Persistent Organic Pollutants

Persistent Organic Pollutants

This article deals with ‘Persistent Organic Pollutants – UPSC.’ This is part of our series on ‘Environment’ which is an important pillar of the GS-3 syllabus. For more articles on Science and technology, you can click here


  • Organic compounds that resist photolytic, biological & chemical degradation are known as Persistent Organic Pollutants or POPs. 
  • Due to persistence, pollutants are capable of long-range transport, bioaccumulation & biomagnification.
  • POPs include pesticides, industrial solvents, polyvinyl chloride & pharmaceuticals.
Persistent Organic Pollutants

Common Characteristics

1. Low water Solubility

  • They aren’t soluble in water.

2. High Lipid Solubility

  • They have high lipid solubility, which leads to bio-accumulation.

3. Semi-Volatile

  • They either occur in nature in the vapour phase or are adsorbed on atmospheric particles, facilitating long-range transport. 

4. Toxicity

  • POPs with higher molecular weights are toxic.

5. Chemical structure

  • Most of the POPs are halogenated & many have chlorine as a component.

Bioaccumulation and  Biomagnification

  • The process by which a pollutant enters the food chain and accumulates in the body of a living organism is known as Bioaccumulation.
  • The tendency of the pollutant to increase in concentration as it moves from lower to higher trophic levels in the food chain is known as Biomagnification.
  • Example
    1. The sewage containing POPs such as DDT is dumped into rivers and oceans, entering the food chain through phytoplankton and zooplankton. The concentration continues to increase in the successive trophic levels. 
    2. Commercial agriculture requires more application of insecticides and pesticides. Hence, pesticides and insecticides enter the food chain and continue to accumulate at successive trophic levels.

Properties of bioaccumulants and biomagnification

  • The bioaccumulants tend to move upwards in a food chain.
  • They are non-biodegradable, and therefore they have a longer life.
  • They are not soluble in water, and therefore they can’t be thrown away by the body through urine and excreta. 
  • Most of the bioaccumulants are fat-soluble, i.e. lipogenic, and hence they are transferred easily from mother’s milk to infants or transferred to the meat and fish-eating population. (example includes mercury poisoning or Minamata disease).

Some of the important bioaccumulants are

1. DDT

  • DDT is used as a pesticide and insecticide to control the mosquito population. 
  • DDT is the major bioaccumulant and has been banned under the Stockholm convention. But it is still used in tropical countries like India to control the spread of malaria, dengue etc. 
  • Its effects include nausea, headache, fatigue, neurological disorders, eggshell thinning (loss of fertility), congenital disabilities, and cancer.

2. Endosulfan

  • It is an insecticide that is used on cashew, rubber and tea plantation.
  • It is a cheap but dangerous bioaccumulant because it is associated with congenital disabilities including cryptorchidism, neurological disorders including autism, neurobehavioral disorders, lower testosterone and cancer. Therefore, Endosulphan was added to the Persistent Organic Pollutants (POPs) list.
  • Supreme Court banned the use of Endosulfan in India after PIL was registered against it due to peculiar health impacts seen after aerial spray in cashew plantations to combat tea mosquitoes in Kerala. Even after that, it is manufactured in India, and India is the biggest consumer of Endosulphan in the world.

3. VOCs

  • These are used in paints, varnishes, fuels, paper bleaching, cosmetics etc.

4. Mercury

  • Mercury is infamous for Minamata disease.

Conventions regarding hazardous wastes and pollutants

There are following conventions

  1. Stockholm Convention 
  2. Rotterdam Convention 
  3. Basel Convention
  4. Bamako Convention

1. Stockholm Convention on POPs

  • It is the convention on bioaccumulants, also known as Persistent Organic Pollutants (POPs).
  • It deals with banning the pollutants known as ‘DIRTY DOZENS’. 
  • The convention was signed in 2001 under the aegis of the United Nations. Consequently, India became a party to the convention in 2005. Presently, it has 179 members. 
  • The global Environmental Facility (GEF) is the designated interim financial mechanism for the Stockholm Convention.

Dirty Dozen or 12 listed POPs  

Dirty Dozen


Most of India’s commonly used insecticides and pesticides have to be mandatorily labelled under the Insecticide Act of 1968 and the rules of 1971. Four colours are used to indicate the toxicity level of insecticide or pesticide

Green Colour Slightly Toxic Eg: Mosquito repellent oils and liquids.
Blue Colour Moderately Toxic Eg: Glyphosate
Yellow Colour Highly Toxic Eg: Endosulphan
Red Label Extremely Toxic Eg: Zinc Phosphide

2. Basel Convention

  • Basel Convention is on the transboundary movement of hazardous waste and its disposal. It was signed to stop the dumping of hazardous chemicals from developed to developing nations. 
  • Most of the pollutants are covered under Basel Convention except radioactive waste.
  • Basel Convention is against the ‘TOXIC COLONIALISM’ (epitomised by KOKO CASE, where Italy used to transport 8,000 barrels of most toxic waste per month to Nigeria in return for the rent of $100 till 1988).
  • It was signed in 1989 and came into effect in 1992. 

3. Rotterdam Convention on International Trade in  Hazardous Substances

  • Rotterdam Convention is on the Prior Informed Consent Procedure for certain Hazardous Chemicals & Pesticides in International Trade.
  • It was signed in 1998 and became effective in 2004.
  • Under the convention, while trading in hazardous chemicals and pesticides, the country has to take prior consent before exporting it to another country. 
  • In the recent meeting of the Rotterdam Convention, Canada has objected to listing asbestos fibres as pollutants. 

4. Bamako Convention

  • It is a convention on controlling transboundary movement and managing hazardous waste, including radioactive waste within Africa (only).

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