Toxic Heavy Metals ( UPSC Prelims)

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News Context

A research conducted by the Bose Institute in Kolkata, under the Department of Science & Technology, debunked the belief of "clean" mountain rain by discovering toxic heavy metal pollution in the Himalayas, with a more significant presence in the Eastern Himalayas.

About Heavy Metals (HM) and HM Pollution

Characteristics: These elements have a high atomic weight ranging from 63.5 to 200.6 and a density greater than 4000 kg/m³. Examples include zinc, copper, cadmium, cobalt, arsenic, lead, and chromium. They consist of over 50 elements on the periodic table, with about 17 being extremely lethal. Heavy metals/metalloids are nondegradable and accumulate in soils over decades.
 Occurrence: They are naturally found in the Earth's crust.
 Sources of Pollution: These include bedrocks (soil parent materials) and atmospheric transportation following volcanic emissions and wind erosion. Other sources are metal-based industrial activities such as smelting, mining, and foundries, as well as the leaching of metals. Agricultural sources include irrigation and phosphorus fertilizers, while household sources include paints and batteries.
 Impact:
  ● Cadmium: Known as a potential human carcinogen, it can cause kidney and bone damage and lung cancer.  
  ● Lead: Causes developmental and neurobehavioral effects on fetuses.  
  ● Arsenic: Highly toxic in its inorganic form; long-term exposure can affect cognitive development, cause cancer, skin lesions, cardiovascular disease, and diabetes.