Environmental and Nutritional Disease Overview

Study Notes

Understand the pathophysiology of toxic effects due to chemical and physical agents.
Identify common air pollutants and their respective pathophysiological impacts.
Learn toxicity mechanisms of prevalent heavy metal toxins.
Recognize commonly encountered industrial and agricultural toxins along with associated diseases.

Focuses on the distribution, effects, and pathophysiology of toxic agents, also known as poisons.
Includes exogenous chemicals (xenobiotics) and physical agents, such as radiation and heat.
Toxicity often depends on dosage; therapeutic drugs can become poisons at high levels.
Chemical toxins are primarily lipophilic, facilitating storage in body tissues.
The liver metabolizes toxins into water-soluble metabolites for excretion, with processes categorized into:
- Phase I: Cytochrome P450 system, influenced by genetics and drug interactions.
- Phase II: Further modifications of metabolites.

Caused by exposure to harmful chemical or physical agents in the environment, including workplace and personal spaces.
Can be the result of major disasters (e.g., nuclear accidents) or chronic low-level exposure to toxins.

Exposure pathways include air, water/food, and soil.
Portals of entry into the body are primarily skin, lungs, and gut.
Once entered, toxins distribute through the bloodstream and may result in:
- Excretion via urine.
- Accumulation in organs.
- Resulting toxic effects in the body.

Key pollutants include ozone (O3), sulfur dioxide (SO2), acid aerosols, and particulate matter.
Inhalation of particulate matter can obstruct airways and lead to severe health complications.

Burn Depths:
- First degree: Only involves the epidermis.
- Second degree: Extends into the upper dermis.
- Third degree: Affects the full thickness of the epidermis and dermis.
- Fourth degree: Extends into subcutaneous tissue.
Burn Severity is assessed based on:
- Depth of injury.
- Percentage of body surface area affected (Rule of Nines).
- Associated injuries (e.g., inhalational injuries).
- Quality and timeliness of treatment.

Injuries may include burns, tetany, and disruptions in physiological electrical impulses leading to potential fatalities like cardiorespiratory failure.
Severity is determined by the amperage and path the electric current travels, governed by Ohm’s Law (Amperage = Voltage/Resistance).

Types of Radiation:
- Non-ionizing: UV light, microwaves, sound (do not displace electrons).
- Ionizing: X-rays and CT scans (can remove electrons).
Radiation Sources:
- Medical: Cancer treatments and diagnostics.
- Environmental: Nuclear events, radon exposure.
- Occupational: Risks faced by workers, such as uranium miners.

Can cause DNA damage, leading to:
- Apoptosis (cell death).
- Carcinogenesis (cancer development).
- Teratogenesis (birth defects).
Endothelial cells can suffer damage, resulting in hypoxia and fibrosis.

The impact of radiation is influenced by:
- Dose received.
- Rate of radiation delivery (single vs. fractionated).
- Field size (whole-body exposure vs. localized).
- Type of tissue affected, with rapidly dividing cells (e.g., gonads, hematolymphoid tissue) being most vulnerable.