MEV 018: Unit 08 – Human Health at Risk
UNIT 8: HUMAN HEALTH AT RISK
8.0 Introduction
Human health is intricately linked to the
environment. Various natural and anthropogenic factors—such as pathogens, toxic
chemicals, and changes in geochemical cycles—can pose serious risks to health.
In many parts of the world, environmental degradation has led to an increase in
communicable and non-communicable diseases. Environmental factors like poor
water quality, exposure to toxic elements, and altered biogeochemical processes
can contribute to conditions such as goitre, fluorosis, and arsenic poisoning.
This unit discusses these risks and the broader epidemiological implications
for public health.
8.1 Objectives
After studying this unit, learners will be able
to:
- Identify and explain environmental pathogens and their effects on
human health.
- Understand the influence of biogeochemical factors on environmental
health.
- Discuss major epidemiological concerns arising from environmental
exposure.
- Describe health risks like goitre, fluorosis, and arsenic poisoning.
- Analyze public health strategies to mitigate such risks.
8.2 Pathogens in the
Environment
Pathogens are biological agents that cause
disease or illness in their host. They include bacteria, viruses, protozoa,
fungi, and helminths. Environmental reservoirs such as water, air, and soil
often harbor these pathogens, which can infect humans through various exposure
routes.
Common Environmental
Pathogens:
|
Pathogen Type |
Example |
Disease Caused |
|
Bacteria |
Vibrio cholerae |
Cholera |
|
Virus |
Hepatitis A virus |
Hepatitis A |
|
Protozoa |
Giardia lamblia |
Giardiasis |
|
Helminths |
Ascarislumbricoides |
Ascariasis |
Transmission Routes:
- Waterborne (e.g., cholera)
- Airborne (e.g., influenza)
- Foodborne (e.g., salmonella)
- Soil-transmitted (e.g., hookworm)
Poor sanitation, contaminated water, inadequate
waste disposal, and climate change enhance pathogen survival and spread.
8.3 Biogeochemical Factors in
Environmental Health
Biogeochemical cycles involve the
movement of elements such as carbon, nitrogen, sulfur, and phosphorus through
the environment. Human interventions (like industrialization, agriculture,
mining) have disrupted these cycles, leading to environmental and health
consequences.
Key Factors:
- Nitrogen and Phosphorus Overload: Leads to algal blooms,
hypoxia, and water contamination.
- Heavy Metal Accumulation: Arsenic, lead, mercury,
and cadmium enter water and food chains.
- Geological Conditions: Natural mineral content
(e.g., fluoride, iodine) varies and affects local populations.
These altered biogeochemical conditions can
result in nutrient deficiencies or toxic exposures that directly affect human
health.
8.4 Epidemiological Issues
Epidemiology is the study of disease
patterns, causes, and effects in populations. In environmental health, it helps
identify links between environmental exposure and disease incidence.
Major Issues:
- Under-reporting of environmental diseases.
- Latency Periods between exposure and disease (e.g., cancer).
- Cumulative Exposure Effects from air, water, and
food.
- Lack of Data in rural and remote areas.
Environmental epidemiology tracks diseases such
as:
- Respiratory illnesses from air pollution.
- Waterborne diseases from unsafe drinking water.
- Cancers from chemical exposure.
Epidemiological surveillance helps in
policy-making, risk assessment, and health interventions.
8.5 Goitre
Goitre is an abnormal enlargement of
the thyroid gland, typically due to iodine deficiency in the diet.
Causes:
- Iodine-deficient soil and water (common in hilly and inland
regions).
- Consumption of goitrogenic substances (e.g., cabbage, millet).
- Lack of iodized salt intake.
Symptoms:
- Swollen neck
- Breathing/swallowing difficulty
- Hormonal imbalances (hypo/hyperthyroidism)
Prevention & Control:
- Use of iodized salt
- Nutrition education
- Monitoring iodine levels in the environment
8.6 Fluorosis
Fluorosis is caused by excessive
fluoride intake, primarily through drinking water or food.
Types:
- Dental Fluorosis: Mottling and
discoloration of teeth.
- Skeletal Fluorosis: Bone deformities,
stiffness, and pain.
Sources:
- Natural fluoride-rich groundwater.
- Industrial emissions and coal combustion.
- Fluoride-containing products (e.g., toothpaste).
Affected Areas:
- Parts of India (Rajasthan, Andhra Pradesh, Gujarat)
- African countries with volcanic rocks
Mitigation:
- Defluoridation of water (using activated alumina, bone char).
- Awareness campaigns.
- Nutritional supplements (calcium, vitamin C).
8.7 Arsenic Poisoning
Arsenic is a toxic metalloid found in
groundwater due to natural and anthropogenic activities.
Sources:
- Geogenic contamination (especially in sedimentary aquifers).
- Industrial effluents, pesticides.
- Burning arsenic-containing coal.
Health Effects:
- Skin lesions (black spots, thickening)
- Peripheral neuropathy
- Cardiovascular and lung diseases
- Increased risk of cancers (skin, bladder, lung)
Geographic Focus:
- West Bengal, Bihar, Uttar Pradesh, and Bangladesh are severely
affected.
Solutions:
- Use of arsenic filters and deep tube wells.
- Rainwater harvesting.
- Community health monitoring and awareness.
8.8 Let Us Sum Up
This unit explored the risks posed to human
health due to environmental factors. Pathogens, toxic metals, and deficiencies
or excesses of trace elements in the environment are major public health
threats. Conditions like goitre, fluorosis, and arsenic poisoning are directly
linked to local geochemical environments and require preventive public health
strategies. Environmental epidemiology plays a crucial role in identifying and
mitigating these health challenges.
8.9 Key Words
- Pathogens: Disease-causing microorganisms in the environment.
- Biogeochemical Factors: Natural cycles and
elements influencing health.
- Epidemiology: Study of disease patterns and causes in populations.
- Goitre: Thyroid gland enlargement due to iodine deficiency.
- Fluorosis: Health condition caused by excessive fluoride intake.
- Arsenic Poisoning: Toxic effect due to
arsenic-contaminated water.
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