ddt and embryological development

7/30/2019 DDT and Embryological Development

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Dichlorodiphenyltrichloroethane = DDT

Organochlorine insecticide

White, crystalline solid, tasteless and almostodourless

Figure 2: ChemicalStructure of DDT



Metabolised /catabolisedto DDE

Soil half-life ranges from 22

days to 30 years (reducedby counteracting withgreen algae extract)

Considered toxic andharmful to the environment

Rats: LD50 = 113mg/kg

Figure 3: DDT Can



First synthesized in 1874 - properties were notdiscovered until 1939

Second part of World War II, used to controlmalaria and typhus among civilians and troops

Swiss chemist Paul Hermann Müller wasawarded the Nobel Prize in Physiology or Medicine in 1948

"for his discovery of the high efficiency of DDT as acontact poison against several arthropods.” [3]

After the war, DDT was made available for useas an agricultural insecticide

Production and use skyrocketed in USA, CHINA

and INDIA [4]

Figure 4: Advertisement for DDT



Silent Spring, by American biologist Rachel Carson,was published in 1962

Book catalogued the environmental impacts of theindiscriminate spraying of DDT in the US

Caused:› cancer in humans› decrease in biodiversity in wildlife (birds)

Banned in US in 1972

DDT was subsequently banned for agricultural useworldwide under the Stockholm Convention, but itslimited use in disease vector control continues to thisday and remains controversial [6,7]

Figure 5: DDT exposure



INSECTS:› absorbed through sensory organs in exoskeleton or GIT

› it opens sodium ion channels in neurons (CNS and PNS)

› spontaneously stimulated neurons → spasms and causeseventual death (irregular vital organ stimulation; SNS and PNS)

Insects with certain mutations intheir sodium channel gene areresistant to DDT

DDT resistance is also conferred byup-regulation of genes expressingcytochrome P450 in some insectspecies [6]

Figure 6: Mosquito



ANIMALS:› DDT has lipophilic properties (accumulates in

adipose tissue)

› High potential to bio-accumulate through the foodchain

› Apex predators e.g. raptor birds concentrate more

DDT than other animals in the same environment

Birds – eggshell thinning

Amphibians – toxic in larval phase



HUMANS:

Half-life ranges from 6 – 10 yrs

1. Directly genotoxic [8]

Also indircetly induce apoptotic enzymes toproduce other genotoxic intermediates andDNA adducts

Figure 7: Soldier Sprayed with DDT



2. Endocrine disruptor [8]

DDT metabolite DDE acts as an anti-androgen(though in some rare cases have proved mild-

estrogen activity)

Disruption:

MEN – semen quality

WOMEN – menstruation (usually causesinfertility)

- gestational length- duration of lactation



3. Other:

Associated with neurological dysfunctions e.g.Parkinson’s Disease

Asthma Cancer: liver, pancreas (associated with Type II

Diabetes), testicles, ovaries and breasts

Figure 8: Breast Cancer



Studies done at the University of California suggests that in vitro

exposure of mice and zebra fish may cause [9]:

› abnormal neural development or complete neurotoxicity in embryodevelopment

Humans [9]:

› Low levels of DDT in umbilical serum are associated with decreasedattention (ADD) and decreased cognitive functions at infancy

› First trimester exposure to DDE may result in retarded psychomotor development

A Japanese study of congenital hypo- and hyperthyroidismconcluded that in utero DDT exposure may affect thyroidfunction resulting in hypo-/hyperthyroidism [10]:

› abnormal levels of T3 and T4 can increase the incidence and/or causation of cretinism



Research done by The Lancet has shown thatexposure to DDT (at amounts that would beneeded in malaria control) may cause [11]:› preterm birth

› low birth weight

› early weaning

› shorten lactation and weaning → malnutrition atinfancy

Study done of Chinese textile workers in 1964found that pregnant women (mostly in firsttrimester) exposed to DDT in factories, had a64% increase in miscarriages [12]



DDT is a toxic and environmentally harmfulchemical Lipophilic accumulative MOA causes

worsening effects at higher levels in the foodchain

Causes decremented effects in reproductivesystem of adults

→ resulting in: 1. abnormal reproductively (male and female),

2. Miscarriage,3. premature birth,4. decreased neurological functioning and/or 5. abnormal endocrine activity in infancy



1. Toxicological Profile: for DDT, DDE, and DDE. Agency for Toxic Substances and DiseaseRegistry, September 2002.

2. DDT and Its Derivatives. Geneva: World Health Organisation. 1989. p. 83. ISBN 92-4-154283-7.

3. NobelPrize.org: The Nobel Prize in Physiology of Medicine 1948 Accessed July 26, 2007.

4. Environmental Health Criteria 9: DDT and its derivatives, World Health Organization, 1979.

5. Lear, Linda (1997). Rachel Carson: Witness for Nature. New York: Henry Hoyten.

6. Larson, Kim (December 1, 2007). "Bad Blood". On Earth (Winter 2008). Retrieved 2008-06-05.

7. Moyers, Bill (2007-09-21), Rachel Carson and DDT, retrieved 2011-03-05

8. Stokstad E (June 2007). "Species conservation. Can the bald eagle still soar after it isdelisted?. Science 316 (5832): 1689 – 90. doi:10.1126/science.316.5832.1689.PMID 17588911.

9. Geisz HN, Dickhut RM, Cochran MA, Fraser WR, Ducklow HW (2005).

10. Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem". Environ.Sci. Technol. ASAP: 3958. doi:10.1021/es702919n. Retrieved 2008-05-07.

11. DAVID, DAVID (July 4, 2008) McIntosh residents file suit against Ciba. Archived from theoriginal on 2010-11-18. Retrieved 2008-07-07.

12. Environmental Cleanup Site Information Database for Arkema (former Pennwalt) facility,Oregon DEQ, April 2009.

13. Rosemary, Rosemary (2008-01-27). Tests shed light on how pCBSA got into St. Louis water



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ddt and embryological development

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