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The Effects of Dioxin. Cassie Kuroda Biology 2B May 04, 2005. The Molecular Structure. Chlorinated organic chemicals with similar structures. The chlorine atoms can be attached in 8 different places on the molecule.

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the effects of dioxin

The Effects of Dioxin

Cassie Kuroda

Biology 2B

May 04, 2005

the molecular structure
The Molecular Structure
  • Chlorinated organic chemicals with similar structures.
  • The chlorine atoms can be attached in 8 different places on the molecule.
  • The harmful effects of dioxin vary according to where the Cl atoms are located.
chemical properties
Chemical Properties
  • Dioxin is almost insoluble in water.
  • Instead, it has a high affinity for lipids.
  • Dioxin tends to stick to organic matter, such as ash, leaves, and soil.
  • Since dioxin binds strongly to soil, it does not easily contaminate the water supply.
  • When dioxin is in water, it sticks to organic matter or even plankton.
where does it come from
Where Does It Come From?
  • Non-human causes are forest fires and volcanic activity, but these produce a minimal amount.
  • There is no industrial use for dioxin. It is an unintentional byproduct caused by incomplete combustion: waste incineration, burning wood, coal, or oil, chlorine bleaching of paper, and cigarette smoke are a few examples.
how does it enter animals
How Does It Enter Animals?
  • Remember that dioxin sticks to plants.
  • Herbivores obtain dioxin by eating plants.
  • Dioxin also sticks to fats, so it will remain in the animal’s fat supply.
  • Larger animals eat the smaller animals with dioxin in their fat supply.
spreading of dioxin
Spreading of Dioxin
  • Biomagnification: The concentration of dioxin increases as you go up the food chain.
  • Bioaccumulation: Dioxin accumulates in the animal’s body and milk supply.
  • Dioxin can then be spread to an animal’s offspring through their milk or even the placenta.
human exposure
Human Exposure
  • Over 90% of human exposure comes from our food supply, mainly from the animals we eat.
  • Our daily intake is about 1-3 pg/kg body weight. The average is 2.2 pg/kg body weight.
  • The WHO (World Health Organization) states that 1-4 pg/kg body weight per day is tolerable.
  • The amount of dioxin in the human body increases during childhood, but reaches equilibrium around age 20.
how does it affect humans
How Does It Affect Humans?
  • Dioxin interacts with AhR (Aryl hydrocarbon receptors), which results in the formation of proteins in the nucleus that interfere with cellular growth and differentiation.
  • Since dioxin dissolves in fat, it must be transformed in the liver to become water soluble so it can be excreted. This is a slow process, so dioxin accumulates in our fat and liver.
what about animal testing
What About Animal Testing?
  • Dioxin itself does not seem to cause cancer. Instead, it promotes the growth of already existing cancers.
  • In rats: Uterine disease, neurobehavioral effects, lower sperm count, female urogenital malformations, effects on the immune system.
  • At the lowest doses in rats: liver tumors and thyroid tumors in males.
studies on humans
Studies on Humans
  • Herbicide plant workers heavily exposed to dioxin have more cancers of all types than the general population.
  • Agent Orange and the US Air Force during Vietnam.
  • There seems to be a 40% increase in cancer risk when heavily exposed to dioxin.
studies in japan and taiwan
Studies in Japan and Taiwan
  • There was a 22 year study done in Japan involving the high dioxin contamination of rice-oil. There was an increase in liver cancer.
  • A 12 year study in Taiwan involving a similar situation, but slightly lower levels of dioxin showed no significant cancer increases.
effects on children
Effects on Children
  • Neurobehavioral effects.
  • They are more easily exposed through the placenta instead of through breast feeding.
  • The newborns in Japan and Taiwan after the rice oil incidents had skin defects, low birth weight, behavioral disorders, reduced height at puberty, and hearing loss.
effects on adults
Effects on Adults
  • Increase in diabetes
  • Cardiovascular diseases in men
  • Higher rate of heart disease in men
  • Liver diseases
  • Chloracne and hyperpigmentation
seveso italy
Seveso, Italy
  • In the summer of 1976, the extreme heat and pressure caused an explosion at a chemical factory.
  • The level of dioxin ranged as high as 56,000 pg/g lipid, but the average was 450 pg/g lipid in Zone A (the most heavily contaminated area) and 126 pg/g lipid in Zone B (just outside of Zone A).
effects in seveso italy
Effects in Seveso, Italy
  • Chloracne in children who were exposed to the toxic clouds.
  • Spontaneous abortions, congenital malformations, impaired liver and lipid formation, immunologic and neurologic impairment.
  • Heavily exposed males fathered fewer boys and more girls.
controversy about seveso
Controversy About Seveso
  • Many believe that dioxin only caused chloracne while the other effects are due to something else.
  • Others believe that dioxin is the cause for all the effects in Seveso.
  • Some are remaining practical and are waiting for more long-term research to be completed in Seveso.
why is the seveso incident so important
Why is the Seveso Incident So Important?
  • It is the only incident involving pure TCDD (the most toxic form of dioxin).
  • Those who were exposed were of all ages and both genders.
  • This allows for more vast research to be done.
the follow up on seveso
The Follow Up on Seveso
  • An increase, but no deaths from liver cancer.
  • An increase in digestive cancers, rectal cancer, and lung cancer.
  • A few deaths from melanoma.
  • Increase in Hodgkin’s disease.
  • However, some believe these increases are not significant enough to draw conclusions about dioxin.
what does the epa have to say about it
What Does the EPA Have To Say About It?
  • The EPA states that the risk of an American getting cancer from exposure to dioxin is1 in 10,000.
  • 1 cancer per million is considered the “acceptable risk value.”
  • Our cancer risk is 100-300 times higher than the “acceptable risk value.”
  • “ [Dioxins] do not pose a significant risk to human health or the environment.” - EPA
what s being done about it
What’s Being Done About It?
  • The amount of dioxin exposure decreased during the 1990’s because of environmental regulations.
  • TCDD only accounts for 10-20% of total dioxin exposure.
  • The World Health Organization (WHO) ultimately wants to decrease human intake levels to below 1 pg/kg body weight per day.
works cited
Works Cited