Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following? 1. Brakes of motor vehicles 2. Engines of motor vehicles 3. Microwave stoves within homes 4. Power plants 5. Telephone lines Select the correct answer using the code given below.
A1, 2, 3 and 5 only
B1, 2 and 4 only
C3, 4 and 5 only
D1, 2, 3, 4 and 5
Answer & Solution
Correct answer: B. 1, 2 and 4 only
Answer: B. Brake-wear (1), engine combustion (2), and power plants (4) generate magnetite particles.
MAGNETITE (Fe3O4) is an iron oxide mineral and at NANOPARTICLE SIZES (less than 200 nm) it has been linked to neurodegenerative diseases — recent studies (Lancaster University 2016) found magnetite nanoparticles in human brain tissue and correlated their abundance with Alzheimer-type pathology.
Sources of environmental magnetite nanoparticles:
(1) BRAKES OF MOTOR VEHICLES: CORRECT. Friction between brake pads and discs releases iron-rich PARTICULATE BRAKE DUST. At combustion temperatures generated by braking, some of this iron oxidises to MAGNETITE NANOPARTICLES that enter ambient air.
(2) ENGINES OF MOTOR VEHICLES: CORRECT. INTERNAL COMBUSTION ENGINES generate magnetite via oxidation of iron components and engine wear. Diesel exhaust in particular contains characteristic iron oxide nanoparticles. The 2016 Lancaster study attributed urban brain magnetite primarily to vehicular sources.
(3) MICROWAVE STOVES: WRONG. Domestic microwave ovens generate no significant magnetite particles. They use electromagnetic waves to heat water in food; they are an electrical appliance with shielded radiation. No combustion or metal-wear emission to ambient air.
(4) POWER PLANTS: CORRECT. COAL-FIRED POWER PLANTS release iron-rich fly ash that contains magnetite nanoparticles. Industrial combustion of fossil fuels is a major source of fine particulate iron oxides.
(5) TELEPHONE LINES: WRONG. Telephone landlines do not generate magnetite. They are signal transmission infrastructure with no combustion or significant abrasive wear.
Source: Maher et al. (PNAS 2016) 'Magnetite pollution nanoparticles in the human brain' / CPCB urban air quality reports.
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