2$), Carbon monoxide ($CO$), Nitrogen dioxide ($NO_2$), Ozone ($O_3$).
    • Particulate Matter (PM): $PM_{2.5}$ (fine, deep lung penetration) & $PM_{10}$ (coarse).
    • Indoor Pollutants: Tobacco smoke (active/passive), Radon (radioactive gas from soil, ↑ lung cancer risk), Formaldehyde (building materials, irritant).
  • Respiratory System Impacts:
    • Inflammation & Irritation: Acute tracheitis, bronchitis.
    • Exacerbation of pre-existing conditions: Asthma, COPD.
    • Chronic Effects: ↓ Lung function, chronic bronchitis.
    • Carcinogenesis: Lung cancer (tobacco smoke, radon, $PM_{2.5}$). Mechanisms include oxidative stress and direct DNA damage.

⭐ $PM_{2.5}$ (particles < 2.5 micrometers) are major contributors to lung disease due to their ability to penetrate deeply into alveoli and even enter systemic circulation, causing inflammation and cardiovascular effects beyond the lungs. Tobacco smoke is a potent mix of carcinogens and irritants, significantly increasing lung cancer risk.

Pneumoconioses - Dusty Lung Diseases

Occupational lung diseases caused by inhalation of mineral dusts, leading to fibrosis.

Chest X-ray showing silicotic nodules

DiseaseAgentOccupationKey PathologyComplications
SilicosisSilicaMining, sandblasting, stone cuttingSilicotic nodules (upper lobes), eggshell calcificationProgressive Massive Fibrosis (PMF), ↑ TB risk, Caplan syndrome
AsbestosisAsbestos fibersShipbuilding, insulation, constructionAsbestos bodies, diffuse interstitial fibrosis (lower lobes), pleural plaquesLung cancer (bronchogenic carcinoma > mesothelioma), Mesothelioma, Caplan syndrome
Coal Worker's Pneumoconiosis (CWP)Coal dustCoal miningCoal macules/nodules (upper lobes)PMF, Caplan syndrome
BerylliosisBerylliumAerospace, electronics, nuclear industryNon-caseating granulomas (similar to sarcoidosis)Chronic beryllium disease, ↑ lung cancer risk

📌 Silicosis: Sandblasting, Stone cutting, Superior (upper) lobes, ↑ TB Susceptibility.

Heavy Metal Poisoning - Toxic Metal Menace

Burton's line in lead poisoning

MetalSources/Abs.Clinical/PathoDiagnosis
PbPaint, pipes (ingest/inhale)CNS (↓IQ child), PNS (wrist drop), GI colic, Burton's line; Basophilic stippling, renal inclusionsBLL (>5 µg/dL child, >10 adult)
HgDental amalgam, fish (ingest), vapor (inhale)Tremors, erethism, Minamata, Acrodynia; ATN, neuronal damageBlood/urine Hg
AsPesticides, water (ingest/inhale)Acute (GI, garlic breath); Chronic (skin, Mee's lines, cancers); Mito/capillary damageUrine As; Hair/nail (chronic)
CdBatteries, smoking (inhale/ingest)Kidney (tubular damage), Lungs (emphysema), Bones (Itai-Itai); Renal tubular necrosisUrine Cd, ↑β2-microglobulin

Chemical & Radiation Hazards - Potent Polluters

  • Pesticides:
    • Organophosphates/Carbamates: Cholinesterase inhibition → SLUDGE syndrome (📌 Salivation, Lacrimation, Urination, Defecation, GI distress, Emesis).
    • Organochlorines (DDT): Neurotoxicity, endocrine disruption.
  • Industrial Chemicals:
    • Vinyl chloride → Angiosarcoma (liver).
    • Benzene → Leukemia (AML).
    • Aromatic amines → Bladder cancer.
  • Radiation Hazards:
    • Ionizing Radiation: DNA damage (direct/indirect). Units: Gray ($Gy$) absorbed dose, Sievert ($Sv$) equivalent dose.
      • Stochastic effects: Cancer risk ↑ with dose (no threshold).
      • Deterministic effects: Severity ↑ with dose (threshold exists, e.g., >2 $Gy$ for hematopoietic syndrome).
      • Highly sensitive tissues: Lymphoid, hematopoietic, gonads.
    • UV Radiation (Sunlight): Pyrimidine dimers in DNA → Skin cancers (melanoma, SCC, BCC).

⭐ Benzene exposure is a significant risk factor for developing Acute Myeloid Leukemia (AML).

High‑Yield Points - ⚡ Biggest Takeaways

  • Lead poisoning: Basophilic stippling, wrist/foot drop, neurotoxicity in children, Burton's line.
  • Mercury poisoning: Minamata disease (organic), CNS/kidney damage (inorganic).
  • Arsenic poisoning: Skin lesions (keratosis, pigmentation), Mees' lines, various cancers.
  • Asbestos: Asbestosis, mesothelioma, lung cancer (synergistic with smoking), ferruginous bodies.
  • Silicosis: Eggshell calcification (hilar nodes), ↑ TB risk, nodular fibrosis.
  • Organophosphates: Acetylcholinesterase inhibition, cholinergic crisis (SLUDGE).
  • PM2.5 air pollution: Exacerbates respiratory/cardiovascular diseases, linked to lung cancer.

Practice Questions: Environmental Pathology

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Indicators of air pollution are:

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Flashcards: Environmental Pathology

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_____ is an iron-dependent pathway of cell death induced by lipid peroxidation.

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_____ is an iron-dependent pathway of cell death induced by lipid peroxidation.

Ferroptosis

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