A new method to manage ecological risks from DDT by binding it with biochar has been developed by the researchers of Sweden’s Chalmers University of Technology.

About the Research

• It is a three-year study conducted on a 23-hectare DDT-contaminated former tree nursery in southern Sweden by mixing Biochar into the contaminated soil.
• Finding:
  • Uptake of DDT by earthworms in the soil was found to have been halved. 
  • Biochar is found to bind DDT efficiently, so that it is not taken up by soil organisms.
• Significance:
  • Enable the cultivation of certain crops on degraded and unusable land due to the environmental risks.
  • Improved Soil Health: Biochar is an environmentally friendly product and binds contaminants and can improve soil health when added to soil improving the soil health.
  • Cost Effective Solution: Biochar is economical to produce, therefore is a cost effective solution for rehabilitating degraded soil.
  • Climate Change Mitigation: Mixing biochar is also useful for climate change mitigation since it can contribute to long-term storage of carbon in the soil.

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About Dichlorodiphenyltrichloroethane (DDT)

• DDT is a toxic, man-made, hazardous chemical which is also a persistent organic pollutant (POPs), first synthesized in 1874.
• Insecticidal Properties: DDT’s insecticidal properties were discovered in 1939 to control vector borne diseases and used to control insects in crops and livestock production, institutions, homes and gardens.
• Impacts: 
  • Bioaccumulation: DDT bioaccumulates in fatty tissues of humans and animals with high intake associated with developmental and reproductive abnormalities.
  • Carcinogenic: DDT is classified as ‘probably carcinogenic’ to humans and can suppress the immune system and disrupt sex hormones
  • Omnipresent: DDT being a POP and its widespread use is stable and persistent in the environment with its residues found everywhere such as the Artic, the Antarctic, open oceans, and high mountain areas.
  • Animal health: DDT causes eggshell thinning in birds and is also acutely toxic to fish and marine invertebrates.
  • Endocrine Disruptor: DDT is highly stable and can accumulate in adipose tissue, so it can be found in the tissues of all living organisms. 
  • Soil Health: DDT was widely used as a pesticide in agriculture and resulted in devastating effects on soil health making it infertile.
    • In 1962, Rachel Carson published “The Silent Spring” documenting the devastating effect of pesticides on the natural world, focusing on DDT.
• DDT in India: 
  • India banned the agricultural use of DDT by 1972.
  • Usage: The Ministry of Health and Family Welfare is the only consumer of DDT 
    • It is used to control vector borne diseases by spraying DDT over walls in malaria-infected houses and buildings in rural and urban areas.
  • Nodal Ministry:  Department of Chemicals, Petrochemical and Fertilizers (DCP) being the nodal committee overseeing the production and supply of DDT.
    • India is the sole producer of DDT globally since 2008.
  • Phase Out: In 2014, India got the first extension for 10 years to phase out DDT by 2024 under the Stockholm Convention. However, it missed the deadline
    • The Convention had outlawed the production and use of DDT and other toxic chemicals and limited it to mosquito control.
  • Exports: India exports the chemical to Botswana, South Africa, Zambia, Mozambique, Namibia and Zimbabwe.

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