From Nobel Prize to Banned Chemical

Starting in the 1940's, the chlorinated hydrocarbon named DDT (dichloro-diphenyl-trichloroethane) was used in vast quantities all over the world for killing insects. It was cheaper and much more effective than other insecticides and kills nearly all insects. (Bryant, 2002)

Figure 1 Spraying of DDT

Source: (The DDT Story)

DDT was then brought to the notice of British and American medical entomologists at a time, during World War II, when supplies of pyrethrum were rapidly falling short of demand. (Nobel Media AB, 2014) Pyrethrum affects the central nervous systems of all types of flying and crawling insects, disrupting normal function, so that nervous impulses fail. (Pyrethrum the natural insecticide, 2010)

Figure 2 Phyrethrum

Source: (Peirce, 2008)

Then, DDT was widely used during the Second World War to protect the troops and civilians from the spread of malaria, typhus and other vector borne diseases. After the war, DDT was continued to be used on a variety of agricultural crops and for the control of disease vectors as well. (6. SUBSTANCE PROFILES FOR THE PERSISTENT ORGANIC POLLUTANTS) 

DDT saved millions of lives by killing the mosquitoes that spread malaria and saved millions from starvation by killing crop pests. (Bryant, 2002) Paul Hermann Müller won The Nobel Prize in Physiology or Medicine 1948 "for his discovery of the high efficiency of DDT as a contact poison against several arthropods.". (Nobel Media AB, Paul Müller - Facts, 2014)

The heavy use of this highly persistent chemical, however, led to widespread environmental contamination and the accumulation of DDT in humans and wildlife - a phenomenon brought to public attention by Rachel Carson in her 1962 book, Silent Spring. (Persistent Organic Pollutants: A Global Issue, A Global Response, 2014)

Figure 3 Silent Spring by Rachel Carson

Source: (HOW SILENT SPRING BECAME NOISY SUMMER**, 2014)

Silent Spring described how DDT entered the food chain and accumulated in the fatty tissues of animals, including human beings, and caused cancer and genetic damage. A single application on a crop, she wrote, killed insects for weeks and months, and not only the targeted insects but countless more and remained toxic in the environment even after it was diluted by rainwater. Carson concluded that DDT and other pesticides had irrevocably harmed birds and animals and had contaminated the entire world food supply. (The Story of Silent Spring, 2013)

Stockholm Convention on Persistent Organic Pollutants- a legally binding international agreement finalized in 2001. (Persistent Organic Pollutants: A Global Issue, A Global Response, 2014) Over 150 countries signed the Convention and it entered into force, on 17 May 2004. (The Stockholm Convention) The Convention aims to protect human health and the environment from the effects of persistent organic pollutants (POPs). The Convention has a range of control measures to reduce and, where feasible, eliminate the release of POPs, including emissions of unintentionally produced POPs such as dioxins. (Stockholm Convention on Persistent Organic Pollutants (POPs))

The Stockholm Convention established an initial list of 12 key POPs chemicals (the so-called dirty dozen) and DDT is one of them. (The Stockholm Convention) POPs are toxic chemicals that adversely affect human health and the environment around the world. They can be transported by wind and water, so they can affect people and wildlife far from where they are used and released. They persist for long periods of time in the environment and can accumulate and pass from one species to the next through the food chain. (Persistent Organic Pollutants: A Global Issue, A Global Response, 2014)

Properties of DDT:

• highly insoluble in water and is soluble in most organic solvents.
• semi-volatile and can be expected to partition into the atmosphere
• lipophilic and partitions readily into the fat of all living organisms

DDT has been demonstrated to bioconcentrate and biomagnify. Due to its potential to spread widely and persistency, DDT is ubiquitous in the environment and residues have even been detected in the arctic. (6. SUBSTANCE PROFILES FOR THE PERSISTENT ORGANIC POLLUTANTS)

Bioaccumulation and Biomagnification of DDT in living organism:

• DDT is not metabolized, and does not break down in the body.
• It is much more soluble in fat than in water. So it accumulates in body fat and is not excreted.
• The transfer of energy from lower trophic levels to higher ones is inefficient -so herbivores eat large quantities of plant material, and carnivores eat many times their body weight of prey during their lifetime. Since DDT is not excreted, the carnivore accumulates most of the DDT that was present in all of the prey organisms (Bryant, 2002)

Figure 4 Illustration on Bioaccumulation and Biomagnification

Source: (Hoop, 2013)

Large amounts of DDT were released into the air and on soil or water when it was sprayed on crops and forests to control insects. It may also enter the air when they evaporate from contaminated water and soil, then deposited on land or surface water again. This cycle of evaporation and deposition may be repeated many times and can be carried long distances in the atmosphere. (Public Health Statement for DDT, DDE, and DDD, 2011) Human still potentially expose to DDT by consuming contaminated fish and crops grown in the contaminated soil even though it was banned.  (DDT, 2011)

What are the harmful effects of DDT on human?

• Probable human carcinogen
• Damages the liver
• Temporarily damages the nervous system
• Reduces reproductive success
• Can cause liver cancer
• Damages reproductive system

The debate on DDT:

• As the discussion of harmful effect brought by DDT, it seems that it is a wise decision to ban DDT. However, there are some “bring back DDT” claims.
• “DDT is cheaper than other pesticides, more effective, and not harmful to human beings or animals.”
• “Even where mosquito populations have developed resistance to DDT, it is more effective (and less problematic) than alternative chemicals. This is because replacement pesticides have to be applied more frequently and are more toxic”
• “POPs Convention Is Genocide”
• “Rachel Carson played on people’s emotions, and to do so, she selected and falsified data from scientific studies, as entomologist Dr. J. Gordon Edwards has documented in his analysis of the original scientific studies that Carson cited.”
• “Mozambique stopped the use of DDT, because 80 percent of the country’s health budget came from donor funds, and donors refused to allow the use of DDT.”

(Hecht, 2002)

There are some people argued for the renewed use of DDT inside houses to fight the spread of malaria. They have pointed out; the standard environmental concerns -- such as eggshell-thinning in raptor birds -- have nothing to do with spraying indoors. Tiny amounts of DDT are used compared with the millions of pounds that were once sprayed on agricultural fields in the 1950s and 60s. The environmental consequences, as a result, would be negligible. (Avery & Avery, 2000)

Figure 5 Some people urged to bring back DDT

Source: (Hecht, 2002)

So, what is your stand? Should DDT be banned?

Lastly, here is an interesting and ironic statement about DDT:

“And its persistency, which is precisely what Müller was looking for, became one of the key problems.” As for Paul Müller, he died in 1965 – three years after the publication of Silent Spring. “He never complained that his compound which was a world saver was no longer in public favour.” (Landon, 2003)

Works Cited

6. SUBSTANCE PROFILES FOR THE PERSISTENT ORGANIC POLLUTANTS. (n.d.). Retrieved October 4, 2014, from United Nations Environment Programme (UNEP): http://www.chem.unep.ch/pops/indxhtms/asses6.html#DDT

Avery, A., & Avery, D. (2000, July 28). Bring Back DDT, and Save Lives. Retrieved October 4, 2014, from THE WALL STREET JOURNAL: http://online.wsj.com/articles/SB964734570707088800

Bryant, P. J. (2002). Chapter 14: HABITAT POLLUTION. Retrieved October 4, 2014, from School of Biological Sciences, University of California: http://darwin.bio.uci.edu/sustain/bio65/lec14/b65lec14.htm

Hecht, M. M. (2002). Bring Back DDT, and Science With It! Retrieved October 4, 2012, from 21st Century Science and Technology Magazine: http://www.21stcenturysciencetech.com/articles/summ02/DDT.html

Hoop, J. v. (2013, January 17). Bioamplification, Bioaccumulation and Bioconcentration. Retrieved October 4, 2014, from Mercury Science and Policy at MIT: http://mercurypolicy.scripts.mit.edu/blog/?p=499

HOW SILENT SPRING BECAME NOISY SUMMER**. (2014, February 7). Retrieved October 4, 2014, from Project One Percent: http://projectonepercent.org/silent-spring-became-noisy-summer/

Landon, V. (2003, May 6). DDT: From miracle chemical to banned pollutant. Retrieved October 4, 2014, from swissinfo: http://www.swissinfo.ch/flash/special/70_years_swissinfo/DVD-ROM/multimedia/malaria/html/swissinfo16b4.html?siteSect=671

Nobel Media AB. (2014). Paul Müller - Biographical. Retrieved October 4, 2014, from Nobel Prize.org: http://www.nobelprize.org/nobel_prizes/medicine/laureates/1948/muller-bio.html

Nobel Media AB. (2014). Paul Müller - Facts. Retrieved October 4, 2014, from Nobelprize.org: http://www.nobelprize.org/nobel_prizes/medicine/laureates/1948/muller-facts.html

Peirce, P. (2008, May 21). Pyrethrum-Based Insecticides from Chrysanthemums. Retrieved October 4, 2014, from Vegetable gardener: http://www.vegetablegardener.com/item/5456/pyrethrum-based-insecticides-from-chrysanthemums

Persistent Organic Pollutants: A Global Issue, A Global Response. (2014, June 12). Retrieved October 4, 2014, from United States Environmental Protection Agency: http://www2.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue-global-response

Public Health Statement for DDT, DDE, and DDD. (2011, March 3). Retrieved October 4, 2014, from Agency for Toxic Substances and Disease Registry: http://www.atsdr.cdc.gov/phs/phs.asp?id=79&tid=20

Pyrethrum the natural insecticide. (2010). Retrieved October 4, 2014, from Botanical Resources Australia Pty Ltd: http://www.botanicalra.com.au/pyrethrum_natural_insecticide.html

Stockholm Convention on Persistent Organic Pollutants (POPs). (n.d.). Retrieved October 4, 2014, from Department of the Environment, Australian Government: http://www.environment.gov.au/topics/environment-protection/chemicals-management/pops

The DDT Story. (n.d.). Retrieved October 4, 2014, from Pesticide Action Network North America: http://www.panna.org/issues/persistent-poisons/the-ddt-story

The Stockholm Convention. (n.d.). Retrieved October 4, 2014, from UNITED NATIONS INDUSTRIAL DEVELOPMENT ORGANIZATION: http://www.unido.org/en/what-we-do/environment/capacity-building-for-the-implementation-of-multilateral-environmental-agreements/the-stockholm-convention.html

The Story of Silent Spring. (2013, May 12). Retrieved October 4, 2014, from Natural Resources Defense Council: http://www.nrdc.org/health/pesticides/hcarson.asp

U.S. ENVIRONMENTAL PROTECTION AGENCY. (2011, April 18). DDT. Retrieved October 4, 2014, from Persistent Bioaccumulative and Toxic (PBT) Chemical Program: http://www.epa.gov/pbt/pubs/ddt.htm