From UPSC perspective, the following things are important :
Prelims level : DDT
Mains level : Paper 3-Pollution and harm to ecology
India has supplied 20.60 MT of DDT to South Africa for its Malaria control program.
Try this question from CSP 2014:
With reference to ‘Global Environment Facility’, which of the following statements is/are correct?
(a) It serves as financial mechanism for ‘Convention on Biological Diversity’ and ‘United Nations Framework Convention on Climate Change’
(b) It undertakes scientific research on environmental issues at global level
(c) It is an agency under OECD to facilitate the transfer of technology and funds to underdeveloped countries with specific aim to protect their environment.
(d) Both (a) and (b)
What is DDT?
- Dichloro-diphenyl-trichloroethane commonly known as DDT is a colorless, tasteless, and almost odorless crystalline chemical compound.
- It was developed as the first of the modern synthetic insecticides in the 1940s.
- It was initially used with great effect to combat malaria, typhus, and other insect-borne human diseases among both military and civilian populations.
Why is it controversial?
- DDT is a persistent organic pollutant that is readily adsorbed to soils and sediments, which can act both as sinks and as long-term sources of exposure affecting organisms.
- Routes of loss and degradation include runoff, volatilization, photolysis and aerobic and anaerobic biodegradation.
- Due to hydrophobic properties, in aquatic ecosystems DDT is absorbed by aquatic organisms and thus bio-accumulates in the food web.
Threats of DDT
- The bioaccumulation of DDT has caused eggshell thinning and population declines in multiple North American and European bird of prey species.
- DDT is an endocrine disruptor. It is considered likely to be a human carcinogen.
In use despite ban
- A worldwide ban on agricultural use of DDT was formalized under the Stockholm Convention on Persistent Organic Pollutants.
- But its limited and still-controversial use in disease vector control continues, because of its effectiveness in reducing malarial infections, balanced by environmental and other health concerns.
Back2Basics: Stockholm Convention on POPs
- Stockholm Convention is an international environmental treaty, signed in 2001 and effective from May 2004 that aims to eliminate or restrict the production and use of persistent organic pollutants (POPs).
- In 1995, the United Nations Environment Programme (UNEP) called for global action to be taken on POPs.
- POPs are defined by the UNEP as chemical substances that persist in the environment, bio-accumulate through the food web, and pose a risk of causing adverse effects to human health and the environment.
Bioaccumulation and Biomagnification
- Bioaccumulation and biomagnification are two different processes that often occur in tandem with one another.
- Bioaccumulation is the process by which toxins enter the food web by building up in individual organisms.
- Biomagnification is the process by which toxins are passed from one trophic level to the next (and thereby increase in concentration) within a food web.