Nutrition, Environmental Health, and Toxicology

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Nutrition, Environmental Health, and Toxicology — Key Facts for FMGE Core concept: Balanced nutrition is fundamental to health; environmental factors (water, sanitation, air) significantly impact disease patterns High-yield point: PEM (protein-energy malnutrition) in children and anemia in women are major nutritional problems in India; know the signs and management ⚡ Exam tip: The WHO classification for malnutrition (weight-for-height, height-for-age, weight-for-age) and the 6 food groups for diet planning are important

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Nutrition, Environmental Health, and Toxicology — FMGE Study Guide

Nutrition

Nutrients and Their Functions

Carbohydrates:

• Primary energy source (4 kcal/g)
• Simple (sugars) vs complex (starch, fiber)
• Dietary reference: 55-65% of total calories

Proteins:

• Body building (4 kcal/g)
• Essential amino acids (8): histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan
• Complete proteins: Animal sources (all amino acids)
• Incomplete proteins: Plant sources (missing some amino acids)
• Protein combining: Combine cereals + legumes for complete protein
• Dietary reference: 10-15% of total calories

Fats:

• Concentrated energy (9 kcal/g)
• Saturated (animal, coconut, palm oil) vs unsaturated (plant oils)
• Essential fatty acids: Linoleic acid (ω-6), α-linolenic acid (ω-3)
• Dietary reference: 20-30% of total calories

Vitamins:

• Fat-soluble (A, D, E, K): Stored in liver/fat; can accumulate
• Water-soluble (B-complex, C): Not stored; regular intake needed

Minerals:

• Major: Calcium, phosphorus, magnesium, sodium, potassium, chloride
• Trace: Iron, zinc, copper, selenium, iodine, fluoride

Balanced Diet

WHO/ICMR recommended:

• Protein: 1 g/kg/day (adult)
• Total calories: Based on age, sex, activity
• Proportion: 60% carbs, 10-15% protein, 20-30% fat
• Fiber: 25-30 g/day

6 Food Groups:

1. Cereals and millets: Energy, some protein
2. Pulses and legumes: Protein, B vitamins
3. Milk and animal foods: Protein, calcium, vitamin B12
4. Fruits and vegetables: Vitamins, minerals, fiber
5. Fats and oils: Energy, essential fatty acids
6. Sugar and jaggery: Energy

Protein-Energy Malnutrition (PEM)

Marasmus:

• Severe caloric deficiency
• Wasted muscles, no edema
• “Old man” appearance
• Normal appetite, alert
• Treatment: Nutritional rehabilitation, high-calorie diet

Kwashiorkor:

• Predominant protein deficiency
• Edema, skin changes, hair changes
• Hepatomegaly (fatty)
• Apathy, anorexia
• Treatment: Protein-rich diet, micronutrient supplementation

Classification (WHO):

• Weight-for-height: Acute malnutrition (wasting)
• Height-for-age: Chronic malnutrition (stunting)
• Weight-for-age: Combined
• Mid-upper arm circumference (MUAC): Used for rapid screening

Micronutrient Deficiencies

Vitamin A deficiency:

• Night blindness, xerophthalmia, Bitot spots, keratomalacia
• Prevention: Supplementation (6 months to 6 years), food fortification

Iron deficiency anemia:

• Most common in India (women, children)
• Pallor, fatigue, pica, koilonychia
• Prevention: IFA tablets, food fortification (iron + folic acid)

Iodine deficiency disorders (IDD):

• Goiter, hypothyroidism, cretinism
• Prevention: Iodized salt (iodization program)

Vitamin D deficiency:

• Rickets in children, osteomalacia in adults
• Prevention: Sunlight exposure, supplementation

Nutritional Assessment

Anthropometry:

• Weight, height, MUAC, skinfold thickness
• BMI = weight (kg) / height² (m²)

Biochemical:

• Hemoglobin (anemia), serum albumin, serum vitamin levels

Clinical:

• Signs of deficiency (skin, hair, nails, eyes)

Dietary:

• 24-hour recall, food frequency questionnaire

Environmental Health

Water and Sanitation

Safe drinking water:

• Free from pathogens and harmful substances
• Steps: Sedimentation → filtration → disinfection (chlorination)
• BIS standards: pH, turbidity, bacterial count, chemical contaminants

Water-related diseases:

• Waterborne: Cholera, typhoid, hepatitis A, dysentery
• Water-washed: Trachoma, skin infections (poor sanitation)
• Water-based: Guinea worm (Dracunculus medinensis), schistosomiasis
• Water-related vector: Mosquito breeding in water → malaria, dengue

Sanitation:

• Sewage disposal: Septic tank, sewerage system
• Excreta disposal: Pit latrines, flush toilets, composting toilets
• Solid waste disposal: Segregation, collection, treatment, disposal

Air Pollution

Outdoor (ambient):

• PM2.5, PM10, NO₂, SO₂, ozone
• Sources: Vehicles, industry, construction
• Health effects: Respiratory, cardiovascular, cancer

Indoor (household air pollution):

• Burning solid fuels for cooking/heating
• Women and children most affected
• COPD, lung cancer, acute respiratory infections

Standards:

• Air Quality Index (AQI): Good (0-50) to Severe (401+)
• National Ambient Air Quality Standards (NAAQS)

Housing and Environment

Ideal housing:

• Adequate space (minimum 30 sq ft per person)
• Ventilation, lighting
• Safe water, sanitation
• Separation of human and animal habitation

Occupational health:

• Dust, chemicals, noise, radiation
• Ergonomic hazards
• Prevention: Engineering controls, PPE, health monitoring

Toxicology

Heavy Metal Poisoning

Lead poisoning:

• Sources: Paint, petrol (historically), occupational
• Children: Intellectual disability, developmental delay
• Adults: Anemia, neuropathy, abdominal colic
• Treatment: EDTA, dimercaprol (BAL)

Mercury poisoning:

• Sources: Fish, dental amalgams, industrial
• Neurological effects: Tremor, ataxia, paresthesias

Arsenic poisoning:

• Sources: Pesticides, contaminated water (West Bengal)
• Skin changes (hyperkeratosis), hyperpigmentation
• “Garlic breath” - characteristic odor

Pesticide Poisoning

Organophosphates (most common):

• Acetylcholinesterase inhibition → cholinergic crisis
• DUMBELS/SLUDGE symptoms
• Treatment: Atropine, pralidoxime

Organochlorines (banned):

• DDT, aldrin, endrin (accumulate in fat)
• CNS effects, liver damage

Food Poisoning

Bacterial:

• Staphylococcus aureus: Preformed toxin; rapid onset (1-6 hours)
• Bacillus cereus: Rice-based foods; two types (emetic/ diarrheal)
• Clostridium perfringens: Reheated meat; 8-16 hours incubation
• Salmonella: Poultry, eggs; 6-72 hours incubation
• E. coli O157:H7: Undercooked beef; bloody diarrhea

Non-bacterial:

• Mushroom poisoning: Amanita phalloides (delayed hepatotoxicity)
• Scombroid fish poisoning: Tuna, mackerel (histamine-like)
• Ciguatera: Large reef fish (ciguatoxin)

Management of Poisoning

Decontamination:

• Skin/eye exposure: Irrigation with water/saline
• Ingested: Gastric lavage (rarely), activated charcoal (if within 1-2 hours)

Antidotes:

• Organophosphates: Atropine + Pralidoxime
• Opioids: Naloxone
• Benzodiazepines: Flumazenil
• Acetaminophen: N-acetylcysteine
• Cyanide: Hydroxocobalamin, nitrite + thiosulfate
• Methanol/ethylene glycol: Fomepizole, ethanol
• Lead: EDTA, dimercaprol

Supportive care:

• Airway, breathing, circulation
• Seizure control
• Correct electrolyte imbalances

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