41  Impacts of pollutants on human health

41.1 What the Syllabus Covers

Pollutants reach human bodies through inhalation, ingestion, and skin contact. The route of exposure matters: airborne fine particles enter the lungs; waterborne contaminants travel through the gut; skin-contact pollutants accumulate in fat.

PYQs reliably ask: (a) match the pollutant to its characteristic disease (mercury → Minamata; cadmium → Itai-itai; arsenic → black-foot disease; fluoride → fluorosis; lead → neuro-developmental damage), (b) identify the PM2.5 vs PM10 distinction, (c) name the NCD epidemic in India, (d) recognise bioaccumulation/biomagnification routes, and (e) identify the WHO air quality guideline values.

41.2 Pathways and Vulnerable Groups

TipThree Routes of Exposure
  • Inhalation — lungs (gases, particulates, aerosols).
  • Ingestion — gut (water, food contaminants).
  • Dermal — skin (pesticides, solvents, heavy metals).
TipVulnerable Groups
  • Children — developing organs, higher exposure per kg.
  • Pregnant women — placental transfer; fetal damage.
  • Elderly — reduced clearance, comorbidities.
  • Outdoor workers — direct exposure (construction, traffic police).
  • Slum / low-income communities — proximity to pollution sources.
  • Patients with pre-existing disease — asthma, COPD, heart disease.
  • Indigenous communities — water/forest dependence.

41.3 Air Pollutants — Health Effects

TipMajor Air Pollutants and Their Health Effects
Pollutant Source Health effect
PM2.5 Combustion, smoke, biomass Penetrates alveoli; lung cancer, IHD, stroke, COPD; premature death
PM10 Dust, construction Asthma, bronchitis
CO Vehicles, cooking fuel Binds Hb (carboxyhaemoglobin) → hypoxia, death
SO₂ Coal-fired plants Bronchoconstriction, acid rain
NO₂ Vehicles, NPK fertilisers Asthma exacerbation, lung function decline
O₃ (ground) Photochemical Inflammation, asthma
VOCs Solvents, paints Eye/throat irritation; some carcinogenic
Benzene Fuel, smoke Leukemia
Formaldehyde Paints, plywood Nasopharyngeal cancer
Lead (Pb) Old paints, batteries Neurotoxin, IQ loss in children
Asbestos Insulation Mesothelioma, asbestosis
Radon Soil, groundwater Lung cancer
Smoking (active/passive) Tobacco Lung cancer, IHD, stroke, COPD

41.3.1 WHO Air-Quality Guidelines (2021)

TipWHO 2021 AQG
  • PM2.5: annual mean 5 µg/m³; 24-hr 15 µg/m³.
  • PM10: annual 15 µg/m³; 24-hr 45 µg/m³.
  • NO₂: annual 10 µg/m³.
  • SO₂: 24-hr 40 µg/m³.
  • O₃: peak season 8-hr 60 µg/m³.

Most Indian cities exceed WHO PM2.5 by 10× to 20×.

41.3.2 Burden of Disease

TipAir Pollution Burden
  • WHO: ~7 million premature deaths/year globally from air pollution (ambient + household).
  • India: ~1.6-1.7 million deaths/year (Lancet Planetary Health 2020).
  • Top causes: IHD, stroke, COPD, lung cancer, lower respiratory infections in children.
  • Life expectancy in India would rise ~5 years if PM2.5 met WHO guideline (AQLI, Energy Policy Institute, U. of Chicago).

41.4 Water Pollutants — Health Effects

TipWaterborne Pollutants and Diseases
Pollutant Source Health effect
Mercury (Hg) Industrial discharge Minamata disease (neuro, congenital); biomagnification in fish
Cadmium (Cd) Industrial waste Itai-itai (bone, kidney damage)
Arsenic (As) Groundwater (West Bengal, Bangladesh) Black foot, skin cancer, neuropathy, IQ loss
Lead (Pb) Old pipes, paint Neurotoxin
Fluoride (F) Geogenic groundwater (Andhra, Rajasthan, Telangana) Fluorosis — dental and skeletal
Nitrate (NO₃) Fertiliser runoff Blue-baby syndrome (methaemoglobinaemia)
Pathogens (E. coli, V. cholerae, Salmonella, rotavirus, Hep A/E) Sewage Cholera, typhoid, hepatitis, diarrhoea
Helminths / cysts (Giardia) Faecal contamination Parasitic infections
POPs (DDT, dioxins, PCBs) Industrial Endocrine disruption, cancer
Microplastics Plastic waste Inflammation, possible endocrine disruption
Pharmaceutical residues Hospital, sewage Antimicrobial resistance

41.4.1 Biomagnification — DDT and Mercury Classics

DDT and methylmercury concentrate up the food chain — top predators (eagles, large fish, humans) accumulate the highest concentrations.

41.4.2 Disease-Causing Waterborne Pathogens

TipMajor Waterborne Diseases
  • Cholera (V. cholerae) — sudden severe diarrhoea, dehydration.
  • Typhoid (Salmonella typhi).
  • Hepatitis A and E.
  • Acute Diarrhoeal Diseases — main child-killer in low-income areas.
  • Polio (faecal-oral).
  • Dysentery (Shigella, Entamoeba).
  • Giardiasis · Cryptosporidiosis.

41.4.3 Famous Indian Cases

TipIndian Waterborne Health Crises
  • Arsenicosis in West Bengal (Murshidabad, Nadia, 24-Parganas) — millions exposed.
  • Fluorosis belt — Andhra Pradesh, Rajasthan, Gujarat, Telangana, Karnataka.
  • Iron toxicity in groundwater of Assam, West Bengal.
  • Bhopal Gas Tragedy (1984) — continuing soil and groundwater contamination.
  • Pesticide poisoning — Endosulfan in Kerala (Kasaragod cashew belt).

41.5 Soil & Pesticide Pollutants — Health Effects

TipSoil and Pesticide Pollutants
  • Pesticides (Organochlorines like DDT, organophosphates) — neurotoxicity, endocrine disruption, cancer.
  • Heavy metals from soil → food chain.
  • Aflatoxins — fungal toxin in stored grain → liver cancer.
  • Endosulfan — banned in India 2011 (Stockholm POP); Kasaragod aerial-spraying disaster.
  • Glyphosate — debated carcinogen.
  • Industrial leaks — Hexavalent chromium (Cr-VI) at Ranipet (TN).

41.6 Noise — Health Effects

TipNoise Health Effects
  • Hearing loss at sustained > 85 dB.
  • Sleep disturbance.
  • Cardiovascular stress — hypertension, ischemic heart disease.
  • Cognitive impairment in children near airports.
  • Annoyance and mental-health effects.
  • Tinnitus.

41.7 Radiation — Health Effects

TipRadiation Health Effects
  • Ionising radiation (UV, X-ray, gamma, alpha, beta) damages DNA.
  • Acute Radiation Syndrome (ARS) at high doses.
  • Cancer — leukemia, thyroid, skin.
  • Sources: medical imaging, nuclear accidents (Chernobyl 1986, Fukushima 2011), radon gas, occupational.
  • Non-ionising radiation (radio, microwave) — heating effect; debated long-term risks.

41.8 Plastic and Microplastic Pollution — Health Effects

TipPlastic and Microplastic
  • Microplastics detected in placenta, blood, breastmilk, lungs.
  • Potential endocrine disruption via phthalates and BPA.
  • Single-Use Plastic (SUP) ban in India — 1 July 2022.
  • Extended Producer Responsibility (EPR) — Plastic Waste Management Rules 2022.

41.9 India’s Triple Burden of Disease

TipIndia’s Disease Burden
  • Infectious diseases — TB, diarrhoea, vector-borne (dengue, malaria, JE, chikungunya, kala-azar).
  • Non-communicable diseases (NCDs) — IHD, stroke, COPD, diabetes, cancers (now 60%+ of deaths).
  • Injuries / road accidents.

Environmental pollution drives a large share across all three.

41.10 Climate Change and Health

TipClimate-Health Linkages
  • Heatwaves — dehydration, heatstroke; vulnerable groups at high risk.
  • Vector range expansion — dengue, malaria moving to new altitudes/regions.
  • Water-borne disease surges after floods.
  • Food insecurity → undernutrition.
  • Air-quality interactions — ozone, smoke from wildfires.
  • Mental health — climate anxiety, displacement.
  • Lancet Countdown annual report tracks climate-health indicators.

41.11 Indian Public-Health Responses

TipIndian Public-Health Responses
  • Ayushman Bharat — PMJAY (2018) — world’s largest health insurance scheme.
  • NHM (National Health Mission, 2013).
  • ABHA / ABDM (2021) — digital health.
  • eSanjeevani — telemedicine.
  • National Programme on Climate Change & Human Health (NPCCHH, 2019).
  • National Action Plan on Heatwave — NDMA.
  • NCAP 2019 — clean-air targets.
  • Jal Jeevan Mission — safe drinking water.
  • Swachh Bharat Mission — sanitation.
  • Ujjwala 2016 — indoor air via LPG.
  • POSHAN Abhiyaan (2018) — nutrition.
  • Tobacco control: Cigarettes and Other Tobacco Products Act (COTPA, 2003).
  • Universal Immunisation Programme (UIP, 1985) — Mission Indradhanush (2014).
  • MoHFW + ICMR + AIIMS / NCDC — central institutions.

41.12 Theory Anchors

TipKey Bodies and Frameworks
Body / Concept Note
WHO UN health agency, Geneva, 1948
IARC International Agency for Research on Cancer (carcinogen classification)
WHO Air Quality Guidelines Latest 2021 revision
Global Burden of Disease (GBD) IHME, Seattle
Lancet Countdown on Climate Change and Health Annual report
MoHFW / ICMR / NCDC / AIIMS Indian health institutions
Bhopal Gas Disaster Research Centre ICMR-BMHRC
NCAP, AQLI Air quality and policy
Minamata Convention 2013 Mercury
Stockholm Convention 2001 POPs (DDT, dioxins, PCBs)
PMJAY 2018 Ayushman Bharat health insurance
NPCCHH 2019 National Programme on Climate Change and Human Health

41.13 Practice Questions

Q 01 Mercury Easy

Minamata disease is caused by chronic poisoning by:

  • AMercury
  • BCadmium
  • CArsenic
  • DLead
View solution
Correct Option: A
Mercury (methylmercury) from Chisso Corp. Japan, 1956.
Q 02 Cadmium Medium

Itai-itai ("it hurts") disease in Japan was caused by:

  • AMercury
  • BCadmium
  • CLead
  • DArsenic
View solution
Correct Option: B
Cadmium from mining contamination of rice paddies. Affects bone (osteomalacia) and kidney.
Q 03 Arsenic Medium

In Bengal and Bangladesh, large populations have been exposed to arsenic through:

  • AAir pollution
  • BGroundwater (tube wells)
  • CPesticide spray
  • DIndustrial smoke
View solution
Correct Option: B
Groundwater arsenic from natural geological sources, accessed through tube wells.
Q 04 Fluoride Medium

Chronic exposure to high fluoride in drinking water causes:

  • AItai-itai
  • BFluorosis
  • CMinamata disease
  • DBlue-baby syndrome
View solution
Correct Option: B
Fluorosis — dental (mottling) + skeletal (joint stiffness). Major issue in Andhra, Rajasthan, Gujarat.
Q 05 Nitrate Hard

"Blue-baby syndrome" (methaemoglobinaemia) in infants is caused by:

  • ALead in air
  • BNitrate in drinking water
  • CDDT in food
  • DCarbon monoxide
View solution
Correct Option: B
Nitrate (NO₃) from fertiliser runoff; converts haemoglobin to methaemoglobin, reducing O₂ delivery.
Q 06 CO Medium

Carbon monoxide (CO) poisoning works by:

  • ABlocking nitrogen pathways
  • BBinding to haemoglobin in place of O₂
  • CDestroying red blood cells
  • DBurning lung tissue
View solution
Correct Option: B
CO binds Hb 200× more strongly than O₂ → carboxyhaemoglobin → hypoxia.
Q 07 PM2.5 Medium

PM2.5 is more dangerous than PM10 because:

  • AIt is heavier
  • BIt can penetrate deep into alveoli and even bloodstream
  • CIt causes only outdoor injury
  • DIt is non-toxic
View solution
Correct Option: B
PM2.5 (≤ 2.5 µm) penetrates alveoli and enters bloodstream → IHD, stroke, lung cancer.
Q 08 WHO AQG Hard

WHO's 2021 air-quality guideline for annual PM2.5 is:

  • A5 µg/m³
  • B10 µg/m³
  • C25 µg/m³
  • D40 µg/m³
View solution
Correct Option: A
5 µg/m³ annual (tightened from 10 in WHO 2021 revision).
Q 09 Endosulfan Hard

The Endosulfan tragedy in India occurred in:

  • ABhopal, Madhya Pradesh
  • BKasaragod, Kerala
  • CTamil Nadu
  • DBihar
View solution
Correct Option: B
Kasaragod, Kerala — aerial spraying on cashew plantations. Endosulfan banned in India 2011.
Q 10 Asbestos Hard

Long-term exposure to asbestos primarily causes:

  • ADiabetes
  • BMesothelioma and asbestosis
  • CLiver cirrhosis
  • DHypothyroidism
View solution
Correct Option: B
Mesothelioma (cancer of pleura), asbestosis (lung scarring), lung cancer.
Q 11 Benzene Hard

Chronic benzene exposure (from fuel and cigarette smoke) is associated with:

  • ALung cancer only
  • BLeukemia
  • CItai-itai
  • DFluorosis
View solution
Correct Option: B
Leukemia — well-established association.
Q 12 Lead Medium

Lead exposure is particularly dangerous in children because it:

  • AReduces IQ and harms neurodevelopment
  • BIncreases bone density
  • CCures asthma
  • DStrengthens immunity
View solution
Correct Option: A
Lead is a neurotoxin; damages developing brain → IQ loss, ADHD-like symptoms.
Q 13 Bhopal Medium

The Bhopal Gas Tragedy (1984) was caused by the leak of:

  • AMethyl isocyanate (MIC)
  • BCarbon monoxide
  • CCFCs
  • DOzone
View solution
Correct Option: A
MIC, Union Carbide India Ltd. ~3,800+ deaths immediately; ongoing health impacts.
Q 14 Noise Medium

Sustained exposure to noise above which level can cause hearing loss?

  • A45 dB
  • B60 dB
  • C85 dB
  • D120 dB
View solution
Correct Option: C
Sustained exposure above 85 dB; immediate damage at > 120 dB.
Q 15 Radiation Hard

Among the following, which is an example of IONISING radiation?

  • AVisible light
  • BMicrowave
  • CGamma rays
  • DRadio waves
View solution
Correct Option: C
Gamma rays; also X-rays, alpha, beta particles. UV can ionise at high energies.
Q 16 Aflatoxin Hard

Aflatoxin, a fungal toxin found in poorly stored grain/peanuts, primarily causes:

  • ALung cancer
  • BLiver cancer
  • CBone disease
  • DSkin cancer
View solution
Correct Option: B
Aflatoxin B1 from Aspergillus flavus → hepatocellular carcinoma.
Q 17 PMJAY Medium

Ayushman Bharat PMJAY, launched 2018, provides:

  • AFree vaccination only
  • BHealth insurance to lower-income families (₹5 lakh per family/year)
  • CPension to elderly
  • DMaternity benefits
View solution
Correct Option: B
PMJAY — world's largest health-insurance scheme; ₹5 lakh/family/year for secondary and tertiary care.
Q 18 India Air Hard

India's air pollution causes approximately how many premature deaths annually (Lancet 2020 estimates)?

  • A~10,000
  • B~100,000
  • C~1.6 million
  • D~10 million
View solution
Correct Option: C
~1.6-1.7 million deaths/year (Lancet Planetary Health 2020).
Q 19 NPCCHH Hard

India's National Programme on Climate Change and Human Health (NPCCHH) was launched in:

  • A2008
  • B2014
  • C2019
  • D2023
View solution
Correct Option: C
NPCCHH 2019 — heatwave, vector-borne, water-borne diseases.
Q 20 Match Hard

Match each pollutant with its characteristic disease:

(i) Mercury (a) Black-foot disease
(ii) Cadmium (b) Fluorosis
(iii) Arsenic (c) Itai-itai
(iv) Fluoride (d) Minamata disease
  • A(i)-d, (ii)-c, (iii)-a, (iv)-b
  • B(i)-a, (ii)-b, (iii)-c, (iv)-d
  • C(i)-c, (ii)-d, (iii)-a, (iv)-b
  • D(i)-b, (ii)-d, (iii)-a, (iv)-c
View solution
Correct Option: A
Mercury → Minamata; Cadmium → Itai-itai; Arsenic → Black-foot; Fluoride → Fluorosis.

41.14 Quick Recall

ImportantQuick recall
  • Exposure routes: Inhalation · Ingestion · Dermal.
  • Vulnerable groups: children · pregnant women · elderly · outdoor workers · low-income/slum · pre-existing-disease patients · indigenous communities.
  • Air pollutants and effects: PM2.5 (alveoli, IHD, stroke, lung cancer) · PM10 · CO (binds Hb → hypoxia) · SO₂ · NO₂ · O₃ · VOCs · Benzene (leukemia) · Formaldehyde · Pb (neurotoxin, IQ loss) · Asbestos (mesothelioma) · Radon (lung cancer).
  • WHO Air Quality Guidelines 2021: PM2.5 annual 5 µg/m³ · PM10 annual 15 · NO₂ annual 10. India typically 10-20× WHO.
  • Air pollution deaths: ~7 M/yr globally; ~1.6-1.7 M/yr in India (Lancet 2020).
  • Water pollutants and diseases:
    • Mercury → Minamata (Japan 1956).
    • Cadmium → Itai-itai.
    • Arsenic → Black-foot, skin cancer (Bengal/Bangladesh groundwater).
    • Fluoride → Fluorosis (Andhra, Rajasthan, Gujarat).
    • Nitrate → Blue-baby syndrome (methaemoglobinaemia).
    • Lead → neuro damage.
    • Pathogens → Cholera, Typhoid, Hep A/E, Dysentery, Diarrhoea, Polio.
    • POPs (DDT, dioxins, PCBs) → endocrine disruption, cancer.
    • Aflatoxin → liver cancer.
  • Famous Indian cases: Bhopal MIC 1984 · Endosulfan Kasaragod Kerala (banned 2011) · Hexavalent chromium Ranipet TN · Arsenicosis West Bengal · Fluorosis belt.
  • Noise: > 85 dB sustained → hearing loss; > 120 dB immediate damage. Cardiovascular stress, sleep loss, cognitive impairment.
  • Radiation: ionising (X, gamma, alpha, beta, high-energy UV) damages DNA → cancer; Chernobyl 1986, Fukushima 2011.
  • Plastics: microplastics in placenta/blood/breastmilk; phthalates/BPA endocrine disruption; India SUP ban 1 July 2022.
  • India’s triple burden: Infectious + NCD + Injuries.
  • Climate health: heatwaves, vector range expansion (dengue/malaria), water-borne post-flood, food insecurity, mental health. Lancet Countdown.
  • Indian responses: PMJAY/Ayushman Bharat 2018 · NHM 2013 · ABDM 2021 · eSanjeevani · NPCCHH 2019 · NDMA heatwave plan · NCAP 2019 · Jal Jeevan 2019 · Swachh Bharat 2014 · Ujjwala 2016 · POSHAN 2018 · COTPA 2003 · UIP 1985 · Mission Indradhanush 2014.
  • Institutions: MoHFW · ICMR · NCDC · AIIMS · BMHRC Bhopal.
  • International conventions: Minamata 2013 (Hg) · Stockholm 2001 (POPs) · Rotterdam 1998 (chemical trade) · Basel 1989 (hazardous waste) · Montreal 1987 (CFCs).